| // Copyright 2006-2008 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. |
| |
| // The common functionality when building with or without snapshots. |
| |
| #include "src/snapshot/snapshot.h" |
| |
| #include "src/api.h" |
| #include "src/base/platform/platform.h" |
| #include "src/full-codegen/full-codegen.h" |
| #include "src/snapshot/deserializer.h" |
| #include "src/snapshot/snapshot-source-sink.h" |
| #include "src/version.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| #ifdef DEBUG |
| bool Snapshot::SnapshotIsValid(v8::StartupData* snapshot_blob) { |
| return !Snapshot::ExtractStartupData(snapshot_blob).is_empty() && |
| !Snapshot::ExtractContextData(snapshot_blob).is_empty(); |
| } |
| #endif // DEBUG |
| |
| |
| bool Snapshot::HaveASnapshotToStartFrom(Isolate* isolate) { |
| // Do not use snapshots if the isolate is used to create snapshots. |
| return isolate->snapshot_blob() != NULL && |
| isolate->snapshot_blob()->data != NULL; |
| } |
| |
| |
| bool Snapshot::EmbedsScript(Isolate* isolate) { |
| if (!isolate->snapshot_available()) return false; |
| return ExtractMetadata(isolate->snapshot_blob()).embeds_script(); |
| } |
| |
| |
| uint32_t Snapshot::SizeOfFirstPage(Isolate* isolate, AllocationSpace space) { |
| DCHECK(space >= FIRST_PAGED_SPACE && space <= LAST_PAGED_SPACE); |
| if (!isolate->snapshot_available()) { |
| return static_cast<uint32_t>(MemoryAllocator::PageAreaSize(space)); |
| } |
| uint32_t size; |
| int offset = kFirstPageSizesOffset + (space - FIRST_PAGED_SPACE) * kInt32Size; |
| memcpy(&size, isolate->snapshot_blob()->data + offset, kInt32Size); |
| return size; |
| } |
| |
| |
| bool Snapshot::Initialize(Isolate* isolate) { |
| if (!isolate->snapshot_available()) return false; |
| base::ElapsedTimer timer; |
| if (FLAG_profile_deserialization) timer.Start(); |
| |
| const v8::StartupData* blob = isolate->snapshot_blob(); |
| Vector<const byte> startup_data = ExtractStartupData(blob); |
| SnapshotData snapshot_data(startup_data); |
| Deserializer deserializer(&snapshot_data); |
| bool success = isolate->Init(&deserializer); |
| if (FLAG_profile_deserialization) { |
| double ms = timer.Elapsed().InMillisecondsF(); |
| int bytes = startup_data.length(); |
| PrintF("[Deserializing isolate (%d bytes) took %0.3f ms]\n", bytes, ms); |
| } |
| return success; |
| } |
| |
| |
| MaybeHandle<Context> Snapshot::NewContextFromSnapshot( |
| Isolate* isolate, Handle<JSGlobalProxy> global_proxy) { |
| if (!isolate->snapshot_available()) return Handle<Context>(); |
| base::ElapsedTimer timer; |
| if (FLAG_profile_deserialization) timer.Start(); |
| |
| const v8::StartupData* blob = isolate->snapshot_blob(); |
| Vector<const byte> context_data = ExtractContextData(blob); |
| SnapshotData snapshot_data(context_data); |
| Deserializer deserializer(&snapshot_data); |
| |
| MaybeHandle<Object> maybe_context = |
| deserializer.DeserializePartial(isolate, global_proxy); |
| Handle<Object> result; |
| if (!maybe_context.ToHandle(&result)) return MaybeHandle<Context>(); |
| CHECK(result->IsContext()); |
| if (FLAG_profile_deserialization) { |
| double ms = timer.Elapsed().InMillisecondsF(); |
| int bytes = context_data.length(); |
| PrintF("[Deserializing context (%d bytes) took %0.3f ms]\n", bytes, ms); |
| } |
| return Handle<Context>::cast(result); |
| } |
| |
| |
| void CalculateFirstPageSizes(bool is_default_snapshot, |
| const SnapshotData& startup_snapshot, |
