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events: optimize condition for optimal scenario

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Instead of always checking whether we've already warned about a
possible EventEmitter memory leak, first run the rest of the
code as accessing random properties on an Array is expensive.

In addition, remove an unnecessary truthy check.

PR-URL: https://github.com/nodejs/node/pull/20452
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
This commit is contained in:
Anatoli Papirovski 2018-05-01 13:32:10 +02:00
parent 2553377d11
commit fe8794560a
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GPG Key ID: 614E2E1ABEB4B2C0
2 changed files with 15 additions and 17 deletions
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2
benchmark/events/ee-add-remove.js
View File

@ -2,7 +2,7 @@
const common = require('../common.js'); const common = require('../common.js');
const events = require('events'); const events = require('events');
const bench = common.createBenchmark(main, { n: [25e4] }); const bench = common.createBenchmark(main, { n: [1e6] });
function main({ n }) { function main({ n }) {
const ee = new events.EventEmitter(); const ee = new events.EventEmitter();

30
lib/events.js
View File

@ -235,22 +235,20 @@ function _addListener(target, type, listener, prepend) {
} }
// Check for listener leak // Check for listener leak
if (!existing.warned) { m = $getMaxListeners(target);
m = $getMaxListeners(target); if (m > 0 && existing.length > m && !existing.warned) {
if (m && m > 0 && existing.length > m) { existing.warned = true;
existing.warned = true; // No error code for this since it is a Warning
// No error code for this since it is a Warning // eslint-disable-next-line no-restricted-syntax
// eslint-disable-next-line no-restricted-syntax const w = new Error('Possible EventEmitter memory leak detected. ' +
const w = new Error('Possible EventEmitter memory leak detected. ' + `${existing.length} ${String(type)} listeners ` +
`${existing.length} ${String(type)} listeners ` + 'added. Use emitter.setMaxListeners() to ' +
'added. Use emitter.setMaxListeners() to ' + 'increase limit');
'increase limit'); w.name = 'MaxListenersExceededWarning';
w.name = 'MaxListenersExceededWarning'; w.emitter = target;
w.emitter = target; w.type = type;
w.type = type; w.count = existing.length;
w.count = existing.length; process.emitWarning(w);
process.emitWarning(w);
}
} }
} }