Use external byte arrays for token stream, this moves the token stream out of the isolate heap. For…

vm/raw_object_snapshot.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/bigint_operations.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 #include "vm/snapshot.h"
 #include "vm/symbols.h"
 #include "vm/visitor.h"
@@ skipping 636 matching lines @@
   intptr_t len = reader->ReadSmiValue();
 
   // Create the token stream object.
   TokenStream& token_stream = TokenStream::ZoneHandle(
       reader->isolate(), NEW_OBJECT_WITH_LEN(TokenStream, len));
   reader->AddBackRef(object_id, &token_stream, kIsDeserialized);
 
   // Set the object tags.
   token_stream.set_tags(tags);
 
-  // Read the stream of tokens into the TokenStream object.
-  {
+  // Read the stream of tokens into the TokenStream object for script
+  // snapshots as we made a copy of token stream.
+  if (kind == Snapshot::kScript) {
     NoGCScope no_gc;
-    reader->ReadBytes(reinterpret_cast<uint8_t*>(token_stream.EntryAddr(0)),
-                      len);
+    RawExternalUint8Array* stream = token_stream.GetStream();
+    reader->ReadBytes(stream->ptr()->external_data_->data(), len);
   }
 
   // Read in the literal/identifier token array.
   *(reader->TokensHandle()) ^= reader->ReadObjectImpl();
   token_stream.SetTokenObjects(*(reader->TokensHandle()));
   // Read in the private key in use by the token stream.
   *(reader->StringHandle()) ^= reader->ReadObjectImpl();
   token_stream.SetPrivateKey(*(reader->StringHandle()));
 
   return token_stream.raw();
 }
 
 
 void RawTokenStream::WriteTo(SnapshotWriter* writer,
                              intptr_t object_id,
                              Snapshot::Kind kind) {
   ASSERT(writer != NULL);
   ASSERT((kind != Snapshot::kMessage) &&
          !RawObject::IsCreatedFromSnapshot(writer->GetObjectTags(this)));
 
   // Write out the serialization header value for this object.
   writer->WriteInlinedObjectHeader(object_id);
 
   // Write out the class and tags information.
   writer->WriteVMIsolateObject(kTokenStreamCid);
   writer->WriteIntptrValue(writer->GetObjectTags(this));
 
   // Write out the length field and the token stream.
-  intptr_t len = Smi::Value(ptr()->length_);
-  writer->Write<RawObject*>(ptr()->length_);
-  writer->WriteBytes(reinterpret_cast<uint8_t*>(ptr()->data_), len);
+  RawExternalUint8Array* stream = ptr()->stream_;
+  intptr_t len = Smi::Value(stream->ptr()->length_);
+  writer->Write<RawObject*>(stream->ptr()->length_);
+  writer->WriteBytes(stream->ptr()->external_data_->data(), len);
 
   // Write out the literal/identifier token array.
   writer->WriteObjectImpl(ptr()->token_objects_);
   // Write out the private key in use by the token stream.
   writer->WriteObjectImpl(ptr()->private_key_);
 }
 
 
 RawScript* Script::ReadFrom(SnapshotReader* reader,
                             intptr_t object_id,
@@ skipping 1475 matching lines @@
   // Write out the class and tags information.
   writer->WriteIndexedObject(kWeakPropertyCid);
   writer->WriteIntptrValue(writer->GetObjectTags(this));
 
   // Write out all the other fields.
   writer->Write<RawObject*>(ptr()->key_);
   writer->Write<RawObject*>(ptr()->value_);
 }
 
 }  // namespace dart