Differential D15703 Diff 37833 webroot/rsrc/externals/javelin/lib/Leader.js

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webroot/rsrc/externals/javelin/lib/Leader.js

Show First 20 Lines • Show All 57 Lines • ