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v8.js
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v8.js
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// Copyright (c) 2014, StrongLoop Inc.
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
'use strict';
const {
Array,
BigInt64Array,
BigUint64Array,
DataView,
Error,
Float32Array,
Float64Array,
Int16Array,
Int32Array,
Int8Array,
ObjectPrototypeToString,
Uint16Array,
Uint32Array,
Uint8Array,
Uint8ClampedArray,
} = primordials;
const { Buffer } = require('buffer');
const { validateString, validateUint32 } = require('internal/validators');
const {
Serializer,
Deserializer
} = internalBinding('serdes');
const {
namespace: startupSnapshot
} = require('internal/v8/startup_snapshot');
let profiler = {};
if (internalBinding('config').hasInspector) {
profiler = internalBinding('profiler');
}
const assert = require('internal/assert');
const { copy } = internalBinding('buffer');
const { inspect } = require('internal/util/inspect');
const { FastBuffer } = require('internal/buffer');
const { getValidatedPath } = require('internal/fs/utils');
const { toNamespacedPath } = require('path');
const {
createHeapSnapshotStream,
triggerHeapSnapshot
} = internalBinding('heap_utils');
const { HeapSnapshotStream } = require('internal/heap_utils');
const promiseHooks = require('internal/promise_hooks');
const { getOptionValue } = require('internal/options');
/**
* Generates a snapshot of the current V8 heap
* and writes it to a JSON file.
* @param {string} [filename]
* @returns {string}
*/
function writeHeapSnapshot(filename) {
if (filename !== undefined) {
filename = getValidatedPath(filename);
filename = toNamespacedPath(filename);
}
return triggerHeapSnapshot(filename);
}
/**
* Generates a snapshot of the current V8 heap
* and returns a Readable Stream.
* @returns {import('./stream.js').Readable}
*/
function getHeapSnapshot() {
const handle = createHeapSnapshotStream();
assert(handle);
return new HeapSnapshotStream(handle);
}
// We need to get the buffer from the binding at the callsite since
// it's re-initialized after deserialization.
const binding = internalBinding('v8');
const {
cachedDataVersionTag,
setFlagsFromString: _setFlagsFromString,
updateHeapStatisticsBuffer,
updateHeapSpaceStatisticsBuffer,
updateHeapCodeStatisticsBuffer,
setHeapSnapshotNearHeapLimit: _setHeapSnapshotNearHeapLimit,
// Properties for heap statistics buffer extraction.
kTotalHeapSizeIndex,
kTotalHeapSizeExecutableIndex,
kTotalPhysicalSizeIndex,
kTotalAvailableSize,
kUsedHeapSizeIndex,
kHeapSizeLimitIndex,
kDoesZapGarbageIndex,
kMallocedMemoryIndex,
kPeakMallocedMemoryIndex,
kNumberOfNativeContextsIndex,
kNumberOfDetachedContextsIndex,
kTotalGlobalHandlesSizeIndex,
kUsedGlobalHandlesSizeIndex,
kExternalMemoryIndex,
// Properties for heap spaces statistics buffer extraction.
kHeapSpaces,
kSpaceSizeIndex,
kSpaceUsedSizeIndex,
kSpaceAvailableSizeIndex,
kPhysicalSpaceSizeIndex,
// Properties for heap code statistics buffer extraction.
kCodeAndMetadataSizeIndex,
kBytecodeAndMetadataSizeIndex,
kExternalScriptSourceSizeIndex,
kCPUProfilerMetaDataSizeIndex,
} = binding;
const kNumberOfHeapSpaces = kHeapSpaces.length;
/**
* Sets V8 command-line flags.
* @param {string} flags
* @returns {void}
*/
function setFlagsFromString(flags) {
validateString(flags, 'flags');
_setFlagsFromString(flags);
}
/**
* Gets the current V8 heap statistics.
