Extract non-IO part of mksnapshot into an API method.

R=vogelheim@chromium.org

Review URL: https://codereview.chromium.org/789213002

Cr-Commit-Position: refs/heads/master@{#25747}

include/v8.h

@@ -5360,6 +5360,13 @@ class V8_EXPORT V8 {
   static void SetNativesDataBlob(StartupData* startup_blob);
   static void SetSnapshotDataBlob(StartupData* startup_blob);
 
+  /**
+   * Create a new isolate and context for the purpose of capturing a snapshot
+   * Returns { NULL, 0 } on failure.
+   * The caller owns the data array in the return value.
+   */
+  static StartupData CreateSnapshotDataBlob();
+
   /**
    * Adds a message listener.
    *

src/api.cc

@@ -206,6 +206,53 @@ void V8::SetSnapshotDataBlob(StartupData* snapshot_blob) {
 }
 
 
+StartupData V8::CreateSnapshotDataBlob() {
+  Isolate::CreateParams params;
+  params.enable_serializer = true;
+  Isolate* isolate = v8::Isolate::New(params);
+  StartupData result = {NULL, 0};
+  {
+    Isolate::Scope isolate_scope(isolate);
+    i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);
+    Persistent<Context> context;
+    {
+      HandleScope handle_scope(isolate);
+      context.Reset(isolate, Context::New(isolate));
+    }
+    if (!context.IsEmpty()) {
+      // Make sure all builtin scripts are cached.
+      {
+        HandleScope scope(isolate);
+        for (int i = 0; i < i::Natives::GetBuiltinsCount(); i++) {
+          internal_isolate->bootstrapper()->NativesSourceLookup(i);
+        }
+      }
+      // If we don't do this then we end up with a stray root pointing at the
+      // context even after we have disposed of the context.
+      internal_isolate->heap()->CollectAllAvailableGarbage("mksnapshot");
+      i::Object* raw_context = *v8::Utils::OpenPersistent(context);
+      context.Reset();
+
+      i::SnapshotByteSink snapshot_sink;
+      i::StartupSerializer ser(internal_isolate, &snapshot_sink);
+      ser.SerializeStrongReferences();
+
+      i::SnapshotByteSink context_sink;
+      i::PartialSerializer context_ser(internal_isolate, &ser, &context_sink);
+      context_ser.Serialize(&raw_context);
+      ser.SerializeWeakReferences();
+
+      i::SnapshotData sd(snapshot_sink, ser);
+      i::SnapshotData csd(context_sink, context_ser);
+
+      result = i::Snapshot::CreateSnapshotBlob(sd.RawData(), csd.RawData());
+    }
+  }
+  isolate->Dispose();
+  return result;
+}
+
+
 void V8::SetFlagsFromString(const char* str, int length) {
   i::FlagList::SetFlagsFromString(str, length);
 }

src/factory.cc

@@ -2156,7 +2156,7 @@ void Factory::SetNumberStringCache(Handle<Object> number,
       // cache in the snapshot to keep  boot-time memory usage down.
       // If we expand the number string cache already while creating
       // the snapshot then that didn't work out.
-      DCHECK(!isolate()->serializer_enabled() || FLAG_extra_code != NULL);
+      DCHECK(!isolate()->serializer_enabled());
       Handle<FixedArray> new_cache = NewFixedArray(full_size, TENURED);
       isolate()->heap()->set_number_string_cache(*new_cache);
       return;

src/flag-definitions.h

@@ -712,12 +712,8 @@ DEFINE_STRING(testing_serialization_file, "/tmp/serdes",
 #endif
 
 // mksnapshot.cc
-DEFINE_STRING(extra_code, NULL,
-              "A filename with extra code to be included in"
-              " the snapshot (mksnapshot only)")
 DEFINE_STRING(startup_blob, NULL,
-              "Write V8 startup blob file. "
-              "(mksnapshot only)")
+              "Write V8 startup blob file. (mksnapshot only)")
 
 // code-stubs-hydrogen.cc
 DEFINE_BOOL(profile_hydrogen_code_stub_compilation, false,

src/mksnapshot.cc

@@ -36,15 +36,11 @@ class SnapshotWriter {
       startup_blob_file_ = GetFileDescriptorOrDie(startup_blob_file);
   }
 
