pdfjs-dist/lib/core/chunked_stream.js

/* Copyright 2017 Mozilla Foundation
 *
 * 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.
 */
'use strict';
var sharedUtil = require('../shared/util.js');
var MissingDataException = sharedUtil.MissingDataException;
var arrayByteLength = sharedUtil.arrayByteLength;
var arraysToBytes = sharedUtil.arraysToBytes;
var assert = sharedUtil.assert;
var createPromiseCapability = sharedUtil.createPromiseCapability;
var isInt = sharedUtil.isInt;
var isEmptyObj = sharedUtil.isEmptyObj;
var ChunkedStream = function ChunkedStreamClosure() {
 function ChunkedStream(length, chunkSize, manager) {
  this.bytes = new Uint8Array(length);
  this.start = 0;
  this.pos = 0;
  this.end = length;
  this.chunkSize = chunkSize;
  this.loadedChunks = [];
  this.numChunksLoaded = 0;
  this.numChunks = Math.ceil(length / chunkSize);
  this.manager = manager;
  this.progressiveDataLength = 0;
  this.lastSuccessfulEnsureByteChunk = -1;
 }
 ChunkedStream.prototype = {
  getMissingChunks: function ChunkedStream_getMissingChunks() {
   var chunks = [];
   for (var chunk = 0, n = this.numChunks; chunk < n; ++chunk) {
    if (!this.loadedChunks[chunk]) {
     chunks.push(chunk);
    }
   }
   return chunks;
  },
  getBaseStreams: function ChunkedStream_getBaseStreams() {
   return [this];
  },
  allChunksLoaded: function ChunkedStream_allChunksLoaded() {
   return this.numChunksLoaded === this.numChunks;
  },
  onReceiveData: function ChunkedStream_onReceiveData(begin, chunk) {
   var end = begin + chunk.byteLength;
   assert(begin % this.chunkSize === 0, 'Bad begin offset: ' + begin);
   var length = this.bytes.length;
   assert(end % this.chunkSize === 0 || end === length, 'Bad end offset: ' + end);
   this.bytes.set(new Uint8Array(chunk), begin);
   var chunkSize = this.chunkSize;
   var beginChunk = Math.floor(begin / chunkSize);
   var endChunk = Math.floor((end - 1) / chunkSize) + 1;
   var curChunk;
   for (curChunk = beginChunk; curChunk < endChunk; ++curChunk) {
    if (!this.loadedChunks[curChunk]) {
     this.loadedChunks[curChunk] = true;
     ++this.numChunksLoaded;
    }
   }
  },
  onReceiveProgressiveData: function ChunkedStream_onReceiveProgressiveData(data) {
   var position = this.progressiveDataLength;
   var beginChunk = Math.floor(position / this.chunkSize);
   this.bytes.set(new Uint8Array(data), position);
   position += data.byteLength;
   this.progressiveDataLength = position;
   var endChunk = position >= this.end ? this.numChunks : Math.floor(position / this.chunkSize);
   var curChunk;
   for (curChunk = beginChunk; curChunk < endChunk; ++curChunk) {
    if (!this.loadedChunks[curChunk]) {
     this.loadedChunks[curChunk] = true;
     ++this.numChunksLoaded;
    }
   }
  },
  ensureByte: function ChunkedStream_ensureByte(pos) {
   var chunk = Math.floor(pos / this.chunkSize);
   if (chunk === this.lastSuccessfulEnsureByteChunk) {
    return;
   }
   if (!this.loadedChunks[chunk]) {
    throw new MissingDataException(pos, pos + 1);
   }
   this.lastSuccessfulEnsureByteChunk = chunk;
  },
  ensureRange: function ChunkedStream_ensureRange(begin, end) {
   if (begin >= end) {
    return;
   }
   if (end <= this.progressiveDataLength) {
    return;
   }
   var chunkSize = this.chunkSize;
   var beginChunk = Math.floor(begin / chunkSize);
   var endChunk = Math.floor((end - 1) / chunkSize) + 1;
   for (var chunk = beginChunk; chunk < endChunk; ++chunk) {
    if (!this.loadedChunks[chunk]) {
     throw new MissingDataException(begin, end);
    }
   }
  },
  nextEmptyChunk: function ChunkedStream_nextEmptyChunk(beginChunk) {
   var chunk, numChunks = this.numChunks;
   for (var i = 0; i < numChunks; ++i) {
