pdfjs-dist/lib/shared/message_handler.js

/**
 * @licstart The following is the entire license notice for the
 * Javascript code in this page
 *
 * Copyright 2019 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.
 *
 * @licend The above is the entire license notice for the
 * Javascript code in this page
 */
"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.MessageHandler = MessageHandler;

var _regenerator = _interopRequireDefault(require("@babel/runtime/regenerator"));

var _util = require("./util");

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { "default": obj }; }

function _typeof(obj) { if (typeof Symbol === "function" && typeof Symbol.iterator === "symbol") { _typeof = function _typeof(obj) { return typeof obj; }; } else { _typeof = function _typeof(obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj; }; } return _typeof(obj); }

function asyncGeneratorStep(gen, resolve, reject, _next, _throw, key, arg) { try { var info = gen[key](arg); var value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { Promise.resolve(value).then(_next, _throw); } }

function _asyncToGenerator(fn) { return function () { var self = this, args = arguments; return new Promise(function (resolve, reject) { var gen = fn.apply(self, args); function _next(value) { asyncGeneratorStep(gen, resolve, reject, _next, _throw, "next", value); } function _throw(err) { asyncGeneratorStep(gen, resolve, reject, _next, _throw, "throw", err); } _next(undefined); }); }; }

function resolveCall(_x, _x2) {
  return _resolveCall.apply(this, arguments);
}

function _resolveCall() {
  _resolveCall = _asyncToGenerator(
  /*#__PURE__*/
  _regenerator["default"].mark(function _callee(fn, args) {
    var thisArg,
        _args = arguments;
    return _regenerator["default"].wrap(function _callee$(_context) {
      while (1) {
        switch (_context.prev = _context.next) {
          case 0:
            thisArg = _args.length > 2 && _args[2] !== undefined ? _args[2] : null;

            if (fn) {
              _context.next = 3;
              break;
            }

            return _context.abrupt("return", undefined);

          case 3:
            return _context.abrupt("return", fn.apply(thisArg, args));

          case 4:
          case "end":
            return _context.stop();
        }
      }
    }, _callee);
  }));
  return _resolveCall.apply(this, arguments);
}

function wrapReason(reason) {
  if (_typeof(reason) !== 'object') {
    return reason;
  }

  switch (reason.name) {
    case 'AbortException':
      return new _util.AbortException(reason.message);

    case 'MissingPDFException':
      return new _util.MissingPDFException(reason.message);

    case 'UnexpectedResponseException':
      return new _util.UnexpectedResponseException(reason.message, reason.status);

    default:
      return new _util.UnknownErrorException(reason.message, reason.details);
  }
}

function makeReasonSerializable(reason) {
  if (!(reason instanceof Error) || reason instanceof _util.AbortException || reason instanceof _util.MissingPDFException || reason instanceof _util.UnexpectedResponseException || reason instanceof _util.UnknownErrorException) {
    return reason;
  }

  return new _util.UnknownErrorException(reason.message, reason.toString());
}

function resolveOrReject(capability, success, reason) {
  if (success) {
    capability.resolve();
  } else {
    capability.reject(reason);
  }
}

function finalize(promise) {
  return Promise.resolve(promise)["catch"](function () {});
}

function MessageHandler(sourceName, targetName, comObj) {
  var _this = this;

  this.sourceName = sourceName;
  this.targetName = targetName;
  this.comObj = comObj;
  this.callbackId = 1;
  this.streamId = 1;
  this.postMessageTransfers = true;
  this.streamSinks = Object.create(null);
  this.streamControllers = Object.create(null);
  var callbacksCapabilities = this.callbacksCapabilities = Object.create(null);
  var ah = this.actionHandler = Object.create(null);

  this._onComObjOnMessage = function (event) {
    var data = event.data;

    if (data.targetName !== _this.sourceName) {
      return;
    }

    if (data.stream) {
      _this._processStreamMessage(data);
    } else if (data.isReply) {
      var callbackId = data.callbackId;

      if (data.callbackId in callbacksCapabilities) {
        var callback = callbacksCapabilities[callbackId];
        delete callbacksCapabilities[callbackId];

        if ('error' in data) {
          callback.reject(wrapReason(data.error));
        } else {
          callback.resolve(data.data);
        }
      } else {
        throw new Error("Cannot resolve callback ".concat(callbackId));
      }
    } else if (data.action in ah) {
      var action = ah[data.action];

