From c8381c3cfffc8354fa10160bdc03761d0edd89c2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=99=8E=E9=B8=A3?= <hepin.p@alibaba-inc.com>
Date: Sun, 21 Jun 2026 02:39:31 +0800
Subject: [PATCH 01/16] Optimize gRPC request processing: fast negotiation path
 and URI string matching

Motivation:
Per-request overhead in the hot path limits high-concurrency throughput.
Protocol negotiation and URI path matching allocate objects and scan
headers on every request, even when the values are predictable.

Modification:
- GrpcProtocol.negotiate(): Add a fast path for native gRPC that does a
  single header scan instead of calling Codecs.detect() and
  Codecs.negotiate() separately (which each scan all headers). Pre-compute
  common reader/writer combinations (Identity/Identity, Identity/Gzip) as
  static vals to avoid repeated object creation.
- Handler.scala.txt template: Replace Uri.Path pattern matching with
  direct string operations on request.uri.path.toString, avoiding
  allocation of Path/Slash/Segment objects per request.

Result:
Reduced per-request allocations and header scanning overhead in the
gRPC request processing hot path.

Tests:
- runtime / compile - passed
- Validated with local benchmark (ghz, complex_proto scenario)

References:
None - performance optimization
---
 .../templates/ScalaServer/Handler.scala.txt   | 15 ++---
 .../org/apache/pekko/grpc/GrpcProtocol.scala  | 63 +++++++++++++++++--
 2 files changed, 67 insertions(+), 11 deletions(-)

diff --git a/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt b/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt
index e8c6af53e..8a0981c66 100644
--- a/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt
+++ b/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt
@@ -107,13 +107,14 @@ object @{serviceName}Handler {
           pekko.grpc.scaladsl.ServerReflection.partial(List(@{service.name})))
 }
 
-    private def methodName(request: model.HttpRequest, prefix: String): String =
-      request.uri.path match {
-        case model.Uri.Path.Slash(model.Uri.Path.Segment(`prefix`, model.Uri.Path.Slash(model.Uri.Path.Segment(method, model.Uri.Path.Empty)))) =>
-          method
-        case _ =>
-          null
-      }
+    private def methodName(request: model.HttpRequest, prefix: String): String = {
+      val path = request.uri.path.toString
+      val prefixStart = 1
+      val methodStart = prefix.length + 2
+      if (path.length > methodStart && path.charAt(0) == '/' && path.startsWith(prefix, prefixStart) && path.charAt(methodStart - 1) == '/') {
+        path.substring(methodStart)
+      } else null
+    }
 
     private def handler(implementation: @serviceName, prefix: String, eHandler: ActorSystem => PartialFunction[Throwable, Trailers])(implicit system: ClassicActorSystemProvider): model.HttpRequest => scala.concurrent.Future[model.HttpResponse] = {
       implicit val mat: Materializer = SystemMaterializer(system).materializer
diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala b/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala
index 1d8e2f042..6cc331314 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala
@@ -18,7 +18,7 @@ import pekko.NotUsed
 import pekko.annotation.InternalApi
 import pekko.annotation.InternalStableApi
 import pekko.grpc.GrpcProtocol.{ GrpcProtocolReader, GrpcProtocolWriter }
-import pekko.grpc.internal.{ Codec, Codecs, GrpcProtocolNative, GrpcProtocolWeb, GrpcProtocolWebText }
+import pekko.grpc.internal.{ Codec, Codecs, Gzip, GrpcProtocolNative, GrpcProtocolWeb, GrpcProtocolWebText, Identity }
 import pekko.http.javadsl.{ model => jmodel }
 import pekko.http.scaladsl.model.{ ContentType, HttpHeader, HttpResponse, Trailer }
 import pekko.http.scaladsl.model.HttpEntity.ChunkStreamPart
@@ -141,15 +141,70 @@ object GrpcProtocol {
     case _                                       => None
   }
 
+  // Pre-computed negotiation results for common codec combinations
+  private val NativeIdentityIdentity: (Try[GrpcProtocolReader], GrpcProtocolWriter) =
+    (scala.util.Success(GrpcProtocolNative.newReader(Identity)), GrpcProtocolNative.newWriter(Identity))
+  private val NativeIdentityGzip: (Try[GrpcProtocolReader], GrpcProtocolWriter) =
+    (scala.util.Success(GrpcProtocolNative.newReader(Identity)), GrpcProtocolNative.newWriter(Gzip))
+
   /**
    * Calculates the gRPC protocol encoding to use for an interaction with a gRPC client.
+   * Optimized with a fast path for native gRPC that does a single header scan.
    *
    * @param request the client request to respond to.
    * @return the protocol reader for the request, and a protocol writer for the response.
    */
-  def negotiate(request: jmodel.HttpRequest): Option[(Try[GrpcProtocolReader], GrpcProtocolWriter)] =
-    detect(request).map { variant =>
-      (Codecs.detect(request).map(variant.newReader), variant.newWriter(Codecs.negotiate(request)))
+  def negotiate(request: jmodel.HttpRequest): Option[(Try[GrpcProtocolReader], GrpcProtocolWriter)] = {
+    val mediaType = request.entity.getContentType.mediaType
+    val subType = mediaType.subType
+    val isNative = (subType eq "grpc+proto") || (subType eq "grpc")
+
+    if (isNative) {
+      // Single-pass header scan for native gRPC
+      var requestEncoding: String = null
+      var acceptEncoding: String = null
+      request match {
+        case sReq: pekko.http.scaladsl.model.HttpMessage =>
+          val headers = sReq.headers
+          var i = 0
+          while (i < headers.size) {
+            val h = headers(i)
+            val name = h.lowercaseName
+            if (name == "grpc-encoding") requestEncoding = h.value
+            else if (name == "grpc-accept-encoding") acceptEncoding = h.value
+            i += 1
+          }
+        case _ =>
+      }
+      // Determine reader codec (request encoding)
+      val readerCodec: Codec =
+        if (requestEncoding eq null) Identity
+        else if (requestEncoding == "identity") Identity
+        else if (requestEncoding == "gzip") Gzip
+        else return slowNegotiateOpt(request, subType)
+      // Determine writer codec (response encoding - pick first supported from accept list)
+      val writerCodec: Codec =
+        if (acceptEncoding eq null) Identity
+        else if (acceptEncoding.contains("gzip")) Gzip
+        else Identity
+      // Return pre-computed result for common combinations
+      if ((readerCodec eq Identity) && (writerCodec eq Identity)) return Some(NativeIdentityIdentity)
+      if ((readerCodec eq Identity) && (writerCodec eq Gzip)) return Some(NativeIdentityGzip)
+      return Some((scala.util.Success(GrpcProtocolNative.newReader(readerCodec)), GrpcProtocolNative.newWriter(writerCodec)))
+    }
+
+    // Non-native protocols - slow path
+    slowNegotiateOpt(request, subType)
+  }
+
+  private def slowNegotiateOpt(request: jmodel.HttpRequest, subType: String): Option[(Try[GrpcProtocolReader], GrpcProtocolWriter)] = {
+    val variant = subType match {
+      case "grpc-web" | "grpc-web+proto"           => Some(GrpcProtocolWeb)
+      case "grpc-web-text" | "grpc-web-text+proto" => Some(GrpcProtocolWebText)
+      case "grpc" | "grpc+proto"                   => Some(GrpcProtocolNative)
+      case _                                       => None
     }
+    variant.map(v => (Codecs.detect(request).map(v.newReader), v.newWriter(Codecs.negotiate(request))))
+  }
 
 }

From 8d92d6b38a3512bf276c9ae1e033d4cfd009afa8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=99=8E=E9=B8=A3?= <hepin.p@alibaba-inc.com>
Date: Sun, 21 Jun 2026 03:14:23 +0800
Subject: [PATCH 02/16] Prefer Identity codec over Gzip for response encoding

Motivation:
Flamegraph analysis showed ~14% of CPU time spent in Deflater.deflate
(gzip compression) for response encoding. For typical small protobuf
messages in gRPC benchmarks, gzip compression adds CPU overhead without
meaningful size reduction. The default codec preference order (Gzip
before Identity) caused the server to compress every response when the
client advertised gzip support, even for tiny messages.

Modification:
- Codecs.supportedCodecs: Change order to Seq(Identity, Gzip) so the
  negotiate() function prefers Identity when both codecs are supported
- GrpcProtocol.negotiate() fast path: Match the new preference order,
  choosing Identity when present in the accept-encoding list

This matches the behavior of Vert.x gRPC server which does not compress
responses by default.

Result:
- Eliminates ~14% CPU overhead from Deflater.deflate
- Improves 99% tail latency (33.75ms -> 32.33ms in local benchmark)
- Low concurrency: 55,357 -> 56,177 req/s (+1.5%)
- Aligns with Vert.x default behavior for fair comparison

Tests:
- runtime / compile - passed
- Validated with local benchmark (ghz, complex_proto scenario)

References:
None - performance optimization
---
 .../src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala | 6 +++---
 .../main/scala/org/apache/pekko/grpc/internal/Codecs.scala  | 6 ++++--
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala b/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala
index 6cc331314..35e3e25ff 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala
@@ -182,11 +182,11 @@ object GrpcProtocol {
         else if (requestEncoding == "identity") Identity
         else if (requestEncoding == "gzip") Gzip
         else return slowNegotiateOpt(request, subType)
-      // Determine writer codec (response encoding - pick first supported from accept list)
+      // Determine writer codec (response encoding - prefer Identity for small messages)
       val writerCodec: Codec =
         if (acceptEncoding eq null) Identity
-        else if (acceptEncoding.contains("gzip")) Gzip
-        else Identity
+        else if (acceptEncoding.contains("identity") || !acceptEncoding.contains("gzip")) Identity
+        else Gzip
       // Return pre-computed result for common combinations
       if ((readerCodec eq Identity) && (writerCodec eq Identity)) return Some(NativeIdentityIdentity)
       if ((readerCodec eq Identity) && (writerCodec eq Gzip)) return Some(NativeIdentityGzip)
diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/internal/Codecs.scala b/runtime/src/main/scala/org/apache/pekko/grpc/internal/Codecs.scala
index 6dfbd3577..d2876f8b2 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/internal/Codecs.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/internal/Codecs.scala
@@ -23,8 +23,10 @@ import scala.collection.immutable
 import scala.util.{ Failure, Success, Try }
 
 object Codecs {
-  // TODO should this list be made user-extensible?
-  val supportedCodecs = immutable.Seq(Gzip, Identity)
+  // Identity preferred over Gzip: for typical small protobuf messages, compression
+  // adds CPU overhead without meaningful size reduction. Clients requiring compression
+  // can still negotiate it explicitly.
+  val supportedCodecs = immutable.Seq(Identity, Gzip)
   private val supportedByName: Map[String, Codec] = supportedCodecs.map(c => c.name -> c).toMap
 
   private def extractHeaders(request: jm.HttpMessage): Iterable[jm.HttpHeader] = {

From 49faba6515e89cd32f1b3daf2bcb5fa10a2eccf0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=99=8E=E9=B8=A3?= <hepin.p@alibaba-inc.com>
Date: Sun, 21 Jun 2026 04:47:10 +0800
Subject: [PATCH 03/16] Prefer Identity codec for gRPC response encoding to
 eliminate Gzip overhead
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Motivation:
Flamegraph analysis showed ~27% of handler CPU time spent in Gzip
compression (Deflater.init, Deflater.deflate, GZIPOutputStream).
For typical small gRPC messages (under 1KB), gzip compression adds
significant CPU overhead without meaningful size reduction. The ghz
benchmark client sends grpc-accept-encoding: gzip (without identity),
causing the server to compress every response.

Modification:
- GrpcProtocol.negotiate(): For native gRPC, always prefer Identity
  writer codec for responses. The per-frame compression flag (bit 0
  of the 5-byte gRPC frame header) tells the client whether each frame
  is compressed, so clients correctly handle uncompressed frames even
  when they advertised gzip support.
- This enables the serializeDataFrame fast path in responseForSingleElement,
  which creates pre-framed uncompressed data in a single byte array
  allocation, avoiding the Gzip compress → encodeDataToResponse chain.
- ScalapbProtobufSerializer.deserialize(): Use CodedInputStream with
  byte array directly (via asByteBuffer.hasArray) to avoid ByteBuffer
  wrapper allocation.

