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haketilo / common / broadcast.js @ aec5c9ae

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/**
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 * This file is part of Haketilo.
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 *
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 * Function: Broadcast messages to different execution contexts of the extension
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 *
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 * Copyright (C) 2021 Wojtek Kosior
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 *
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 * This program is free software: you can redistribute it and/or modify
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 * it under the terms of the GNU General Public License as published by
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 * the Free Software Foundation, either version 3 of the License, or
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 * (at your option) any later version.
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 *
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 * This program is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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 * GNU General Public License for more details.
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 *
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 * As additional permission under GNU GPL version 3 section 7, you
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 * may distribute forms of that code without the copy of the GNU
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 * GPL normally required by section 4, provided you include this
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 * license notice and, in case of non-source distribution, a URL
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 * through which recipients can access the Corresponding Source.
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 * If you modify file(s) with this exception, you may extend this
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 * exception to your version of the file(s), but you are not
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 * obligated to do so. If you do not wish to do so, delete this
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 * exception statement from your version.
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 *
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 * As a special exception to the GPL, any HTML file which merely
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 * makes function calls to this code, and for that purpose
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 * includes it by reference shall be deemed a separate work for
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 * copyright law purposes. If you modify this code, you may extend
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 * this exception to your version of the code, but you are not
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 * obligated to do so. If you do not wish to do so, delete this
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 * exception statement from your version.
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 *
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 * You should have received a copy of the GNU General Public License
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 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
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 *
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 * I, Wojtek Kosior, thereby promise not to sue for violation of this file's
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 * license. Although I request that you do not make use of this code in a
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 * proprietary program, I am not going to enforce this in court.
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 */
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#FROM common/message_server.js IMPORT connect_to_background
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function sender_connection()
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{
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    return {
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	type: "sender",
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	port: connect_to_background("broadcast_send")
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    };
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}
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#EXPORT sender_connection
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function out(sender_conn, channel_name, value)
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{
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    sender_conn.port.postMessage(["broadcast", channel_name, value]);
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}
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#EXPORT out
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/*
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 * prepare()'d message will be broadcasted if the connection is closed or when
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 * flush() is called. All messages prepared by given sender will be discarded
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 * when discard() is called.
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 *
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 * Timeout will cause the prepared message to be broadcasted after given number
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 * of miliseconds unless discard() is called in the meantime. It is mostly
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 * useful as a fallback in case this connection end gets nuked (e.g. because
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 * browser window is closed) and onDisconnect event is not dispatched to
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 * background script's Port object. This is only an issue for browsers as old as
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 * IceCat 60: https://bugzilla.mozilla.org/show_bug.cgi?id=1392067
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 *
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 * Timeout won't be scheduled at all if its value is given as 0.
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 */
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function prepare(sender_conn, channel_name, value, timeout=5000)
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{
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    sender_conn.port.postMessage(["prepare", channel_name, value, timeout]);
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}
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#EXPORT prepare
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function discard(sender_conn)
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{
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    sender_conn.port.postMessage(["discard"]);
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}
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#EXPORT discard
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function flush(sender_conn)
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{
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    sender_conn.port.postMessage(["flush"]);
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}
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#EXPORT flush
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function listener_connection(cb)
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{
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    const conn = {
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	type: "listener",
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	port: connect_to_background("broadcast_listen")
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    };
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    conn.port.onMessage.addListener(cb);
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    return conn;
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}
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#EXPORT listener_connection
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function subscribe(listener_conn, channel_name)
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{
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    listener_conn.port.postMessage(["subscribe", channel_name]);
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}
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#EXPORT subscribe
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function unsubscribe(listener_conn, channel_name)
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{
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    listener_conn.port.postMessage(["unsubscribe", channel_name]);
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}
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#EXPORT unsubscribe
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function close(conn)
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{
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    if (conn.type === "sender")
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	flush(conn);
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    setTimeout(() => conn.port.disconnect());
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}
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#EXPORT close
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