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// 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::ExtractNumContexts(snapshot_blob) > 0;
}
#endif // DEBUG
bool Snapshot::HasContextSnapshot(Isolate* isolate, size_t index) {
// Do not use snapshots if the isolate is used to create snapshots.
const v8::StartupData* blob = isolate->snapshot_blob();
if (blob == nullptr) return false;
if (blob->data == nullptr) return false;
size_t num_contexts = static_cast<size_t>(ExtractNumContexts(blob));
return index < num_contexts;
}
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,
size_t context_index) {
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, static_cast<int>(context_index));
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 #%zu (%d bytes) took %0.3f ms]\n",
context_index, bytes, ms);
}
return Handle<Context>::cast(result);
}
void ProfileDeserialization(const SnapshotData* startup_snapshot,
const List<SnapshotData*>* context_snapshots) {
if (FLAG_profile_deserialization) {
int startup_total = 0;
PrintF("Deserialization will reserve:\n");
for (const auto& reservation : startup_snapshot->Reservations()) {
startup_total += reservation.chunk_size();
}
PrintF("%10d bytes per isolate\n", startup_total);
for (int i = 0; i < context_snapshots->length(); i++) {
int context_total = 0;
for (const auto& reservation : context_snapshots->at(i)->Reservations()) {
context_total += reservation.chunk_size();
}
PrintF("%10d bytes per context #%d\n", context_total, i);
}
}
}
v8::StartupData Snapshot::CreateSnapshotBlob(
const SnapshotData* startup_snapshot,
const List<SnapshotData*>* context_snapshots) {
int num_contexts = context_snapshots->length();
int startup_snapshot_offset = StartupSnapshotOffset(num_contexts);
int total_length = startup_snapshot_offset;
total_length += startup_snapshot->RawData().length();
for (const auto& context_snapshot : *context_snapshots) {
total_length += context_snapshot->RawData().length();
}
ProfileDeserialization(startup_snapshot, context_snapshots);
char* data = new char[total_length];
memcpy(data + kNumberOfContextsOffset, &num_contexts, kInt32Size);
int payload_offset = StartupSnapshotOffset(num_contexts);
int payload_length = startup_snapshot->RawData().length();
memcpy(data + payload_offset, startup_snapshot->RawData().start(),
payload_length);
if (FLAG_profile_deserialization) {
PrintF("Snapshot blob consists of:\n%10d bytes for startup\n",
payload_length);
}
payload_offset += payload_length;
for (int i = 0; i < num_contexts; i++) {
memcpy(data + ContextSnapshotOffsetOffset(i), &payload_offset, kInt32Size);
SnapshotData* context_snapshot = context_snapshots->at(i);
payload_length = context_snapshot->RawData().length();
memcpy(data + payload_offset, context_snapshot->RawData().start(),
payload_length);
if (FLAG_profile_deserialization) {
PrintF("%10d bytes for context #%d\n", payload_length, i);
}
payload_offset += payload_length;
}
v8::StartupData result = {data, total_length};
return result;
}
int Snapshot::ExtractNumContexts(const v8::StartupData* data) {
CHECK_LT(kNumberOfContextsOffset, data->raw_size);
int num_contexts;
memcpy(&num_contexts, data->data + kNumberOfContextsOffset, kInt32Size);
return num_contexts;
}
Vector<const byte> Snapshot::ExtractStartupData(const v8::StartupData* data) {
int num_contexts = ExtractNumContexts(data);
int startup_offset = StartupSnapshotOffset(num_contexts);
CHECK_LT(startup_offset, data->raw_size);
int first_context_offset;
memcpy(&first_context_offset, data->data + ContextSnapshotOffsetOffset(0),
kInt32Size);
CHECK_LT(first_context_offset, data->raw_size);
int startup_length = first_context_offset - startup_offset;
const byte* startup_data =
reinterpret_cast<const byte*>(data->data + startup_offset);
return Vector<const byte>(startup_data, startup_length);
}
Vector<const byte> Snapshot::ExtractContextData(const v8::StartupData* data,
int index) {
int num_contexts = ExtractNumContexts(data);
CHECK_LT(index, num_contexts);
int context_offset;
memcpy(&context_offset, data->data + ContextSnapshotOffsetOffset(index),
kInt32Size);
int next_context_offset;
if (index == num_contexts - 1) {
next_context_offset = data->raw_size;
} else {
memcpy(&next_context_offset,
data->data + ContextSnapshotOffsetOffset(index + 1), kInt32Size);
CHECK_LT(next_context_offset, data->raw_size);
}
const byte* context_data =
reinterpret_cast<const byte*>(data->data + context_offset);
int context_length = next_context_offset - context_offset;
return Vector<const byte>(context_data, context_length);
}
SnapshotData::SnapshotData(const Serializer* serializer) {
DisallowHeapAllocation no_gc;
List<Reservation> reservations;
serializer->EncodeReservations(&reservations);
const List<byte>* payload = serializer->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(serializer->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
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