Build lite runtime of protobuf-java

Saves ~400kb (3.25mb -> 2.85mb) of runtime+reflect size

generators/infrastructure/build-protobuf-lite.kts

@@ -0,0 +1,87 @@
+package org.jetbrains.kotlin.infrastructure
+
+import java.io.BufferedOutputStream
+import java.io.File
+import java.io.FileOutputStream
+import java.util.jar.JarEntry
+import java.util.jar.JarFile
+import java.util.zip.ZipOutputStream
+
+/**
+ * Strip away all unneeded classes from protobuf-java-*.jar to make a LITE version of the protobuf runtime.
+ * To do this, we load pom.xml from protobuf jar and heuristically extract information about which classes
+ * are kept in the lite runtime.
+ * (This could be done with actually parsing the XML, but this solution works just fine at the moment.)
+ * Then we take the full protobuf.jar and copy its contents to another jar, except those classes
+ * which are not needed in the lite runtime.
+ */
+
+fun main(args: Array<String>) {
+    val INCLUDE_START = "<include>**/"
+    val INCLUDE_END = ".java</include>"
+    val POM_PATH = "META-INF/maven/com.google.protobuf/protobuf-java/pom.xml"
+
+    if (args.size() != 2) {
+        error("Usage: kotlinc -script build-protobuf-lite.kts <path-to-protobuf-jar> <output-path>")
+    }
+
+    val jarFile = File(args[0])
+    val outputPath = args[1]
+
+    assert(jarFile.exists()) { "protobuf jar not found at $jarFile" }
+
+    fun loadAllFromJar(file: File): Map<String, Pair<JarEntry, ByteArray>> {
+        val result = hashMapOf<String, Pair<JarEntry, ByteArray>>()
+        val jar = JarFile(file)
+        try {
+            for (jarEntry in jar.entries()) {
+                result[jarEntry.getName()] = Pair(jarEntry, jar.getInputStream(jarEntry).readBytes())
+            }
+        }
+        finally {
+            // Yes, JarFile does not extend Closeable on JDK 6 so we can't use "use" here
+            jar.close()
+        }
+        return result
+    }
+
+    val allFiles = loadAllFromJar(jarFile)
+
+    val keepClasses = arrayListOf<String>()
+
+    val pomBytes = allFiles[POM_PATH]?.second ?: error("pom.xml is not found in protobuf jar at $POM_PATH")
+    val lines = String(pomBytes).split("\n")
+
+    var liteProfileReached = false
+    for (lineUntrimmed in lines) {
+        val line = lineUntrimmed.trim()
+
+        if (liteProfileReached && line == "</includes>") {
+            break
+        }
+        else if (line == "<id>lite</id>") {
+            liteProfileReached = true
+            continue
+        }
+
+        if (liteProfileReached && line.startsWith(INCLUDE_START) && line.endsWith(INCLUDE_END)) {
+            keepClasses.add(line.substringAfter(INCLUDE_START).substringBeforeLast(INCLUDE_END))
+        }
+    }
+
+    assert(liteProfileReached && keepClasses.isNotEmpty()) { "Wrong pom.xml or the format has changed, check its contents at $POM_PATH" }
+
+    ZipOutputStream(BufferedOutputStream(FileOutputStream(File(outputPath)))).use { output ->
+        for ((name, value) in allFiles) {
+            val className = name.substringAfter("com/google/protobuf/").substringBeforeLast(".class")
+            if (keepClasses.any { className == it || className.startsWith(it + "$") }) {
+                val (entry, bytes) = value
+                output.putNextEntry(entry)
+                output.write(bytes)
+                output.closeEntry()
+            }
+        }
+    }
+}
+
+main(args)

update_dependencies.xml

@@ -279,6 +279,17 @@
         </sequential>
     </macrodef>
 
+    <macrodef name="build-protobuf-java-lite">
+        <sequential>
+            <exec executable="dependencies/bootstrap-compiler/Kotlin/kotlinc/bin/kotlinc" failonerror="true" vmlauncher="false">
+                <arg value="-script"/>
+                <arg value="generators/infrastructure/build-protobuf-lite.kts"/>
+                <arg value="${basedir}/ideaSDK/lib/protobuf-2.5.0.jar"/>
+                <arg value="${basedir}/dependencies/protobuf-2.5.0-lite.jar"/>
+            </exec>
+        </sequential>
+    </macrodef>
+
     <macrodef name="get-asm-sources-and-rename-packages">
         <attribute name="asm.version"/>
         <sequential>
@@ -469,6 +480,8 @@
                  many nice features of IDEA including diffs in the test console.
             -->
             <delete file="ideaSDK/lib/junit.jar"/>
+
+            <build-protobuf-java-lite/>
         </sequential>
     </macrodef>