Current File : //usr/share/node_modules/@types/node/v8.d.ts
/**
* The `v8` module exposes APIs that are specific to the version of [V8](https://developers.google.com/v8/) built into the Node.js binary. It can be accessed using:
*
* ```js
* const v8 = require('v8');
* ```
* @see [source](https://github.com/nodejs/node/blob/v18.0.0/lib/v8.js)
*/
declare module "v8" {
import { Readable } from "node:stream";
interface HeapSpaceInfo {
space_name: string;
space_size: number;
space_used_size: number;
space_available_size: number;
physical_space_size: number;
}
// ** Signifies if the --zap_code_space option is enabled or not. 1 == enabled, 0 == disabled. */
type DoesZapCodeSpaceFlag = 0 | 1;
interface HeapInfo {
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: DoesZapCodeSpaceFlag;
number_of_native_contexts: number;
number_of_detached_contexts: number;
}
interface HeapCodeStatistics {
code_and_metadata_size: number;
bytecode_and_metadata_size: number;
external_script_source_size: number;
}
/**
* Returns an integer representing a version tag derived from the V8 version,
* command-line flags, and detected CPU features. This is useful for determining
* whether a `vm.Script` `cachedData` buffer is compatible with this instance
* of V8.
*
* ```js
* console.log(v8.cachedDataVersionTag()); // 3947234607
* // The value returned by v8.cachedDataVersionTag() is derived from the V8
* // version, command-line flags, and detected CPU features. Test that the value
* // does indeed update when flags are toggled.
* v8.setFlagsFromString('--allow_natives_syntax');
* console.log(v8.cachedDataVersionTag()); // 183726201
* ```
* @since v8.0.0
*/
function cachedDataVersionTag(): number;
/**
* Returns an object with the following properties:
*
* `does_zap_garbage` is a 0/1 boolean, which signifies whether the`--zap_code_space` option is enabled or not. This makes V8 overwrite heap
* garbage with a bit pattern. The RSS footprint (resident set size) gets bigger
* because it continuously touches all heap pages and that makes them less likely
* to get swapped out by the operating system.
*
* `number_of_native_contexts` The value of native\_context is the number of the
* top-level contexts currently active. Increase of this number over time indicates
* a memory leak.
*
* `number_of_detached_contexts` The value of detached\_context is the number
* of contexts that were detached and not yet garbage collected. This number
* being non-zero indicates a potential memory leak.
*
* ```js
* {
* total_heap_size: 7326976,
* total_heap_size_executable: 4194304,
* total_physical_size: 7326976,
* total_available_size: 1152656,
* used_heap_size: 3476208,
* heap_size_limit: 1535115264,
* malloced_memory: 16384,
* peak_malloced_memory: 1127496,
* does_zap_garbage: 0,
* number_of_native_contexts: 1,
* number_of_detached_contexts: 0
* }
* ```
* @since v1.0.0
*/
function getHeapStatistics(): HeapInfo;
/**
* Returns statistics about the V8 heap spaces, i.e. the segments which make up
* the V8 heap. Neither the ordering of heap spaces, nor the availability of a
* heap space can be guaranteed as the statistics are provided via the
* V8[`GetHeapSpaceStatistics`](https://v8docs.nodesource.com/node-13.2/d5/dda/classv8_1_1_isolate.html#ac673576f24fdc7a33378f8f57e1d13a4) function and may change from one V8 version to the
* next.
*
* The value returned is an array of objects containing the following properties:
*
* ```json
* [
* {
* "space_name": "new_space",
* "space_size": 2063872,
* "space_used_size": 951112,
* "space_available_size": 80824,
* "physical_space_size": 2063872
* },
* {
* "space_name": "old_space",
* "space_size": 3090560,
* "space_used_size": 2493792,
* "space_available_size": 0,
* "physical_space_size": 3090560
* },
* {
* "space_name": "code_space",
* "space_size": 1260160,
* "space_used_size": 644256,
* "space_available_size": 960,
* "physical_space_size": 1260160
* },
* {
* "space_name": "map_space",
* "space_size": 1094160,
* "space_used_size": 201608,
* "space_available_size": 0,
* "physical_space_size": 1094160
* },
* {
* "space_name": "large_object_space",
* "space_size": 0,
* "space_used_size": 0,
* "space_available_size": 1490980608,
* "physical_space_size": 0
* }
* ]
* ```
* @since v6.0.0
*/
function getHeapSpaceStatistics(): HeapSpaceInfo[];
/**
* The `v8.setFlagsFromString()` method can be used to programmatically set
* V8 command-line flags. This method should be used with care. Changing settings
* after the VM has started may result in unpredictable behavior, including
* crashes and data loss; or it may simply do nothing.
