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523a1550a3
The emit{Before,After} APIs in AsyncResource are problematic.
* emit{Before,After} are named to suggest that the only thing they do
is emit the before and after hooks. However, they in fact, mutate
the current execution context.
* They must be properly nested. Failure to do so by user code leads
to catastrophic (unrecoverable) exceptions. It is very easy for the
users to forget that they must be using a try/finally block around
the code that must be surrounded by these operations. Even the
example provided in the official docs makes this mistake. Failing
to use a finally can lead to a catastrophic crash if the callback
ends up throwing.
This change provides a safer `runInAsyncScope` API as an alternative
and deprecates emit{Before,After}.
PR-URL: https://github.com/nodejs/node/pull/18513
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Andreas Madsen <amwebdk@gmail.com>
41 lines
1.2 KiB
JavaScript
41 lines
1.2 KiB
JavaScript
'use strict';
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const common = require('../common');
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const assert = require('assert');
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const async_hooks = require('async_hooks');
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const id_obj = {};
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let collect = true;
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const hook = async_hooks.createHook({
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before(id) { if (collect) id_obj[id] = true; },
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after(id) { delete id_obj[id]; },
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}).enable();
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process.once('uncaughtException', common.mustCall((er) => {
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assert.strictEqual(er.message, 'bye');
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collect = false;
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}));
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setImmediate(common.mustCall(() => {
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process.nextTick(common.mustCall(() => {
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assert.strictEqual(Object.keys(id_obj).length, 0);
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hook.disable();
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}));
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// Create a stack of async ids that will need to be emitted in the case of
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// an uncaught exception.
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const ar1 = new async_hooks.AsyncResource('Mine');
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ar1.runInAsyncScope(() => {
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const ar2 = new async_hooks.AsyncResource('Mine');
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ar2.runInAsyncScope(() => {
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throw new Error('bye');
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});
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});
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// TODO(trevnorris): This test shows that the after() hooks are always called
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// correctly, but it doesn't solve where the emitDestroy() is missed because
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// of the uncaught exception. Simple solution is to always call emitDestroy()
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// before the emitAfter(), but how to codify this?
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}));
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