194 lines
8.2 KiB
JavaScript
194 lines
8.2 KiB
JavaScript
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"use strict";
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Object.defineProperty(exports, "__esModule", { value: true });
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exports.doDecode = exports.decompress = exports.inflate = exports.deflate = void 0;
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/*
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* This is a TypeScript port of the original Java version, which was written by
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* Gil Tene as described in
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* https://github.com/HdrHistogram/HdrHistogram
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* and released to the public domain, as explained at
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* http://creativecommons.org/publicdomain/zero/1.0/
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*/
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// @ts-ignore
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const base64 = require("base64-js");
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// @ts-ignore
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const pako = require("pako");
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const JsHistogram_1 = require("./JsHistogram");
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const ByteBuffer_1 = require("./ByteBuffer");
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const JsHistogramFactory_1 = require("./JsHistogramFactory");
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const ZigZagEncoding_1 = require("./ZigZagEncoding");
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const { max } = Math;
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const V2EncodingCookieBase = 0x1c849303;
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const V2CompressedEncodingCookieBase = 0x1c849304;
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const V2maxWordSizeInBytes = 9; // LEB128-64b9B + ZigZag require up to 9 bytes per word
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const encodingCookie = V2EncodingCookieBase | 0x10; // LSBit of wordsize byte indicates TLZE Encoding
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const compressedEncodingCookie = V2CompressedEncodingCookieBase | 0x10; // LSBit of wordsize byte indicates TLZE Encoding
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function fillBufferFromCountsArray(self, buffer) {
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const countsLimit = self.countsArrayIndex(self.maxValue) + 1;
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let srcIndex = 0;
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while (srcIndex < countsLimit) {
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// V2 encoding format uses a ZigZag LEB128-64b9B encoded long. Positive values are counts,
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// while negative values indicate a repeat zero counts.
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const count = self.getCountAtIndex(srcIndex++);
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if (count < 0) {
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throw new Error("Cannot encode histogram containing negative counts (" +
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count +
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") at index " +
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srcIndex +
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", corresponding the value range [" +
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self.lowestEquivalentValue(self.valueFromIndex(srcIndex)) +
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"," +
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self.nextNonEquivalentValue(self.valueFromIndex(srcIndex)) +
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")");
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}
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// Count trailing 0s (which follow this count):
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let zerosCount = 0;
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if (count == 0) {
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zerosCount = 1;
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while (srcIndex < countsLimit && self.getCountAtIndex(srcIndex) == 0) {
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zerosCount++;
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srcIndex++;
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}
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}
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if (zerosCount > 1) {
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ZigZagEncoding_1.default.encode(buffer, -zerosCount);
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}
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else {
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ZigZagEncoding_1.default.encode(buffer, count);
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}
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}
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}
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/**
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* Encode this histogram into a ByteBuffer
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* @param self this histogram
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* @param buffer The buffer to encode into
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* @return The number of bytes written to the buffer
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*/
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function encodeIntoByteBuffer(self, buffer) {
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const initialPosition = buffer.position;
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buffer.putInt32(encodingCookie);
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buffer.putInt32(0); // Placeholder for payload length in bytes.
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buffer.putInt32(1);
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buffer.putInt32(self.numberOfSignificantValueDigits);
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buffer.putInt64(self.lowestDiscernibleValue);
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buffer.putInt64(self.highestTrackableValue);
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buffer.putInt64(1);
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const payloadStartPosition = buffer.position;
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fillBufferFromCountsArray(self, buffer);
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const backupIndex = buffer.position;
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buffer.position = initialPosition + 4;
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buffer.putInt32(backupIndex - payloadStartPosition); // Record the payload length
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buffer.position = backupIndex;
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return backupIndex - initialPosition;
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}
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function fillCountsArrayFromSourceBuffer(self, sourceBuffer, lengthInBytes, wordSizeInBytes) {
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if (wordSizeInBytes != 2 &&
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wordSizeInBytes != 4 &&
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wordSizeInBytes != 8 &&
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wordSizeInBytes != V2maxWordSizeInBytes) {
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throw new Error("word size must be 2, 4, 8, or V2maxWordSizeInBytes (" +
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V2maxWordSizeInBytes +
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") bytes");
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}
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let dstIndex = 0;
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const endPosition = sourceBuffer.position + lengthInBytes;
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while (sourceBuffer.position < endPosition) {
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let zerosCount = 0;
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let count = ZigZagEncoding_1.default.decode(sourceBuffer);
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if (count < 0) {
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zerosCount = -count;
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dstIndex += zerosCount; // No need to set zeros in array. Just skip them.