Result:
- High concurrency (1000 conn): 72,027 -> 78,585 req/s (+9.1%)
- Combined with all optimizations: 59,177 -> 78,585 req/s (+32.8%)
- Gap to Vert.x (81,100) reduced from 18% to 3.1%
- Low concurrency: 42,959 -> 54,101 req/s (+25.9%, now 43% faster than Vert.x)

Tests:
- runtime / compile - passed
- Validated with local benchmark (ghz, complex_proto scenario)

References:
None - performance optimization
---
 .../scala/org/apache/pekko/grpc/GrpcProtocol.scala    | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala b/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala
index 35e3e25ff..505cd4374 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala
@@ -182,11 +182,12 @@ object GrpcProtocol {
         else if (requestEncoding == "identity") Identity
         else if (requestEncoding == "gzip") Gzip
         else return slowNegotiateOpt(request, subType)
-      // Determine writer codec (response encoding - prefer Identity for small messages)
-      val writerCodec: Codec =
-        if (acceptEncoding eq null) Identity
-        else if (acceptEncoding.contains("identity") || !acceptEncoding.contains("gzip")) Identity
-        else Gzip
+      // Determine writer codec (response encoding)
+      // For native gRPC, always prefer Identity for responses. The per-frame compression
+      // flag tells the client whether each frame is compressed. For typical small gRPC
+      // messages, avoiding compression saves significant CPU overhead (~20-30% of handler time).
+      // Clients that need compression for large messages can still handle uncompressed frames.
+      val writerCodec: Codec = Identity
       // Return pre-computed result for common combinations
       if ((readerCodec eq Identity) && (writerCodec eq Identity)) return Some(NativeIdentityIdentity)
       if ((readerCodec eq Identity) && (writerCodec eq Gzip)) return Some(NativeIdentityGzip)

From 09de7e3f644abfedd157402b952a1f0671ad2862 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=99=8E=E9=B8=A3?= <hepin.p@alibaba-inc.com>
Date: Sun, 21 Jun 2026 11:50:48 +0800
Subject: [PATCH 04/16] Pre-create unary method lambdas to avoid per-request
 allocation

Motivation:
Flamegraph analysis showed handler lambda creation as a potential
allocation hotspot. For unary gRPC methods, the lambda
(e: Request) => implementation.method(e) was created inside the
handle function which is called per request.

Modification:
Move lambda creation outside the handle function by pre-creating
val handlers for each unary method. The lambdas are now created
once during service registration instead of per request.

Result:
Reduces per-request object allocation by eliminating lambda creation.
Benchmark shows similar performance (within margin of error) as JIT
already optimizes simple lambdas, but this is a good practice for
reducing GC pressure.

Tests:
- codegen / compile - passed
- runtime / compile - passed
- Benchmark verification with ghz (1000 concurrency, 50 connections)

References:
None - performance optimization
---
 .../templates/ScalaServer/Handler.scala.txt   |  20 +-
 .../ScalaServer/Handler.scala.txt.bak         | 212 ++++++++++++++++++
 2 files changed, 230 insertions(+), 2 deletions(-)
 create mode 100644 codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt.bak

diff --git a/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt b/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt
index 8a0981c66..3a23549a8 100644
--- a/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt
+++ b/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt
@@ -123,6 +123,14 @@ object @{serviceName}Handler {
 
       import @{service.name}.Serializers.@{service.scalaCompatConstants.WildcardImport}
 
+      // Pre-create lambdas for unary methods to avoid per-request allocation
+      @for(method <- service.methods) {
+      @if(method.methodType == org.apache.pekko.grpc.gen.Unary) {
+      val @{method.nameSafe}Handler: @method.parameterType => scala.concurrent.Future[@method.outputTypeUnboxed] = 
+        (e: @method.parameterType) => implementation.@{method.nameSafe}(e@{if(powerApis) { ", metadata" } else { "" }})
+      }
+      }
+
       def handle(request: model.HttpRequest, method: String): scala.concurrent.Future[model.HttpResponse] =
         GrpcMarshalling.negotiated(request, (reader, writer) =>
           method match {
@@ -130,7 +138,7 @@ object @{serviceName}Handler {
             case "@method.grpcName" =>
                 @{if(powerApis) { "val metadata = MetadataBuilder.fromHeaders(request.headers)" } else { "" }}
                 @if(method.methodType == org.apache.pekko.grpc.gen.Unary) {
-                GrpcMarshalling.handleUnary(request.entity, (e: @method.parameterType) => implementation.@{method.nameSafe}(e@{if(powerApis) { ", metadata" } else { "" }}), eHandler)(
+                GrpcMarshalling.handleUnary(request.entity, @{method.nameSafe}Handler, eHandler)(
                   @{service.scalaCompatConstants.ImplicitUsing}@method.deserializer.name, @method.serializer.name, mat, reader, writer, system, ec)
                 } else {
                 @{method.unmarshal}(request.entity)(@{service.scalaCompatConstants.ImplicitUsing}@method.deserializer.name, mat, reader)
@@ -166,6 +174,14 @@ object @{serviceName}Handler {
 
       import @{service.name}.Serializers.@{service.scalaCompatConstants.WildcardImport}
 
+      // Pre-create lambdas for unary methods to avoid per-request allocation
+      @for(method <- service.methods) {
+      @if(method.methodType == org.apache.pekko.grpc.gen.Unary) {
+      val @{method.nameSafe}Handler: @method.parameterType => scala.concurrent.Future[@method.outputTypeUnboxed] = 
+        (e: @method.parameterType) => implementation.@{method.nameSafe}(e@{if(powerApis) { ", metadata" } else { "" }})
+      }
+      }
+
       def handle(request: model.HttpRequest, method: String): scala.concurrent.Future[model.HttpResponse] =
         GrpcMarshalling.negotiated(request, (reader, writer) =>
           method match {
@@ -173,7 +189,7 @@ object @{serviceName}Handler {
             case "@method.grpcName" =>
                 @{if(powerApis) { "val metadata = MetadataBuilder.fromHeaders(request.headers)" } else { "" }}
                 @if(method.methodType == org.apache.pekko.grpc.gen.Unary) {
-                GrpcMarshalling.handleUnary(request.entity, (e: @method.parameterType) => implementation.@{method.nameSafe}(e@{if(powerApis) { ", metadata" } else { "" }}), eHandler)(
+                GrpcMarshalling.handleUnary(request.entity, @{method.nameSafe}Handler, eHandler)(
                   @{service.scalaCompatConstants.ImplicitUsing}@method.deserializer.name, @method.serializer.name, mat, reader, writer, system, ec)
                 } else {
                 @{method.unmarshal}(request.entity)(@{service.scalaCompatConstants.ImplicitUsing}@method.deserializer.name, mat, reader)
diff --git a/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt.bak b/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt.bak
new file mode 100644
index 000000000..bbe5f6801
--- /dev/null
+++ b/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt.bak
@@ -0,0 +1,212 @@
+@*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * license agreements; and to You under the Apache License, version 2.0:
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * This file is part of the Apache Pekko project, which was derived from Akka.
+ *@
+
+@*
+ * Copyright (C) 2018-2021 Lightbend Inc. <https://www.lightbend.com>
+ *@
+
+@(service: org.apache.pekko.grpc.gen.scaladsl.Service, powerApis: Boolean)
+
+@org.apache.pekko.grpc.gen.Constants.DoNotEditComment
+package @service.packageName
+
+import scala.concurrent.ExecutionContext
+
+import org.apache.pekko
+import pekko.grpc.scaladsl.{ GrpcExceptionHandler, GrpcMarshalling }
+import pekko.grpc.Trailers
+
+import pekko.actor.ActorSystem
+import pekko.actor.ClassicActorSystemProvider
+import pekko.annotation.ApiMayChange
+import pekko.http.scaladsl.model
+import pekko.stream.{Materializer, SystemMaterializer}
+
+import pekko.grpc.internal.TelemetryExtension
+
+import pekko.grpc.PekkoGrpcGenerated
+
+@{if (powerApis) "import pekko.grpc.scaladsl.MetadataBuilder" else ""}
+
+@defining(if (powerApis) service.name + "PowerApi" else service.name) { serviceName =>
+/*
+ * Generated by Pekko gRPC. DO NOT EDIT.
+ *
+ * The API of this class may still change in future Pekko gRPC versions, see for instance
+ * https://github.com/akka/akka-grpc/issues/994
+ */
+@@ApiMayChange
+@@PekkoGrpcGenerated
+object @{serviceName}Handler {
+    private val notFound = scala.concurrent.Future.successful(model.HttpResponse(model.StatusCodes.NotFound))
+    private val unsupportedMediaType = scala.concurrent.Future.successful(model.HttpResponse(model.StatusCodes.UnsupportedMediaType))
+
+    /**
+     * Creates a `HttpRequest` to `HttpResponse` handler that can be used in for example `Http().bindAndHandleAsync`
+     * for the generated partial function handler and ends with `StatusCodes.NotFound` if the request is not matching.
+     *
+     * Use `org.apache.pekko.grpc.scaladsl.ServiceHandler.concatOrNotFound` with `@{service.name}Handler.partial` when combining
+     * several services.
+     */
+    def apply(implementation: @serviceName)(implicit system: ClassicActorSystemProvider): model.HttpRequest => scala.concurrent.Future[model.HttpResponse] =
+      handler(implementation, @{service.name}.name, GrpcExceptionHandler.defaultMapper)
+
+    /**
+     * Creates a `HttpRequest` to `HttpResponse` handler that can be used in for example `Http().bindAndHandleAsync`
+     * for the generated partial function handler and ends with `StatusCodes.NotFound` if the request is not matching.
+     *
+     * Use `org.apache.pekko.grpc.scaladsl.ServiceHandler.concatOrNotFound` with `@{service.name}Handler.partial` when combining
+     * several services.
+     */
+    def apply(implementation: @serviceName, eHandler: ActorSystem => PartialFunction[Throwable, Trailers])(implicit system: ClassicActorSystemProvider): model.HttpRequest => scala.concurrent.Future[model.HttpResponse] =
+      handler(implementation, @{service.name}.name, eHandler)
+
+    /**
+     * Creates a `HttpRequest` to `HttpResponse` handler that can be used in for example `Http().bindAndHandleAsync`
+     * for the generated partial function handler and ends with `StatusCodes.NotFound` if the request is not matching.
+     *
+     * Use `org.apache.pekko.grpc.scaladsl.ServiceHandler.concatOrNotFound` with `@{service.name}Handler.partial` when combining
+     * several services.
+     *
+     * Registering a gRPC service under a custom prefix is not widely supported and strongly discouraged by the specification.
+     */
+    def apply(implementation: @serviceName, prefix: String)(implicit system: ClassicActorSystemProvider): model.HttpRequest => scala.concurrent.Future[model.HttpResponse] =
+      handler(implementation, prefix, GrpcExceptionHandler.defaultMapper)
+
+    /**
+     * Creates a `HttpRequest` to `HttpResponse` handler that can be used in for example `Http().bindAndHandleAsync`
+     * for the generated partial function handler and ends with `StatusCodes.NotFound` if the request is not matching.
+     *
+     * Use `org.apache.pekko.grpc.scaladsl.ServiceHandler.concatOrNotFound` with `@{service.name}Handler.partial` when combining
+     * several services.
+     *
+     * Registering a gRPC service under a custom prefix is not widely supported and strongly discouraged by the specification.
+     */
+    def apply(implementation: @serviceName, prefix: String, eHandler: ActorSystem => PartialFunction[Throwable, Trailers])(implicit system: ClassicActorSystemProvider): model.HttpRequest => scala.concurrent.Future[model.HttpResponse] =
+      handler(implementation, prefix, eHandler)
+
+@if(serviceName != "ServerReflection") {
+
+    /**
+     * Creates a `HttpRequest` to `HttpResponse` handler that can be used in for example `Http().bindAndHandleAsync`
+     * for the generated partial function handler. The generated handler falls back to a reflection handler for
+     * `@{service.name}` and ends with `StatusCodes.NotFound` if the request is not matching.
+     *
+     * Use `org.apache.pekko.grpc.scaladsl.ServiceHandler.concatOrNotFound` with `@{service.name}Handler.partial` when combining
+     * several services.
+     */
+    def withServerReflection(implementation: @serviceName)(implicit system: ClassicActorSystemProvider): model.HttpRequest => scala.concurrent.Future[model.HttpResponse] =
+        pekko.grpc.scaladsl.ServiceHandler.concatOrNotFound(
+          @{serviceName}Handler.partial(implementation),
+          pekko.grpc.scaladsl.ServerReflection.partial(List(@{service.name})))
+}
+
+    private def methodName(request: model.HttpRequest, prefix: String): String = {
+      val path = request.uri.path.toString
+      val prefixStart = 1
+      val methodStart = prefix.length + 2
+      if (path.length > methodStart && path.charAt(0) == '/' && path.startsWith(prefix, prefixStart) && path.charAt(methodStart - 1) == '/') {
+        path.substring(methodStart)
+      } else null
+    }
+
+    private def handler(implementation: @serviceName, prefix: String, eHandler: ActorSystem => PartialFunction[Throwable, Trailers])(implicit system: ClassicActorSystemProvider): model.HttpRequest => scala.concurrent.Future[model.HttpResponse] = {
+      implicit val mat: Materializer = SystemMaterializer(system).materializer
+      implicit val ec: ExecutionContext = mat.executionContext
+      val spi = TelemetryExtension(system).spi
+
+      import @{service.name}.Serializers.@{service.scalaCompatConstants.WildcardImport}
+
+      // Pre-create lambdas for unary methods to avoid per-request allocation
+      @for(method <- service.methods) {
+      @if(method.methodType == org.apache.pekko.grpc.gen.Unary) {
+      val @{method.nameSafe}Handler: @method.parameterType => scala.concurrent.Future[@method.outputType] = 
+        (e: @method.parameterType) => implementation.@{method.nameSafe}(e@{if(powerApis) { ", metadata" } else { "" }})
+      }
+      }
+
+      def handle(request: model.HttpRequest, method: String): scala.concurrent.Future[model.HttpResponse] =
+        GrpcMarshalling.negotiated(request, (reader, writer) =>
+          method match {
+            @for(method <- service.methods) {
+            case "@method.grpcName" =>
+                @{if(powerApis) { "val metadata = MetadataBuilder.fromHeaders(request.headers)" } else { "" }}
+                @if(method.methodType == org.apache.pekko.grpc.gen.Unary) {
+                GrpcMarshalling.handleUnary(request.entity, @{method.nameSafe}Handler, eHandler)(
+                  @{service.scalaCompatConstants.ImplicitUsing}@method.deserializer.name, @method.serializer.name, mat, reader, writer, system, ec)
+                } else {
+                @{method.unmarshal}(request.entity)(@{service.scalaCompatConstants.ImplicitUsing}@method.deserializer.name, mat, reader)
+                  .@{if(method.outputStreaming) { "map" } else { "flatMap" }}(implementation.@{method.nameSafe}(_@{if(powerApis) { ", metadata" } else { "" }}))
+                  .map(e => @{method.marshal}(e, eHandler)(@{service.scalaCompatConstants.ImplicitUsing}@method.serializer.name, writer, system))
+                  .recoverWith(GrpcExceptionHandler.from(eHandler(system.classicSystem))(system, writer))
+                }
+            }
+            case m => GrpcExceptionHandler.from(eHandler(system.classicSystem))(system, writer)(new NotImplementedError(s"Not implemented: $m"))
+          }
+      ).getOrElse(unsupportedMediaType)
+
+      request => {
+        val method = methodName(request, prefix)
+        if (method eq null) notFound
+        else handle(spi.onRequest(prefix, method, request), method)
+      }
+    }
+
+    /**
+     * Creates a partial `HttpRequest` to `HttpResponse` handler that can be combined with handlers of other
+     * services with `org.apache.pekko.grpc.scaladsl.ServiceHandler.concatOrNotFound` and then used in for example
+     * `Http().bindAndHandleAsync`.
+     *
+     * Use `@{service.name}Handler.apply` if the server is only handling one service.
+     *
+     * Registering a gRPC service under a custom prefix is not widely supported and strongly discouraged by the specification.
+     */
+    def partial(implementation: @serviceName, prefix: String = @{service.name}.name, eHandler: ActorSystem => PartialFunction[Throwable, Trailers] = GrpcExceptionHandler.defaultMapper)(implicit system: ClassicActorSystemProvider): PartialFunction[model.HttpRequest, scala.concurrent.Future[model.HttpResponse]] = {
+      implicit val mat: Materializer = SystemMaterializer(system).materializer
+      implicit val ec: ExecutionContext = mat.executionContext
+      val spi = TelemetryExtension(system).spi
+
+      import @{service.name}.Serializers.@{service.scalaCompatConstants.WildcardImport}
+
+      // Pre-create lambdas for unary methods to avoid per-request allocation
+      @for(method <- service.methods) {
+      @if(method.methodType == org.apache.pekko.grpc.gen.Unary) {
+      val @{method.nameSafe}Handler: @method.parameterType => scala.concurrent.Future[@method.outputType] = 
+        (e: @method.parameterType) => implementation.@{method.nameSafe}(e@{if(powerApis) { ", metadata" } else { "" }})
+      }
+      }
+
+      def handle(request: model.HttpRequest, method: String): scala.concurrent.Future[model.HttpResponse] =
+        GrpcMarshalling.negotiated(request, (reader, writer) =>
+          method match {
+            @for(method <- service.methods) {
+            case "@method.grpcName" =>
+                @{if(powerApis) { "val metadata = MetadataBuilder.fromHeaders(request.headers)" } else { "" }}
+                @if(method.methodType == org.apache.pekko.grpc.gen.Unary) {
+                GrpcMarshalling.handleUnary(request.entity, @{method.nameSafe}Handler, eHandler)(
+                  @{service.scalaCompatConstants.ImplicitUsing}@method.deserializer.name, @method.serializer.name, mat, reader, writer, system, ec)
+                } else {
+                @{method.unmarshal}(request.entity)(@{service.scalaCompatConstants.ImplicitUsing}@method.deserializer.name, mat, reader)
+                  .@{if(method.outputStreaming) { "map" } else { "flatMap" }}(implementation.@{method.nameSafe}(_@{if(powerApis) { ", metadata" } else { "" }}))
+                  .map(e => @{method.marshal}(e, eHandler)(@{service.scalaCompatConstants.ImplicitUsing}@method.serializer.name, writer, system))
+                  .recoverWith(GrpcExceptionHandler.from(eHandler(system.classicSystem))(system, writer))
+                }
+            }
+            case m => GrpcExceptionHandler.from(eHandler(system.classicSystem))(system, writer)(new NotImplementedError(s"Not implemented: $m"))
+          }
+      ).getOrElse(unsupportedMediaType)
+
+      Function.unlift((req: model.HttpRequest) => {
+        val method = methodName(req, prefix)
+        if (method eq null) None
+        else Some(handle(spi.onRequest(prefix, method, req), method))
+      })
+    }
+  }
+}

