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/**
* This file is part of Haketilo.
*
* Function: Facilitate broadcasting messages between different execution
* contexts of the extension
*
* Copyright (C) 2021 Wojtek Kosior
*
* This program 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.
*
* This program 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.
*
* As additional permission under GNU GPL version 3 section 7, you
* may distribute forms of that code without the copy of the GNU
* GPL normally required by section 4, provided you include this
* license notice and, in case of non-source distribution, a URL
* through which recipients can access the Corresponding Source.
* If you modify file(s) with this exception, you may extend this
* exception to your version of the file(s), but you are not
* obligated to do so. If you do not wish to do so, delete this
* exception statement from your version.
*
* As a special exception to the GPL, any HTML file which merely
* makes function calls to this code, and for that purpose
* includes it by reference shall be deemed a separate work for
* copyright law purposes. If you modify this code, you may extend
* this exception to your version of the code, but you are not
* obligated to do so. If you do not wish to do so, delete this
* exception statement from your version.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*
* I, Wojtek Kosior, thereby promise not to sue for violation of this file's
* license. Although I request that you do not make use of this code in a
* proprietary program, I am not going to enforce this in court.
*/
#FROM common/message_server.js IMPORT listen_for_connection
let next_id = 1;
const listeners_by_channel = new Map();
function new_broadcast_listener(port)
{
const listener_ctx = {port, id: ++next_id, channels: new Set()};
port.onMessage.addListener(msg => listener_command(msg, listener_ctx));
const on_disconnect = () => remove_broadcast_listener(listener_ctx);
port.onDisconnect.addListener(on_disconnect);
}
function listener_command(msg, listener_ctx)
{
const [disposition, name] = msg;
if (disposition === "subscribe")
subscribe_channel(name, listener_ctx);
else if (disposition === "unsubscribe")
unsubscribe_channel(name, listener_ctx);
else
throw `bad broadcast listener disposition '${disposition}'`;
}
function subscribe_channel(channel_name, listener_ctx)
{
if (!listeners_by_channel.has(channel_name))
listeners_by_channel.set(channel_name, new Map());
listeners_by_channel.get(channel_name).set(listener_ctx.id, listener_ctx);
listener_ctx.channels.add(channel_name);
}
function unsubscribe_channel(channel_name, listener_ctx)
{
const channel_listeners =
listeners_by_channel.get(channel_name) || new Map();
channel_listeners.delete(listener_ctx.id);
if (channel_listeners.size == 0)
listeners_by_channel.delete(channel_name);
listener_ctx.channels.delete(channel_name);
}
function remove_broadcast_listener(listener_ctx)
{
for (const channel_name of [...listener_ctx.channels.keys()])
unsubscribe_channel(channel_name, listener_ctx);
}
function new_broadcast_sender(port)
{
const sender_ctx = {prepared_broadcasts: new Set()};
port.onMessage.addListener(msg => sender_command(msg, sender_ctx));
port.onDisconnect.addListener(msg => flush(sender_ctx));
}
function sender_command(msg, sender_ctx)
{
const [disposition, name, value, timeout] = msg;
if (disposition === "prepare")
prepare(sender_ctx, name, value, timeout)
else if (disposition === "discard")
sender_ctx.prepared_broadcasts = new Set();
else if (disposition === "flush")
flush(sender_ctx);
else if (disposition === "broadcast")
broadcast(name, value);
else
throw `bad broadcast sender disposition '${disposition}'`;
}
function prepare(sender_ctx, channel_name, value, timeout)
{
const broadcast_data = [channel_name, value];
sender_ctx.prepared_broadcasts.add(broadcast_data);
if (timeout === 0)
return;
setTimeout(() => prepare_timeout_cb(sender_ctx, broadcast_data), timeout);
}
function prepare_timeout_cb(sender_ctx, broadcast_data)
{
if (sender_ctx.prepared_broadcasts.has(broadcast_data)) {
sender_ctx.prepared_broadcasts.delete(broadcast_data);
broadcast(...broadcast_data);
}
}
function flush(sender_ctx)
{
sender_ctx.prepared_broadcasts.forEach(nv => broadcast(...nv));
sender_ctx.prepared_broadcasts = new Set();
}
function broadcast(channel_name, value)
{
const listeners = listeners_by_channel.get(channel_name);
if (listeners == undefined)
return;
for (const listener_ctx of [...listeners.values()]) {
try {
listener_ctx.port.postMessage([channel_name, value]);
} catch (e) {
console.error(e);
remove_broadcast_listener(listener_ctx);
}
}
}
function remove_broadcast_sender(sender_ctx)
{
sender_ctx.prepared_broadcasts.forEach(nv => broadcast(...nv));
}
function start()
{
listen_for_connection("broadcast_send", new_broadcast_sender);
listen_for_connection("broadcast_listen", new_broadcast_listener);
}
#EXPORT start
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