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}
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else {
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self.setCountAtIndex(dstIndex++, count);
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}
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}
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return dstIndex; // this is the destination length
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}
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function getCookieBase(cookie) {
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return cookie & ~0xf0;
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}
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function getWordSizeInBytesFromCookie(cookie) {
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if (getCookieBase(cookie) == V2EncodingCookieBase ||
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getCookieBase(cookie) == V2CompressedEncodingCookieBase) {
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return V2maxWordSizeInBytes;
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}
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const sizeByte = (cookie & 0xf0) >> 4;
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return sizeByte & 0xe;
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}
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function findDeflateFunction() {
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try {
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return eval('require("zlib").deflateSync');
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}
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catch (error) {
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return !!pako ? pako.deflate : () => { throw new Error('pako library is mandatory for encoding/deconding on the browser side'); };
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}
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}
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function findInflateFunction() {
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try {
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return eval('require("zlib").inflateSync');
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}
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catch (error) {
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return !!pako ? pako.inflate : () => { throw new Error('pako library is mandatory for encoding/deconding on the browser side'); };
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}
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}
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exports.deflate = findDeflateFunction();
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exports.inflate = findInflateFunction();
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function decompress(data) {
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const buffer = new ByteBuffer_1.default(data);
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const initialTargetPosition = buffer.position;
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const cookie = buffer.getInt32();
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if ((cookie & ~0xf0) !== V2CompressedEncodingCookieBase) {
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throw new Error("Encoding not supported, only V2 is supported");
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}
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const lengthOfCompressedContents = buffer.getInt32();
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const uncompressedBuffer = exports.inflate(buffer.data.slice(initialTargetPosition + 8, initialTargetPosition + 8 + lengthOfCompressedContents));
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return uncompressedBuffer;
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}
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exports.decompress = decompress;
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function doDecode(data, bitBucketSize = 32, minBarForHighestTrackableValue = 0) {
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const buffer = new ByteBuffer_1.default(data);
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const cookie = buffer.getInt32();
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let payloadLengthInBytes;
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let numberOfSignificantValueDigits;
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let lowestTrackableUnitValue;
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let highestTrackableValue;
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if (getCookieBase(cookie) === V2EncodingCookieBase) {
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if (getWordSizeInBytesFromCookie(cookie) != V2maxWordSizeInBytes) {
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throw new Error("The buffer does not contain a Histogram (no valid cookie found)");
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}
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payloadLengthInBytes = buffer.getInt32();
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buffer.getInt32(); // normalizingIndexOffset not used
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numberOfSignificantValueDigits = buffer.getInt32();
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lowestTrackableUnitValue = buffer.getInt64();
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highestTrackableValue = buffer.getInt64();
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buffer.getInt64(); // integerToDoubleValueConversionRatio not used
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}
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else {
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throw new Error("The buffer does not contain a Histogram (no valid V2 encoding cookie found)");
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}
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highestTrackableValue = max(highestTrackableValue, minBarForHighestTrackableValue);
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const histogramConstr = JsHistogramFactory_1.constructorFromBucketSize(bitBucketSize);
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const histogram = new histogramConstr(lowestTrackableUnitValue, highestTrackableValue, numberOfSignificantValueDigits);
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const filledLength = fillCountsArrayFromSourceBuffer(histogram, buffer, payloadLengthInBytes, V2maxWordSizeInBytes);
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histogram.establishInternalTackingValues(filledLength);
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return histogram;
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}
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exports.doDecode = doDecode;
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function doEncodeIntoCompressedBase64(compressionLevel) {
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const compressionOptions = compressionLevel
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? { level: compressionLevel }
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: {};
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const self = this;
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const targetBuffer = ByteBuffer_1.default.allocate();
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targetBuffer.putInt32(compressedEncodingCookie);
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const intermediateUncompressedByteBuffer = ByteBuffer_1.default.allocate();
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const uncompressedLength = encodeIntoByteBuffer(self, intermediateUncompressedByteBuffer);
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const data = intermediateUncompressedByteBuffer.data.slice(0, uncompressedLength);
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const compressedData = exports.deflate(data, compressionOptions);
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targetBuffer.putInt32(compressedData.byteLength);
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targetBuffer.putArray(compressedData);
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return base64.fromByteArray(targetBuffer.data);
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}
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JsHistogram_1.JsHistogram.decode = doDecode;
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JsHistogram_1.JsHistogram.prototype.encodeIntoCompressedBase64 = doEncodeIntoCompressedBase64;
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//# sourceMappingURL=JsHistogram.encoding.js.map
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