Do not allocate a buffer of 64KB by default when writing a message out. Start

vm/snapshot.h

 // 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.
 
 #ifndef VM_SNAPSHOT_H_
 #define VM_SNAPSHOT_H_
 
 #include "platform/assert.h"
 #include "vm/allocation.h"
 #include "vm/bitfield.h"
@@ skipping 370 matching lines @@
     value = SerializedHeaderData::update(id, value);
     WriteIntptrValue(value);
   }
 
   // Write out a buffer of bytes.
   void WriteBytes(const uint8_t* addr, intptr_t len) {
     stream_.WriteBytes(addr, len);
   }
 
  protected:
-  BaseWriter(uint8_t** buffer, ReAlloc alloc) : stream_(buffer, alloc) {
+  BaseWriter(uint8_t** buffer,
+             ReAlloc alloc,
+             intptr_t increment_size) : stream_(buffer, alloc, increment_size) {
     ASSERT(buffer != NULL);
     ASSERT(alloc != NULL);
   }
   ~BaseWriter() { }
 
   void ReserveHeader() {
     // Make room for recording snapshot buffer size.
     stream_.set_current(stream_.buffer() + Snapshot::kHeaderSize);
   }
 
   void FillHeader(Snapshot::Kind kind) {
     int32_t* data = reinterpret_cast<int32_t*>(stream_.buffer());
     data[Snapshot::kLengthIndex] = stream_.bytes_written();
     data[Snapshot::kSnapshotFlagIndex] = kind;
   }
 
  private:
   WriteStream stream_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(BaseWriter);
 };
 
 
 class SnapshotWriter : public BaseWriter {
  protected:
-  SnapshotWriter(Snapshot::Kind kind, uint8_t** buffer, ReAlloc alloc)
-      : BaseWriter(buffer, alloc),
+  SnapshotWriter(Snapshot::Kind kind,
+                 uint8_t** buffer,
+                 ReAlloc alloc,
+                 intptr_t increment_size)
+      : BaseWriter(buffer, alloc, increment_size),
         kind_(kind),
         object_store_(Isolate::Current()->object_store()),
         class_table_(Isolate::Current()->class_table()),
         forward_list_() {
   }
 
  public:
   // Snapshot kind.
   Snapshot::Kind kind() const { return kind_; }
 
@@ skipping 56 matching lines @@
   friend class RawScript;
   friend class RawTokenStream;
   friend class RawTypeArguments;
   friend class SnapshotWriterVisitor;
   DISALLOW_COPY_AND_ASSIGN(SnapshotWriter);
 };
 
 
 class FullSnapshotWriter : public SnapshotWriter {
  public:
+  static const intptr_t kIncrementSize = 64 * KB;
   FullSnapshotWriter(uint8_t** buffer, ReAlloc alloc)
-      : SnapshotWriter(Snapshot::kFull, buffer, alloc) {
+      : SnapshotWriter(Snapshot::kFull, buffer, alloc, kIncrementSize) {
     ASSERT(buffer != NULL);
     ASSERT(alloc != NULL);
   }
   ~FullSnapshotWriter() { }
 
   // Writes a full snapshot of the Isolate.
   void WriteFullSnapshot();
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FullSnapshotWriter);
 };
 
 
 class ScriptSnapshotWriter : public SnapshotWriter {
  public:
+  static const intptr_t kIncrementSize = 64 * KB;
   ScriptSnapshotWriter(uint8_t** buffer, ReAlloc alloc)
-      : SnapshotWriter(Snapshot::kScript, buffer, alloc) {
+      : SnapshotWriter(Snapshot::kScript, buffer, alloc, kIncrementSize) {
     ASSERT(buffer != NULL);
     ASSERT(alloc != NULL);
   }
   ~ScriptSnapshotWriter() { }
 
   // Writes a partial snapshot of the script.
   void WriteScriptSnapshot(const Library& lib);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ScriptSnapshotWriter);
 };
 
 
 class MessageWriter : public SnapshotWriter {
  public:
+  static const intptr_t kIncrementSize = 512;
   MessageWriter(uint8_t** buffer, ReAlloc alloc)
-      : SnapshotWriter(Snapshot::kMessage, buffer, alloc) {
+      : SnapshotWriter(Snapshot::kMessage, buffer, alloc, kIncrementSize) {
     ASSERT(buffer != NULL);
     ASSERT(alloc != NULL);
   }
   ~MessageWriter() { }
 
   void WriteMessage(const Object& obj);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MessageWriter);
 };
@@ skipping 18 matching lines @@
  private:
   SnapshotWriter* writer_;
   bool as_references_;
 
   DISALLOW_COPY_AND_ASSIGN(SnapshotWriterVisitor);
 };
 
 }  // namespace dart
 
 #endif  // VM_SNAPSHOT_H_