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56 lines
1.1 KiB
56 lines
1.1 KiB
'use strict';
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/**
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* Calculate data maxRate
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* @param {Number} [samplesCount= 10]
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* @param {Number} [min= 1000]
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* @returns {Function}
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*/
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function speedometer(samplesCount, min) {
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samplesCount = samplesCount || 10;
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const bytes = new Array(samplesCount);
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const timestamps = new Array(samplesCount);
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let head = 0;
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let tail = 0;
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let firstSampleTS;
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min = min !== undefined ? min : 1000;
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return function push(chunkLength) {
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const now = Date.now();
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const startedAt = timestamps[tail];
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if (!firstSampleTS) {
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firstSampleTS = now;
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}
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bytes[head] = chunkLength;
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timestamps[head] = now;
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let i = tail;
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let bytesCount = 0;
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while (i !== head) {
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bytesCount += bytes[i++];
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i = i % samplesCount;
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}
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head = (head + 1) % samplesCount;
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if (head === tail) {
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tail = (tail + 1) % samplesCount;
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}
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if (now - firstSampleTS < min) {
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return;
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}
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const passed = startedAt && now - startedAt;
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return passed ? Math.round(bytesCount * 1000 / passed) : undefined;
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};
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}
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export default speedometer;
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