* @returns {{
* total_heap_size: number;
* total_heap_size_executable: number;
* total_physical_size: number;
* total_available_size: number;
* used_heap_size: number;
* heap_size_limit: number;
* malloced_memory: number;
* peak_malloced_memory: number;
* does_zap_garbage: number;
* number_of_native_contexts: number;
* number_of_detached_contexts: number;
* }}
*/
function getHeapStatistics() {
const buffer = binding.heapStatisticsBuffer;
updateHeapStatisticsBuffer();
return {
total_heap_size: buffer[kTotalHeapSizeIndex],
total_heap_size_executable: buffer[kTotalHeapSizeExecutableIndex],
total_physical_size: buffer[kTotalPhysicalSizeIndex],
total_available_size: buffer[kTotalAvailableSize],
used_heap_size: buffer[kUsedHeapSizeIndex],
heap_size_limit: buffer[kHeapSizeLimitIndex],
malloced_memory: buffer[kMallocedMemoryIndex],
peak_malloced_memory: buffer[kPeakMallocedMemoryIndex],
does_zap_garbage: buffer[kDoesZapGarbageIndex],
number_of_native_contexts: buffer[kNumberOfNativeContextsIndex],
number_of_detached_contexts: buffer[kNumberOfDetachedContextsIndex],
total_global_handles_size: buffer[kTotalGlobalHandlesSizeIndex],
used_global_handles_size: buffer[kUsedGlobalHandlesSizeIndex],
external_memory: buffer[kExternalMemoryIndex]
};
}
/**
* Gets the current V8 heap space statistics.
* @returns {{
* space_name: string;
* space_size: number;
* space_used_size: number;
* space_available_size: number;
* physical_space_size: number;
* }[]}
*/
function getHeapSpaceStatistics() {
const heapSpaceStatistics = new Array(kNumberOfHeapSpaces);
const buffer = binding.heapSpaceStatisticsBuffer;
for (let i = 0; i < kNumberOfHeapSpaces; i++) {
updateHeapSpaceStatisticsBuffer(i);
heapSpaceStatistics[i] = {
space_name: kHeapSpaces[i],
space_size: buffer[kSpaceSizeIndex],
space_used_size: buffer[kSpaceUsedSizeIndex],
space_available_size: buffer[kSpaceAvailableSizeIndex],
physical_space_size: buffer[kPhysicalSpaceSizeIndex]
};
}
return heapSpaceStatistics;
}
/**
* Gets the current V8 heap code statistics.
* @returns {{
* code_and_metadata_size: number;
* bytecode_and_metadata_size: number;
* external_script_source_size: number;
* cpu_profiler_metadata_size: number;
* }}
*/
function getHeapCodeStatistics() {
const buffer = binding.heapCodeStatisticsBuffer;
updateHeapCodeStatisticsBuffer();
return {
code_and_metadata_size: buffer[kCodeAndMetadataSizeIndex],
bytecode_and_metadata_size: buffer[kBytecodeAndMetadataSizeIndex],
external_script_source_size: buffer[kExternalScriptSourceSizeIndex],
cpu_profiler_metadata_size: buffer[kCPUProfilerMetaDataSizeIndex],
};
}
let heapSnapshotNearHeapLimitCallbackAdded = false;
function setHeapSnapshotNearHeapLimit(limit) {
validateUint32(limit, 'limit', 1);
if (heapSnapshotNearHeapLimitCallbackAdded ||
getOptionValue('--heapsnapshot-near-heap-limit') > 0
) {
return;
}
heapSnapshotNearHeapLimitCallbackAdded = true;
_setHeapSnapshotNearHeapLimit(limit);
}
/* V8 serialization API */
/* JS methods for the base objects */
Serializer.prototype._getDataCloneError = Error;
/**
* Reads raw bytes from the deserializer's internal buffer.
* @param {number} length
* @returns {Buffer}
*/
Deserializer.prototype.readRawBytes = function readRawBytes(length) {
const offset = this._readRawBytes(length);
// `this.buffer` can be a Buffer or a plain Uint8Array, so just calling
// `.slice()` doesn't work.
return new FastBuffer(this.buffer.buffer,
this.buffer.byteOffset + offset,
length);
};
function arrayBufferViewTypeToIndex(abView) {
const type = ObjectPrototypeToString(abView);
if (type === '[object Int8Array]') return 0;
if (type === '[object Uint8Array]') return 1;
if (type === '[object Uint8ClampedArray]') return 2;
if (type === '[object Int16Array]') return 3;
if (type === '[object Uint16Array]') return 4;
if (type === '[object Int32Array]') return 5;
if (type === '[object Uint32Array]') return 6;
if (type === '[object Float32Array]') return 7;
if (type === '[object Float64Array]') return 8;
if (type === '[object DataView]') return 9;
// Index 10 is FastBuffer.
