summaryrefslogtreecommitdiffstats
path: root/toolkit/components/extensions/MessageManagerProxy.sys.mjs
blob: 110a98a05d9faa7e373790b5314bf94780f23339 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
/* vim: set sts=2 sw=2 et tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

// @ts-nocheck TODO: Many references to old types which don't exist anymore.

import { ExtensionUtils } from "resource://gre/modules/ExtensionUtils.sys.mjs";

const { DefaultMap } = ExtensionUtils;

/**
 * Acts as a proxy for a message manager or message manager owner, and
 * tracks docShell swaps so that messages are always sent to the same
 * receiver, even if it is moved to a different <browser>.
 *
 * @param {nsIMessageSender|Element} target
 *        The target message manager on which to send messages, or the
 *        <browser> element which owns it.
 */
export class MessageManagerProxy {
  constructor(target) {
    this.listeners = new DefaultMap(() => new Map());
    this.closed = false;

    if (target instanceof Ci.nsIMessageSender) {
      this.messageManager = target;
    } else {
      this.addListeners(target);
    }

    Services.obs.addObserver(this, "message-manager-close");
  }

  /**
   * Disposes of the proxy object, removes event listeners, and drops
   * all references to the underlying message manager.
   *
   * Must be called before the last reference to the proxy is dropped,
   * unless the underlying message manager or <browser> is also being
   * destroyed.
   */
  dispose() {
    if (this.eventTarget) {
      this.removeListeners(this.eventTarget);
      this.eventTarget = null;
    }
    this.messageManager = null;

    Services.obs.removeObserver(this, "message-manager-close");
  }

  observe(subject, topic) {
    if (topic === "message-manager-close") {
      if (subject === this.messageManager) {
        this.closed = true;
      }
    }
  }

  /**
   * Returns true if the given target is the same as, or owns, the given
   * message manager.
   *
   * @param {nsIMessageSender|MessageManagerProxy|Element} target
   *        The message manager, MessageManagerProxy, or <browser>
   *        element against which to match.
   * @param {nsIMessageSender} messageManager
   *        The message manager against which to match `target`.
   *
   * @returns {boolean}
   *        True if `messageManager` is the same object as `target`, or
   *        `target` is a MessageManagerProxy or <browser> element that
   *        is tied to it.
   */
  static matches(target, messageManager) {
    return (
      target === messageManager || target.messageManager === messageManager
    );
  }

  /**
   * @property {nsIMessageSender|null} messageManager
   *        The message manager that is currently being proxied. This
   *        may change during the life of the proxy object, so should
   *        not be stored elsewhere.
   */

  /**
   * Sends a message on the proxied message manager.
   *
   * @param {Array} args
   *        Arguments to be passed verbatim to the underlying
   *        sendAsyncMessage method.
   * @returns {undefined}
   */
  sendAsyncMessage(...args) {
    if (this.messageManager) {
      return this.messageManager.sendAsyncMessage(...args);
    }

    Cu.reportError(
      `Cannot send message: Other side disconnected: ${uneval(args)}`
    );
  }

  get isDisconnected() {
    return this.closed || !this.messageManager;
  }

  /**
   * Adds a message listener to the current message manager, and
   * transfers it to the new message manager after a docShell swap.
   *
   * @param {string} message
   *        The name of the message to listen for.
   * @param {nsIMessageListener} listener
   *        The listener to add.
   * @param {boolean} [listenWhenClosed = false]
   *        If true, the listener will receive messages which were sent
   *        after the remote side of the listener began closing.
   */
  addMessageListener(message, listener, listenWhenClosed = false) {
    this.messageManager.addMessageListener(message, listener, listenWhenClosed);
    this.listeners.get(message).set(listener, listenWhenClosed);
  }

  /**
   * Adds a message listener from the current message manager.
   *
   * @param {string} message
   *        The name of the message to stop listening for.
   * @param {nsIMessageListener} listener
   *        The listener to remove.
   */
  removeMessageListener(message, listener) {
    this.messageManager.removeMessageListener(message, listener);

    let listeners = this.listeners.get(message);
    listeners.delete(listener);
    if (!listeners.size) {
      this.listeners.delete(message);
    }
  }

  /**
   * Iterates over all of the currently registered message listeners.
   *
   * @private
   */
  *iterListeners() {
    for (let [message, listeners] of this.listeners) {
      for (let [listener, listenWhenClosed] of listeners) {
        yield { message, listener, listenWhenClosed };
      }
    }
  }

  /**
   * Adds docShell swap listeners to the message manager owner.
   *
   * @param {Browser} target
   *        The target element.
   * @private
   */
  addListeners(target) {
    target.addEventListener("SwapDocShells", this);

    this.eventTarget = target;
    this.messageManager = target.messageManager;

    for (let { message, listener, listenWhenClosed } of this.iterListeners()) {
      this.messageManager.addMessageListener(
        message,
        listener,
        listenWhenClosed
      );
    }
  }

  /**
   * Removes docShell swap listeners to the message manager owner.
   *
   * @param {Element} target
   *        The target element.
   * @private
   */
  removeListeners(target) {
    target.removeEventListener("SwapDocShells", this);

    for (let { message, listener } of this.iterListeners()) {
      this.messageManager.removeMessageListener(message, listener);
    }
  }

  handleEvent(event) {
    if (event.type == "SwapDocShells") {
      this.removeListeners(this.eventTarget);
      // The SwapDocShells event is dispatched for both browsers that are being
      // swapped. To avoid double-swapping, register the event handler after
      // both SwapDocShells events have fired.
      this.eventTarget.addEventListener(
        "EndSwapDocShells",
        () => {
          this.addListeners(event.detail);
        },
        { once: true }
      );
    }
  }
}