      if (data.callbackId) {
        var _sourceName = _this.sourceName;
        var _targetName = data.sourceName;
        Promise.resolve().then(function () {
          return action[0].call(action[1], data.data);
        }).then(function (result) {
          comObj.postMessage({
            sourceName: _sourceName,
            targetName: _targetName,
            isReply: true,
            callbackId: data.callbackId,
            data: result
          });
        }, function (reason) {
          comObj.postMessage({
            sourceName: _sourceName,
            targetName: _targetName,
            isReply: true,
            callbackId: data.callbackId,
            error: makeReasonSerializable(reason)
          });
        });
      } else if (data.streamId) {
        _this._createStreamSink(data);
      } else {
        action[0].call(action[1], data.data);
      }
    } else {
      throw new Error("Unknown action from worker: ".concat(data.action));
    }
  };

  comObj.addEventListener('message', this._onComObjOnMessage);
}

MessageHandler.prototype = {
  on: function on(actionName, handler, scope) {
    var ah = this.actionHandler;

    if (ah[actionName]) {
      throw new Error("There is already an actionName called \"".concat(actionName, "\""));
    }

    ah[actionName] = [handler, scope];
  },
  send: function send(actionName, data, transfers) {
    var message = {
      sourceName: this.sourceName,
      targetName: this.targetName,
      action: actionName,
      data: data
    };
    this.postMessage(message, transfers);
  },
  sendWithPromise: function sendWithPromise(actionName, data, transfers) {
    var callbackId = this.callbackId++;
    var message = {
      sourceName: this.sourceName,
      targetName: this.targetName,
      action: actionName,
      data: data,
      callbackId: callbackId
    };
    var capability = (0, _util.createPromiseCapability)();
    this.callbacksCapabilities[callbackId] = capability;

    try {
      this.postMessage(message, transfers);
    } catch (e) {
      capability.reject(e);
    }

    return capability.promise;
  },
  sendWithStream: function sendWithStream(actionName, data, queueingStrategy, transfers) {
    var _this2 = this;

    var streamId = this.streamId++;
    var sourceName = this.sourceName;
    var targetName = this.targetName;
    return new _util.ReadableStream({
      start: function start(controller) {
        var startCapability = (0, _util.createPromiseCapability)();
        _this2.streamControllers[streamId] = {
          controller: controller,
          startCall: startCapability,
          isClosed: false
        };

        _this2.postMessage({
          sourceName: sourceName,
          targetName: targetName,
          action: actionName,
          streamId: streamId,
          data: data,
          desiredSize: controller.desiredSize
        });

        return startCapability.promise;
      },
      pull: function pull(controller) {
        var pullCapability = (0, _util.createPromiseCapability)();
        _this2.streamControllers[streamId].pullCall = pullCapability;

        _this2.postMessage({
          sourceName: sourceName,
          targetName: targetName,
          stream: 'pull',
          streamId: streamId,
          desiredSize: controller.desiredSize
        });

        return pullCapability.promise;
      },
      cancel: function cancel(reason) {
        var cancelCapability = (0, _util.createPromiseCapability)();
        _this2.streamControllers[streamId].cancelCall = cancelCapability;
        _this2.streamControllers[streamId].isClosed = true;

        _this2.postMessage({
          sourceName: sourceName,
          targetName: targetName,
          stream: 'cancel',
          reason: reason,
          streamId: streamId
        });

        return cancelCapability.promise;
      }
    }, queueingStrategy);
  },
  _createStreamSink: function _createStreamSink(data) {
    var _this3 = this;

    var self = this;
    var action = this.actionHandler[data.action];
    var streamId = data.streamId;
    var desiredSize = data.desiredSize;
    var sourceName = this.sourceName;
    var targetName = data.sourceName;
    var capability = (0, _util.createPromiseCapability)();

    var sendStreamRequest = function sendStreamRequest(_ref) {
      var stream = _ref.stream,
          chunk = _ref.chunk,
          transfers = _ref.transfers,
          success = _ref.success,
          reason = _ref.reason;

      _this3.postMessage({
        sourceName: sourceName,
        targetName: targetName,
        stream: stream,
        streamId: streamId,
        chunk: chunk,
        success: success,
        reason: reason
      }, transfers);
    };

    var streamSink = {
      enqueue: function enqueue(chunk) {
        var size = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : 1;
        var transfers = arguments.length > 2 ? arguments[2] : undefined;

        if (this.isCancelled) {
          return;
        }

        var lastDesiredSize = this.desiredSize;
        this.desiredSize -= size;

        if (lastDesiredSize > 0 && this.desiredSize <= 0) {
          this.sinkCapability = (0, _util.createPromiseCapability)();
          this.ready = this.sinkCapability.promise;
        }

        sendStreamRequest({
          stream: 'enqueue',
          chunk: chunk,
          transfers: transfers
        });
      },
      close: function close() {
        if (this.isCancelled) {
          return;
        }

        this.isCancelled = true;
        sendStreamRequest({
          stream: 'close'
        });
        delete self.streamSinks[streamId];
      },
      error: function error(reason) {
        if (this.isCancelled) {
          return;
        }