*
* The V8 options available for a version of Node.js may be determined by running`node --v8-options`.
*
* Usage:
*
* ```js
* // Print GC events to stdout for one minute.
* const v8 = require('v8');
* v8.setFlagsFromString('--trace_gc');
* setTimeout(() => { v8.setFlagsFromString('--notrace_gc'); }, 60e3);
* ```
* @since v1.0.0
*/
function setFlagsFromString(flags: string): void;
/**
* Generates a snapshot of the current V8 heap and returns a Readable
* Stream that may be used to read the JSON serialized representation.
* This JSON stream format is intended to be used with tools such as
* Chrome DevTools. The JSON schema is undocumented and specific to the
* V8 engine. Therefore, the schema may change from one version of V8 to the next.
*
* Creating a heap snapshot requires memory about twice the size of the heap at
* the time the snapshot is created. This results in the risk of OOM killers
* terminating the process.
*
* Generating a snapshot is a synchronous operation which blocks the event loop
* for a duration depending on the heap size.
*
* ```js
* // Print heap snapshot to the console
* const v8 = require('v8');
* const stream = v8.getHeapSnapshot();
* stream.pipe(process.stdout);
* ```
* @since v11.13.0
* @return A Readable Stream containing the V8 heap snapshot
*/
function getHeapSnapshot(): Readable;
/**
* Generates a snapshot of the current V8 heap and writes it to a JSON
* file. This file is intended to be used with tools such as Chrome
* DevTools. The JSON schema is undocumented and specific to the V8
* engine, and may change from one version of V8 to the next.
*
* A heap snapshot is specific to a single V8 isolate. When using `worker threads`, a heap snapshot generated from the main thread will
* not contain any information about the workers, and vice versa.
*
* Creating a heap snapshot requires memory about twice the size of the heap at
* the time the snapshot is created. This results in the risk of OOM killers
* terminating the process.
*
* Generating a snapshot is a synchronous operation which blocks the event loop
* for a duration depending on the heap size.
*
* ```js
* const { writeHeapSnapshot } = require('v8');
* const {
* Worker,
* isMainThread,
* parentPort
* } = require('worker_threads');
*
* if (isMainThread) {
* const worker = new Worker(__filename);
*
* worker.once('message', (filename) => {
* console.log(`worker heapdump: ${filename}`);
* // Now get a heapdump for the main thread.
* console.log(`main thread heapdump: ${writeHeapSnapshot()}`);
* });
*
* // Tell the worker to create a heapdump.
* worker.postMessage('heapdump');
* } else {
* parentPort.once('message', (message) => {
* if (message === 'heapdump') {
* // Generate a heapdump for the worker
* // and return the filename to the parent.
* parentPort.postMessage(writeHeapSnapshot());
* }
* });
* }
* ```
* @since v11.13.0
* @param filename The file path where the V8 heap snapshot is to be saved. If not specified, a file name with the pattern `'Heap-${yyyymmdd}-${hhmmss}-${pid}-${thread_id}.heapsnapshot'` will be
* generated, where `{pid}` will be the PID of the Node.js process, `{thread_id}` will be `0` when `writeHeapSnapshot()` is called from the main Node.js thread or the id of a
* worker thread.
* @return The filename where the snapshot was saved.
*/
function writeHeapSnapshot(filename?: string): string;
/**
* Returns an object with the following properties:
*
* ```js
* {
* code_and_metadata_size: 212208,
* bytecode_and_metadata_size: 161368,
* external_script_source_size: 1410794
* }
* ```
* @since v12.8.0
*/
function getHeapCodeStatistics(): HeapCodeStatistics;
/**
* @since v8.0.0
*/
class Serializer {
/**
* Writes out a header, which includes the serialization format version.
*/
writeHeader(): void;
/**
* Serializes a JavaScript value and adds the serialized representation to the
* internal buffer.
*
* This throws an error if `value` cannot be serialized.
*/
writeValue(val: any): boolean;
/**
* Returns the stored internal buffer. This serializer should not be used once
* the buffer is released. Calling this method results in undefined behavior
* if a previous write has failed.
*/
releaseBuffer(): Buffer;
/**
* Marks an `ArrayBuffer` as having its contents transferred out of band.
* Pass the corresponding `ArrayBuffer` in the deserializing context to `deserializer.transferArrayBuffer()`.
* @param id A 32-bit unsigned integer.
* @param arrayBuffer An `ArrayBuffer` instance.
*/
transferArrayBuffer(id: number, arrayBuffer: ArrayBuffer): void;
/**
* Write a raw 32-bit unsigned integer.
* For use inside of a custom `serializer._writeHostObject()`.
*/
writeUint32(value: number): void;
/**
* Write a raw 64-bit unsigned integer, split into high and low 32-bit parts.
