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// Copyright 2018 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/snapshot/read-only-serializer.h"
#include "src/api/api.h"
#include "src/diagnostics/code-tracer.h"
#include "src/execution/v8threads.h"
#include "src/handles/global-handles.h"
#include "src/heap/read-only-heap.h"
#include "src/objects/objects-inl.h"
#include "src/objects/slots.h"
#include "src/snapshot/startup-serializer.h"
namespace v8 {
namespace internal {
ReadOnlySerializer::ReadOnlySerializer(Isolate* isolate,
Snapshot::SerializerFlags flags)
: RootsSerializer(isolate, flags, RootIndex::kFirstReadOnlyRoot) {
STATIC_ASSERT(RootIndex::kFirstReadOnlyRoot == RootIndex::kFirstRoot);
allocator()->UseCustomChunkSize(FLAG_serialization_chunk_size);
}
ReadOnlySerializer::~ReadOnlySerializer() {
OutputStatistics("ReadOnlySerializer");
}
void ReadOnlySerializer::SerializeObject(HeapObject obj) {
CHECK(ReadOnlyHeap::Contains(obj));
CHECK_IMPLIES(obj.IsString(), obj.IsInternalizedString());
if (SerializeHotObject(obj)) return;
if (IsRootAndHasBeenSerialized(obj) && SerializeRoot(obj)) {
return;
}
if (SerializeBackReference(obj)) return;
CheckRehashability(obj);
// Object has not yet been serialized. Serialize it here.
ObjectSerializer object_serializer(this, obj, &sink_);
object_serializer.Serialize();
#ifdef DEBUG
serialized_objects_.insert(obj);
#endif
}
void ReadOnlySerializer::SerializeReadOnlyRoots() {
// No active threads.
CHECK_NULL(isolate()->thread_manager()->FirstThreadStateInUse());
// No active or weak handles.
CHECK_IMPLIES(!allow_active_isolate_for_testing(),
isolate()->handle_scope_implementer()->blocks()->empty());
ReadOnlyRoots(isolate()).Iterate(this);
}
void ReadOnlySerializer::FinalizeSerialization() {
// This comes right after serialization of the other snapshots, where we
// add entries to the read-only object cache. Add one entry with 'undefined'
// to terminate the read-only object cache.
Object undefined = ReadOnlyRoots(isolate()).undefined_value();
VisitRootPointer(Root::kReadOnlyObjectCache, nullptr,
FullObjectSlot(&undefined));
SerializeDeferredObjects();
Pad();
#ifdef DEBUG
// Check that every object on read-only heap is reachable (and was
// serialized).
ReadOnlyHeapObjectIterator iterator(isolate()->read_only_heap());
for (HeapObject object = iterator.Next(); !object.is_null();
object = iterator.Next()) {
CHECK(serialized_objects_.count(object));
}
#endif
}
bool ReadOnlySerializer::MustBeDeferred(HeapObject object) {
if (root_has_been_serialized(RootIndex::kFreeSpaceMap) &&
root_has_been_serialized(RootIndex::kOnePointerFillerMap) &&
root_has_been_serialized(RootIndex::kTwoPointerFillerMap)) {
// All required root objects are serialized, so any aligned objects can
// be saved without problems.
return false;
}
// Just defer everything except for Map objects until all required roots are
// serialized. Some objects may have special alignment requirements, that may
// not be fulfilled during deserialization until few first root objects are
// serialized. But we must serialize Map objects since deserializer checks
// that these root objects are indeed Maps.
return !object.IsMap();
}
bool ReadOnlySerializer::SerializeUsingReadOnlyObjectCache(
SnapshotByteSink* sink, HeapObject obj) {
if (!ReadOnlyHeap::Contains(obj)) return false;
// Get the cache index and serialize it into the read-only snapshot if
// necessary.
int cache_index = SerializeInObjectCache(obj);
// Writing out the cache entry into the calling serializer's sink.
sink->Put(kReadOnlyObjectCache, "ReadOnlyObjectCache");
sink->PutInt(cache_index, "read_only_object_cache_index");
return true;
}
} // namespace internal
} // namespace v8
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