        this.isCancelled = true;
        sendStreamRequest({
          stream: 'error',
          reason: reason
        });
      },
      sinkCapability: capability,
      onPull: null,
      onCancel: null,
      isCancelled: false,
      desiredSize: desiredSize,
      ready: null
    };
    streamSink.sinkCapability.resolve();
    streamSink.ready = streamSink.sinkCapability.promise;
    this.streamSinks[streamId] = streamSink;
    resolveCall(action[0], [data.data, streamSink], action[1]).then(function () {
      sendStreamRequest({
        stream: 'start_complete',
        success: true
      });
    }, function (reason) {
      sendStreamRequest({
        stream: 'start_complete',
        success: false,
        reason: reason
      });
    });
  },
  _processStreamMessage: function _processStreamMessage(data) {
    var _this4 = this;

    var sourceName = this.sourceName;
    var targetName = data.sourceName;
    var streamId = data.streamId;

    var sendStreamResponse = function sendStreamResponse(_ref2) {
      var stream = _ref2.stream,
          success = _ref2.success,
          reason = _ref2.reason;

      _this4.comObj.postMessage({
        sourceName: sourceName,
        targetName: targetName,
        stream: stream,
        success: success,
        streamId: streamId,
        reason: reason
      });
    };

    var deleteStreamController = function deleteStreamController() {
      Promise.all([_this4.streamControllers[data.streamId].startCall, _this4.streamControllers[data.streamId].pullCall, _this4.streamControllers[data.streamId].cancelCall].map(function (capability) {
        return capability && finalize(capability.promise);
      })).then(function () {
        delete _this4.streamControllers[data.streamId];
      });
    };

    switch (data.stream) {
      case 'start_complete':
        resolveOrReject(this.streamControllers[data.streamId].startCall, data.success, wrapReason(data.reason));
        break;

      case 'pull_complete':
        resolveOrReject(this.streamControllers[data.streamId].pullCall, data.success, wrapReason(data.reason));
        break;

      case 'pull':
        if (!this.streamSinks[data.streamId]) {
          sendStreamResponse({
            stream: 'pull_complete',
            success: true
          });
          break;
        }

        if (this.streamSinks[data.streamId].desiredSize <= 0 && data.desiredSize > 0) {
          this.streamSinks[data.streamId].sinkCapability.resolve();
        }

        this.streamSinks[data.streamId].desiredSize = data.desiredSize;
        resolveCall(this.streamSinks[data.streamId].onPull).then(function () {
          sendStreamResponse({
            stream: 'pull_complete',
            success: true
          });
        }, function (reason) {
          sendStreamResponse({
            stream: 'pull_complete',
            success: false,
            reason: reason
          });
        });
        break;

      case 'enqueue':
        (0, _util.assert)(this.streamControllers[data.streamId], 'enqueue should have stream controller');

        if (!this.streamControllers[data.streamId].isClosed) {
          this.streamControllers[data.streamId].controller.enqueue(data.chunk);
        }

        break;

      case 'close':
        (0, _util.assert)(this.streamControllers[data.streamId], 'close should have stream controller');

        if (this.streamControllers[data.streamId].isClosed) {
          break;
        }

        this.streamControllers[data.streamId].isClosed = true;
        this.streamControllers[data.streamId].controller.close();
        deleteStreamController();
        break;

      case 'error':
        (0, _util.assert)(this.streamControllers[data.streamId], 'error should have stream controller');
        this.streamControllers[data.streamId].controller.error(wrapReason(data.reason));
        deleteStreamController();
        break;

      case 'cancel_complete':
        resolveOrReject(this.streamControllers[data.streamId].cancelCall, data.success, wrapReason(data.reason));
        deleteStreamController();
        break;

      case 'cancel':
        if (!this.streamSinks[data.streamId]) {
          break;
        }

        resolveCall(this.streamSinks[data.streamId].onCancel, [wrapReason(data.reason)]).then(function () {
          sendStreamResponse({
            stream: 'cancel_complete',
            success: true
          });
        }, function (reason) {
          sendStreamResponse({
            stream: 'cancel_complete',
            success: false,
            reason: reason
          });
        });
        this.streamSinks[data.streamId].sinkCapability.reject(wrapReason(data.reason));
        this.streamSinks[data.streamId].isCancelled = true;
        delete this.streamSinks[data.streamId];
        break;

      default:
        throw new Error('Unexpected stream case');
    }
  },
  postMessage: function postMessage(message, transfers) {
    if (transfers && this.postMessageTransfers) {
      this.comObj.postMessage(message, transfers);
    } else {
      this.comObj.postMessage(message);
    }
  },
  destroy: function destroy() {
    this.comObj.removeEventListener('message', this._onComObjOnMessage);
  }
};