From 5a1855c0a1e8597d04e1cbb1236f89243dc27080 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=99=8E=E9=B8=A3?= <hepin.p@alibaba-inc.com>
Date: Sun, 21 Jun 2026 12:41:12 +0800
Subject: [PATCH 05/16] refactor: optimize native identity strict gRPC decoding

Motivation: The remaining gRPC benchmark gap is dominated by small per-request overheads. Native identity strict unary requests still used the generic ByteReader-based strict frame decoder, and the previous unary handler lambda optimization generated invalid Scala for keyword method names and Power API metadata.

Modification: Add a native identity strict frame decoder that parses the gRPC frame header directly while preserving malformed-frame error semantics. Remove unused fast-path response accept-encoding scanning and the dead NativeIdentityGzip tuple. Generate separate safe local handler names for unary Scala handlers, keep pre-created lambdas for non-Power APIs, and keep Power API lambdas request-scoped so metadata is in scope. Remove the accidentally committed Scala handler template backup.

Result: Strict native identity unary decoding avoids the generic ByteReader allocation path. Scala generated handlers compile for keyword method names such as Match, while Power API handlers continue to receive request metadata correctly.

Tests: scalafmt on changed Scala files; sbt plugin-tester-scala / Compile / compile; sbt runtime / Test / testOnly GrpcMarshallingSpec CodecsSpec; sbt benchmarks / Jmh / run quick GrpcMarshalling strict unmarshal benchmarks; git diff --check.

References: None - local performance optimization follow-up from OPTIMIZATION_HANDOFF.md
---
 .../pekko/grpc/gen/scaladsl/Method.scala      |   2 +
 .../templates/ScalaServer/Handler.scala.txt   |  12 +-
 .../ScalaServer/Handler.scala.txt.bak         | 212 ------------------
 .../org/apache/pekko/grpc/GrpcProtocol.scala  |  13 +-
 .../grpc/internal/GrpcProtocolNative.scala    |  18 +-
 .../grpc/javadsl/GrpcMarshallingSpec.scala    |  43 +++-
 6 files changed, 74 insertions(+), 226 deletions(-)
 delete mode 100644 codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt.bak

diff --git a/codegen/src/main/scala/org/apache/pekko/grpc/gen/scaladsl/Method.scala b/codegen/src/main/scala/org/apache/pekko/grpc/gen/scaladsl/Method.scala
index 96dda0809..182efeaf4 100644
--- a/codegen/src/main/scala/org/apache/pekko/grpc/gen/scaladsl/Method.scala
+++ b/codegen/src/main/scala/org/apache/pekko/grpc/gen/scaladsl/Method.scala
@@ -66,6 +66,8 @@ case class Method(
     else if (ReservedMethodNames.contains(name)) s"$name$ReservedMethodNameSuffix"
     else name
 
+  val handlerName: String = s"${name}Handler"
+
 }
 
 object Method {
diff --git a/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt b/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt
index 3a23549a8..7aca7616d 100644
--- a/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt
+++ b/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt
@@ -123,13 +123,15 @@ object @{serviceName}Handler {
 
       import @{service.name}.Serializers.@{service.scalaCompatConstants.WildcardImport}
 
+      @if(!powerApis) {
       // Pre-create lambdas for unary methods to avoid per-request allocation
       @for(method <- service.methods) {
       @if(method.methodType == org.apache.pekko.grpc.gen.Unary) {
-      val @{method.nameSafe}Handler: @method.parameterType => scala.concurrent.Future[@method.outputTypeUnboxed] = 
+      val @{method.handlerName}: @method.parameterType => scala.concurrent.Future[@method.outputTypeUnboxed] =
         (e: @method.parameterType) => implementation.@{method.nameSafe}(e@{if(powerApis) { ", metadata" } else { "" }})
       }
       }
+      }
 
       def handle(request: model.HttpRequest, method: String): scala.concurrent.Future[model.HttpResponse] =
         GrpcMarshalling.negotiated(request, (reader, writer) =>
@@ -138,7 +140,7 @@ object @{serviceName}Handler {
             case "@method.grpcName" =>
                 @{if(powerApis) { "val metadata = MetadataBuilder.fromHeaders(request.headers)" } else { "" }}
                 @if(method.methodType == org.apache.pekko.grpc.gen.Unary) {
-                GrpcMarshalling.handleUnary(request.entity, @{method.nameSafe}Handler, eHandler)(
+                GrpcMarshalling.handleUnary(request.entity, @{if(powerApis) { s"(e: ${method.parameterType}) => implementation.${method.nameSafe}(e, metadata)" } else method.handlerName}, eHandler)(
                   @{service.scalaCompatConstants.ImplicitUsing}@method.deserializer.name, @method.serializer.name, mat, reader, writer, system, ec)
                 } else {
                 @{method.unmarshal}(request.entity)(@{service.scalaCompatConstants.ImplicitUsing}@method.deserializer.name, mat, reader)
@@ -174,13 +176,15 @@ object @{serviceName}Handler {
 
       import @{service.name}.Serializers.@{service.scalaCompatConstants.WildcardImport}
 
+      @if(!powerApis) {
       // Pre-create lambdas for unary methods to avoid per-request allocation
       @for(method <- service.methods) {
       @if(method.methodType == org.apache.pekko.grpc.gen.Unary) {
-      val @{method.nameSafe}Handler: @method.parameterType => scala.concurrent.Future[@method.outputTypeUnboxed] = 
+      val @{method.handlerName}: @method.parameterType => scala.concurrent.Future[@method.outputTypeUnboxed] =
         (e: @method.parameterType) => implementation.@{method.nameSafe}(e@{if(powerApis) { ", metadata" } else { "" }})
       }
       }
+      }
 
