43 lines
1.1 KiB
JavaScript
43 lines
1.1 KiB
JavaScript
var baseSetData = require('./_baseSetData'),
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now = require('./now');
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/** Used to detect hot functions by number of calls within a span of milliseconds. */
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var HOT_COUNT = 150,
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HOT_SPAN = 16;
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/**
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* Sets metadata for `func`.
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*
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* **Note:** If this function becomes hot, i.e. is invoked a lot in a short
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* period of time, it will trip its breaker and transition to an identity
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* function to avoid garbage collection pauses in V8. See
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* [V8 issue 2070](https://bugs.chromium.org/p/v8/issues/detail?id=2070)
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* for more details.
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*
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* @private
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* @param {Function} func The function to associate metadata with.
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* @param {*} data The metadata.
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* @returns {Function} Returns `func`.
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*/
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var setData = (function() {
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var count = 0,
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lastCalled = 0;
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return function(key, value) {
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var stamp = now(),
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remaining = HOT_SPAN - (stamp - lastCalled);
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lastCalled = stamp;
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if (remaining > 0) {
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if (++count >= HOT_COUNT) {
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return key;
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}
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} else {
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count = 0;
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}
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return baseSetData(key, value);
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};
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}());
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module.exports = setData;
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