    chunk = (beginChunk + i) % numChunks;
    if (!this.loadedChunks[chunk]) {
     return chunk;
    }
   }
   return null;
  },
  hasChunk: function ChunkedStream_hasChunk(chunk) {
   return !!this.loadedChunks[chunk];
  },
  get length() {
   return this.end - this.start;
  },
  get isEmpty() {
   return this.length === 0;
  },
  getByte: function ChunkedStream_getByte() {
   var pos = this.pos;
   if (pos >= this.end) {
    return -1;
   }
   this.ensureByte(pos);
   return this.bytes[this.pos++];
  },
  getUint16: function ChunkedStream_getUint16() {
   var b0 = this.getByte();
   var b1 = this.getByte();
   if (b0 === -1 || b1 === -1) {
    return -1;
   }
   return (b0 << 8) + b1;
  },
  getInt32: function ChunkedStream_getInt32() {
   var b0 = this.getByte();
   var b1 = this.getByte();
   var b2 = this.getByte();
   var b3 = this.getByte();
   return (b0 << 24) + (b1 << 16) + (b2 << 8) + b3;
  },
  getBytes: function ChunkedStream_getBytes(length) {
   var bytes = this.bytes;
   var pos = this.pos;
   var strEnd = this.end;
   if (!length) {
    this.ensureRange(pos, strEnd);
    return bytes.subarray(pos, strEnd);
   }
   var end = pos + length;
   if (end > strEnd) {
    end = strEnd;
   }
   this.ensureRange(pos, end);
   this.pos = end;
   return bytes.subarray(pos, end);
  },
  peekByte: function ChunkedStream_peekByte() {
   var peekedByte = this.getByte();
   this.pos--;
   return peekedByte;
  },
  peekBytes: function ChunkedStream_peekBytes(length) {
   var bytes = this.getBytes(length);
   this.pos -= bytes.length;
   return bytes;
  },
  getByteRange: function ChunkedStream_getBytes(begin, end) {
   this.ensureRange(begin, end);
   return this.bytes.subarray(begin, end);
  },
  skip: function ChunkedStream_skip(n) {
   if (!n) {
    n = 1;
   }
   this.pos += n;
  },
  reset: function ChunkedStream_reset() {
   this.pos = this.start;
  },
  moveStart: function ChunkedStream_moveStart() {
   this.start = this.pos;
  },
  makeSubStream: function ChunkedStream_makeSubStream(start, length, dict) {
   this.ensureRange(start, start + length);
   function ChunkedStreamSubstream() {
   }
   ChunkedStreamSubstream.prototype = Object.create(this);
   ChunkedStreamSubstream.prototype.getMissingChunks = function () {
    var chunkSize = this.chunkSize;
    var beginChunk = Math.floor(this.start / chunkSize);
    var endChunk = Math.floor((this.end - 1) / chunkSize) + 1;
    var missingChunks = [];
    for (var chunk = beginChunk; chunk < endChunk; ++chunk) {
     if (!this.loadedChunks[chunk]) {
      missingChunks.push(chunk);
     }
    }
    return missingChunks;
   };
   var subStream = new ChunkedStreamSubstream();
   subStream.pos = subStream.start = start;
   subStream.end = start + length || this.end;
   subStream.dict = dict;
   return subStream;
  }
 };
 return ChunkedStream;
}();
var ChunkedStreamManager = function ChunkedStreamManagerClosure() {
 function ChunkedStreamManager(pdfNetworkStream, args) {
  var chunkSize = args.rangeChunkSize;
  var length = args.length;
  this.stream = new ChunkedStream(length, chunkSize, this);
  this.length = length;
  this.chunkSize = chunkSize;
  this.pdfNetworkStream = pdfNetworkStream;
  this.url = args.url;
  this.disableAutoFetch = args.disableAutoFetch;
  this.msgHandler = args.msgHandler;
  this.currRequestId = 0;
  this.chunksNeededByRequest = Object.create(null);
  this.requestsByChunk = Object.create(null);
  this.promisesByRequest = Object.create(null);
  this.progressiveDataLength = 0;
  this.aborted = false;
  this._loadedStreamCapability = createPromiseCapability();
 }
 ChunkedStreamManager.prototype = {
  onLoadedStream: function ChunkedStreamManager_getLoadedStream() {