| const SnapshotData& context_snapshot, |
| uint32_t* sizes_out) { |
| Vector<const SerializedData::Reservation> startup_reservations = |
| startup_snapshot.Reservations(); |
| Vector<const SerializedData::Reservation> context_reservations = |
| context_snapshot.Reservations(); |
| int startup_index = 0; |
| int context_index = 0; |
| |
| if (FLAG_profile_deserialization) { |
| int startup_total = 0; |
| int context_total = 0; |
| for (auto& reservation : startup_reservations) { |
| startup_total += reservation.chunk_size(); |
| } |
| for (auto& reservation : context_reservations) { |
| context_total += reservation.chunk_size(); |
| } |
| PrintF( |
| "Deserialization will reserve:\n" |
| "%10d bytes per isolate\n" |
| "%10d bytes per context\n", |
| startup_total, context_total); |
| } |
| |
| for (int space = 0; space < i::Serializer::kNumberOfSpaces; space++) { |
| bool single_chunk = true; |
| while (!startup_reservations[startup_index].is_last()) { |
| single_chunk = false; |
| startup_index++; |
| } |
| while (!context_reservations[context_index].is_last()) { |
| single_chunk = false; |
| context_index++; |
| } |
| |
| uint32_t required = kMaxUInt32; |
| if (single_chunk) { |
| // If both the startup snapshot data and the context snapshot data on |
| // this space fit in a single page, then we consider limiting the size |
| // of the first page. For this, we add the chunk sizes and some extra |
| // allowance. This way we achieve a smaller startup memory footprint. |
| required = (startup_reservations[startup_index].chunk_size() + |
| 2 * context_reservations[context_index].chunk_size()) + |
| Page::kObjectStartOffset; |
| // Add a small allowance to the code space for small scripts. |
| if (space == CODE_SPACE) required += 32 * KB; |
| } else if (!FLAG_debug_code) { |
| // We expect the vanilla snapshot to only require one page per space, |
| // unless we are emitting debug code. |
| DCHECK(!is_default_snapshot); |
| } |
| |
| if (space >= FIRST_PAGED_SPACE && space <= LAST_PAGED_SPACE) { |
| uint32_t max_size = |
| MemoryAllocator::PageAreaSize(static_cast<AllocationSpace>(space)); |
| sizes_out[space - FIRST_PAGED_SPACE] = Min(required, max_size); |
| } else { |
| DCHECK(single_chunk); |
| } |
| startup_index++; |
| context_index++; |
| } |
| |
| DCHECK_EQ(startup_reservations.length(), startup_index); |
| DCHECK_EQ(context_reservations.length(), context_index); |
| } |
| |
| |
| v8::StartupData Snapshot::CreateSnapshotBlob( |
| const i::StartupSerializer& startup_ser, |
| const i::PartialSerializer& context_ser, Snapshot::Metadata metadata) { |
| SnapshotData startup_snapshot(startup_ser); |
| SnapshotData context_snapshot(context_ser); |
| Vector<const byte> startup_data = startup_snapshot.RawData(); |
| Vector<const byte> context_data = context_snapshot.RawData(); |
| |
| uint32_t first_page_sizes[kNumPagedSpaces]; |
| |
| CalculateFirstPageSizes(!metadata.embeds_script(), startup_snapshot, |
| context_snapshot, first_page_sizes); |
| |
| int startup_length = startup_data.length(); |
| int context_length = context_data.length(); |
| int context_offset = ContextOffset(startup_length); |
| |
| int length = context_offset + context_length; |
| char* data = new char[length]; |
| |
| memcpy(data + kMetadataOffset, &metadata.RawValue(), kInt32Size); |
| memcpy(data + kFirstPageSizesOffset, first_page_sizes, |
| kNumPagedSpaces * kInt32Size); |
