Optionally compress V8 code cache data with snappy.

Source/bindings/core/v8/V8ScriptRunner.cpp

Index: Source/bindings/core/v8/V8ScriptRunner.cpp
diff --git a/Source/bindings/core/v8/V8ScriptRunner.cpp b/Source/bindings/core/v8/V8ScriptRunner.cpp
index 71a86becbd9539d4911793591189016ed0bade6c..3fea6fa726713b638b60812b545344e3fa949178 100644
--- a/Source/bindings/core/v8/V8ScriptRunner.cpp
+++ b/Source/bindings/core/v8/V8ScriptRunner.cpp
@@ -37,6 +37,7 @@
 #include "core/fetch/ScriptResource.h"
 #include "platform/ScriptForbiddenScope.h"
 #include "platform/TraceEvent.h"
+#include "third_party/snappy/src/snappy.h"
 
 namespace blink {
 
@@ -64,29 +65,49 @@ v8::Local<v8::Value> throwStackOverflowExceptionIfNeeded(v8::Isolate* isolate)
     return result;
 }
 
-v8::Local<v8::Script> compileAndProduceCache(v8::Isolate* isolate, v8::Handle<v8::String> code, v8::ScriptOrigin origin, ScriptResource* resource, v8::ScriptCompiler::CompileOptions options, unsigned cacheTag, Resource::MetadataCacheType cacheType)
+void writeToCache(ScriptResource* resource, unsigned cacheTag, Resource::MetadataCacheType cacheType, const v8::ScriptCompiler::CachedData* cachedData, bool compressed)
+{
+    const char* data = reinterpret_cast<const char*>(cachedData->data);
+    int length = cachedData->length;
+    std::string compressedOutput;
+    if (compressed) {
+        snappy::Compress(data, length, &compressedOutput);
+        data = compressedOutput.data();
+        length = compressedOutput.length();
+    }
+    resource->clearCachedMetadata();
+    resource->setCachedMetadata(
+        cacheTag,
+        data,
+        length,
+        cacheType);
+}
+
+v8::Local<v8::Script> compileAndProduceCache(v8::Isolate* isolate, v8::Handle<v8::String> code, v8::ScriptOrigin origin, ScriptResource* resource, v8::ScriptCompiler::CompileOptions options, unsigned cacheTag, Resource::MetadataCacheType cacheType, bool compressed)
 {
     v8::ScriptCompiler::Source source(code, origin);
     v8::Local<v8::Script> script = v8::ScriptCompiler::Compile(isolate, &source, options);
     const v8::ScriptCompiler::CachedData* cachedData = source.GetCachedData();
-    if (resource && cachedData) {
-        resource->clearCachedMetadata();
-        resource->setCachedMetadata(
-            cacheTag,
-            reinterpret_cast<const char*>(cachedData->data),
-            cachedData->length,
-            cacheType);
-    }
+    if (resource && cachedData)
+        writeToCache(resource, cacheTag, cacheType, cachedData, compressed);
     return script;
 }
 
-v8::Local<v8::Script> compileAndConsumeCache(v8::Isolate* isolate, v8::Handle<v8::String> code, v8::ScriptOrigin origin, ScriptResource* resource, v8::ScriptCompiler::CompileOptions options, unsigned cacheTag)
+v8::Local<v8::Script> compileAndConsumeCache(v8::Isolate* isolate, v8::Handle<v8::String> code, v8::ScriptOrigin origin, ScriptResource* resource, v8::ScriptCompiler::CompileOptions options, unsigned cacheTag, bool compressed)
 {
     // Consume existing cache data:
     CachedMetadata* cachedMetadata = resource->cachedMetadata(cacheTag);
+    const char* data = cachedMetadata->data();
+    int length = cachedMetadata->size();
+    std::string uncompressedOutput;
+    if (compressed) {
+        snappy::Uncompress(data, length, &uncompressedOutput);
+        data = uncompressedOutput.data();
+        length = uncompressedOutput.length();
+    }
     v8::ScriptCompiler::CachedData* cachedData = new v8::ScriptCompiler::CachedData(
-        reinterpret_cast<const uint8_t*>(cachedMetadata->data()),
-        cachedMetadata->size(),
+        reinterpret_cast<const uint8_t*>(data),
+        length,
         v8::ScriptCompiler::CachedData::BufferNotOwned);
     v8::ScriptCompiler::Source source(code, origin, cachedData);
     return v8::ScriptCompiler::Compile(isolate, &source, options);
@@ -114,6 +135,7 @@ v8::Local<v8::Script> V8ScriptRunner::compileScript(v8::Handle<v8::String> code,
 
