From 49c00cfeeb177cf33832ca1e77ba7aa4cde15932 Mon Sep 17 00:00:00 2001
From: Martin Hutchinson <mhutchinson@gmail.com>
Date: Tue, 21 Jul 2026 13:36:41 +0000
Subject: [PATCH] [VIndex] Make number of InputLog readers configurable

This can increase download time, particularly for logs with high latency.
This bumps the default value from 2 to 4.
---
 vindex/cmd/logandmap/main.go  | 13 ++++++++-----
 vindex/cmd/sumdbindex/main.go |  2 ++
 vindex/inputlog.go            |  6 +++++-
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/vindex/cmd/logandmap/main.go b/vindex/cmd/logandmap/main.go
index e0dd361..cf97ae8 100644
--- a/vindex/cmd/logandmap/main.go
+++ b/vindex/cmd/logandmap/main.go
@@ -59,6 +59,7 @@ var (
 	storageDir           = flag.String("storage_dir", "", "Root directory in which to store the data for the demo. This will create subdirectories for the Input Log, Output Log, and allocate space to store the verifiable map persistence.")
 	persistIndex         = flag.Bool("persist_index", true, "Set to false to use a memory-based implementation of the verifiable index.")
 	listen               = flag.String("listen", ":8088", "Address to set up HTTP server listening on")
+	inputLogReaders      = flag.Uint("input_log_readers", 4, "Number of parallel readers for the input log")
 )
 
 func main() {
@@ -181,8 +182,9 @@ func inputLogOrDie(ctx context.Context, inputLogDir string) (log logReaderSource
 	}
 
 	inputLog := logReaderSource{
-		r: inputReader,
-		v: ilv,
+		r:          inputReader,
+		v:          ilv,
+		numReaders: *inputLogReaders,
 	}
 
 	// Submits new entries to the log in the background.
@@ -197,8 +199,9 @@ func inputLogOrDie(ctx context.Context, inputLogDir string) (log logReaderSource
 
 // logReaderSource adapts a tessera.LogReader to a vindex.InputLog.
 type logReaderSource struct {
-	r tessera.LogReader
-	v note.Verifier
+	r          tessera.LogReader
+	v          note.Verifier
+	numReaders uint
 }
 
 func (s logReaderSource) Checkpoint(ctx context.Context) (checkpoint []byte, err error) {
@@ -214,7 +217,7 @@ func (s logReaderSource) Leaves(ctx context.Context, start, end uint64) iter.Seq
 	tsf := func(ctx context.Context) (uint64, error) {
 		return end, nil
 	}
-	bi := client.EntryBundles(ctx, 2, tsf, s.r.ReadEntryBundle, start, end-start)
+	bi := client.EntryBundles(ctx, s.numReaders, tsf, s.r.ReadEntryBundle, start, end-start)
 	unbundleFn := func(bundle []byte) ([][]byte, error) {
 		eb := &api.EntryBundle{}
 		if err := eb.UnmarshalText(bundle); err != nil {
diff --git a/vindex/cmd/sumdbindex/main.go b/vindex/cmd/sumdbindex/main.go
index e575427..5aef3bd 100644
--- a/vindex/cmd/sumdbindex/main.go
+++ b/vindex/cmd/sumdbindex/main.go
@@ -58,6 +58,7 @@ var (
 
 	oneShot          = flag.Bool("oneshot", false, "Set to true to build the map once and then exit")
 	inputOverrideUrl = flag.String("input_override_url", "", "Set this to read from a different URL than the local proxy. Supports file paths. Intended for performance testing. Note this log MUST be presented as tlog-tiles format.")
+	inputLogReaders  = flag.Uint("input_log_readers", 4, "Number of parallel readers for the input log")
 )
 
 func main() {
@@ -117,6 +118,7 @@ func run(ctx context.Context) error {
 	inputLog, err := vindex.NewTiledInputLog(sumUrl, sumV, vindex.InputLogOpts{
 		HttpClient: http.DefaultClient,
 		Origin:     "go.sum database tree",
+		NumReaders: *inputLogReaders,
 	})
 	if err != nil {
 		return err
diff --git a/vindex/inputlog.go b/vindex/inputlog.go
index dfab6c4..752347c 100644
--- a/vindex/inputlog.go
+++ b/vindex/inputlog.go
@@ -36,6 +36,7 @@ type fetcher interface {
 type InputLogOpts struct {
 	HttpClient *http.Client
 	Origin     string
+	NumReaders uint
 }
 
 func NewTiledInputLog(base *url.URL, v note.Verifier, o InputLogOpts) (InputLog, error) {
@@ -46,6 +47,9 @@ func NewTiledInputLog(base *url.URL, v note.Verifier, o InputLogOpts) (InputLog,
 	if len(o.Origin) == 0 {
 		o.Origin = v.Name()
 	}
+	if o.NumReaders == 0 {
+		o.NumReaders = 4
+	}
 
 	var src fetcher
 
@@ -88,7 +92,7 @@ func (s logReaderSource) Leaves(ctx context.Context, start, end uint64) iter.Seq
 	tsf := func(ctx context.Context) (uint64, error) {
 		return end, nil
 	}
-	bi := client.EntryBundles(ctx, 2, tsf, s.f.ReadEntryBundle, start, end-start)
+	bi := client.EntryBundles(ctx, s.opts.NumReaders, tsf, s.f.ReadEntryBundle, start, end-start)
 	unbundleFn := func(bundle []byte) ([][]byte, error) {
 		eb := &api.EntryBundle{}
 		if err := eb.UnmarshalText(bundle); err != nil {