* For use inside of a custom `serializer._writeHostObject()`.
*/
writeUint64(hi: number, lo: number): void;
/**
* Write a JS `number` value.
* For use inside of a custom `serializer._writeHostObject()`.
*/
writeDouble(value: number): void;
/**
* Write raw bytes into the serializer’s internal buffer. The deserializer
* will require a way to compute the length of the buffer.
* For use inside of a custom `serializer._writeHostObject()`.
*/
writeRawBytes(buffer: NodeJS.TypedArray): void;
}
/**
* A subclass of `Serializer` that serializes `TypedArray`(in particular `Buffer`) and `DataView` objects as host objects, and only
* stores the part of their underlying `ArrayBuffer`s that they are referring to.
* @since v8.0.0
*/
class DefaultSerializer extends Serializer {}
/**
* @since v8.0.0
*/
class Deserializer {
constructor(data: NodeJS.TypedArray);
/**
* Reads and validates a header (including the format version).
* May, for example, reject an invalid or unsupported wire format. In that case,
* an `Error` is thrown.
*/
readHeader(): boolean;
/**
* Deserializes a JavaScript value from the buffer and returns it.
*/
readValue(): any;
/**
* Marks an `ArrayBuffer` as having its contents transferred out of band.
* Pass the corresponding `ArrayBuffer` in the serializing context to `serializer.transferArrayBuffer()` (or return the `id` from `serializer._getSharedArrayBufferId()` in the case of
* `SharedArrayBuffer`s).
* @param id A 32-bit unsigned integer.
* @param arrayBuffer An `ArrayBuffer` instance.
*/
transferArrayBuffer(id: number, arrayBuffer: ArrayBuffer): void;
/**
* Reads the underlying wire format version. Likely mostly to be useful to
* legacy code reading old wire format versions. May not be called before`.readHeader()`.
*/
getWireFormatVersion(): number;
/**
* Read a raw 32-bit unsigned integer and return it.
* For use inside of a custom `deserializer._readHostObject()`.
*/
readUint32(): number;
/**
* Read a raw 64-bit unsigned integer and return it as an array `[hi, lo]`with two 32-bit unsigned integer entries.
* For use inside of a custom `deserializer._readHostObject()`.
*/
readUint64(): [number, number];
/**
* Read a JS `number` value.
* For use inside of a custom `deserializer._readHostObject()`.
*/
readDouble(): number;
/**
* Read raw bytes from the deserializer’s internal buffer. The `length` parameter
* must correspond to the length of the buffer that was passed to `serializer.writeRawBytes()`.
* For use inside of a custom `deserializer._readHostObject()`.
*/
readRawBytes(length: number): Buffer;
}
/**
* A subclass of `Deserializer` corresponding to the format written by `DefaultSerializer`.
* @since v8.0.0
*/
class DefaultDeserializer extends Deserializer {}
/**
* Uses a `DefaultSerializer` to serialize `value` into a buffer.
*
* `ERR_BUFFER_TOO_LARGE` will be thrown when trying to
* serialize a huge object which requires buffer
* larger than `buffer.constants.MAX_LENGTH`.
* @since v8.0.0
*/
function serialize(value: any): Buffer;
/**
* Uses a `DefaultDeserializer` with default options to read a JS value
* from a buffer.
* @since v8.0.0
* @param buffer A buffer returned by {@link serialize}.
*/
function deserialize(buffer: NodeJS.TypedArray): any;
/**
* The `v8.takeCoverage()` method allows the user to write the coverage started by `NODE_V8_COVERAGE` to disk on demand. This method can be invoked multiple
* times during the lifetime of the process. Each time the execution counter will
* be reset and a new coverage report will be written to the directory specified
* by `NODE_V8_COVERAGE`.
*
* When the process is about to exit, one last coverage will still be written to
* disk unless {@link stopCoverage} is invoked before the process exits.
* @since v15.1.0, v14.18.0, v12.22.0
*/
function takeCoverage(): void;
/**
* The `v8.stopCoverage()` method allows the user to stop the coverage collection
* started by `NODE_V8_COVERAGE`, so that V8 can release the execution count
* records and optimize code. This can be used in conjunction with {@link takeCoverage} if the user wants to collect the coverage on demand.
* @since v15.1.0, v14.18.0, v12.22.0
*/
function stopCoverage(): void;
/**
* This API collects GC data in current thread.
*/
class GCProfiler {
/**
* Start collecting GC data.
*/
start(): void;
/**
* Stop collecting GC data and return a object.