       def handle(request: model.HttpRequest, method: String): scala.concurrent.Future[model.HttpResponse] =
         GrpcMarshalling.negotiated(request, (reader, writer) =>
@@ -189,7 +193,7 @@ object @{serviceName}Handler {
             case "@method.grpcName" =>
                 @{if(powerApis) { "val metadata = MetadataBuilder.fromHeaders(request.headers)" } else { "" }}
                 @if(method.methodType == org.apache.pekko.grpc.gen.Unary) {
-                GrpcMarshalling.handleUnary(request.entity, @{method.nameSafe}Handler, eHandler)(
+                GrpcMarshalling.handleUnary(request.entity, @{if(powerApis) { s"(e: ${method.parameterType}) => implementation.${method.nameSafe}(e, metadata)" } else method.handlerName}, eHandler)(
                   @{service.scalaCompatConstants.ImplicitUsing}@method.deserializer.name, @method.serializer.name, mat, reader, writer, system, ec)
                 } else {
                 @{method.unmarshal}(request.entity)(@{service.scalaCompatConstants.ImplicitUsing}@method.deserializer.name, mat, reader)
diff --git a/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt.bak b/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt.bak
deleted file mode 100644
index bbe5f6801..000000000
--- a/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt.bak
+++ /dev/null
@@ -1,212 +0,0 @@
-@*
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * license agreements; and to You under the Apache License, version 2.0:
- *
- *   https://www.apache.org/licenses/LICENSE-2.0
- *
- * This file is part of the Apache Pekko project, which was derived from Akka.
- *@
-
-@*
- * Copyright (C) 2018-2021 Lightbend Inc. <https://www.lightbend.com>
- *@
-
-@(service: org.apache.pekko.grpc.gen.scaladsl.Service, powerApis: Boolean)
-
-@org.apache.pekko.grpc.gen.Constants.DoNotEditComment
-package @service.packageName
-
-import scala.concurrent.ExecutionContext
-
-import org.apache.pekko
-import pekko.grpc.scaladsl.{ GrpcExceptionHandler, GrpcMarshalling }
-import pekko.grpc.Trailers
-
-import pekko.actor.ActorSystem
-import pekko.actor.ClassicActorSystemProvider
-import pekko.annotation.ApiMayChange
-import pekko.http.scaladsl.model
-import pekko.stream.{Materializer, SystemMaterializer}
-
-import pekko.grpc.internal.TelemetryExtension
-
-import pekko.grpc.PekkoGrpcGenerated
-
-@{if (powerApis) "import pekko.grpc.scaladsl.MetadataBuilder" else ""}
-
-@defining(if (powerApis) service.name + "PowerApi" else service.name) { serviceName =>
-/*
- * Generated by Pekko gRPC. DO NOT EDIT.
- *
- * The API of this class may still change in future Pekko gRPC versions, see for instance
- * https://github.com/akka/akka-grpc/issues/994
- */
-@@ApiMayChange
-@@PekkoGrpcGenerated
-object @{serviceName}Handler {
-    private val notFound = scala.concurrent.Future.successful(model.HttpResponse(model.StatusCodes.NotFound))
-    private val unsupportedMediaType = scala.concurrent.Future.successful(model.HttpResponse(model.StatusCodes.UnsupportedMediaType))
-
-    /**
-     * Creates a `HttpRequest` to `HttpResponse` handler that can be used in for example `Http().bindAndHandleAsync`
-     * for the generated partial function handler and ends with `StatusCodes.NotFound` if the request is not matching.
-     *
-     * Use `org.apache.pekko.grpc.scaladsl.ServiceHandler.concatOrNotFound` with `@{service.name}Handler.partial` when combining
-     * several services.
-     */
-    def apply(implementation: @serviceName)(implicit system: ClassicActorSystemProvider): model.HttpRequest => scala.concurrent.Future[model.HttpResponse] =
-      handler(implementation, @{service.name}.name, GrpcExceptionHandler.defaultMapper)
-
-    /**
-     * Creates a `HttpRequest` to `HttpResponse` handler that can be used in for example `Http().bindAndHandleAsync`
-     * for the generated partial function handler and ends with `StatusCodes.NotFound` if the request is not matching.
-     *
-     * Use `org.apache.pekko.grpc.scaladsl.ServiceHandler.concatOrNotFound` with `@{service.name}Handler.partial` when combining
-     * several services.
-     */
-    def apply(implementation: @serviceName, eHandler: ActorSystem => PartialFunction[Throwable, Trailers])(implicit system: ClassicActorSystemProvider): model.HttpRequest => scala.concurrent.Future[model.HttpResponse] =
-      handler(implementation, @{service.name}.name, eHandler)
-
-    /**
-     * Creates a `HttpRequest` to `HttpResponse` handler that can be used in for example `Http().bindAndHandleAsync`
-     * for the generated partial function handler and ends with `StatusCodes.NotFound` if the request is not matching.
-     *
-     * Use `org.apache.pekko.grpc.scaladsl.ServiceHandler.concatOrNotFound` with `@{service.name}Handler.partial` when combining
-     * several services.
-     *
-     * Registering a gRPC service under a custom prefix is not widely supported and strongly discouraged by the specification.
-     */
-    def apply(implementation: @serviceName, prefix: String)(implicit system: ClassicActorSystemProvider): model.HttpRequest => scala.concurrent.Future[model.HttpResponse] =
-      handler(implementation, prefix, GrpcExceptionHandler.defaultMapper)
-
-    /**
-     * Creates a `HttpRequest` to `HttpResponse` handler that can be used in for example `Http().bindAndHandleAsync`
-     * for the generated partial function handler and ends with `StatusCodes.NotFound` if the request is not matching.
-     *
-     * Use `org.apache.pekko.grpc.scaladsl.ServiceHandler.concatOrNotFound` with `@{service.name}Handler.partial` when combining
-     * several services.
-     *
-     * Registering a gRPC service under a custom prefix is not widely supported and strongly discouraged by the specification.
-     */
-    def apply(implementation: @serviceName, prefix: String, eHandler: ActorSystem => PartialFunction[Throwable, Trailers])(implicit system: ClassicActorSystemProvider): model.HttpRequest => scala.concurrent.Future[model.HttpResponse] =
-      handler(implementation, prefix, eHandler)
-
-@if(serviceName != "ServerReflection") {
-
-    /**
-     * Creates a `HttpRequest` to `HttpResponse` handler that can be used in for example `Http().bindAndHandleAsync`
-     * for the generated partial function handler. The generated handler falls back to a reflection handler for
-     * `@{service.name}` and ends with `StatusCodes.NotFound` if the request is not matching.
-     *
-     * Use `org.apache.pekko.grpc.scaladsl.ServiceHandler.concatOrNotFound` with `@{service.name}Handler.partial` when combining
-     * several services.
-     */
-    def withServerReflection(implementation: @serviceName)(implicit system: ClassicActorSystemProvider): model.HttpRequest => scala.concurrent.Future[model.HttpResponse] =
-        pekko.grpc.scaladsl.ServiceHandler.concatOrNotFound(
-          @{serviceName}Handler.partial(implementation),
-          pekko.grpc.scaladsl.ServerReflection.partial(List(@{service.name})))
-}
-
-    private def methodName(request: model.HttpRequest, prefix: String): String = {
-      val path = request.uri.path.toString
-      val prefixStart = 1
-      val methodStart = prefix.length + 2
-      if (path.length > methodStart && path.charAt(0) == '/' && path.startsWith(prefix, prefixStart) && path.charAt(methodStart - 1) == '/') {
-        path.substring(methodStart)
-      } else null
-    }
-
-    private def handler(implementation: @serviceName, prefix: String, eHandler: ActorSystem => PartialFunction[Throwable, Trailers])(implicit system: ClassicActorSystemProvider): model.HttpRequest => scala.concurrent.Future[model.HttpResponse] = {
-      implicit val mat: Materializer = SystemMaterializer(system).materializer
-      implicit val ec: ExecutionContext = mat.executionContext
-      val spi = TelemetryExtension(system).spi
-
-      import @{service.name}.Serializers.@{service.scalaCompatConstants.WildcardImport}
-
-      // Pre-create lambdas for unary methods to avoid per-request allocation
-      @for(method <- service.methods) {
-      @if(method.methodType == org.apache.pekko.grpc.gen.Unary) {
-      val @{method.nameSafe}Handler: @method.parameterType => scala.concurrent.Future[@method.outputType] = 
-        (e: @method.parameterType) => implementation.@{method.nameSafe}(e@{if(powerApis) { ", metadata" } else { "" }})
-      }
-      }
-
-      def handle(request: model.HttpRequest, method: String): scala.concurrent.Future[model.HttpResponse] =
-        GrpcMarshalling.negotiated(request, (reader, writer) =>
-          method match {
-            @for(method <- service.methods) {
-            case "@method.grpcName" =>
-                @{if(powerApis) { "val metadata = MetadataBuilder.fromHeaders(request.headers)" } else { "" }}
-                @if(method.methodType == org.apache.pekko.grpc.gen.Unary) {
-                GrpcMarshalling.handleUnary(request.entity, @{method.nameSafe}Handler, eHandler)(
-                  @{service.scalaCompatConstants.ImplicitUsing}@method.deserializer.name, @method.serializer.name, mat, reader, writer, system, ec)
-                } else {
-                @{method.unmarshal}(request.entity)(@{service.scalaCompatConstants.ImplicitUsing}@method.deserializer.name, mat, reader)
-                  .@{if(method.outputStreaming) { "map" } else { "flatMap" }}(implementation.@{method.nameSafe}(_@{if(powerApis) { ", metadata" } else { "" }}))
-                  .map(e => @{method.marshal}(e, eHandler)(@{service.scalaCompatConstants.ImplicitUsing}@method.serializer.name, writer, system))
-                  .recoverWith(GrpcExceptionHandler.from(eHandler(system.classicSystem))(system, writer))
-                }
-            }
-            case m => GrpcExceptionHandler.from(eHandler(system.classicSystem))(system, writer)(new NotImplementedError(s"Not implemented: $m"))
-          }
-      ).getOrElse(unsupportedMediaType)
-
-      request => {
-        val method = methodName(request, prefix)
-        if (method eq null) notFound
-        else handle(spi.onRequest(prefix, method, request), method)
-      }
-    }
-
-    /**
-     * Creates a partial `HttpRequest` to `HttpResponse` handler that can be combined with handlers of other
-     * services with `org.apache.pekko.grpc.scaladsl.ServiceHandler.concatOrNotFound` and then used in for example
-     * `Http().bindAndHandleAsync`.
-     *
-     * Use `@{service.name}Handler.apply` if the server is only handling one service.
-     *
-     * Registering a gRPC service under a custom prefix is not widely supported and strongly discouraged by the specification.
-     */
-    def partial(implementation: @serviceName, prefix: String = @{service.name}.name, eHandler: ActorSystem => PartialFunction[Throwable, Trailers] = GrpcExceptionHandler.defaultMapper)(implicit system: ClassicActorSystemProvider): PartialFunction[model.HttpRequest, scala.concurrent.Future[model.HttpResponse]] = {
-      implicit val mat: Materializer = SystemMaterializer(system).materializer
-      implicit val ec: ExecutionContext = mat.executionContext
-      val spi = TelemetryExtension(system).spi
-
-      import @{service.name}.Serializers.@{service.scalaCompatConstants.WildcardImport}
-
-      // Pre-create lambdas for unary methods to avoid per-request allocation
-      @for(method <- service.methods) {
-      @if(method.methodType == org.apache.pekko.grpc.gen.Unary) {
-      val @{method.nameSafe}Handler: @method.parameterType => scala.concurrent.Future[@method.outputType] = 
-        (e: @method.parameterType) => implementation.@{method.nameSafe}(e@{if(powerApis) { ", metadata" } else { "" }})
-      }
-      }
-
-      def handle(request: model.HttpRequest, method: String): scala.concurrent.Future[model.HttpResponse] =
-        GrpcMarshalling.negotiated(request, (reader, writer) =>
-          method match {
-            @for(method <- service.methods) {
-            case "@method.grpcName" =>
-                @{if(powerApis) { "val metadata = MetadataBuilder.fromHeaders(request.headers)" } else { "" }}
-                @if(method.methodType == org.apache.pekko.grpc.gen.Unary) {
-                GrpcMarshalling.handleUnary(request.entity, @{method.nameSafe}Handler, eHandler)(
-                  @{service.scalaCompatConstants.ImplicitUsing}@method.deserializer.name, @method.serializer.name, mat, reader, writer, system, ec)
-                } else {
-                @{method.unmarshal}(request.entity)(@{service.scalaCompatConstants.ImplicitUsing}@method.deserializer.name, mat, reader)
-                  .@{if(method.outputStreaming) { "map" } else { "flatMap" }}(implementation.@{method.nameSafe}(_@{if(powerApis) { ", metadata" } else { "" }}))
-                  .map(e => @{method.marshal}(e, eHandler)(@{service.scalaCompatConstants.ImplicitUsing}@method.serializer.name, writer, system))
-                  .recoverWith(GrpcExceptionHandler.from(eHandler(system.classicSystem))(system, writer))
-                }
-            }
-            case m => GrpcExceptionHandler.from(eHandler(system.classicSystem))(system, writer)(new NotImplementedError(s"Not implemented: $m"))
-          }
-      ).getOrElse(unsupportedMediaType)
-
-      Function.unlift((req: model.HttpRequest) => {
-        val method = methodName(req, prefix)
-        if (method eq null) None
-        else Some(handle(spi.onRequest(prefix, method, req), method))
-      })
-    }
-  }
-}
diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala b/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala
index 505cd4374..6fce22483 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala
@@ -18,7 +18,7 @@ import pekko.NotUsed
 import pekko.annotation.InternalApi
 import pekko.annotation.InternalStableApi
 import pekko.grpc.GrpcProtocol.{ GrpcProtocolReader, GrpcProtocolWriter }
-import pekko.grpc.internal.{ Codec, Codecs, Gzip, GrpcProtocolNative, GrpcProtocolWeb, GrpcProtocolWebText, Identity }
+import pekko.grpc.internal.{ Codec, Codecs, GrpcProtocolNative, GrpcProtocolWeb, GrpcProtocolWebText, Gzip, Identity }
 import pekko.http.javadsl.{ model => jmodel }
 import pekko.http.scaladsl.model.{ ContentType, HttpHeader, HttpResponse, Trailer }
 import pekko.http.scaladsl.model.HttpEntity.ChunkStreamPart
@@ -144,8 +144,6 @@ object GrpcProtocol {
   // Pre-computed negotiation results for common codec combinations
   private val NativeIdentityIdentity: (Try[GrpcProtocolReader], GrpcProtocolWriter) =
     (scala.util.Success(GrpcProtocolNative.newReader(Identity)), GrpcProtocolNative.newWriter(Identity))
-  private val NativeIdentityGzip: (Try[GrpcProtocolReader], GrpcProtocolWriter) =
-    (scala.util.Success(GrpcProtocolNative.newReader(Identity)), GrpcProtocolNative.newWriter(Gzip))
 
