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Merge pull request #33 from yaxia/master
Storage Client Library - 0.4.1
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@@ -13,4 +13,4 @@ results | |
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| npm-debug.log | ||
| node_modules | ||
| docs | ||
| docs | ||
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| Original file line number | Diff line number | Diff line change |
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| // | ||
| // Copyright (c) Microsoft and contributors. All rights reserved. | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| // | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
| // | ||
|
|
||
| var Constants = require('./../util/constants'); | ||
| var SR = require('./../util/sr'); | ||
| var EventEmitter = require('events').EventEmitter; | ||
|
|
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| /** | ||
| * Range stream | ||
| */ | ||
| function RangeStream(serviceClient, options) { | ||
| this.serviceClient = serviceClient; | ||
| this.rangeSize = -1; | ||
| this._emitter = new EventEmitter(); | ||
| this._paused = false; | ||
| this._emittedAll = false; | ||
| this._emittedRangeIndex = 0; | ||
| this._rangelist = []; | ||
| this._resourcePath = []; | ||
| this._isEmitting = false; | ||
| this._rangeStreamEnded = false; | ||
| this._lengthHeader = Constants.HeaderConstants.CONTENT_LENGTH_HEADER; | ||
| this._minRangeSize = Constants.BlobConstants.MIN_WRITE_PAGE_SIZE_IN_BYTES; | ||
| this._maxRangeSize = Constants.BlobConstants.DEFAULT_WRITE_PAGE_SIZE_IN_BYTES; | ||
| if (options.rangeStart) { | ||
| this._startOffset = options.rangeStart; | ||
| } else { | ||
| this._startOffset = 0; | ||
| } | ||
| this._dataOffset = this._startOffset; | ||
| if (options.rangeEnd) { | ||
| this._endOffset = options.rangeEnd; | ||
| } else { | ||
| this._endOffset = Number.MAX_VALUE; | ||
| } | ||
| } | ||
|
|
||
| /** | ||
| * Get range list | ||
| */ | ||
| RangeStream.prototype.list = function (options) { | ||
| var self = this; | ||
| var start = this._startOffset; | ||
| var singleRangeSize = Constants.BlobConstants.MAX_SINGLE_GET_PAGE_RANGE_SIZE; | ||
| var end = Math.min(this._startOffset + singleRangeSize - 1, this._endOffset); | ||
| options.rangeStart = start | ||
| options.rangeEnd = end; | ||
|
|
||
| if (this._listFunc == undefined) { | ||
| throw new Error(SR.NO_LIST_FUNC_PROVIDED); | ||
| } | ||
|
|
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| var onList = function (error, ranges, response) { | ||
| if (error) throw error; | ||
| var totalSize = parseInt(response.headers[self._lengthHeader], 10); | ||
| var endOffset = Math.min(totalSize - 1, self._endOffset); | ||
| var rangeEnd = Math.min(end, endOffset); | ||
| self.rangeSize = totalSize; | ||
| if (!ranges.length) { | ||
| // convert single object to range | ||
| // start >= end means there is no valid regions | ||
| ranges.push({ start : start, end : rangeEnd, dataSize: 0 }); | ||
| } else if (ranges[ranges.length - 1].end !== rangeEnd) { | ||
| // don't forget the zero chunk at the end of range | ||
| ranges.push({ start : ranges[ranges.length - 1].end + 1, end : rangeEnd, dataSize: 0 }); | ||
| } | ||
|
|
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| if (end >= endOffset) { | ||
| self._rangeStreamEnded = true; | ||
| } | ||
| self.resizeAndSaveRanges(ranges); | ||
| self._startOffset += singleRangeSize; | ||
| self._emitRange(); | ||
|
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| if (end < endOffset) { | ||
| process.nextTick(function () { | ||
| ranges = null; | ||
| self.list(options); | ||
| self = null; | ||
| }); | ||
| } | ||
| }; | ||
|
|
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| var callArguments = Array.prototype.slice.call(this._resourcePath); | ||
| callArguments.push(options); | ||
| callArguments.push(onList); | ||
| this._listFunc.apply(this.serviceClient, callArguments); | ||
| }; | ||
|
|
||
| /** | ||
| * Resize regions: | ||
| * 1. Merge small pieces into a range no less than this._minRangeSize | ||
| * 2. Split large pieces into ranges no more than this._maxRangeSize | ||
| */ | ||
| RangeStream.prototype.resizeAndSaveRanges = function (ranges) { | ||
| var rangeList = this._rangelist; | ||
| var holdingRange = { type : 'range', size : 0, dataSize : 0, start : this._startOffset, end : -1 }; | ||
| var readingRange = null; | ||
| var rangeSize = 0; | ||
|
|
||
| for (var index = 0; index < ranges.length; index++) { | ||
| readingRange = ranges[index]; | ||
| rangeSize = readingRange.end - holdingRange.start + 1; | ||
|
