Refactoring of snapshots. This simplifies and improves

src/snapshot-common.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 19 matching lines @@
 #include "v8.h"
 
 #include "api.h"
 #include "serialize.h"
 #include "snapshot.h"
 #include "platform.h"
 
 namespace v8 {
 namespace internal {
 
-bool Snapshot::Deserialize(const byte* content, int len) {
-  SnapshotByteSource source(content, len);
-  Deserializer deserializer(&source);
-  return V8::Initialize(&deserializer);
+
+static void ReserveSpaceForSnapshot(Deserializer* deserializer,
+                                    const char* file_name) {
+  int file_name_length = StrLength(file_name) + 10;
+  Vector<char> name = Vector<char>::New(file_name_length + 1);
+  OS::SNPrintF(name, "%s.size", file_name);
+  FILE* fp = OS::FOpen(name.start(), "r");
+  CHECK_NE(NULL, fp);
+  int new_size, pointer_size, data_size, code_size, map_size, cell_size;
+#ifdef _MSC_VER
+  // Avoid warning about unsafe fscanf from MSVC.
+  // Please note that this is only fine if %c and %s are not being used.
+#define fscanf fscanf_s
+#endif
+  CHECK_EQ(1, fscanf(fp, "new %d\n", &new_size));
+  CHECK_EQ(1, fscanf(fp, "pointer %d\n", &pointer_size));
+  CHECK_EQ(1, fscanf(fp, "data %d\n", &data_size));
+  CHECK_EQ(1, fscanf(fp, "code %d\n", &code_size));
+  CHECK_EQ(1, fscanf(fp, "map %d\n", &map_size));
+  CHECK_EQ(1, fscanf(fp, "cell %d\n", &cell_size));
+#ifdef _MSC_VER
+#undef fscanf
+#endif
+  fclose(fp);
+  deserializer->set_reservation(NEW_SPACE, new_size);
+  deserializer->set_reservation(OLD_POINTER_SPACE, pointer_size);
+  deserializer->set_reservation(OLD_DATA_SPACE, data_size);
+  deserializer->set_reservation(CODE_SPACE, code_size);
+  deserializer->set_reservation(MAP_SPACE, map_size);
+  deserializer->set_reservation(CELL_SPACE, cell_size);
+  name.Dispose();
+}
+
+
+void Snapshot::ReserveSpaceForLinkedInSnapshot(Deserializer* deserializer) {
+  deserializer->set_reservation(NEW_SPACE, new_space_used_);
+  deserializer->set_reservation(OLD_POINTER_SPACE, pointer_space_used_);
+  deserializer->set_reservation(OLD_DATA_SPACE, data_space_used_);
+  deserializer->set_reservation(CODE_SPACE, code_space_used_);
+  deserializer->set_reservation(MAP_SPACE, map_space_used_);
+  deserializer->set_reservation(CELL_SPACE, cell_space_used_);
 }
 
 
 bool Snapshot::Initialize(const char* snapshot_file) {
   if (snapshot_file) {
     int len;
     byte* str = ReadBytes(snapshot_file, &len);
     if (!str) return false;
-    Deserialize(str, len);
+    SnapshotByteSource source(str, len);
+    Deserializer deserializer(&source);
+    ReserveSpaceForSnapshot(&deserializer, snapshot_file);
+    bool success = V8::Initialize(&deserializer);

[Yang, 2012/09/13 08:47:59]

Is there any plans to include a SnapshotByteSink that writes to file in
mksnapshot so that it can be read here?

[Erik Corry, 2012/09/13 12:13:35]

This is currently only used for tests.

     DeleteArray(str);
-    return true;
+    return success;
   } else if (size_ > 0) {
-    Deserialize(raw_data_, raw_size_);
-    return true;
+    SnapshotByteSource source(raw_data_, raw_size_);
+    Deserializer deserializer(&source);
+    ReserveSpaceForLinkedInSnapshot(&deserializer);
+    return V8::Initialize(&deserializer);
   }
   return false;
 }
 
 
 bool Snapshot::HaveASnapshotToStartFrom() {
   return size_ != 0;
 }
 
 
 Handle<Context> Snapshot::NewContextFromSnapshot() {
   if (context_size_ == 0) {
     return Handle<Context>();
   }
-  HEAP->ReserveSpace(new_space_used_,
-                     pointer_space_used_,
-                     data_space_used_,
-                     code_space_used_,
-                     map_space_used_,
-                     cell_space_used_,
-                     large_space_used_);
   SnapshotByteSource source(context_raw_data_,
                             context_raw_size_);
   Deserializer deserializer(&source);
   Object* root;
+  deserializer.set_reservation(NEW_SPACE, context_new_space_used_);
+  deserializer.set_reservation(OLD_POINTER_SPACE, context_pointer_space_used_);
+  deserializer.set_reservation(OLD_DATA_SPACE, context_data_space_used_);
+  deserializer.set_reservation(CODE_SPACE, context_code_space_used_);
+  deserializer.set_reservation(MAP_SPACE, context_map_space_used_);
+  deserializer.set_reservation(CELL_SPACE, context_cell_space_used_);
   deserializer.DeserializePartial(&root);
   CHECK(root->IsContext());
   return Handle<Context>(Context::cast(root));
 }
 
 } }  // namespace v8::internal