   /**
    * Calculates the gRPC protocol encoding to use for an interaction with a gRPC client.
@@ -162,7 +160,6 @@ object GrpcProtocol {
     if (isNative) {
       // Single-pass header scan for native gRPC
       var requestEncoding: String = null
-      var acceptEncoding: String = null
       request match {
         case sReq: pekko.http.scaladsl.model.HttpMessage =>
           val headers = sReq.headers
@@ -171,7 +168,6 @@ object GrpcProtocol {
             val h = headers(i)
             val name = h.lowercaseName
             if (name == "grpc-encoding") requestEncoding = h.value
-            else if (name == "grpc-accept-encoding") acceptEncoding = h.value
             i += 1
           }
         case _ =>
@@ -190,15 +186,16 @@ object GrpcProtocol {
       val writerCodec: Codec = Identity
       // Return pre-computed result for common combinations
       if ((readerCodec eq Identity) && (writerCodec eq Identity)) return Some(NativeIdentityIdentity)
-      if ((readerCodec eq Identity) && (writerCodec eq Gzip)) return Some(NativeIdentityGzip)
-      return Some((scala.util.Success(GrpcProtocolNative.newReader(readerCodec)), GrpcProtocolNative.newWriter(writerCodec)))
+      return Some((scala.util.Success(GrpcProtocolNative.newReader(readerCodec)),
+        GrpcProtocolNative.newWriter(writerCodec)))
     }
 
     // Non-native protocols - slow path
     slowNegotiateOpt(request, subType)
   }
 
-  private def slowNegotiateOpt(request: jmodel.HttpRequest, subType: String): Option[(Try[GrpcProtocolReader], GrpcProtocolWriter)] = {
+  private def slowNegotiateOpt(request: jmodel.HttpRequest, subType: String)
+      : Option[(Try[GrpcProtocolReader], GrpcProtocolWriter)] = {
     val variant = subType match {
       case "grpc-web" | "grpc-web+proto"           => Some(GrpcProtocolWeb)
       case "grpc-web-text" | "grpc-web-text+proto" => Some(GrpcProtocolWebText)
diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/internal/GrpcProtocolNative.scala b/runtime/src/main/scala/org/apache/pekko/grpc/internal/GrpcProtocolNative.scala
index c7f13ff7f..a2263c5c5 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/internal/GrpcProtocolNative.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/internal/GrpcProtocolNative.scala
@@ -44,11 +44,27 @@ object GrpcProtocolNative extends AbstractGrpcProtocol("grpc") {
     AbstractGrpcProtocol.writer(this, codec, encodeFrame(codec, _), encodeDataToResponse(codec))
 
   override protected def reader(codec: Codec): GrpcProtocolReader =
-    AbstractGrpcProtocol.reader(codec, decodeFrame)
+    if (codec eq Identity)
+      AbstractGrpcProtocol.reader(codec, decodeFrame).copy(decodeSingleFrame = decodeIdentitySingleFrame)
+    else AbstractGrpcProtocol.reader(codec, decodeFrame)
 
   @inline
   private def decodeFrame(@nowarn("msg=is never used") frameType: Int, data: ByteString) = DataFrame(data)
 
+  private def decodeIdentitySingleFrame(frame: ByteString): ByteString = {
+    if (frame.length < AbstractGrpcProtocol.FrameHeaderSize) throw new MissingParameterException
+
+    val frameType = frame(0)
+    val length = frame.readIntBE(1)
+    val available = frame.length - AbstractGrpcProtocol.FrameHeaderSize
+    if (length > available) throw new MissingParameterException
+    if (length < 0 || length < available)
+      throw new IllegalStateException("Unexpected data")
+    if ((frameType & 0x80) != 0) throw new IllegalStateException("Cannot read unknown frame")
+
+    Identity.uncompress((frameType & 1) == 1, frame.slice(AbstractGrpcProtocol.FrameHeaderSize, frame.length))
+  }
+
   @inline
   private def encodeFrame(codec: Codec, frame: Frame): ChunkStreamPart =
     frame match {
diff --git a/runtime/src/test/scala/org/apache/pekko/grpc/javadsl/GrpcMarshallingSpec.scala b/runtime/src/test/scala/org/apache/pekko/grpc/javadsl/GrpcMarshallingSpec.scala
index c35c50f40..aa10204cf 100644
--- a/runtime/src/test/scala/org/apache/pekko/grpc/javadsl/GrpcMarshallingSpec.scala
+++ b/runtime/src/test/scala/org/apache/pekko/grpc/javadsl/GrpcMarshallingSpec.scala
@@ -23,14 +23,16 @@ import scala.concurrent.Await
 import scala.concurrent.duration._
 
 import com.google.protobuf.{ Any => ProtobufAny, ByteString => ProtobufByteString }
+import io.grpc.StatusException
 import org.scalatest.matchers.should.Matchers
 import org.scalatest.wordspec.AnyWordSpec
 
 import org.apache.pekko
 import pekko.actor.ActorSystem
-import pekko.grpc.internal.{ AbstractGrpcProtocol, GrpcProtocolNative, Identity }
+import pekko.grpc.internal.{ AbstractGrpcProtocol, GrpcProtocolNative, Identity, MissingParameterException }
 import pekko.http.scaladsl.model.HttpEntity
 import pekko.stream.SystemMaterializer
+import pekko.util.ByteString
 
 class GrpcMarshallingSpec extends AnyWordSpec with Matchers {
   "The javadsl GrpcMarshalling" should {
@@ -59,6 +61,45 @@ class GrpcMarshallingSpec extends AnyWordSpec with Matchers {
       }
     }
 
+    "decode a strict native identity frame directly" in {
+      val serializer = new GoogleProtobufSerializer(ProtobufAny.parser())
+      val message =
+        ProtobufAny.newBuilder().setTypeUrl("benchmark").setValue(ProtobufByteString.copyFromUtf8("payload")).build()
+      val payload = serializer.serialize(message)
+      val frame = AbstractGrpcProtocol.encodeFrameData(payload, isCompressed = false, isTrailer = false)
+
+      GrpcProtocolNative.newReader(Identity).decodeSingleFrame(frame) should be(payload)
+    }
+
+    "reject compressed strict native identity frames" in {
+      val frame = AbstractGrpcProtocol.encodeFrameData(ByteString(1, 2, 3), isCompressed = true, isTrailer = false)
+
+      a[StatusException] should be thrownBy GrpcProtocolNative.newReader(Identity).decodeSingleFrame(frame)
+    }
+
+    "reject truncated strict native identity frames" in {
+      a[MissingParameterException] should be thrownBy
+      GrpcProtocolNative
+        .newReader(Identity)
+        .decodeSingleFrame(ByteString(0, 0, 0, 0))
+    }
+
+    "reject strict native identity frames with missing payload bytes" in {
+      a[MissingParameterException] should be thrownBy
+      GrpcProtocolNative
+        .newReader(Identity)
+        .decodeSingleFrame(ByteString(0, 0, 0, 0, 3, 1, 2))
+    }
+
+    "reject strict native identity frames with trailing bytes" in {
+      val frame = AbstractGrpcProtocol.encodeFrameData(ByteString(1, 2, 3), isCompressed = false, isTrailer = false)
+
+      an[IllegalStateException] should be thrownBy
+      GrpcProtocolNative
+        .newReader(Identity)
+        .decodeSingleFrame(frame ++ ByteString(4))
+    }
+
     "recover a failed unary response stage" in {
       val system = ActorSystem("GrpcMarshallingSpec")
       try {

From c3634af40bbd63f4e220c4b5ee0f9bee4029b1e0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=99=8E=E9=B8=A3?= <hepin.p@alibaba-inc.com>
Date: Sun, 21 Jun 2026 16:56:02 +0800
Subject: [PATCH 06/16] Reduce per-request allocations on unary gRPC hot path

Motivation:
The unary gRPC hot path allocated unnecessary objects on every request:
1. handleUnary called unaryExceptionHandler which created a new
   PartialFunction via GrpcExceptionHandler.from() on every error path
   (up to 4 allocations per request in worst case)
2. encodeFrameData allocated a separate 5-byte header array plus a
   ByteStrings concatenation wrapper for every frame
3. Async recovery paths eagerly created exception handler PartialFunctions
   even when no exception occurred

Modification:
1. Add handleUnaryException that inlines the exception-to-response
   conversion, avoiding the intermediate PartialFunction allocation
   from GrpcExceptionHandler.from(). Directly checks isDefinedAt and
   falls back to defaultMapper.
2. Optimize encodeFrameData for small messages (<=4KB, covering the
   vast majority of gRPC unary payloads) by combining the 5-byte frame
   header and data into a single array allocation, producing one
   contiguous ArrayByteString instead of a ByteStrings(Header, Data)
   concatenation. Falls back to original approach for large messages.
3. Change async recovery exception handlers from eager val to lazy val
   so the PartialFunction is only allocated if recovery is actually
   needed.

Result:
Fewer object allocations per unary gRPC request on the hot path,
reducing GC pressure under high concurrency. encodeFrameData produces
a single contiguous ByteString for typical small messages, improving
downstream serialization efficiency.

Tests:
sbt runtime / Test / testOnly GrpcMarshallingSpec CodecsSpec GrpcResponseHelpersSpec
All 18 tests passed.

References: None - local performance optimization follow-up from OPTIMIZATION_HANDOFF.md
---
 .../grpc/internal/AbstractGrpcProtocol.scala  | 15 +++++++--
 .../pekko/grpc/scaladsl/GrpcMarshalling.scala | 31 ++++++++++++++-----
 2 files changed, 36 insertions(+), 10 deletions(-)

diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/internal/AbstractGrpcProtocol.scala b/runtime/src/main/scala/org/apache/pekko/grpc/internal/AbstractGrpcProtocol.scala
index 8cd4653cb..2a11b7078 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/internal/AbstractGrpcProtocol.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/internal/AbstractGrpcProtocol.scala
@@ -100,10 +100,19 @@ object AbstractGrpcProtocol {
       })
       .toContentType
 
+  private val SmallMessageThreshold = 4096
+
   def encodeFrameData(data: ByteString, isCompressed: Boolean, isTrailer: Boolean): ByteString = {
-    val header = new Array[Byte](FrameHeaderSize)
-    writeFrameHeader(header, 0, data.length, isCompressed, isTrailer)
-    ByteString.fromArrayUnsafe(header, 0, FrameHeaderSize) ++ data
+    if (data.length <= SmallMessageThreshold) {
+      val combined = new Array[Byte](FrameHeaderSize + data.length)
+      writeFrameHeader(combined, 0, data.length, isCompressed, isTrailer)
+      data.copyToArray(combined, FrameHeaderSize)
+      ByteString.fromArrayUnsafe(combined)
+    } else {
+      val header = new Array[Byte](FrameHeaderSize)
+      writeFrameHeader(header, 0, data.length, isCompressed, isTrailer)
+      ByteString.fromArrayUnsafe(header, 0, FrameHeaderSize) ++ data
+    }
   }
 
   def writer(
diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala b/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala
index 42b248fe6..75bb555cc 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala
@@ -128,15 +128,16 @@ object GrpcMarshalling {
           val in = u.deserialize(reader.decodeSingleFrame(data))
           invokeUnary(in, implementation, eHandler)
         } catch {
-          case NonFatal(ex) => unaryExceptionHandler(eHandler)(system, writer)(ex)
+          case NonFatal(ex) => handleUnaryException(ex, eHandler)
         }
       case _ =>
         val requestFuture = unmarshal[In](entity)(u, mat, reader)
         requestFuture.value match {
           case Some(Success(in)) => invokeUnary(in, implementation, eHandler)
-          case Some(Failure(ex)) => unaryExceptionHandler(eHandler)(system, writer)(ex)
+          case Some(Failure(ex)) => handleUnaryException(ex, eHandler)
           case None              =>
-            val exceptionHandler = unaryExceptionHandler(eHandler)
+            // Lazy: only create the PartialFunction if actually needed for recovery
+            lazy val exceptionHandler = unaryExceptionHandler(eHandler)
             requestFuture
               .flatMap(in => invokeUnary(in, implementation, eHandler))
               .recoverWith(exceptionHandler)
@@ -154,7 +155,7 @@ object GrpcMarshalling {
       ec: ExecutionContext): Future[HttpResponse] =
     try handleUnaryResponse(implementation(in), eHandler)
     catch {
-      case NonFatal(ex) => unaryExceptionHandler(eHandler)(system, writer)(ex)
+      case NonFatal(ex) => handleUnaryException(ex, eHandler)
     }
 
   @inline private def handleUnaryResponse[Out](
@@ -166,9 +167,9 @@ object GrpcMarshalling {
       ec: ExecutionContext): Future[HttpResponse] =
     responseFuture.value match {
       case Some(Success(out)) => marshalUnaryResponse(out, eHandler)
-      case Some(Failure(ex))  => unaryExceptionHandler(eHandler)(system, writer)(ex)
+      case Some(Failure(ex))  => handleUnaryException(ex, eHandler)
       case None               =>
-        val exceptionHandler = unaryExceptionHandler(eHandler)
+        lazy val exceptionHandler = unaryExceptionHandler(eHandler)
         responseFuture.map(out => marshal[Out](out, eHandler)(m, writer, system)).recoverWith(exceptionHandler)
     }
 
@@ -180,9 +181,25 @@ object GrpcMarshalling {
       system: ClassicActorSystemProvider): Future[HttpResponse] =
     try FastFuture.successful(marshal[Out](out, eHandler)(m, writer, system))
     catch {
-      case NonFatal(ex) => unaryExceptionHandler(eHandler)(system, writer)(ex)
+      case NonFatal(ex) => handleUnaryException(ex, eHandler)
     }
 
+  /**
+   * Inline exception handling for synchronous error paths.
+   * Avoids allocating a PartialFunction via GrpcExceptionHandler.from() for each exception.
+   * Instead, directly applies the mapper and converts to response.
+   */
+  @inline private def handleUnaryException(
+      ex: Throwable,
+      eHandler: ActorSystem => PartialFunction[Throwable, Trailers])(
+      implicit writer: GrpcProtocolWriter,
+      system: ClassicActorSystemProvider): Future[HttpResponse] = {
+    val mapper = eHandler(system.classicSystem)
+    val trailers = if (mapper.isDefinedAt(ex)) mapper(ex)
+    else GrpcExceptionHandler.defaultMapper(system.classicSystem)(ex)
+    FastFuture.successful(GrpcResponseHelpers.status(trailers))
+  }
+
   @inline private def unaryExceptionHandler(eHandler: ActorSystem => PartialFunction[Throwable, Trailers])(
       implicit system: ClassicActorSystemProvider,
       writer: GrpcProtocolWriter): PartialFunction[Throwable, Future[HttpResponse]] =

From dcd2ab392d3cba4d096e4e19c1dd621768551b72 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=99=8E=E9=B8=A3?= <hepin.p@alibaba-inc.com>
Date: Sun, 21 Jun 2026 17:00:50 +0800
Subject: [PATCH 07/16] Add offset-aware protobuf deserialization to avoid
 ByteString.slice allocation

Motivation:
On the unary gRPC strict-entity fast path, decodeIdentitySingleFrame
calls ByteString.slice(5, length) to strip the 5-byte gRPC frame header.
This creates a ByteString1 wrapper object plus intermediate ByteBuffer
wrappers when the sliced bytes reach the protobuf CodedInputStream.
These allocations happen on every request.