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| if (rangeSize < this._minRangeSize) { | ||
| // merge fragment ranges | ||
| this.mergeRanges(holdingRange, readingRange); | ||
| } else { | ||
| if (holdingRange.end != -1) { | ||
| // save the holding range list and hold the reading range | ||
| this.splitAndSaveRanges(holdingRange, rangeList); | ||
| holdingRange = readingRange; | ||
| } | ||
|
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||
| if (this._dataOffset != readingRange.start) { | ||
| // padding zero for empty range and hold the reading range | ||
| this.putZeroRange(this._dataOffset, readingRange.start - 1, rangeList); | ||
| holdingRange = readingRange; | ||
| } else if (holdingRange.end == -1) { | ||
| // if holdingRange is never set, it means readingRange exceeds MIN_WRITE_FILE_SIZE_IN_BYTES | ||
| this.splitAndSaveRanges(readingRange, rangeList); | ||
| // reading range has been saved, offset the holding start position for calculating the range size in next loop | ||
| holdingRange.start = readingRange.end + 1; | ||
| } | ||
| } | ||
|
|
||
| // If it is the last range, put the holding range into list anyway | ||
| if (index == ranges.length - 1 && holdingRange.end > holdingRange.start) { | ||
| this.splitAndSaveRanges(holdingRange, rangeList); | ||
| } | ||
|
|
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| this._dataOffset = readingRange.end + 1; | ||
| } | ||
| }; | ||
|
|
||
| /** | ||
| * Put a zero range into range list | ||
| */ | ||
| RangeStream.prototype.putZeroRange = function (startOffset, endOffset, rangeList) { | ||
| var zeroDataRange = { type : 'range', size : -1, dataSize : 0, start : startOffset, end : endOffset }; | ||
| this.splitAndSaveRanges(zeroDataRange, rangeList); | ||
| }; | ||
|
|
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| /** | ||
| * Merge small ranges | ||
| */ | ||
| RangeStream.prototype.mergeRanges = function (holdingRange, readingRange) { | ||
| holdingRange.size = readingRange.end - holdingRange.start + 1; | ||
| holdingRange.dataSize += readingRange.dataSize; | ||
| holdingRange.end = readingRange.end; | ||
| return holdingRange; | ||
| }; | ||
|
|
||
| /** | ||
| * Split range into small pieces with maximum _maxRangeSize and minimum _minRangeSize size. | ||
| * For example, [0, 10G - 1] => [0, 4MB - 1], [4MB, 8MB - 1] ... [10GB - 4MB, 10GB - 1] | ||
| */ | ||
| RangeStream.prototype.splitAndSaveRanges = function (range, rangeList) { | ||
| var rangeSize = range.end - range.start + 1; | ||
| var offset = range.start; | ||
| var limitedSize = 0; | ||
|
|
||
| while (rangeSize > 0) { | ||
| var newRange = { type : 'range', size : 0, dataSize : 0, start : -1, end : -1 }; | ||
| limitedSize = Math.min(rangeSize, this._maxRangeSize); | ||
| newRange.start = offset; | ||
| newRange.size = limitedSize; | ||
| if (range.dataSize === 0) { | ||
| newRange.dataSize = 0; | ||
| } else { | ||
| newRange.dataSize = limitedSize; | ||
| } | ||
| offset += limitedSize; | ||
| newRange.end = offset - 1; | ||
| rangeList.push(newRange); | ||
| rangeSize -= limitedSize; | ||
| } | ||
| }; | ||
|
|
||
| /** | ||
| * Emit a range | ||
| */ | ||
| RangeStream.prototype._emitRange = function () { | ||
| if (this._paused || this._emittedAll || this._isEmitting) return; | ||
| this._isEmitting = true; | ||
| try { | ||
| for (; this._emittedRangeIndex < this._rangelist.length; this._emittedRangeIndex++) { | ||
| if (this._paused) { | ||
| return; | ||
| } | ||
| var range = this._rangelist[this._emittedRangeIndex]; | ||
| this._emitter.emit('range', range); | ||
| this._rangelist[this._emittedRangeIndex] = null; | ||
| } | ||
|
|
||
| if (this._rangeStreamEnded) { | ||
| this._rangelist = null; | ||
| this._emittedAll = true; | ||
| this._emitter.emit('end'); | ||
| } | ||
| } finally { | ||
| this._isEmitting = false; | ||
| } | ||
| }; | ||
|
|
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| /** | ||
| * Add event listener | ||
| */ | ||
| RangeStream.prototype.on = function (event, listener) { | ||
| this._emitter.on(event, listener); | ||
| }; | ||
|
|
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| /** | ||
| * Pause the stream | ||
| */ | ||
| RangeStream.prototype.pause = function () { | ||
| this._paused = true; | ||
| }; | ||
|
|
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| /** | ||
| * Resume the stream | ||
| */ | ||
| RangeStream.prototype.resume = function () { | ||
| this._paused = false; | ||
| if (!this._isEmitting) { | ||
| this._emitRange(); | ||
| } | ||
| }; | ||
|
|
||
| module.exports = RangeStream; |
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