181 lines
7.3 KiB
JavaScript
181 lines
7.3 KiB
JavaScript
"use strict";
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Object.defineProperty(exports, "__esModule", { value: true });
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exports.PackedArray = 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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const PackedArrayContext_1 = require("./PackedArrayContext");
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const NUMBER_OF_SETS = 8;
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const { pow, floor } = Math;
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/**
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* A Packed array of signed 64 bit values, and supports {@link #get get()}, {@link #set set()},
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* {@link #add add()} and {@link #increment increment()} operations on the logical contents of the array.
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*
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* An {@link PackedLongArray} Uses {@link PackedArrayContext} to track
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* the array's logical contents. Contexts may be switched when a context requires resizing
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* to complete logical array operations (get, set, add, increment). Contexts are
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* established and used within critical sections in order to facilitate concurrent
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* implementors.
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*
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*/
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class PackedArray {
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constructor(virtualLength, initialPhysicalLength = PackedArrayContext_1.MINIMUM_INITIAL_PACKED_ARRAY_CAPACITY) {
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this.arrayContext = new PackedArrayContext_1.PackedArrayContext(virtualLength, initialPhysicalLength);
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}
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setVirtualLength(newVirtualArrayLength) {
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if (newVirtualArrayLength < this.length()) {
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throw new Error("Cannot set virtual length, as requested length " +
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newVirtualArrayLength +
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" is smaller than the current virtual length " +
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this.length());
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}
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const currentArrayContext = this.arrayContext;
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if (currentArrayContext.isPacked &&
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currentArrayContext.determineTopLevelShiftForVirtualLength(newVirtualArrayLength) == currentArrayContext.getTopLevelShift()) {
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// No changes to the array context contents is needed. Just change the virtual length.
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currentArrayContext.setVirtualLength(newVirtualArrayLength);
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return;
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}
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this.arrayContext = currentArrayContext.copyAndIncreaseSize(this.getPhysicalLength(), newVirtualArrayLength);
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}
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/**
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* Get value at virtual index in the array
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* @param index the virtual array index
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* @return the array value at the virtual index given
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*/
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get(index) {
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let value = 0;
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for (let byteNum = 0; byteNum < NUMBER_OF_SETS; byteNum++) {
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let byteValueAtPackedIndex = 0;
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// Deal with unpacked context:
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if (!this.arrayContext.isPacked) {
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return this.arrayContext.getAtUnpackedIndex(index);
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}
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// Context is packed:
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const packedIndex = this.arrayContext.getPackedIndex(byteNum, index, false);
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if (packedIndex < 0) {
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return value;
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}
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byteValueAtPackedIndex =
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this.arrayContext.getAtByteIndex(packedIndex) * pow(2, byteNum << 3);
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value += byteValueAtPackedIndex;
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}
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return value;
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}
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/**
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* Increment value at a virrual index in the array
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* @param index virtual index of value to increment
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*/
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increment(index) {
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this.add(index, 1);
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}
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safeGetPackedIndexgetPackedIndex(setNumber, virtualIndex) {
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//do {
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//try {
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return this.arrayContext.getPackedIndex(setNumber, virtualIndex, true);
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/*} catch (ex) {
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if (ex instanceof ResizeError) {
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this.arrayContext.resizeArray(ex.newSize);
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} else {
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throw ex;
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}
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}*/
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//} while (true);
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}
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/**
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* Add to a value at a virtual index in the array
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* @param index the virtual index of the value to be added to
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* @param value the value to add
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*/
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add(index, value) {
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let remainingValueToAdd = value;
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for (let byteNum = 0, byteShift = 0; byteNum < NUMBER_OF_SETS; byteNum++, byteShift += 8) {
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// Deal with unpacked context:
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if (!this.arrayContext.isPacked) {
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this.arrayContext.addAndGetAtUnpackedIndex(index, value);
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return;
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}
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// Context is packed:
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const packedIndex = this.safeGetPackedIndexgetPackedIndex(byteNum, index);
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const byteToAdd = remainingValueToAdd & 0xff;
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const afterAddByteValue = this.arrayContext.addAtByteIndex(packedIndex, byteToAdd);
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// Reduce remaining value to add by amount just added:
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remainingValueToAdd -= byteToAdd;
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remainingValueToAdd = remainingValueToAdd / pow(2, 8);
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// Account for carry:
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remainingValueToAdd += floor(afterAddByteValue / pow(2, 8));
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if (remainingValueToAdd == 0) {
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return; // nothing to add to higher magnitudes
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}
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}
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}
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/**
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* Set the value at a virtual index in the array
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* @param index the virtual index of the value to set
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* @param value the value to set
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*/
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set(index, value) {
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let bytesAlreadySet = 0;
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let valueForNextLevels = value;
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for (let byteNum = 0; byteNum < NUMBER_OF_SETS; byteNum++) {
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// Establish context within: critical section
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// Deal with unpacked context:
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if (!this.arrayContext.isPacked) {
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this.arrayContext.setAtUnpackedIndex(index, value);
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return;
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}
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// Context is packed:
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if (valueForNextLevels == 0) {
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// Special-case zeros to avoid inflating packed array for no reason
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const packedIndex = this.arrayContext.getPackedIndex(byteNum, index, false);
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if (packedIndex < 0) {
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return; // no need to create entries for zero values if they don't already exist
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}
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}
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// Make sure byte is populated:
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const packedIndex = this.arrayContext.getPackedIndex(byteNum, index, true);
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// Determine value to write, and prepare for next levels
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const byteToWrite = valueForNextLevels & 0xff;
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valueForNextLevels = floor(valueForNextLevels / pow(2, 8));
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if (byteNum < bytesAlreadySet) {
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// We want to avoid writing to the same byte twice when not doing so for the
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// entire 64 bit value atomically, as doing so opens a race with e.g. concurrent
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// adders. So dobn't actually write the byte if has been written before.
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continue;
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}
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this.arrayContext.setAtByteIndex(packedIndex, byteToWrite);
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bytesAlreadySet++;
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}
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}
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/**
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* Get the current physical length (in longs) of the array's backing storage
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* @return the current physical length (in longs) of the array's current backing storage
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*/
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getPhysicalLength() {
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return this.arrayContext.physicalLength;
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}
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/**
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* Get the (virtual) length of the array
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* @return the (virtual) length of the array
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*/
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length() {
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return this.arrayContext.getVirtualLength();
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}
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/**
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* Clear the array contents
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*/
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clear() {
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this.arrayContext.clear();
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}
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toString() {
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let output = "PackedArray:\n";
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output += this.arrayContext.toString();
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return output;
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}
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}
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exports.PackedArray = PackedArray;
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//# sourceMappingURL=PackedArray.js.map
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