     v8::Local<v8::Script> script;
     unsigned cacheTag = 0;
+    bool compressed = cacheOptions == V8CacheOptionsCodeCompressed;
     if (streamer) {
         // We don't stream scripts which don't have a Resource.
         ASSERT(resource);
@@ -126,37 +148,38 @@ v8::Local<v8::Script> V8ScriptRunner::compileScript(v8::Handle<v8::String> code,
         // streamer is started. Here we only need to get the data out.
         const v8::ScriptCompiler::CachedData* newCachedData = streamer->source()->GetCachedData();
         if (newCachedData) {
-            resource->clearCachedMetadata();
-            resource->setCachedMetadata(streamer->cachedDataType(), reinterpret_cast<const char*>(newCachedData->data), newCachedData->length, Resource::CacheLocally);
+            // TODO(yangguo,vogelheim): code cache should use Resource::SendToPlatform.
+            writeToCache(resource, streamer->cachedDataType(), Resource::CacheLocally, newCachedData, compressed);
         }
     } else if (!resource || !resource->url().protocolIsInHTTPFamily() || code->Length() < 1024) {
         v8::ScriptCompiler::Source source(code, origin);
         script = v8::ScriptCompiler::Compile(isolate, &source, v8::ScriptCompiler::kNoCompileOptions);
     } else {
+        Resource::MetadataCacheType cacheType = Resource::CacheLocally;
+        v8::ScriptCompiler::CompileOptions consumeOption = v8::ScriptCompiler::kConsumeParserCache;
+        v8::ScriptCompiler::CompileOptions produceOption = v8::ScriptCompiler::kProduceParserCache;
         switch (cacheOptions) {
+        case V8CacheOptionsOff:
+            // Use default.
+            cacheTag = tagForParserCache();
+            break;
         case V8CacheOptionsParse:
             cacheTag = tagForParserCache();
-            script = resource->cachedMetadata(cacheTag)
-                ? compileAndConsumeCache(isolate, code, origin, resource, v8::ScriptCompiler::kConsumeParserCache, cacheTag)
-                : compileAndProduceCache(isolate, code, origin, resource, v8::ScriptCompiler::kProduceParserCache, cacheTag, Resource::SendToPlatform);
+            cacheType = Resource::SendToPlatform;
+            consumeOption = v8::ScriptCompiler::kConsumeParserCache;
+            produceOption = v8::ScriptCompiler::kProduceParserCache;
             break;
+        case V8CacheOptionsCodeCompressed:
         case V8CacheOptionsCode:
             cacheTag = tagForCodeCache();
-            script = resource->cachedMetadata(cacheTag)
-                ? compileAndConsumeCache(isolate, code, origin, resource, v8::ScriptCompiler::kConsumeCodeCache, cacheTag)
-                : compileAndProduceCache(isolate, code, origin, resource, v8::ScriptCompiler::kProduceCodeCache, cacheTag, Resource::SendToPlatform);
-            break;
-        case V8CacheOptionsOff:
-            // Previous behaviour was to always generate an in-memory parser
-            // cache. We emulate this here.
-            // FIXME: Determine whether this should get its own setting, so we
-            //        can also have a true 'off'.
-            cacheTag = tagForParserCache();
-            script = resource->cachedMetadata(cacheTag)
-                ? compileAndConsumeCache(isolate, code, origin, resource, v8::ScriptCompiler::kConsumeParserCache, cacheTag)
-                : compileAndProduceCache(isolate, code, origin, resource, v8::ScriptCompiler::kProduceParserCache, cacheTag, Resource::CacheLocally);
+            cacheType = Resource::SendToPlatform;
+            consumeOption = v8::ScriptCompiler::kConsumeCodeCache;
+            produceOption = v8::ScriptCompiler::kProduceCodeCache;
             break;
         }
+        script = resource->cachedMetadata(cacheTag)
+            ? compileAndConsumeCache(isolate, code, origin, resource, consumeOption, cacheTag, compressed)
+            : compileAndProduceCache(isolate, code, origin, resource, produceOption, cacheTag, cacheType, compressed);
     }
     return script;
 }