Use locker when creating snapshot if necessary.

src/api.cc

 // Copyright 2012 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.
 
 #include "src/api.h"
 
 #include <string.h>  // For memcpy, strlen.
 #ifdef V8_USE_ADDRESS_SANITIZER
 #include <sanitizer/asan_interface.h>
 #endif  // V8_USE_ADDRESS_SANITIZER
@@ skipping 304 matching lines @@
   if (try_catch.HasCaught()) return false;
   ScriptOrigin origin(String::NewFromUtf8(isolate, "<embedded script>"));
   ScriptCompiler::Source source(source_string, origin);
   Local<Script> script = ScriptCompiler::Compile(isolate, &source);
   if (try_catch.HasCaught()) return false;
   script->Run();
   return !try_catch.HasCaught();
 }
 
 
+StartupData CreateSnapshotWithinIsolate(Isolate* isolate,
+                                        const char* custom_source) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  Isolate::Scope isolate_scope(isolate);
+  i_isolate->Init(NULL);
+  Persistent<Context> context;
+  i::Snapshot::Metadata metadata;
+  {
+    HandleScope handle_scope(isolate);
+    Handle<Context> new_context = Context::New(isolate);
+    context.Reset(isolate, new_context);
+    if (custom_source != NULL) {
+      metadata.set_embeds_script(true);
+      Context::Scope context_scope(new_context);
+      if (!RunExtraCode(isolate, custom_source)) context.Reset();
+    }
+  }
+
+  if (context.IsEmpty()) return {NULL, 0};
+
+  // Make sure all builtin scripts are cached.
+  {
+    HandleScope scope(isolate);
+    for (int i = 0; i < i::Natives::GetBuiltinsCount(); i++) {
+      i_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.
+  i_isolate->heap()->CollectAllAvailableGarbage("CreateSnapshotDataBlob");
+  i::Object* raw_context = *v8::Utils::OpenPersistent(context);
+  context.Reset();
+
+  i::SnapshotByteSink snapshot_sink;
+  i::StartupSerializer ser(i_isolate, &snapshot_sink);
+  ser.SerializeStrongReferences();
+
+  i::SnapshotByteSink context_sink;
+  i::PartialSerializer context_ser(i_isolate, &ser, &context_sink);
+  context_ser.Serialize(&raw_context);
+  ser.SerializeWeakReferences();
+
+  return i::Snapshot::CreateSnapshotBlob(ser, context_ser, metadata);
+}
+
+
 StartupData V8::CreateSnapshotDataBlob(const char* custom_source) {
-  i::Isolate* internal_isolate = new i::Isolate(true);
-  Isolate* isolate = reinterpret_cast<Isolate*>(internal_isolate);
+  Isolate* isolate = reinterpret_cast<Isolate*>(new i::Isolate(true));
   StartupData result = {NULL, 0};
-  {
-    Isolate::Scope isolate_scope(isolate);
-    internal_isolate->Init(NULL);
-    Persistent<Context> context;
-    i::Snapshot::Metadata metadata;
-    {
-      HandleScope handle_scope(isolate);
-      Handle<Context> new_context = Context::New(isolate);
-      context.Reset(isolate, new_context);
-      if (custom_source != NULL) {
-        metadata.set_embeds_script(true);
-        Context::Scope context_scope(new_context);
-        if (!RunExtraCode(isolate, custom_source)) context.Reset();
-      }
-    }
-    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();
-
-      result = i::Snapshot::CreateSnapshotBlob(ser, context_ser, metadata);
-    }
+  if (Locker::IsActive()) {
+    Locker lock(isolate);
+    result = CreateSnapshotWithinIsolate(isolate, custom_source);
+  } else {
+    result = CreateSnapshotWithinIsolate(isolate, custom_source);

[vogelheim, 2015/03/03 13:18:29]

I'm confused by this. Admittedly I don't understand how the locker is supposed
to work and I'm mostly pattern-matching the code review, so quite possibly the
confusion is on my part...

I take it the Locker is meant to be used be the embedder. For all I can see,
this is the only case in the API where the API instantiates a Locker itself.
Also, I can't find the pattern of Locker-ing things if Locker::IsActive
elsewhere. Why is this the right thing to do here? Is is because we also create
our own Isolate here?

   }
   isolate->Dispose();
   return result;
 }
 
 
 void V8::SetFlagsFromString(const char* str, int length) {
   i::FlagList::SetFlagsFromString(str, length);
 }
 
@@ skipping 7597 matching lines @@
   Isolate* isolate = reinterpret_cast<Isolate*>(info.GetIsolate());
   Address callback_address =
       reinterpret_cast<Address>(reinterpret_cast<intptr_t>(callback));
   VMState<EXTERNAL> state(isolate);
   ExternalCallbackScope call_scope(isolate, callback_address);
   callback(info);
 }
 
 
 } }  // namespace v8::internal