Streaming journal

pom.xml

@@ -5,7 +5,7 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.codeforces.inmemo</groupId>
     <artifactId>inmemo</artifactId>
-    <version>2.0.2-SNAPSHOT</version>
+    <version>2.0.4-SNAPSHOT</version>
     <packaging>jar</packaging>
     <name>inmemo</name>
     <distributionManagement>
@@ -46,6 +46,7 @@
     </scm>
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <surefire.argLine>-Dfile.encoding=UTF-8 -Xmx1200M</surefire.argLine>
     </properties>
     <build>
         <plugins>
@@ -76,16 +77,22 @@
                 <artifactId>maven-surefire-plugin</artifactId>
                 <version>2.22.2</version>
                 <configuration>
-                    <argLine>-Dfile.encoding=UTF-8</argLine>
-                    <argLine>-Xmx1200M</argLine>
-                    <!-- Uncomment to build with JDK 9+ -->
-                    <!--
-                    <argLine>&#45;&#45;add&#45;opens java.base/java.lang=ALL&#45;UNNAMED &#45;&#45;add&#45;opens java.base/java.util=ALL&#45;UNNAMED &#45;&#45;add&#45;opens java.base/java.io=ALL&#45;UNNAMED</argLine>
-                    -->
+                    <argLine>${surefire.argLine}</argLine>
                 </configuration>
             </plugin>
         </plugins>
     </build>
+    <profiles>
+        <profile>
+            <id>jdk9-plus-tests</id>
+            <activation>
+                <jdk>[9,)</jdk>
+            </activation>
+            <properties>
+                <surefire.argLine>-Dfile.encoding=UTF-8 -Xmx1200M --add-opens java.base/java.lang=ALL-UNNAMED --add-opens java.base/java.util=ALL-UNNAMED --add-opens java.base/java.io=ALL-UNNAMED</surefire.argLine>
+            </properties>
+        </profile>
+    </profiles>
     <dependencies>
         <dependency>
             <groupId>org.xerial.snappy</groupId>

src/main/java/com/codeforces/inmemo/JournalFormat.java

@@ -0,0 +1,90 @@
+package com.codeforces.inmemo;
+
+import org.apache.log4j.Logger;
+import org.xerial.snappy.Snappy;
+
+import java.nio.charset.StandardCharsets;
+
+final class JournalFormat {
+    static final byte[] MAGIC = "INMEMO_JOURNAL_2".getBytes(StandardCharsets.US_ASCII);
+    static final int VERSION = 1;
+
+    static final int MAX_BLOCK_ROWS = 1 << 20;
+    static final int MAX_BLOCK_RAW_BYTES = 128 * 1024 * 1024;
+    static final int MAX_BLOCK_COMPRESSED_BYTES = Snappy.maxCompressedLength(MAX_BLOCK_RAW_BYTES);
+    static final int MAX_HEADER_STRING_BYTES = 65_536;
+
+    static final int DEFAULT_BLOCK_ROWS = 65_536;
+    static final int DEFAULT_TARGET_RAW_BYTES = 64 * 1024 * 1024;
+    static final int MIN_TARGET_RAW_BYTES = 1 * 1024 * 1024;
+
+    static final String BLOCK_ROWS_PROPERTY = "Inmemo.JournalBlockRows";
+    static final String TARGET_RAW_BYTES_PROPERTY = "Inmemo.JournalBlockTargetBytes";
+    static final String MAX_AGE_HOURS_PROPERTY = "Inmemo.JournalMaxAgeHours";
+
+    private static final long DEFAULT_MAX_AGE_HOURS = 36L;
+
+    private JournalFormat() {
+        // No operations.
+    }
+
+    static int getBlockRows(Logger logger) {
+        return getIntProperty(logger, BLOCK_ROWS_PROPERTY, DEFAULT_BLOCK_ROWS, 1, MAX_BLOCK_ROWS);
+    }
+
+    static int getTargetRawBytes(Logger logger) {
+        return getIntProperty(logger, TARGET_RAW_BYTES_PROPERTY, DEFAULT_TARGET_RAW_BYTES,
+                MIN_TARGET_RAW_BYTES, MAX_BLOCK_RAW_BYTES / 2);
+    }
+
+    static long getMaxAgeMillis(Logger logger) {
+        long hours = getLongProperty(logger, MAX_AGE_HOURS_PROPERTY, DEFAULT_MAX_AGE_HOURS, 1L, 24L * 365L);
+        return hours * 60L * 60L * 1000L;
+    }
+
+    private static int getIntProperty(Logger logger, String name, int defaultValue, int minValue, int maxValue) {
+        String value = System.getProperty(name);
+        if (value == null) {
+            return defaultValue;
+        }
+
+        try {
+            int parsedValue = Integer.parseInt(value.trim());
+            if (parsedValue < minValue) {
+                logger.warn("Property " + name + "=" + value + " is too small, using " + minValue + '.');
+                return minValue;
+            }
+            if (parsedValue > maxValue) {
+                logger.warn("Property " + name + "=" + value + " is too large, using " + maxValue + '.');
+                return maxValue;
+            }
+            return parsedValue;
+        } catch (NumberFormatException e) {
+            logger.warn("Property " + name + "=" + value + " is invalid, using " + defaultValue + '.', e);
+            return defaultValue;
+        }
+    }
+
+    private static long getLongProperty(Logger logger, String name, long defaultValue, long minValue, long maxValue) {
+        String value = System.getProperty(name);
+        if (value == null) {
+            return defaultValue;
+        }
+
+        try {
+            long parsedValue = Long.parseLong(value.trim());
+            if (parsedValue < minValue) {
+                logger.warn("Property " + name + "=" + value + " is too small, using " + minValue + '.');
+                return minValue;
+            }
+            if (parsedValue > maxValue) {
+                logger.warn("Property " + name + "=" + value + " is too large, using " + maxValue + '.');
+                return maxValue;
+            }
+            return parsedValue;
+        } catch (NumberFormatException e) {
+            logger.warn("Property " + name + "=" + value + " is invalid, using " + defaultValue + '.', e);
+            return defaultValue;
+        }
+    }
+}