Current File : //usr/share/node_modules/@types/node/trace_events.d.ts
/**
* The `trace_events` module provides a mechanism to centralize tracing information
* generated by V8, Node.js core, and userspace code.
*
* Tracing can be enabled with the `--trace-event-categories` command-line flag
* or by using the `trace_events` module. The `--trace-event-categories` flag
* accepts a list of comma-separated category names.
*
* The available categories are:
*
* * `node`: An empty placeholder.
* * `node.async_hooks`: Enables capture of detailed `async_hooks` trace data.
* The `async_hooks` events have a unique `asyncId` and a special `triggerId` `triggerAsyncId` property.
* * `node.bootstrap`: Enables capture of Node.js bootstrap milestones.
* * `node.console`: Enables capture of `console.time()` and `console.count()`output.
* * `node.dns.native`: Enables capture of trace data for DNS queries.
* * `node.environment`: Enables capture of Node.js Environment milestones.
* * `node.fs.sync`: Enables capture of trace data for file system sync methods.
* * `node.perf`: Enables capture of `Performance API` measurements.
* * `node.perf.usertiming`: Enables capture of only Performance API User Timing
* measures and marks.
* * `node.perf.timerify`: Enables capture of only Performance API timerify
* measurements.
* * `node.promises.rejections`: Enables capture of trace data tracking the number
* of unhandled Promise rejections and handled-after-rejections.
* * `node.vm.script`: Enables capture of trace data for the `vm` module's`runInNewContext()`, `runInContext()`, and `runInThisContext()` methods.
* * `v8`: The `V8` events are GC, compiling, and execution related.
*
* By default the `node`, `node.async_hooks`, and `v8` categories are enabled.
*
* ```bash
* node --trace-event-categories v8,node,node.async_hooks server.js
* ```
*
* Prior versions of Node.js required the use of the `--trace-events-enabled`flag to enable trace events. This requirement has been removed. However, the`--trace-events-enabled` flag _may_ still be
* used and will enable the`node`, `node.async_hooks`, and `v8` trace event categories by default.
*
* ```bash
* node --trace-events-enabled
*
* # is equivalent to
*
* node --trace-event-categories v8,node,node.async_hooks
* ```
*
* Alternatively, trace events may be enabled using the `trace_events` module:
*
* ```js
* const trace_events = require('trace_events');
* const tracing = trace_events.createTracing({ categories: ['node.perf'] });
* tracing.enable(); // Enable trace event capture for the 'node.perf' category
*
* // do work
*
* tracing.disable(); // Disable trace event capture for the 'node.perf' category
* ```
*
* Running Node.js with tracing enabled will produce log files that can be opened
* in the [`chrome://tracing`](https://www.chromium.org/developers/how-tos/trace-event-profiling-tool) tab of Chrome.
*
* The logging file is by default called `node_trace.${rotation}.log`, where`${rotation}` is an incrementing log-rotation id. The filepath pattern can
* be specified with `--trace-event-file-pattern` that accepts a template
* string that supports `${rotation}` and `${pid}`:
*
* ```bash
* node --trace-event-categories v8 --trace-event-file-pattern '${pid}-${rotation}.log' server.js
* ```
*
* To guarantee that the log file is properly generated after signal events like`SIGINT`, `SIGTERM`, or `SIGBREAK`, make sure to have the appropriate handlers
* in your code, such as:
*
* ```js
* process.on('SIGINT', function onSigint() {
* console.info('Received SIGINT.');
* process.exit(130); // Or applicable exit code depending on OS and signal
* });
* ```
*
* The tracing system uses the same time source
* as the one used by `process.hrtime()`.
* However the trace-event timestamps are expressed in microseconds,
* unlike `process.hrtime()` which returns nanoseconds.
*
* The features from this module are not available in `Worker` threads.
* @experimental
* @see [source](https://github.com/nodejs/node/blob/v18.0.0/lib/trace_events.js)
*/
declare module "trace_events" {
/**
* The `Tracing` object is used to enable or disable tracing for sets of
* categories. Instances are created using the
* `trace_events.createTracing()` method.
*
* When created, the `Tracing` object is disabled. Calling the
* `tracing.enable()` method adds the categories to the set of enabled trace
* event categories. Calling `tracing.disable()` will remove the categories
* from the set of enabled trace event categories.
*/
interface Tracing {
/**
* A comma-separated list of the trace event categories covered by this
* `Tracing` object.
*/
readonly categories: string;
/**
* Disables this `Tracing` object.
*
* Only trace event categories _not_ covered by other enabled `Tracing`
* objects and _not_ specified by the `--trace-event-categories` flag
* will be disabled.
*/
disable(): void;
/**
* Enables this `Tracing` object for the set of categories covered by
* the `Tracing` object.
*/
enable(): void;
/**
* `true` only if the `Tracing` object has been enabled.
*/
readonly enabled: boolean;
}
interface CreateTracingOptions {
/**
* An array of trace category names. Values included in the array are
* coerced to a string when possible. An error will be thrown if the
* value cannot be coerced.
*/
categories: string[];
}
/**
* Creates and returns a `Tracing` object for the given set of `categories`.
*
* ```js
* const trace_events = require('trace_events');
* const categories = ['node.perf', 'node.async_hooks'];
* const tracing = trace_events.createTracing({ categories });
* tracing.enable();
* // do stuff
* tracing.disable();
* ```
* @since v10.0.0
* @return .
*/
function createTracing(options: CreateTracingOptions): Tracing;
/**
* Returns a comma-separated list of all currently-enabled trace event
* categories. The current set of enabled trace event categories is determined
* by the _union_ of all currently-enabled `Tracing` objects and any categories
* enabled using the `--trace-event-categories` flag.
*
* Given the file `test.js` below, the command`node --trace-event-categories node.perf test.js` will print`'node.async_hooks,node.perf'` to the console.
*
* ```js
* const trace_events = require('trace_events');
* const t1 = trace_events.createTracing({ categories: ['node.async_hooks'] });
* const t2 = trace_events.createTracing({ categories: ['node.perf'] });
* const t3 = trace_events.createTracing({ categories: ['v8'] });
*
* t1.enable();
* t2.enable();
*
* console.log(trace_events.getEnabledCategories());
* ```
* @since v10.0.0
*/
function getEnabledCategories(): string | undefined;
}
declare module "node:trace_events" {
export * from "trace_events";
}
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