diff --git a/doc/api/diagnostics_channel.md b/doc/api/diagnostics_channel.md index e27c55eedf3a61..a6a47d5921a5cb 100644 --- a/doc/api/diagnostics_channel.md +++ b/doc/api/diagnostics_channel.md @@ -977,6 +977,44 @@ channels.asyncStart.bindStore(myStore, (data) => { }); ``` +#### `tracingChannel.hasSubscribers` + + + +> Stability: 1 - Experimental + +* Returns: {boolean} `true` if any of the individual channels has a subscriber, + `false` if not. + +This is a helper method available on a [`TracingChannel`][] instance to check if +any of the [TracingChannel Channels][] have subscribers. A `true` is returned if +any of them have at least one subscriber, a `false` is returned otherwise. + +```mjs +import diagnostics_channel from 'node:diagnostics_channel'; + +const channels = diagnostics_channel.tracingChannel('my-channel'); + +if (channels.hasSubscribers) { + // Do something +} +``` + +```cjs +const diagnostics_channel = require('node:diagnostics_channel'); + +const channels = diagnostics_channel.tracingChannel('my-channel'); + +if (channels.hasSubscribers) { + // Do something +} +``` + + ### TracingChannel Channels A TracingChannel is a collection of several diagnostics\_channels representing diff --git a/test/parallel/test-diagnostics-channel-tracing-channel-has-subscribers.spec.js b/test/parallel/test-diagnostics-channel-tracing-channel-has-subscribers.spec.js new file mode 100644 index 00000000000000..2d29cbb91932aa --- /dev/null +++ b/test/parallel/test-diagnostics-channel-tracing-channel-has-subscribers.spec.js @@ -0,0 +1,51 @@ +'use strict'; + +const common = require('../common'); +const dc = require('../dc-polyfill.js'); +const assert = require('assert'); + +const handler = common.mustNotCall(); + +{ + const handlers = { + start: common.mustNotCall() + }; + + const channel = dc.tracingChannel('test'); + + assert.strictEqual(channel.hasSubscribers, false); + + channel.subscribe(handlers); + assert.strictEqual(channel.hasSubscribers, true); + + channel.unsubscribe(handlers); + assert.strictEqual(channel.hasSubscribers, false); + + channel.start.subscribe(handler); + assert.strictEqual(channel.hasSubscribers, true); + + channel.start.unsubscribe(handler); + assert.strictEqual(channel.hasSubscribers, false); +} + +{ + const handlers = { + asyncEnd: common.mustNotCall() + }; + + const channel = dc.tracingChannel('test'); + + assert.strictEqual(channel.hasSubscribers, false); + + channel.subscribe(handlers); + assert.strictEqual(channel.hasSubscribers, true); + + channel.unsubscribe(handlers); + assert.strictEqual(channel.hasSubscribers, false); + + channel.asyncEnd.subscribe(handler); + assert.strictEqual(channel.hasSubscribers, true); + + channel.asyncEnd.unsubscribe(handler); + assert.strictEqual(channel.hasSubscribers, false); +}