-  void WriteSnapshot(const i::SnapshotData& sd,
-                     const i::SnapshotData& csd) const {
-    i::SnapshotByteSink sink;
-    sink.PutBlob(sd.RawData(), "startup");
-    sink.PutBlob(csd.RawData(), "context");
-    const i::Vector<const i::byte>& blob = sink.data().ToConstVector();
-
-    WriteSnapshotFile(blob);
-    MaybeWriteStartupBlob(blob);
+  void WriteSnapshot(v8::StartupData blob) const {
+    i::Vector<const i::byte> blob_vector(
+        reinterpret_cast<const i::byte*>(blob.data), blob.raw_size);
+    WriteSnapshotFile(blob_vector);
+    MaybeWriteStartupBlob(blob_vector);
   }
 
  private:
@@ -115,18 +111,6 @@ class SnapshotWriter {
 };
 
 
-void DumpException(Handle<Message> message) {
-  String::Utf8Value message_string(message->Get());
-  String::Utf8Value message_line(message->GetSourceLine());
-  fprintf(stderr, "%s at line %d\n", *message_string, message->GetLineNumber());
-  fprintf(stderr, "%s\n", *message_line);
-  for (int i = 0; i <= message->GetEndColumn(); ++i) {
-    fprintf(stderr, "%c", i < message->GetStartColumn() ? ' ' : '^');
-  }
-  fprintf(stderr, "\n");
-}
-
-
 int main(int argc, char** argv) {
   // By default, log code create information in the snapshot.
   i::FLAG_log_code = true;
@@ -135,6 +119,8 @@ int main(int argc, char** argv) {
   // at runtime.
   i::FLAG_harmony_shipping = false;
 
+  i::FLAG_logfile_per_isolate = false;
+
   // Print the usage if an error occurs when parsing the command line
   // flags or if the help flag is set.
   int result = i::FlagList::SetFlagsFromCommandLine(&argc, argv, true);
@@ -150,101 +136,15 @@ int main(int argc, char** argv) {
   v8::V8::InitializePlatform(platform);
   v8::V8::Initialize();
 
-  i::FLAG_logfile_per_isolate = false;
-
-  Isolate::CreateParams params;
-  params.enable_serializer = true;
-  Isolate* isolate = v8::Isolate::New(params);
-  { Isolate::Scope isolate_scope(isolate);
-    i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);
-
-    Persistent<Context> context;
-    {
-      HandleScope handle_scope(isolate);
-      context.Reset(isolate, Context::New(isolate));
-    }
-
-    if (context.IsEmpty()) {
-      fprintf(stderr,
-              "\nException thrown while compiling natives - see above.\n\n");
-      exit(1);
-    }
-    if (i::FLAG_extra_code != NULL) {
-      // Capture 100 frames if anything happens.
-      V8::SetCaptureStackTraceForUncaughtExceptions(true, 100);
-      HandleScope scope(isolate);
-      v8::Context::Scope cscope(v8::Local<v8::Context>::New(isolate, context));
-      const char* name = i::FLAG_extra_code;
-      FILE* file = base::OS::FOpen(name, "rb");
-      if (file == NULL) {
-        fprintf(stderr, "Failed to open '%s': errno %d\n", name, errno);
-        exit(1);
-      }
-
-      fseek(file, 0, SEEK_END);
-      int size = ftell(file);
-      rewind(file);
-
-      char* chars = new char[size + 1];
-      chars[size] = '\0';
-      for (int i = 0; i < size;) {
-        int read = static_cast<int>(fread(&chars[i], 1, size - i, file));
-        if (read < 0) {
-          fprintf(stderr, "Failed to read '%s': errno %d\n", name, errno);
-          exit(1);
-        }
-        i += read;
-      }
-      fclose(file);
-      Local<String> source = String::NewFromUtf8(isolate, chars);
-      TryCatch try_catch;
-      Local<Script> script = Script::Compile(source);
-      if (try_catch.HasCaught()) {
-        fprintf(stderr, "Failure compiling '%s'\n", name);
-        DumpException(try_catch.Message());
-        exit(1);
-      }
-      script->Run();
-      if (try_catch.HasCaught()) {
-        fprintf(stderr, "Failure running '%s'\n", name);
-        DumpException(try_catch.Message());
-        exit(1);
-      }
-    }
-    // Make sure all builtin scripts are cached.
-    { HandleScope scope(isolate);
-      for (int i = 0; i < i::Natives::GetBuiltinsCount(); i++) {
-        internal_isolate->bootstrapper()->NativesSourceLookup(i);
-      }
-    }
-    // If we don't do this then we end up with a stray root pointing at the
-    // context even after we have disposed of the context.
-    internal_isolate->heap()->CollectAllAvailableGarbage("mksnapshot");
-    i::Object* raw_context = *v8::Utils::OpenPersistent(context);
-    context.Reset();
-
-    // This results in a somewhat smaller snapshot, probably because it gets
-    // rid of some things that are cached between garbage collections.
-    i::SnapshotByteSink snapshot_sink;
-    i::StartupSerializer ser(internal_isolate, &snapshot_sink);
-    ser.SerializeStrongReferences();
-
-    i::SnapshotByteSink context_sink;
-    i::PartialSerializer context_ser(internal_isolate, &ser, &context_sink);
-    context_ser.Serialize(&raw_context);
-    ser.SerializeWeakReferences();
-
-    {
-      SnapshotWriter writer(argv[1]);
-      if (i::FLAG_startup_blob)
-        writer.SetStartupBlobFile(i::FLAG_startup_blob);
-      i::SnapshotData sd(snapshot_sink, ser);
-      i::SnapshotData csd(context_sink, context_ser);
-      writer.WriteSnapshot(sd, csd);
-    }
+  {
+    SnapshotWriter writer(argv[1]);
+    if (i::FLAG_startup_blob) writer.SetStartupBlobFile(i::FLAG_startup_blob);
+    StartupData blob = v8::V8::CreateSnapshotDataBlob();
+    CHECK(blob.data);
+    writer.WriteSnapshot(blob);
+    delete[] blob.data;
   }
 
