package node; /** The `node:diagnostics_channel` module provides an API to create named channels to report arbitrary message data for diagnostics purposes. It can be accessed using: ```js import diagnostics_channel from 'node:diagnostics_channel'; ``` It is intended that a module writer wanting to report diagnostics messages will create one or many top-level channels to report messages through. Channels may also be acquired at runtime but it is not encouraged due to the additional overhead of doing so. Channels may be exported for convenience, but as long as the name is known it can be acquired anywhere. If you intend for your module to produce diagnostics data for others to consume it is recommended that you include documentation of what named channels are used along with the shape of the message data. Channel names should generally include the module name to avoid collisions with data from other modules. **/ @:jsRequire("diagnostics_channel") @valueModuleOnly extern class Diagnostics_channel { /** Check if there are active subscribers to the named channel. This is helpful if the message you want to send might be expensive to prepare. This API is optional but helpful when trying to publish messages from very performance-sensitive code. ```js import diagnostics_channel from 'node:diagnostics_channel'; if (diagnostics_channel.hasSubscribers('my-channel')) { // There are subscribers, prepare and publish message } ``` **/ static function hasSubscribers(name:ts.AnyOf2):Bool; /** This is the primary entry-point for anyone wanting to publish to a named channel. It produces a channel object which is optimized to reduce overhead at publish time as much as possible. ```js import diagnostics_channel from 'node:diagnostics_channel'; const channel = diagnostics_channel.channel('my-channel'); ``` **/ static function channel(name:ts.AnyOf2):node.diagnostics_channel.Channel; /** Register a message handler to subscribe to this channel. This message handler will be run synchronously whenever a message is published to the channel. Any errors thrown in the message handler will trigger an `'uncaughtException'`. ```js import diagnostics_channel from 'node:diagnostics_channel'; diagnostics_channel.subscribe('my-channel', (message, name) => { // Received data }); ``` **/ static function subscribe(name:ts.AnyOf2, onMessage:node.diagnostics_channel.ChannelListener):Void; /** Remove a message handler previously registered to this channel with {@link subscribe}. ```js import diagnostics_channel from 'node:diagnostics_channel'; function onMessage(message, name) { // Received data } diagnostics_channel.subscribe('my-channel', onMessage); diagnostics_channel.unsubscribe('my-channel', onMessage); ``` **/ static function unsubscribe(name:ts.AnyOf2, onMessage:node.diagnostics_channel.ChannelListener):Bool; }