*/
stop(): GCProfilerResult;
}
interface GCProfilerResult {
version: number;
startTime: number;
endTime: number;
statistics: Array<{
gcType: string;
cost: number;
beforeGC: {
heapStatistics: HeapStatistics;
heapSpaceStatistics: HeapSpaceStatistics[];
};
afterGC: {
heapStatistics: HeapStatistics;
heapSpaceStatistics: HeapSpaceStatistics[];
};
}>;
}
interface HeapStatistics {
totalHeapSize: number;
totalHeapSizeExecutable: number;
totalPhysicalSize: number;
totalAvailableSize: number;
totalGlobalHandlesSize: number;
usedGlobalHandlesSize: number;
usedHeapSize: number;
heapSizeLimit: number;
mallocedMemory: number;
externalMemory: number;
peakMallocedMemory: number;
}
interface HeapSpaceStatistics {
spaceName: string;
spaceSize: number;
spaceUsedSize: number;
spaceAvailableSize: number;
physicalSpaceSize: number;
}
/**
* Called when a promise is constructed. This does not mean that corresponding before/after events will occur, only that the possibility exists. This will
* happen if a promise is created without ever getting a continuation.
* @since v17.1.0, v16.14.0
* @param promise The promise being created.
* @param parent The promise continued from, if applicable.
*/
interface Init {
(promise: Promise<unknown>, parent: Promise<unknown>): void;
}
/**
* Called before a promise continuation executes. This can be in the form of `then()`, `catch()`, or `finally()` handlers or an await resuming.
*
* The before callback will be called 0 to N times. The before callback will typically be called 0 times if no continuation was ever made for the promise.
* The before callback may be called many times in the case where many continuations have been made from the same promise.
* @since v17.1.0, v16.14.0
*/
interface Before {
(promise: Promise<unknown>): void;
}
/**
* Called immediately after a promise continuation executes. This may be after a `then()`, `catch()`, or `finally()` handler or before an await after another await.
* @since v17.1.0, v16.14.0
*/
interface After {
(promise: Promise<unknown>): void;
}
/**
* Called when the promise receives a resolution or rejection value. This may occur synchronously in the case of {@link Promise.resolve()} or
* {@link Promise.reject()}.
* @since v17.1.0, v16.14.0
*/
interface Settled {
(promise: Promise<unknown>): void;
}
/**
* Key events in the lifetime of a promise have been categorized into four areas: creation of a promise, before/after a continuation handler is called or
* around an await, and when the promise resolves or rejects.
*
* Because promises are asynchronous resources whose lifecycle is tracked via the promise hooks mechanism, the `init()`, `before()`, `after()`, and
* `settled()` callbacks must not be async functions as they create more promises which would produce an infinite loop.
* @since v17.1.0, v16.14.0
*/
interface HookCallbacks {
init?: Init;
before?: Before;
after?: After;
settled?: Settled;
}
interface PromiseHooks {
/**
* The `init` hook must be a plain function. Providing an async function will throw as it would produce an infinite microtask loop.
* @since v17.1.0, v16.14.0
* @param init The {@link Init | `init` callback} to call when a promise is created.
* @return Call to stop the hook.
*/
onInit: (init: Init) => Function;
/**
* The `settled` hook must be a plain function. Providing an async function will throw as it would produce an infinite microtask loop.
* @since v17.1.0, v16.14.0
* @param settled The {@link Settled | `settled` callback} to call when a promise is created.
* @return Call to stop the hook.
*/
onSettled: (settled: Settled) => Function;
/**
* The `before` hook must be a plain function. Providing an async function will throw as it would produce an infinite microtask loop.
* @since v17.1.0, v16.14.0
* @param before The {@link Before | `before` callback} to call before a promise continuation executes.
* @return Call to stop the hook.
*/
onBefore: (before: Before) => Function;
/**
* The `after` hook must be a plain function. Providing an async function will throw as it would produce an infinite microtask loop.
* @since v17.1.0, v16.14.0
* @param after The {@link After | `after` callback} to call after a promise continuation executes.
* @return Call to stop the hook.
*/
onAfter: (after: After) => Function;
/**
* Registers functions to be called for different lifetime events of each promise.
* The callbacks `init()`/`before()`/`after()`/`settled()` are called for the respective events during a promise's lifetime.
* All callbacks are optional. For example, if only promise creation needs to be tracked, then only the init callback needs to be passed.
* The hook callbacks must be plain functions. Providing async functions will throw as it would produce an infinite microtask loop.
* @since v17.1.0, v16.14.0
* @param callbacks The {@link HookCallbacks | Hook Callbacks} to register
* @return Used for disabling hooks
*/
createHook: (callbacks: HookCallbacks) => Function;
}
/**
* The `promiseHooks` interface can be used to track promise lifecycle events.
* @since v17.1.0, v16.14.0
*/
const promiseHooks: PromiseHooks;
}
declare module "node:v8" {
export * from "v8";
}
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