| memcpy(data + kStartupLengthOffset, &startup_length, kInt32Size); |
| memcpy(data + kStartupDataOffset, startup_data.begin(), startup_length); |
| memcpy(data + context_offset, context_data.begin(), context_length); |
| v8::StartupData result = {data, length}; |
| |
| if (FLAG_profile_deserialization) { |
| PrintF( |
| "Snapshot blob consists of:\n" |
| "%10d bytes for startup\n" |
| "%10d bytes for context\n", |
| startup_length, context_length); |
| } |
| return result; |
| } |
| |
| |
| Snapshot::Metadata Snapshot::ExtractMetadata(const v8::StartupData* data) { |
| uint32_t raw; |
| memcpy(&raw, data->data + kMetadataOffset, kInt32Size); |
| return Metadata(raw); |
| } |
| |
| |
| Vector<const byte> Snapshot::ExtractStartupData(const v8::StartupData* data) { |
| DCHECK_LT(kIntSize, data->raw_size); |
| int startup_length; |
| memcpy(&startup_length, data->data + kStartupLengthOffset, kInt32Size); |
| DCHECK_LT(startup_length, data->raw_size); |
| const byte* startup_data = |
| reinterpret_cast<const byte*>(data->data + kStartupDataOffset); |
| return Vector<const byte>(startup_data, startup_length); |
| } |
| |
| |
| Vector<const byte> Snapshot::ExtractContextData(const v8::StartupData* data) { |
| DCHECK_LT(kIntSize, data->raw_size); |
| int startup_length; |
| memcpy(&startup_length, data->data + kStartupLengthOffset, kIntSize); |
| int context_offset = ContextOffset(startup_length); |
| const byte* context_data = |
| reinterpret_cast<const byte*>(data->data + context_offset); |
| DCHECK_LT(context_offset, data->raw_size); |
| int context_length = data->raw_size - context_offset; |
| return Vector<const byte>(context_data, context_length); |
| } |
| |
| SnapshotData::SnapshotData(const Serializer& ser) { |
| DisallowHeapAllocation no_gc; |
| List<Reservation> reservations; |
| ser.EncodeReservations(&reservations); |
| const List<byte>& payload = ser.sink()->data(); |
| |
| // Calculate sizes. |
| int reservation_size = reservations.length() * kInt32Size; |
| int size = kHeaderSize + reservation_size + payload.length(); |
| |
| // Allocate backing store and create result data. |
| AllocateData(size); |
| |
| // Set header values. |
| SetMagicNumber(ser.isolate()); |
| SetHeaderValue(kCheckSumOffset, Version::Hash()); |
| SetHeaderValue(kNumReservationsOffset, reservations.length()); |
| SetHeaderValue(kPayloadLengthOffset, payload.length()); |
| |
| // Copy reservation chunk sizes. |
| CopyBytes(data_ + kHeaderSize, reinterpret_cast<byte*>(reservations.begin()), |
| reservation_size); |
| |
| // Copy serialized data. |
| CopyBytes(data_ + kHeaderSize + reservation_size, payload.begin(), |
| static_cast<size_t>(payload.length())); |
| } |
| |
| bool SnapshotData::IsSane() { |
| return GetHeaderValue(kCheckSumOffset) == Version::Hash(); |
| } |
| |
| Vector<const SerializedData::Reservation> SnapshotData::Reservations() const { |
| return Vector<const Reservation>( |
| reinterpret_cast<const Reservation*>(data_ + kHeaderSize), |
| GetHeaderValue(kNumReservationsOffset)); |
| } |
| |
| Vector<const byte> SnapshotData::Payload() const { |
| int reservations_size = GetHeaderValue(kNumReservationsOffset) * kInt32Size; |
| const byte* payload = data_ + kHeaderSize + reservations_size; |
| int length = GetHeaderValue(kPayloadLengthOffset); |
| DCHECK_EQ(data_ + size_, payload + length); |
| return Vector<const byte>(payload, length); |
| } |
| |
| } // namespace internal |
| } // namespace v8 |