Reland "Use same blob format for internal and external snapshots."

src/snapshot-external.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Used for building with external snapshots.
 
 #include "src/snapshot.h"
 
 #include "src/serialize.h"
 #include "src/snapshot-source-sink.h"
 #include "src/v8.h"  // for V8::Initialize
 
+
+#ifndef V8_USE_EXTERNAL_STARTUP_DATA
+#error snapshot-external.cc is used only for the external snapshot build.
+#endif  // V8_USE_EXTERNAL_STARTUP_DATA
+
+
 namespace v8 {
 namespace internal {
 
-
-struct SnapshotImpl {
- public:
-  const byte* data;
-  int size;
-  const byte* context_data;
-  int context_size;
-};
-
-
-static SnapshotImpl* snapshot_impl_ = NULL;
-
-
-bool Snapshot::HaveASnapshotToStartFrom() {
-  return snapshot_impl_ != NULL;
-}
-
-
-bool Snapshot::Initialize(Isolate* isolate) {
-  if (!HaveASnapshotToStartFrom()) return false;
-  base::ElapsedTimer timer;
-  if (FLAG_profile_deserialization) timer.Start();
-
-  SnapshotData snapshot_data(snapshot_impl_->data, snapshot_impl_->size);
-  Deserializer deserializer(&snapshot_data);
-  bool success = isolate->Init(&deserializer);
-  if (FLAG_profile_deserialization) {
-    double ms = timer.Elapsed().InMillisecondsF();
-    PrintF("[Snapshot loading and deserialization took %0.3f ms]\n", ms);
-  }
-  return success;
-}
-
-
-Handle<Context> Snapshot::NewContextFromSnapshot(Isolate* isolate) {
-  if (!HaveASnapshotToStartFrom()) return Handle<Context>();
-
-  SnapshotData snapshot_data(snapshot_impl_->context_data,
-                             snapshot_impl_->context_size);
-  Deserializer deserializer(&snapshot_data);
-  Object* root;
-  deserializer.DeserializePartial(isolate, &root);
-  CHECK(root->IsContext());
-  return Handle<Context>(Context::cast(root));
-}
-
+static v8::StartupData external_startup_blob = {NULL, 0};

[vogelheim, 2014/12/10 11:41:58]

Hmm... does this count as a static initializer, which I hear we don't like very
much?

(Sorry for the vagueness, but actually I'm not entirely sure what V8's and/or
Chromium's rules on this are.)

 
 void SetSnapshotFromFile(StartupData* snapshot_blob) {
   DCHECK(snapshot_blob);
   DCHECK(snapshot_blob->data);
   DCHECK(snapshot_blob->raw_size > 0);
-  DCHECK(!snapshot_impl_);
+  DCHECK(!external_startup_blob.data);
+  external_startup_blob = *snapshot_blob;
 
-  snapshot_impl_ = new SnapshotImpl;
-  SnapshotByteSource source(reinterpret_cast<const byte*>(snapshot_blob->data),
-                            snapshot_blob->raw_size);
-  bool success = source.GetBlob(&snapshot_impl_->data,
-                                &snapshot_impl_->size);
-  success &= source.GetBlob(&snapshot_impl_->context_data,
-                            &snapshot_impl_->context_size);
-  DCHECK(success);
+  // Validate snapshot blob.
+  DCHECK(!Snapshot::StartupSnapshot().is_empty());
+  DCHECK(!Snapshot::ContextSnapshot().is_empty());
 }
 
+
+const v8::StartupData Snapshot::SnapshotBlob() { return external_startup_blob; }
 } }  // namespace v8::internal