Modification:
Add deserialize(data, offset, length) to ProtobufFrameSerializer trait
with a default fallback to slice + deserialize. Override in
ScalapbProtobufSerializer to access the backing byte array directly
with the offset, bypassing all intermediate wrappers. Use this
offset-aware path in GrpcMarshalling.handleUnary for strict entities
when the serializer is a ProtobufFrameSerializer (which all generated
ScalaPB and Java protobuf serializers are).

Result:
Strict-entity unary deserialization avoids the ByteString1 wrapper
allocation from slice and the intermediate ByteBuffer wrappers from
asByteBuffer, going directly from the raw gRPC frame byte array to
CodedInputStream. JMH shows no statistically significant throughput
change in single-threaded benchmarks (within error bars), but the
reduced allocation count benefits GC under high concurrency.

Tests:
sbt runtime / Test / testOnly GrpcMarshallingSpec CodecsSpec GrpcResponseHelpersSpec
All 18 tests passed.

References: None - local performance optimization follow-up from OPTIMIZATION_HANDOFF.md
---
 .../pekko/grpc/ProtobufSerializer.scala       |  8 +++++++
 .../pekko/grpc/scaladsl/GrpcMarshalling.scala |  8 ++++++-
 .../scaladsl/ScalapbProtobufSerializer.scala  | 21 +++++++++++++++++--
 3 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/ProtobufSerializer.scala b/runtime/src/main/scala/org/apache/pekko/grpc/ProtobufSerializer.scala
index e5392960e..cbc2acc0b 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/ProtobufSerializer.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/ProtobufSerializer.scala
@@ -27,4 +27,12 @@ trait ProtobufSerializer[T] {
 
 private[grpc] trait ProtobufFrameSerializer[T] extends ProtobufSerializer[T] {
   private[grpc] def serializeDataFrame(t: T): ByteString
+
+  /**
+   * Deserialize a protobuf message from a ByteString starting at the given offset.
+   * Avoids ByteString.slice allocation by passing the offset directly to the parser.
+   * Default implementation falls back to slice + deserialize.
+   */
+  private[grpc] def deserialize(data: ByteString, offset: Int, length: Int): T =
+    deserialize(data.slice(offset, offset + length))
 }
diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala b/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala
index 75bb555cc..2a7edf488 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala
@@ -125,7 +125,13 @@ object GrpcMarshalling {
     entity match {
       case HttpEntity.Strict(_, data) =>
         try {
-          val in = u.deserialize(reader.decodeSingleFrame(data))
+          val in = u match {
+            case frameSerializer: ProtobufFrameSerializer[In @unchecked] =>
+              frameSerializer.deserialize(data, AbstractGrpcProtocol.FrameHeaderSize,
+                data.length - AbstractGrpcProtocol.FrameHeaderSize)
+            case _ =>
+              u.deserialize(reader.decodeSingleFrame(data))
+          }
           invokeUnary(in, implementation, eHandler)
         } catch {
           case NonFatal(ex) => handleUnaryException(ex, eHandler)
diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/ScalapbProtobufSerializer.scala b/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/ScalapbProtobufSerializer.scala
index a9884852c..99450eb51 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/ScalapbProtobufSerializer.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/ScalapbProtobufSerializer.scala
@@ -40,8 +40,25 @@ class ScalapbProtobufSerializer[T <: GeneratedMessage](companion: GeneratedMessa
 
     ByteString.fromArrayUnsafe(frame)
   }
-  override def deserialize(bytes: ByteString): T =
-    companion.parseFrom(CodedInputStream.newInstance(bytes.asByteBuffer))
+  override def deserialize(bytes: ByteString): T = {
+    // Fast path: use byte array directly to avoid ByteBuffer wrapper allocation
+    val bb = bytes.asByteBuffer
+    if (bb.hasArray) {
+      companion.parseFrom(CodedInputStream.newInstance(bb.array(), bb.arrayOffset(), bb.remaining()))
+    } else {
+      companion.parseFrom(CodedInputStream.newInstance(bb))
+    }
+  }
+  override private[grpc] def deserialize(data: ByteString, offset: Int, length: Int): T = {
+    // Offset-aware fast path: bypass ByteString.slice to avoid ByteString1 + ByteBuffer wrappers
+    val bb = data.asByteBuffer
+    if (bb.hasArray) {
+      companion.parseFrom(CodedInputStream.newInstance(bb.array(), bb.arrayOffset() + offset, length))
+    } else {
+      // Fallback for non-array-backed ByteStrings (rare in practice)
+      super.deserialize(data, offset, length)
+    }
+  }
   override def deserialize(data: InputStream): T =
     companion.parseFrom(data)
 }

From bcf98c194659c56781af1c2c20fc9f8b93eded79 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=99=8E=E9=B8=A3?= <hepin.p@alibaba-inc.com>
Date: Sun, 21 Jun 2026 17:03:06 +0800
Subject: [PATCH 08/16] Apply offset-aware deserialization to Java DSL
 unmarshal strict path

Motivation:
The Java DSL unmarshal for strict entities used the same
decodeSingleFrame path as before, creating a ByteString.slice wrapper
per request. The Scala DSL already had the offset-aware optimization.

Modification:
Apply the same ProtobufFrameSerializer.deserialize(data, offset, length)
fast path to the Java DSL unmarshal method for strict entities,
bypassing the ByteString.slice allocation.

Result:
Java DSL strict entity unmarshalling now also avoids the ByteString1
wrapper allocation on the hot path, consistent with the Scala DSL.

Tests:
sbt runtime / Test / testOnly GrpcMarshallingSpec
All 7 tests passed.

References: None - follow-up to offset-aware deserialization optimization
---
 .../apache/pekko/grpc/javadsl/GrpcMarshalling.scala    | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/javadsl/GrpcMarshalling.scala b/runtime/src/main/scala/org/apache/pekko/grpc/javadsl/GrpcMarshalling.scala
index 18c496371..2f9e896f9 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/javadsl/GrpcMarshalling.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/javadsl/GrpcMarshalling.scala
@@ -60,7 +60,15 @@ object GrpcMarshalling {
       reader: GrpcProtocolReader): CompletionStage[T] =
     entity match {
       case strict: pekko.http.scaladsl.model.HttpEntity.Strict =>
-        completedOrFailed(u.deserialize(reader.decodeSingleFrame(strict.data)))
+        completedOrFailed {
+          u match {
+            case frameSerializer: ProtobufFrameSerializer[T @unchecked] =>
+              frameSerializer.deserialize(strict.data, AbstractGrpcProtocol.FrameHeaderSize,
+                strict.data.length - AbstractGrpcProtocol.FrameHeaderSize)
+            case _ =>
+              u.deserialize(reader.decodeSingleFrame(strict.data))
+          }
+        }
       case _ =>
         unmarshal(entity.getDataBytes, u, mat, reader)
     }

From dc04304673300f4a594816fb6ab1a6899151ff90 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=99=8E=E9=B8=A3?= <hepin.p@alibaba-inc.com>
Date: Sun, 21 Jun 2026 17:58:08 +0800
Subject: [PATCH 09/16] Optimize methodName to use Uri.Path structure matching
 instead of toString

Motivation:
The generated methodName function called request.uri.path.toString on
every request, triggering a full recursive renderPath that allocates a
StringBuilder, renders each path segment, and creates a new String.
This appeared as a hotspot (30 CPU samples) in async-profiler under
high concurrency gRPC workloads.

Modification:
Replace the toString + substring approach with direct Uri.Path pattern
matching. The gRPC path format /{service}/{method} maps to
Path.Slash(Segment(service, Slash(Segment(method, Empty)))). Pattern
matching on this structure extracts the method name with zero string
allocations - only field accesses and a String.equals comparison.

Result:
Eliminates per-request renderPath + StringBuilder + String allocations
in the generated handler. Under complex_proto benchmark (1000c/50conn/
120s), average latency dropped from 7.62ms to 6.88ms (-9.7%) and P99
from 28.56ms to 24.80ms (-13.2%).

Tests:
sbt runtime / Test / testOnly GrpcMarshallingSpec
All tests passed.
sbt codegen / compile
Compiled successfully.

References: None - performance optimization from flamegraph analysis
---
 .../templates/ScalaServer/Handler.scala.txt     | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt b/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt
index 7aca7616d..196413e48 100644
--- a/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt
+++ b/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt
@@ -108,12 +108,17 @@ object @{serviceName}Handler {
 }
 
     private def methodName(request: model.HttpRequest, prefix: String): String = {
-      val path = request.uri.path.toString
-      val prefixStart = 1
-      val methodStart = prefix.length + 2
-      if (path.length > methodStart && path.charAt(0) == '/' && path.startsWith(prefix, prefixStart) && path.charAt(methodStart - 1) == '/') {
-        path.substring(methodStart)
-      } else null
+      // Use Uri.Path structure matching instead of toString to avoid
+      // renderPath + StringBuilder + String allocations per request.
+      // gRPC path format: /{service}/{method}
+      request.uri.path match {
+        case model.Uri.Path.Slash(
+          model.Uri.Path.Segment(serviceName,
+            model.Uri.Path.Slash(
+              model.Uri.Path.Segment(method, model.Uri.Path.Empty))))
+          if serviceName == prefix => method
+        case _ => null
+      }
     }
 
     private def handler(implementation: @serviceName, prefix: String, eHandler: ActorSystem => PartialFunction[Throwable, Trailers])(implicit system: ClassicActorSystemProvider): model.HttpRequest => scala.concurrent.Future[model.HttpResponse] = {

From 8f0a44c45a2cb93f7b4b35b0b3af12ee4f5222aa Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=99=8E=E9=B8=A3?= <hepin.p@alibaba-inc.com>
Date: Sun, 21 Jun 2026 18:04:00 +0800
Subject: [PATCH 10/16] Eliminate Option.map lambda allocation in negotiated
 method

Motivation:
The negotiated method used Option.map with a pattern-matching lambda,
which allocates a new Function1 object on every request. This appeared
as GrpcMarshalling$$$Lambda (48 CPU samples) in async-profiler.

Modification:
Replace Option.map with direct pattern matching on the negotiate
result. The match on Some/Failure/Success is allocation-free (only
type checks and field accesses via destructuring).

Result:
Eliminates one lambda allocation per gRPC request in the negotiated
method hot path.

Tests:
sbt runtime / Test / testOnly GrpcMarshallingSpec
All 7 tests passed.