   return this._loadedStreamCapability.promise;
  },
  sendRequest: function ChunkedStreamManager_sendRequest(begin, end) {
   var rangeReader = this.pdfNetworkStream.getRangeReader(begin, end);
   if (!rangeReader.isStreamingSupported) {
    rangeReader.onProgress = this.onProgress.bind(this);
   }
   var chunks = [], loaded = 0;
   var manager = this;
   var promise = new Promise(function (resolve, reject) {
    var readChunk = function (chunk) {
     try {
      if (!chunk.done) {
       var data = chunk.value;
       chunks.push(data);
       loaded += arrayByteLength(data);
       if (rangeReader.isStreamingSupported) {
        manager.onProgress({ loaded: loaded });
       }
       rangeReader.read().then(readChunk, reject);
       return;
      }
      var chunkData = arraysToBytes(chunks);
      chunks = null;
      resolve(chunkData);
     } catch (e) {
      reject(e);
     }
    };
    rangeReader.read().then(readChunk, reject);
   });
   promise.then(function (data) {
    if (this.aborted) {
     return;
    }
    this.onReceiveData({
     chunk: data,
     begin: begin
    });
   }.bind(this));
  },
  requestAllChunks: function ChunkedStreamManager_requestAllChunks() {
   var missingChunks = this.stream.getMissingChunks();
   this._requestChunks(missingChunks);
   return this._loadedStreamCapability.promise;
  },
  _requestChunks: function ChunkedStreamManager_requestChunks(chunks) {
   var requestId = this.currRequestId++;
   var i, ii;
   var chunksNeeded = Object.create(null);
   this.chunksNeededByRequest[requestId] = chunksNeeded;
   for (i = 0, ii = chunks.length; i < ii; i++) {
    if (!this.stream.hasChunk(chunks[i])) {
     chunksNeeded[chunks[i]] = true;
    }
   }
   if (isEmptyObj(chunksNeeded)) {
    return Promise.resolve();
   }
   var capability = createPromiseCapability();
   this.promisesByRequest[requestId] = capability;
   var chunksToRequest = [];
   for (var chunk in chunksNeeded) {
    chunk = chunk | 0;
    if (!(chunk in this.requestsByChunk)) {
     this.requestsByChunk[chunk] = [];
     chunksToRequest.push(chunk);
    }
    this.requestsByChunk[chunk].push(requestId);
   }
   if (!chunksToRequest.length) {
    return capability.promise;
   }
   var groupedChunksToRequest = this.groupChunks(chunksToRequest);
   for (i = 0; i < groupedChunksToRequest.length; ++i) {
    var groupedChunk = groupedChunksToRequest[i];
    var begin = groupedChunk.beginChunk * this.chunkSize;
    var end = Math.min(groupedChunk.endChunk * this.chunkSize, this.length);
    this.sendRequest(begin, end);
   }
   return capability.promise;
  },
  getStream: function ChunkedStreamManager_getStream() {
   return this.stream;
  },
  requestRange: function ChunkedStreamManager_requestRange(begin, end) {
   end = Math.min(end, this.length);
   var beginChunk = this.getBeginChunk(begin);
   var endChunk = this.getEndChunk(end);
   var chunks = [];
   for (var chunk = beginChunk; chunk < endChunk; ++chunk) {
    chunks.push(chunk);
   }
   return this._requestChunks(chunks);
  },
  requestRanges: function ChunkedStreamManager_requestRanges(ranges) {
   ranges = ranges || [];
   var chunksToRequest = [];
   for (var i = 0; i < ranges.length; i++) {
    var beginChunk = this.getBeginChunk(ranges[i].begin);
    var endChunk = this.getEndChunk(ranges[i].end);
    for (var chunk = beginChunk; chunk < endChunk; ++chunk) {
     if (chunksToRequest.indexOf(chunk) < 0) {
      chunksToRequest.push(chunk);
     }
    }
   }
   chunksToRequest.sort(function (a, b) {
    return a - b;
   });
   return this._requestChunks(chunksToRequest);
  },
  groupChunks: function ChunkedStreamManager_groupChunks(chunks) {