-  isolate->Dispose();
   V8::Dispose();
   V8::ShutdownPlatform();
   delete platform;

src/snapshot-common.cc

@@ -19,37 +19,13 @@ bool Snapshot::HaveASnapshotToStartFrom() {
 }
 
 
-const Vector<const byte> Snapshot::StartupSnapshot() {
-  DCHECK(HaveASnapshotToStartFrom());
-  const v8::StartupData blob = SnapshotBlob();
-  SnapshotByteSource source(blob.data, blob.raw_size);
-  const byte* data;
-  int length;
-  bool success = source.GetBlob(&data, &length);
-  CHECK(success);
-  return Vector<const byte>(data, length);
-}
-
-
-const Vector<const byte> Snapshot::ContextSnapshot() {
-  DCHECK(HaveASnapshotToStartFrom());
-  const v8::StartupData blob = SnapshotBlob();
-  SnapshotByteSource source(blob.data, blob.raw_size);
-  const byte* data;
-  int length;
-  bool success = source.GetBlob(&data, &length);
-  success &= source.GetBlob(&data, &length);
-  CHECK(success);
-  return Vector<const byte>(data, length);
-}
-
-
 bool Snapshot::Initialize(Isolate* isolate) {
   if (!HaveASnapshotToStartFrom()) return false;
   base::ElapsedTimer timer;
   if (FLAG_profile_deserialization) timer.Start();
 
-  SnapshotData snapshot_data(StartupSnapshot());
+  const v8::StartupData blob = SnapshotBlob();
+  SnapshotData snapshot_data(ExtractStartupData(&blob));
   Deserializer deserializer(&snapshot_data);
   bool success = isolate->Init(&deserializer);
   if (FLAG_profile_deserialization) {
@@ -63,7 +39,8 @@ bool Snapshot::Initialize(Isolate* isolate) {
 Handle<Context> Snapshot::NewContextFromSnapshot(Isolate* isolate) {
   if (!HaveASnapshotToStartFrom()) return Handle<Context>();
 
-  SnapshotData snapshot_data(ContextSnapshot());
+  const v8::StartupData blob = SnapshotBlob();
+  SnapshotData snapshot_data(ExtractContextData(&blob));
   Deserializer deserializer(&snapshot_data);
   Object* root;
   deserializer.DeserializePartial(isolate, &root);
@@ -71,4 +48,44 @@ Handle<Context> Snapshot::NewContextFromSnapshot(Isolate* isolate) {
   return Handle<Context>(Context::cast(root));
 }
 
