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Diffstat (limited to 'remote/shared/listeners/ConsoleAPIListener.sys.mjs')
-rw-r--r-- | remote/shared/listeners/ConsoleAPIListener.sys.mjs | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/remote/shared/listeners/ConsoleAPIListener.sys.mjs b/remote/shared/listeners/ConsoleAPIListener.sys.mjs new file mode 100644 index 0000000000..7f5c850945 --- /dev/null +++ b/remote/shared/listeners/ConsoleAPIListener.sys.mjs @@ -0,0 +1,124 @@ +/* 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/. */ + +const lazy = {}; + +ChromeUtils.defineESModuleGetters(lazy, { + EventEmitter: "resource://gre/modules/EventEmitter.sys.mjs", +}); + +ChromeUtils.defineLazyGetter(lazy, "ConsoleAPIStorage", () => { + return Cc["@mozilla.org/consoleAPI-storage;1"].getService( + Ci.nsIConsoleAPIStorage + ); +}); + +/** + * The ConsoleAPIListener can be used to listen for messages coming from console + * API usage in a given windowGlobal, eg. console.log, console.error, ... + * + * Example: + * ``` + * const listener = new ConsoleAPIListener(innerWindowId); + * listener.on("message", onConsoleAPIMessage); + * listener.startListening(); + * + * const onConsoleAPIMessage = (eventName, data = {}) => { + * const { arguments: msgArguments, level, stacktrace, timeStamp } = data; + * ... + * }; + * ``` + * + * @fires message + * The ConsoleAPIListener emits "message" events, with the following object as + * payload: + * - {Array<Object>} arguments - Arguments as passed-in when the method was called. + * - {String} level - Importance, one of `info`, `warn`, `error`, `debug`, `trace`. + * - {Array<Object>} stacktrace - List of stack frames, starting from most recent. + * - {Number} timeStamp - Timestamp when the method was called. + */ +export class ConsoleAPIListener { + #emittedMessages; + #innerWindowId; + #listening; + + /** + * Create a new ConsoleAPIListener instance. + * + * @param {number} innerWindowId + * The inner window id to filter the messages for. + */ + constructor(innerWindowId) { + lazy.EventEmitter.decorate(this); + + this.#emittedMessages = new Set(); + this.#innerWindowId = innerWindowId; + this.#listening = false; + } + + destroy() { + this.stopListening(); + this.#emittedMessages = null; + } + + startListening() { + if (this.#listening) { + return; + } + + lazy.ConsoleAPIStorage.addLogEventListener( + this.#onConsoleAPIMessage, + Cc["@mozilla.org/systemprincipal;1"].createInstance(Ci.nsIPrincipal) + ); + + // Emit cached messages after registering the listener, to make sure we + // don't miss any message. + this.#emitCachedMessages(); + + this.#listening = true; + } + + stopListening() { + if (!this.#listening) { + return; + } + + lazy.ConsoleAPIStorage.removeLogEventListener(this.#onConsoleAPIMessage); + this.#listening = false; + } + + #emitCachedMessages() { + const cachedMessages = lazy.ConsoleAPIStorage.getEvents( + this.#innerWindowId + ); + for (const message of cachedMessages) { + this.#onConsoleAPIMessage(message); + } + } + + #onConsoleAPIMessage = message => { + const messageObject = message.wrappedJSObject; + + // Bail if this message was already emitted, useful to filter out cached + // messages already received by the consumer. + if (this.#emittedMessages.has(messageObject)) { + return; + } + + this.#emittedMessages.add(messageObject); + + if (messageObject.innerID !== this.#innerWindowId) { + // If the message doesn't match the innerWindowId of the current context + // ignore it. + return; + } + + this.emit("message", { + arguments: messageObject.arguments, + level: messageObject.level, + stacktrace: messageObject.stacktrace, + timeStamp: messageObject.timeStamp, + }); + }; +} |