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RedisListener.js
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RedisListener.js
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var redis = require("redis");
var timer = require("timers");
var config = require("./config").config;
var max_chans = config.redis.listener.max_channels;
if (!max_chans) {
max_chans = 16;
}
var rlctr = 0;
function RedisListener (pool)
{
this.id = rlctr++;
this.chan_set = {};
this.chan_sub_count = {};
this.nr_chans = 0;
this.pool = pool;
this.redis_ready = false;
this.connect();
}
exports.RedisListener = RedisListener;
RedisListener.prototype.connect = function ()
{
global.trace("RedisListener " + this.id + ": Attempting connect");
// No pinging should take place until we enter the idle state
this.stopPingTimer();
// Create redis connection
var rc = global.newRedisClient();
// Error handler
var rl = this;
rc.on("error", function (err) {
console.warn("RedisListener " + rl.id + " error: " + err);
});
// Notifies of connection
rc.on("connect", function () {
global.trace("RedisListener " + rl.id + ": Connected to Redis");
});
// Subscribes to any channels being watched
rc.on("ready", function () {
rl.redis_ready = true;
global.trace("RedisListener " + rl.id + ": Ready");
var chan_set_length = Object.keys(rl.chan_set).length;
if (chan_set_length > 0) {
global.trace(
"RedisListener " + rl.id + ": " +
"Subscribing to " + chan_set_length + " " +
"channels"
);
rc.subscribe(Object.keys(rl.chan_set));
}
});
// Dispatches Pub/Sub messages to listeners
rc.on("message", function (channel, message) {
// Get event handler
var eventHandlers = rl.chan_set[channel];
if (!eventHandlers) {
return;
}
// Log dispatch
global.trace(
"RedisListener " + rl.id + ": " +
"Got Redis message on channel " + channel
);
// Dispatch to event handler
eventHandlers.message(channel, message);
});
// Dispatches subscriptions to subscriber
rc.on("subscribe", function (channel, count) {
// Get event handler
var eventHandlers = rl.chan_set[channel];
if (!eventHandlers) {
return;
}
// Dispatch to event handler
if (eventHandlers.subscribe) {
eventHandlers.subscribe(channel);
}
});
// Turns the ping timer on and off
rc.on("idle", function () {
if (rl.nr_chans == 0) {
if (!rl.ping_timer) {
rl.ping_timer = timer.setInterval(
function () {
rl.ping();
}, 60000
);
}
}
else {
rl.stopPingTimer();
}
});
this.redis_client = rc;
}
RedisListener.prototype.ping = function ()
{
if (this.redis_ready) {
this.redis_client.ping();
}
}
RedisListener.prototype.stopPingTimer = function ()
{
if (this.ping_timer) {
timer.clearInterval(this.ping_timer);
delete this.ping_timer;
}
}
RedisListener.prototype.addChan = function (chan_id, eventHandlers)
{
// Track addChan
if (!this.chan_sub_count[chan_id]) {
this.chan_sub_count[chan_id] = 0;
}
var sub_cnt = ++this.chan_sub_count[chan_id];
if (sub_cnt > 1) {
this.chan_set[chan_id].kill();
}
// Remember callback
this.chan_set[chan_id] = eventHandlers;
// Update tree position / number of channels
this.pool.removeFromTree();
this.nr_chans++;
this.pool.addToTree();
// PING isn't allowed in Pub/Sub mode
this.stopPingTimer();
// Send subscribe command if connected
if (this.redis_ready) {
this.redis_client.subscribe(chan_id);
}
}
RedisListener.prototype.removeChan = function (chan_id)
{
// Update tree position / number of channels
this.pool.removeFromTree();
this.nr_chans--;
this.pool.addToTree();
// Let pool expire empty RedisListeners
this.pool.trimPool();
// Hacky: This channel protection prevents us from unsubscribing /
// forgetting the callback if we have a new request come in with the
// same watch task id
if (--this.chan_sub_count[chan_id] > 0) {
return;
}
global.trace(
"RedisListener " + this.id + ": Really unsubscribing " +
"from " + chan_id
);
// Forget callback
delete this.chan_set[chan_id];
delete this.chan_sub_count[chan_id];
// Send unsubscribe command if connected
if (this.redis_client) {
this.redis_client.unsubscribe(chan_id);
}
}
RedisListener.prototype.getFreeChans = function ()
{
return max_chans - this.nr_chans;
}
RedisListener.prototype.getUsedChans = function ()
{
return this.nr_chans;
}