mirror of https://github.com/jkjoy/sunpeiwen.git
37 lines
1.6 KiB
Markdown
37 lines
1.6 KiB
Markdown
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# diagnostics_channel-polyfill
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Exposes a polyfill for the Node.js module `diagnostics_channel`.
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As of now, the Node.js module `diagnostics_channel` is only available in Node `^14.17.0 || >=15.1.0`.
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This aim to allow using the same API on older versions of Node.
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### Install
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```sh
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npm i diagnostics_channel
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```
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### Usage
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Refer to the official documentation: https://nodejs.org/api/diagnostics_channel.html
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### Notes
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- This module and the one included in Node core do NOT share the same channels, they live independently.
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- Since `WeakReference` is not available, channels will NOT be garbage collected when no reference is held in user-land. An additional function is provided to do manual cleanup if needed: `dc.deleteChannel()`. **This should not be needed in a typical scenario. Only use this method if you know why you are doing it.**
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```js
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const dc = require('diagnostics_channel');
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const a = dc.channel('test');
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const b = dc.channel('test');
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// channel is memoized
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console.log(a === b); // true
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dc.deleteChannel('test');
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const c = dc.channel('test');
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// memoized channel was deleted and a new instance was memoized
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console.log(a === c); // false
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```
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- Since `ERR_INVALID_ARG_TYPE` is not available, a simplfied copy of this error is included.
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- Since `triggerUncaughtException()` is not available, if an exception is thrown in a subscriber, the polyfill will instead simply re-throw the error inside a `process.nextTick()`, which has a similar behavior except when the process crashes because of that exception: the crash message will point to this polyfill instead of where the error was created (ie: in the subscriber).
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