if (type === '[object BigInt64Array]') return 11;
if (type === '[object BigUint64Array]') return 12;
return -1;
}
function arrayBufferViewIndexToType(index) {
if (index === 0) return Int8Array;
if (index === 1) return Uint8Array;
if (index === 2) return Uint8ClampedArray;
if (index === 3) return Int16Array;
if (index === 4) return Uint16Array;
if (index === 5) return Int32Array;
if (index === 6) return Uint32Array;
if (index === 7) return Float32Array;
if (index === 8) return Float64Array;
if (index === 9) return DataView;
if (index === 10) return FastBuffer;
if (index === 11) return BigInt64Array;
if (index === 12) return BigUint64Array;
return undefined;
}
class DefaultSerializer extends Serializer {
constructor() {
super();
this._setTreatArrayBufferViewsAsHostObjects(true);
}
/**
* Used to write some kind of host object, i.e. an
* object that is created by native C++ bindings.
* @param {object} abView
* @returns {void}
*/
_writeHostObject(abView) {
// Keep track of how to handle different ArrayBufferViews. The default
// Serializer for Node does not use the V8 methods for serializing those
// objects because Node's `Buffer` objects use pooled allocation in many
// cases, and their underlying `ArrayBuffer`s would show up in the
// serialization. Because a) those may contain sensitive data and the user
// may not be aware of that and b) they are often much larger than the
// `Buffer` itself, custom serialization is applied.
let i = 10; // FastBuffer
if (abView.constructor !== Buffer) {
i = arrayBufferViewTypeToIndex(abView);
if (i === -1) {
throw new this._getDataCloneError(
`Unserializable host object: ${inspect(abView)}`);
}
}
this.writeUint32(i);
this.writeUint32(abView.byteLength);
this.writeRawBytes(new Uint8Array(abView.buffer,
abView.byteOffset,
abView.byteLength));
}
}
class DefaultDeserializer extends Deserializer {
/**
* Used to read some kind of host object, i.e. an
* object that is created by native C++ bindings.
* @returns {any}
*/
_readHostObject() {
const typeIndex = this.readUint32();
const ctor = arrayBufferViewIndexToType(typeIndex);
const byteLength = this.readUint32();
const byteOffset = this._readRawBytes(byteLength);
const BYTES_PER_ELEMENT = ctor.BYTES_PER_ELEMENT || 1;
const offset = this.buffer.byteOffset + byteOffset;
if (offset % BYTES_PER_ELEMENT === 0) {
return new ctor(this.buffer.buffer,
offset,
byteLength / BYTES_PER_ELEMENT);
}
// Copy to an aligned buffer first.
const buffer_copy = Buffer.allocUnsafe(byteLength);
copy(this.buffer, buffer_copy, 0, byteOffset, byteOffset + byteLength);
return new ctor(buffer_copy.buffer,
buffer_copy.byteOffset,
byteLength / BYTES_PER_ELEMENT);
}
}
/**
* Uses a `DefaultSerializer` to serialize `value`
* into a buffer.
* @param {any} value
* @returns {Buffer}
*/
function serialize(value) {
const ser = new DefaultSerializer();
ser.writeHeader();
ser.writeValue(value);
return ser.releaseBuffer();
}
/**
* Uses a `DefaultDeserializer` with default options
* to read a JavaScript value from a buffer.
* @param {Buffer | TypedArray | DataView} buffer
* @returns {any}
*/
function deserialize(buffer) {
const der = new DefaultDeserializer(buffer);
der.readHeader();
return der.readValue();
}
module.exports = {
cachedDataVersionTag,
getHeapSnapshot,
getHeapStatistics,
getHeapSpaceStatistics,
getHeapCodeStatistics,
setFlagsFromString,
Serializer,
Deserializer,
DefaultSerializer,
DefaultDeserializer,
deserialize,
takeCoverage: profiler.takeCoverage,
stopCoverage: profiler.stopCoverage,
serialize,
writeHeapSnapshot,
promiseHooks,
startupSnapshot,
setHeapSnapshotNearHeapLimit,
};