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