/
broadcaster.js
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/
broadcaster.js
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/*
This file is part of Talkie -- text-to-speech browser extension button.
<https://joelpurra.com/projects/talkie/>
Copyright (c) 2016, 2017 Joel Purra <https://joelpurra.com/>
Talkie is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Talkie is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with Talkie. If not, see <https://www.gnu.org/licenses/>.
*/
import {
logTrace,
logWarn,
logError,
} from "./log";
import {
promiseTry,
} from "./promise";
import {
isDeadWrapper,
} from "./tabs";
export default class Broadcaster {
constructor() {
this.actionListeningMap = {};
}
unregisterListeningAction(actionName, listeningActionHandler) {
return promiseTry(
() => {
if (!this.actionListeningMap[actionName]) {
throw new Error("No listening action(s) registered for action: " + actionName);
}
const countBefore = this.actionListeningMap[actionName].length;
this.actionListeningMap[actionName] = this.actionListeningMap[actionName].filter((registeredListeningActionHandler) => registeredListeningActionHandler !== listeningActionHandler);
const countAfter = this.actionListeningMap[actionName].length;
if (countBefore === countAfter) {
throw new Error("The specific listening action handler was not registered for action: " + actionName);
}
}
);
}
registerListeningAction(actionName, listeningActionHandler) {
return promiseTry(
() => {
this.actionListeningMap[actionName] = (this.actionListeningMap[actionName] || []).concat(listeningActionHandler);
const killSwitch = () => {
// NOTE: the promise chain probably won't be completed (by the caller, outside of this function), as the kill switch might be executed during the "onunload" event.
return this.unregisterListeningAction(actionName, listeningActionHandler);
};
return killSwitch;
}
);
}
broadcastEvent(actionName, actionData) {
return promiseTry(
() => {
logTrace("Start", "Sending message", actionName, actionData);
const listeningActions = this.actionListeningMap[actionName];
if (!listeningActions || listeningActions.length === 0) {
logTrace("Skipping", "Sending message", actionName, actionData);
return [];
}
const listeningActionPromises = listeningActions.map((action) => {
return promiseTry(
() => {
// NOTE: check for dead objects from cross-page (background, popup, options, ...) memory leaks.
// NOTE: this is just in case the killSwitch hasn't been called.
// https://developer.mozilla.org/en-US/docs/Extensions/Common_causes_of_memory_leaks_in_extensions#Failing_to_clean_up_event_listeners
// TODO: throw error instead of cleaning up?
// TODO: clean up code to avoid memory leaks, primarly in Firefox as it doesn't have onSuspend at the moment.
if (isDeadWrapper(action)) {
logWarn("Dead wrapper (detected)", "Sending message", actionName, actionData);
return this.unregisterListeningAction(actionName, action);
}
return action(actionName, actionData);
})
.catch((error) => {
if (error && typeof error.message === "string" && error.message.includes("access dead object")) {
// NOTE: it's a dead wrapper, but it wasn't detected by isDeadWrapper() above. Ignore.
logWarn("Dead wrapper (caught)", "Sending message", actionName, actionData);
return this.unregisterListeningAction(actionName, action);
}
throw error;
});
});
return Promise.all(listeningActionPromises)
.then((responses) => {
logTrace("Done", "Sending message", actionName, actionData, responses);
return responses;
})
.catch((error) => {
logError("Sending message", actionName, actionData);
throw error;
});
});
}
}