   var groupedChunks = [];
   var beginChunk = -1;
   var prevChunk = -1;
   for (var i = 0; i < chunks.length; ++i) {
    var chunk = chunks[i];
    if (beginChunk < 0) {
     beginChunk = chunk;
    }
    if (prevChunk >= 0 && prevChunk + 1 !== chunk) {
     groupedChunks.push({
      beginChunk: beginChunk,
      endChunk: prevChunk + 1
     });
     beginChunk = chunk;
    }
    if (i + 1 === chunks.length) {
     groupedChunks.push({
      beginChunk: beginChunk,
      endChunk: chunk + 1
     });
    }
    prevChunk = chunk;
   }
   return groupedChunks;
  },
  onProgress: function ChunkedStreamManager_onProgress(args) {
   var bytesLoaded = this.stream.numChunksLoaded * this.chunkSize + args.loaded;
   this.msgHandler.send('DocProgress', {
    loaded: bytesLoaded,
    total: this.length
   });
  },
  onReceiveData: function ChunkedStreamManager_onReceiveData(args) {
   var chunk = args.chunk;
   var isProgressive = args.begin === undefined;
   var begin = isProgressive ? this.progressiveDataLength : args.begin;
   var end = begin + chunk.byteLength;
   var beginChunk = Math.floor(begin / this.chunkSize);
   var endChunk = end < this.length ? Math.floor(end / this.chunkSize) : Math.ceil(end / this.chunkSize);
   if (isProgressive) {
    this.stream.onReceiveProgressiveData(chunk);
    this.progressiveDataLength = end;
   } else {
    this.stream.onReceiveData(begin, chunk);
   }
   if (this.stream.allChunksLoaded()) {
    this._loadedStreamCapability.resolve(this.stream);
   }
   var loadedRequests = [];
   var i, requestId;
   for (chunk = beginChunk; chunk < endChunk; ++chunk) {
    var requestIds = this.requestsByChunk[chunk] || [];
    delete this.requestsByChunk[chunk];
    for (i = 0; i < requestIds.length; ++i) {
     requestId = requestIds[i];
     var chunksNeeded = this.chunksNeededByRequest[requestId];
     if (chunk in chunksNeeded) {
      delete chunksNeeded[chunk];
     }
     if (!isEmptyObj(chunksNeeded)) {
      continue;
     }
     loadedRequests.push(requestId);
    }
   }
   if (!this.disableAutoFetch && isEmptyObj(this.requestsByChunk)) {
    var nextEmptyChunk;
    if (this.stream.numChunksLoaded === 1) {
     var lastChunk = this.stream.numChunks - 1;
     if (!this.stream.hasChunk(lastChunk)) {
      nextEmptyChunk = lastChunk;
     }
    } else {
     nextEmptyChunk = this.stream.nextEmptyChunk(endChunk);
    }
    if (isInt(nextEmptyChunk)) {
     this._requestChunks([nextEmptyChunk]);
    }
   }
   for (i = 0; i < loadedRequests.length; ++i) {
    requestId = loadedRequests[i];
    var capability = this.promisesByRequest[requestId];
    delete this.promisesByRequest[requestId];
    capability.resolve();
   }
   this.msgHandler.send('DocProgress', {
    loaded: this.stream.numChunksLoaded * this.chunkSize,
    total: this.length
   });
  },
  onError: function ChunkedStreamManager_onError(err) {
   this._loadedStreamCapability.reject(err);
  },
  getBeginChunk: function ChunkedStreamManager_getBeginChunk(begin) {
   var chunk = Math.floor(begin / this.chunkSize);
   return chunk;
  },
  getEndChunk: function ChunkedStreamManager_getEndChunk(end) {
   var chunk = Math.floor((end - 1) / this.chunkSize) + 1;
   return chunk;
  },
  abort: function ChunkedStreamManager_abort() {
   this.aborted = true;
   if (this.pdfNetworkStream) {
    this.pdfNetworkStream.cancelAllRequests('abort');
   }
   for (var requestId in this.promisesByRequest) {
    var capability = this.promisesByRequest[requestId];
    capability.reject(new Error('Request was aborted'));
   }
  }
 };
 return ChunkedStreamManager;
}();
exports.ChunkedStream = ChunkedStream;
exports.ChunkedStreamManager = ChunkedStreamManager;