+
+v8::StartupData Snapshot::CreateSnapshotBlob(
+    const Vector<const byte> startup_data,
+    const Vector<const byte> context_data) {
+  int startup_length = startup_data.length();
+  int context_length = context_data.length();
+  int context_offset = kIntSize + startup_length;
+  int length = context_offset + context_length;
+  char* data = new char[length];
+
+  memcpy(data, &startup_length, kIntSize);
+  memcpy(data + kIntSize, startup_data.begin(), startup_length);
+  memcpy(data + context_offset, context_data.begin(), context_length);
+  v8::StartupData result = {data, length};
+  return result;
+}
+
+
+Vector<const byte> Snapshot::ExtractStartupData(const v8::StartupData* data) {
+  DCHECK_LT(kIntSize, data->raw_size);
+  int startup_length;
+  memcpy(&startup_length, data->data, kIntSize);
+  DCHECK_LT(startup_length, data->raw_size);
+  const byte* startup_data =
+      reinterpret_cast<const byte*>(data->data + kIntSize);
+  return Vector<const byte>(startup_data, startup_length);
+}
+
+
+Vector<const byte> Snapshot::ExtractContextData(const v8::StartupData* data) {
+  DCHECK_LT(kIntSize, data->raw_size);
+  int startup_length;
+  memcpy(&startup_length, data->data, kIntSize);
+  int context_offset = kIntSize + startup_length;
+  const byte* context_data =
+      reinterpret_cast<const byte*>(data->data + context_offset);
+  DCHECK_LT(context_offset, data->raw_size);
+  int context_length = data->raw_size - context_offset;
+  return Vector<const byte>(context_data, context_length);
+}
 } }  // namespace v8::internal

src/snapshot-external.cc

@@ -26,11 +26,10 @@ void SetSnapshotFromFile(StartupData* snapshot_blob) {
   DCHECK(snapshot_blob->data);
   DCHECK(snapshot_blob->raw_size > 0);
   DCHECK(!external_startup_blob.data);
-  external_startup_blob = *snapshot_blob;
-
   // Validate snapshot blob.
-  DCHECK(!Snapshot::StartupSnapshot().is_empty());
-  DCHECK(!Snapshot::ContextSnapshot().is_empty());
+  DCHECK(!Snapshot::ExtractStartupData(snapshot_blob).is_empty());
+  DCHECK(!Snapshot::ExtractContextData(snapshot_blob).is_empty());
+  external_startup_blob = *snapshot_blob;
 }
 
 

src/snapshot-source-sink.cc

@@ -50,13 +50,6 @@ void SnapshotByteSink::PutRaw(const byte* data, int number_of_bytes,
 }
 
 
-void SnapshotByteSink::PutBlob(Vector<const byte> blob,
-                               const char* description) {
-  PutInt(blob.length(), description);
-  PutRaw(blob.start(), blob.length(), description);
-}
-
-
 bool SnapshotByteSource::AtEOF() {
   if (0u + length_ - position_ > 2 * sizeof(uint32_t)) return false;
   for (int x = position_; x < length_; x++) {

src/snapshot-source-sink.h

@@ -91,7 +91,6 @@ class SnapshotByteSink {
 
   void PutInt(uintptr_t integer, const char* description);
   void PutRaw(const byte* data, int number_of_bytes, const char* description);
-  void PutBlob(Vector<const byte> blob, const char* description);
   int Position() { return data_.length(); }
 
   const List<byte>& data() const { return data_; }

src/snapshot.h

@@ -10,7 +10,7 @@
 namespace v8 {
 namespace internal {
 
-class Snapshot {
+class Snapshot : public AllStatic {
  public:
   // Initialize the Isolate from the internal snapshot. Returns false if no
   // snapshot could be found.
@@ -18,12 +18,18 @@ class Snapshot {
   // Create a new context using the internal partial snapshot.
   static Handle<Context> NewContextFromSnapshot(Isolate* isolate);
 
-  static const Vector<const byte> StartupSnapshot();
-  static const Vector<const byte> ContextSnapshot();
   static bool HaveASnapshotToStartFrom();
 
+  // To be implemented by the snapshot source.
   static const v8::StartupData SnapshotBlob();
 
+  static v8::StartupData CreateSnapshotBlob(
+      const Vector<const byte> startup_data,
+      const Vector<const byte> context_data);
+
+  static Vector<const byte> ExtractStartupData(const v8::StartupData* data);
+  static Vector<const byte> ExtractContextData(const v8::StartupData* data);
+
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(Snapshot);
 };