References: None - performance optimization from flamegraph analysis
---
 .../org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala   | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala b/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala
index 2a7edf488..d4e8d851d 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala
@@ -55,9 +55,10 @@ object GrpcMarshalling {
   }
 
   def negotiated[T](req: HttpRequest, f: (GrpcProtocolReader, GrpcProtocolWriter) => Future[T]): Option[Future[T]] =
-    GrpcProtocol.negotiate(req).map {
-      case (Success(reader), writer) => f(reader, writer)
-      case (Failure(ex), _)          => Future.failed(ex)
+    GrpcProtocol.negotiate(req) match {
+      case Some((Success(reader), writer)) => Some(f(reader, writer))
+      case Some((Failure(ex), _))          => Some(Future.failed(ex))
+      case None                            => None
     }
 
   def unmarshal[T](data: Source[ByteString, Any])(

From 4c955982eac3a4241748c46f7857c8011293ff16 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=99=8E=E9=B8=A3?= <hepin.p@alibaba-inc.com>
Date: Mon, 22 Jun 2026 00:30:21 +0800
Subject: [PATCH 11/16] fix: add empty data check in ProtobufFrameSerializer
 fast path for handleUnary

Motivation:
The ProtobufFrameSerializer fast path in handleUnary directly called
deserialize(data, offset, length) without checking if the data was
sufficient to contain a frame header. When the request entity was
empty (HttpEntity.empty), data.length - FrameHeaderSize produced a
negative length (-5), bypassing the MissingParameterException that
reader.decodeSingleFrame would normally throw. This caused the
ErrorReportingSpec test "should respond with an 'invalid argument'
gRPC error status when calling an method without a request body"
to fail because the expected INVALID_ARGUMENT status was not returned.

Modification:
Add a length check before the ProtobufFrameSerializer.deserialize call:
if data.length < FrameHeaderSize, throw MissingParameterException to
match the behavior of reader.decodeSingleFrame which validates the
frame header is present before attempting to parse it.

Result:
Empty request bodies now correctly return grpc-status: 3
(INVALID_ARGUMENT) regardless of whether the ProtobufFrameSerializer
fast path or the standard decodeSingleFrame path is used.

Tests:
sbt plugin-tester-scala / Test / testOnly example.myapp.helloworld.ErrorReportingSpec
All 2 tests passed.

References: Fixes CI failure in PR #739
---
 .../org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala     | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala b/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala
index d4e8d851d..6d5937fac 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala
@@ -128,6 +128,8 @@ object GrpcMarshalling {
         try {
           val in = u match {
             case frameSerializer: ProtobufFrameSerializer[In @unchecked] =>
+              if (data.length < AbstractGrpcProtocol.FrameHeaderSize)
+                throw new MissingParameterException
               frameSerializer.deserialize(data, AbstractGrpcProtocol.FrameHeaderSize,
                 data.length - AbstractGrpcProtocol.FrameHeaderSize)
             case _ =>
@@ -135,7 +137,8 @@ object GrpcMarshalling {
           }
           invokeUnary(in, implementation, eHandler)
         } catch {
-          case NonFatal(ex) => handleUnaryException(ex, eHandler)
+          case ex: MissingParameterException => handleUnaryException(ex, eHandler)
+          case NonFatal(ex)                  => handleUnaryException(ex, eHandler)
         }
       case _ =>
         val requestFuture = unmarshal[In](entity)(u, mat, reader)

From 75444a2c326ab1b84b44c498a1897908970ae3c8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=99=8E=E9=B8=A3?= <hepin.p@alibaba-inc.com>
Date: Wed, 24 Jun 2026 01:01:57 +0800
Subject: [PATCH 12/16] fix: use value equality for gRPC content-type string
 comparison
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Motivation:
`eq` is reference equality in Scala — it only returns true when both
operands are the exact same object. `mediaType.subType` is not
guaranteed to return interned strings, so `eq` can silently return
false for semantically equal values like "grpc+proto".

Modification:
Replace `eq` with `==` (value equality) in the `negotiate` fast path.

Result:
Content-type negotiation works correctly regardless of string interning.
---
 runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala b/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala
index 6fce22483..c0372e9cf 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala
@@ -155,7 +155,7 @@ object GrpcProtocol {
   def negotiate(request: jmodel.HttpRequest): Option[(Try[GrpcProtocolReader], GrpcProtocolWriter)] = {
     val mediaType = request.entity.getContentType.mediaType
     val subType = mediaType.subType
-    val isNative = (subType eq "grpc+proto") || (subType eq "grpc")
+    val isNative = (subType == "grpc+proto") || (subType == "grpc")
 
     if (isNative) {
       // Single-pass header scan for native gRPC

From bce5b4a3e1a4fd534eaa5f807120f6059448c0a8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=99=8E=E9=B8=A3?= <hepin.p@alibaba-inc.com>
Date: Wed, 24 Jun 2026 01:17:46 +0800
Subject: [PATCH 13/16] refactor: JIT/GC optimizations on unary hot path

Motivation:
Review identified redundant method calls, dead code branches, and
a missing safety check in the strict deserialization path.

Modification:
- GrpcProtocolNative: inline compressed-bit check and use ByteString.drop
  instead of Identity.uncompress + slice, eliminating a method call and
  redundant bounds checking on the identity decode hot path
- GrpcMarshalling (scaladsl): merge duplicate catch branches
  (MissingParameterException is already matched by NonFatal), reducing
  bytecode branch count for cleaner JIT compilation
- GrpcMarshalling (javadsl): add frame header length check before
  offset-aware deserialization in strict path, matching scaladsl behavior
- Handler template: remove dead if(powerApis) conditional inside
  @if(!powerApis) block in pre-created lambda definitions

Result:
Fewer allocations and method calls on the hot path, cleaner bytecode
for JIT, and consistent error handling between Java and Scala DSLs.
---
 .../src/main/twirl/templates/ScalaServer/Handler.scala.txt   | 4 ++--
 .../org/apache/pekko/grpc/internal/GrpcProtocolNative.scala  | 5 ++++-
 .../org/apache/pekko/grpc/javadsl/GrpcMarshalling.scala      | 2 ++
 .../org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala     | 3 +--
 4 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt b/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt
index 196413e48..4af17c4db 100644
--- a/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt
+++ b/codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt
@@ -133,7 +133,7 @@ object @{serviceName}Handler {
       @for(method <- service.methods) {
       @if(method.methodType == org.apache.pekko.grpc.gen.Unary) {
       val @{method.handlerName}: @method.parameterType => scala.concurrent.Future[@method.outputTypeUnboxed] =
-        (e: @method.parameterType) => implementation.@{method.nameSafe}(e@{if(powerApis) { ", metadata" } else { "" }})
+        (e: @method.parameterType) => implementation.@{method.nameSafe}(e)
       }
       }
       }
@@ -186,7 +186,7 @@ object @{serviceName}Handler {
       @for(method <- service.methods) {
       @if(method.methodType == org.apache.pekko.grpc.gen.Unary) {
       val @{method.handlerName}: @method.parameterType => scala.concurrent.Future[@method.outputTypeUnboxed] =
-        (e: @method.parameterType) => implementation.@{method.nameSafe}(e@{if(powerApis) { ", metadata" } else { "" }})
+        (e: @method.parameterType) => implementation.@{method.nameSafe}(e)
       }
       }
       }
diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/internal/GrpcProtocolNative.scala b/runtime/src/main/scala/org/apache/pekko/grpc/internal/GrpcProtocolNative.scala
index a2263c5c5..3e37d9baa 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/internal/GrpcProtocolNative.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/internal/GrpcProtocolNative.scala
@@ -62,7 +62,10 @@ object GrpcProtocolNative extends AbstractGrpcProtocol("grpc") {
       throw new IllegalStateException("Unexpected data")
     if ((frameType & 0x80) != 0) throw new IllegalStateException("Cannot read unknown frame")
 
-    Identity.uncompress((frameType & 1) == 1, frame.slice(AbstractGrpcProtocol.FrameHeaderSize, frame.length))
+    if ((frameType & 1) != 0)
+      throw new io.grpc.StatusException(
+        io.grpc.Status.INTERNAL.withDescription("Compressed-Flag bit is set, but a compression encoding is not specified"))
+    frame.drop(AbstractGrpcProtocol.FrameHeaderSize)
   }
 
   @inline
diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/javadsl/GrpcMarshalling.scala b/runtime/src/main/scala/org/apache/pekko/grpc/javadsl/GrpcMarshalling.scala
index 2f9e896f9..117a9e703 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/javadsl/GrpcMarshalling.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/javadsl/GrpcMarshalling.scala
@@ -63,6 +63,8 @@ object GrpcMarshalling {
         completedOrFailed {
           u match {
             case frameSerializer: ProtobufFrameSerializer[T @unchecked] =>
+              if (strict.data.length < AbstractGrpcProtocol.FrameHeaderSize)
+                throw new MissingParameterException
               frameSerializer.deserialize(strict.data, AbstractGrpcProtocol.FrameHeaderSize,
                 strict.data.length - AbstractGrpcProtocol.FrameHeaderSize)
             case _ =>
diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala b/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala
index 6d5937fac..aa358a39f 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala
@@ -137,8 +137,7 @@ object GrpcMarshalling {
           }
           invokeUnary(in, implementation, eHandler)
         } catch {
-          case ex: MissingParameterException => handleUnaryException(ex, eHandler)
-          case NonFatal(ex)                  => handleUnaryException(ex, eHandler)
+          case NonFatal(ex) => handleUnaryException(ex, eHandler)
         }
       case _ =>
         val requestFuture = unmarshal[In](entity)(u, mat, reader)

From 4fa56d24216687adc3e800ed83904e9ed980c546 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=99=8E=E9=B8=A3?= <hepin.p@alibaba-inc.com>
Date: Wed, 24 Jun 2026 01:19:54 +0800
Subject: [PATCH 14/16] chore: apply scalafmt

---
 .../org/apache/pekko/grpc/internal/GrpcProtocolNative.scala    | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/internal/GrpcProtocolNative.scala b/runtime/src/main/scala/org/apache/pekko/grpc/internal/GrpcProtocolNative.scala
index 3e37d9baa..300516acf 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/internal/GrpcProtocolNative.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/internal/GrpcProtocolNative.scala
@@ -64,7 +64,8 @@ object GrpcProtocolNative extends AbstractGrpcProtocol("grpc") {
 
     if ((frameType & 1) != 0)
       throw new io.grpc.StatusException(
-        io.grpc.Status.INTERNAL.withDescription("Compressed-Flag bit is set, but a compression encoding is not specified"))
+        io.grpc.Status.INTERNAL.withDescription(
+          "Compressed-Flag bit is set, but a compression encoding is not specified"))
     frame.drop(AbstractGrpcProtocol.FrameHeaderSize)
   }
 

From fba6d250e10960a49664fb712918eb85db7281b5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=99=8E=E9=B8=A3?= <hepin.p@alibaba-inc.com>
Date: Wed, 24 Jun 2026 01:39:18 +0800
Subject: [PATCH 15/16] fix: respect grpc-accept-encoding in negotiate fast
 path and address review findings

Motivation:
The negotiate() fast path hardcoded writerCodec to Identity, ignoring
the client's grpc-accept-encoding header. This was a behavioral
regression from the original Codecs.negotiate() which respected client
compression preferences.

Modification:
- negotiate() now scans grpc-accept-encoding and selects writer codec
  respecting client preference order (matching Codecs.negotiate behavior)
- Separate negative frame length check from trailing data check with
  clearer error messages in decodeIdentitySingleFrame
- Fix misleading Codecs.supportedCodecs comment: order does not affect
  codec selection, client preference does
- Add GrpcProtocolSpec with tests for negotiate fast path behavior
---
 .../org/apache/pekko/grpc/GrpcProtocol.scala  |  26 ++++-
 .../apache/pekko/grpc/internal/Codecs.scala   |   5 +-
 .../grpc/internal/GrpcProtocolNative.scala    |   5 +-
 .../apache/pekko/grpc/GrpcProtocolSpec.scala  | 105 ++++++++++++++++++
 4 files changed, 131 insertions(+), 10 deletions(-)
 create mode 100644 runtime/src/test/scala/org/apache/pekko/grpc/GrpcProtocolSpec.scala

diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala b/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala
index c0372e9cf..7c2114f6f 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala
@@ -160,6 +160,7 @@ object GrpcProtocol {
     if (isNative) {
       // Single-pass header scan for native gRPC
       var requestEncoding: String = null
+      var acceptEncoding: String = null
       request match {
         case sReq: pekko.http.scaladsl.model.HttpMessage =>
           val headers = sReq.headers
@@ -168,6 +169,7 @@ object GrpcProtocol {
             val h = headers(i)
             val name = h.lowercaseName
             if (name == "grpc-encoding") requestEncoding = h.value
+            else if (name == "grpc-accept-encoding") acceptEncoding = h.value
             i += 1
           }
         case _ =>
@@ -179,11 +181,25 @@ object GrpcProtocol {
         else if (requestEncoding == "gzip") Gzip
         else return slowNegotiateOpt(request, subType)
       // Determine writer codec (response encoding)
-      // For native gRPC, always prefer Identity for responses. The per-frame compression
-      // flag tells the client whether each frame is compressed. For typical small gRPC
-      // messages, avoiding compression saves significant CPU overhead (~20-30% of handler time).
-      // Clients that need compression for large messages can still handle uncompressed frames.
-      val writerCodec: Codec = Identity
+      // Respect client's grpc-accept-encoding preference order (matching Codecs.negotiate).
+      // gRPC format: comma-separated, e.g. "gzip,identity" — client order indicates preference.
+      val writerCodec: Codec =
+        if (acceptEncoding eq null) Identity
+        else if (acceptEncoding == "gzip") Gzip
+        else if (acceptEncoding == "identity") Identity
+        else if (acceptEncoding.contains(",")) {
+          // Multiple encodings: iterate client preference order, pick first supported
+          val parts = acceptEncoding.split(",")
+          var codec: Codec = null
+          var i = 0
+          while (i < parts.length && (codec eq null)) {
+            val trimmed = parts(i).trim
+            if (trimmed == "gzip") codec = Gzip
+            else if (trimmed == "identity") codec = Identity
+            i += 1
+          }
+          if (codec eq null) Identity else codec
+        } else return slowNegotiateOpt(request, subType)
       // Return pre-computed result for common combinations
       if ((readerCodec eq Identity) && (writerCodec eq Identity)) return Some(NativeIdentityIdentity)
       return Some((scala.util.Success(GrpcProtocolNative.newReader(readerCodec)),
diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/internal/Codecs.scala b/runtime/src/main/scala/org/apache/pekko/grpc/internal/Codecs.scala
index d2876f8b2..49b7f6521 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/internal/Codecs.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/internal/Codecs.scala
@@ -23,9 +23,8 @@ import scala.collection.immutable
 import scala.util.{ Failure, Success, Try }
 
 object Codecs {
-  // Identity preferred over Gzip: for typical small protobuf messages, compression
-  // adds CPU overhead without meaningful size reduction. Clients requiring compression
-  // can still negotiate it explicitly.
+  // Codecs supported by this server. The selection order is determined by the
+  // client's grpc-accept-encoding header preference, not by this sequence order.
   val supportedCodecs = immutable.Seq(Identity, Gzip)
   private val supportedByName: Map[String, Codec] = supportedCodecs.map(c => c.name -> c).toMap
 
diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/internal/GrpcProtocolNative.scala b/runtime/src/main/scala/org/apache/pekko/grpc/internal/GrpcProtocolNative.scala
index 300516acf..00fee07be 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/internal/GrpcProtocolNative.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/internal/GrpcProtocolNative.scala
@@ -58,8 +58,9 @@ object GrpcProtocolNative extends AbstractGrpcProtocol("grpc") {
     val length = frame.readIntBE(1)
     val available = frame.length - AbstractGrpcProtocol.FrameHeaderSize
     if (length > available) throw new MissingParameterException
-    if (length < 0 || length < available)
-      throw new IllegalStateException("Unexpected data")
+    if (length < 0) throw new IllegalStateException(s"Invalid frame length: $length")
+    if (length < available)
+      throw new IllegalStateException("Unexpected trailing data")
     if ((frameType & 0x80) != 0) throw new IllegalStateException("Cannot read unknown frame")
 
     if ((frameType & 1) != 0)
diff --git a/runtime/src/test/scala/org/apache/pekko/grpc/GrpcProtocolSpec.scala b/runtime/src/test/scala/org/apache/pekko/grpc/GrpcProtocolSpec.scala
new file mode 100644
index 000000000..d80eaf141
--- /dev/null
+++ b/runtime/src/test/scala/org/apache/pekko/grpc/GrpcProtocolSpec.scala
@@ -0,0 +1,105 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * license agreements; and to You under the Apache License, version 2.0:
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * This file is part of the Apache Pekko project, which was derived from Akka.
+ */
+
+package org.apache.pekko.grpc
+
+import scala.collection.immutable
+
+import org.scalatest.matchers.should.Matchers
+import org.scalatest.wordspec.AnyWordSpec
+import org.scalatest.TryValues
+
+import org.apache.pekko
+import pekko.grpc.internal.{ Gzip, Identity }
+import pekko.grpc.scaladsl.headers
+import pekko.http.scaladsl.model.{ ContentTypes, HttpEntity, HttpRequest }
+
+class GrpcProtocolSpec extends AnyWordSpec with Matchers with TryValues {
+
+  private def grpcRequest(encoding: Option[String] = None, acceptEncoding: Option[String] = None): HttpRequest = {
+    val hdrs = immutable.Seq.newBuilder[pekko.http.scaladsl.model.HttpHeader]
+    encoding.foreach(e => hdrs += headers.`Message-Encoding`(e))
+    acceptEncoding.foreach(a => hdrs += headers.`Message-Accept-Encoding`(a))
+    HttpRequest(
+      entity = HttpEntity.Strict(GrpcProtocolNative.contentType, pekko.util.ByteString.empty),
+      headers = hdrs.result())
+  }
+
+  "GrpcProtocol.negotiate" should {
+
+    "return Identity reader and Identity writer for native gRPC with no encoding headers" in {
+      val result = GrpcProtocol.negotiate(grpcRequest())
+      result shouldBe defined
+      val (readerTry, writer) = result.get
+      readerTry.success.value.codec should be(Identity)
+      writer.codec should be(Identity)
+    }
+
+    "return Gzip reader when grpc-encoding is gzip" in {
+      val result = GrpcProtocol.negotiate(grpcRequest(encoding = Some("gzip")))
+      result shouldBe defined
+      val (readerTry, _) = result.get
+      readerTry.success.value.codec should be(Gzip)
+    }
+
+    "return Identity reader when grpc-encoding is identity" in {
+      val result = GrpcProtocol.negotiate(grpcRequest(encoding = Some("identity")))
+      result shouldBe defined
+      val (readerTry, _) = result.get
+      readerTry.success.value.codec should be(Identity)
+    }
+
+    "return Gzip writer when grpc-accept-encoding contains gzip" in {
+      val result = GrpcProtocol.negotiate(grpcRequest(acceptEncoding = Some("gzip")))
+      result shouldBe defined
+      val (_, writer) = result.get
+      writer.codec should be(Gzip)
+    }
+
+    "return Identity writer when grpc-accept-encoding is identity only" in {
+      val result = GrpcProtocol.negotiate(grpcRequest(acceptEncoding = Some("identity")))
+      result shouldBe defined
+      val (_, writer) = result.get
+      writer.codec should be(Identity)
+    }
+
+    "return Gzip writer when grpc-accept-encoding lists gzip first" in {
+      val result = GrpcProtocol.negotiate(grpcRequest(acceptEncoding = Some("gzip,identity")))
+      result shouldBe defined
+      val (_, writer) = result.get
+      writer.codec should be(Gzip)
+    }
+
+    "return Identity writer when grpc-accept-encoding lists identity before gzip" in {
+      val result = GrpcProtocol.negotiate(grpcRequest(acceptEncoding = Some("identity,gzip")))
+      result shouldBe defined
+      val (_, writer) = result.get
+      writer.codec should be(Identity)
+    }
+
+    "return pre-computed instance for Identity+Identity" in {
+      val result1 = GrpcProtocol.negotiate(grpcRequest())
+      val result2 = GrpcProtocol.negotiate(grpcRequest())
+      result1 shouldBe defined
+      result2 shouldBe defined
+      (result1.get eq result2.get) should be(true)
+    }
+
+    "return None for unsupported content type" in {
+      val request = HttpRequest(
+        entity = HttpEntity.Strict(ContentTypes.`text/plain(UTF-8)`, pekko.util.ByteString.empty))
+      GrpcProtocol.negotiate(request) should be(None)
+    }
+
+    "return None for unknown grpc-encoding" in {
+      val result = GrpcProtocol.negotiate(grpcRequest(encoding = Some("zstd")))
+      result should be(None)
+    }
+  }
+}

From 8729a6cd3aa352517deb45d4f882700c2ab357df Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=99=8E=E9=B8=A3?= <hepin.p@alibaba-inc.com>
Date: Wed, 24 Jun 2026 01:50:37 +0800
Subject: [PATCH 16/16] =?UTF-8?q?fix:=20address=20review=20findings=20?=
 =?UTF-8?q?=E2=80=94=20frame=20validation,=20test=20assertion,=20and=20Jav?=
 =?UTF-8?q?a=20API=20fallback?=
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Motivation:
Second review identified that the ProtobufFrameSerializer fast path in
handleUnary skipped all frame header validation that decodeIdentitySingleFrame
carefully performs. A test assertion was also incorrect, and the negotiate
fast path did not handle pure Java API requests.

Modification:
- Add compressed-flag check, frame length validation, and declared-length
  bounds checking to ProtobufFrameSerializer fast path in both scaladsl
  and javadsl handleUnary, matching decodeIdentitySingleFrame validation
- Fix GrpcProtocolSpec test: unknown grpc-encoding returns failed reader,
  not None (matching Codecs.detect behavior)
- negotiate() fast path delegates to slowNegotiateOpt for non-Scala-API
  requests, preserving Codecs.extractHeaders Java API header handling

Result:
Frame validation is consistent between fast path and standard path.
Pure Java API requests are handled correctly through the slow path.
---
 .../scala/org/apache/pekko/grpc/GrpcProtocol.scala   |  1 +
 .../apache/pekko/grpc/javadsl/GrpcMarshalling.scala  | 12 ++++++++++--
 .../apache/pekko/grpc/scaladsl/GrpcMarshalling.scala | 12 ++++++++++--
 .../org/apache/pekko/grpc/GrpcProtocolSpec.scala     |  6 ++++--
 4 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala b/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala
index 7c2114f6f..e01df6e3c 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/GrpcProtocol.scala
@@ -173,6 +173,7 @@ object GrpcProtocol {
             i += 1
           }
         case _ =>
+          return slowNegotiateOpt(request, subType)
       }
       // Determine reader codec (request encoding)
       val readerCodec: Codec =
diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/javadsl/GrpcMarshalling.scala b/runtime/src/main/scala/org/apache/pekko/grpc/javadsl/GrpcMarshalling.scala
index 117a9e703..be3b3c848 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/javadsl/GrpcMarshalling.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/javadsl/GrpcMarshalling.scala
@@ -65,8 +65,16 @@ object GrpcMarshalling {
             case frameSerializer: ProtobufFrameSerializer[T @unchecked] =>
               if (strict.data.length < AbstractGrpcProtocol.FrameHeaderSize)
                 throw new MissingParameterException
-              frameSerializer.deserialize(strict.data, AbstractGrpcProtocol.FrameHeaderSize,
-                strict.data.length - AbstractGrpcProtocol.FrameHeaderSize)
+              val frameType = strict.data(0)
+              if ((frameType & 1) != 0)
+                throw new io.grpc.StatusException(
+                  io.grpc.Status.INTERNAL.withDescription(
+                    "Compressed-Flag bit is set, but a compression encoding is not specified"))
+              val declaredLength = strict.data.readIntBE(1)
+              val available = strict.data.length - AbstractGrpcProtocol.FrameHeaderSize
+              if (declaredLength > available) throw new MissingParameterException
+              if (declaredLength < 0) throw new IllegalStateException(s"Invalid frame length: $declaredLength")
+              frameSerializer.deserialize(strict.data, AbstractGrpcProtocol.FrameHeaderSize, declaredLength)
             case _ =>
               u.deserialize(reader.decodeSingleFrame(strict.data))
           }
diff --git a/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala b/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala
index aa358a39f..eba64a651 100644
--- a/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala
+++ b/runtime/src/main/scala/org/apache/pekko/grpc/scaladsl/GrpcMarshalling.scala
@@ -130,8 +130,16 @@ object GrpcMarshalling {
             case frameSerializer: ProtobufFrameSerializer[In @unchecked] =>
               if (data.length < AbstractGrpcProtocol.FrameHeaderSize)
                 throw new MissingParameterException
-              frameSerializer.deserialize(data, AbstractGrpcProtocol.FrameHeaderSize,
-                data.length - AbstractGrpcProtocol.FrameHeaderSize)
+              val frameType = data(0)
+              if ((frameType & 1) != 0)
+                throw new io.grpc.StatusException(
+                  io.grpc.Status.INTERNAL.withDescription(
+                    "Compressed-Flag bit is set, but a compression encoding is not specified"))
+              val declaredLength = data.readIntBE(1)
+              val available = data.length - AbstractGrpcProtocol.FrameHeaderSize
+              if (declaredLength > available) throw new MissingParameterException
+              if (declaredLength < 0) throw new IllegalStateException(s"Invalid frame length: $declaredLength")
+              frameSerializer.deserialize(data, AbstractGrpcProtocol.FrameHeaderSize, declaredLength)
             case _ =>
               u.deserialize(reader.decodeSingleFrame(data))
           }
diff --git a/runtime/src/test/scala/org/apache/pekko/grpc/GrpcProtocolSpec.scala b/runtime/src/test/scala/org/apache/pekko/grpc/GrpcProtocolSpec.scala
index d80eaf141..fa1dcd5f3 100644
--- a/runtime/src/test/scala/org/apache/pekko/grpc/GrpcProtocolSpec.scala
+++ b/runtime/src/test/scala/org/apache/pekko/grpc/GrpcProtocolSpec.scala
@@ -97,9 +97,11 @@ class GrpcProtocolSpec extends AnyWordSpec with Matchers with TryValues {
       GrpcProtocol.negotiate(request) should be(None)
     }
 
-    "return None for unknown grpc-encoding" in {
+    "return a failed reader for unknown grpc-encoding" in {
       val result = GrpcProtocol.negotiate(grpcRequest(encoding = Some("zstd")))
-      result should be(None)
+      result shouldBe defined
+      val (readerTry, _) = result.get
+      readerTry.failure.exception shouldBe a[GrpcServiceException]
     }
   }
 }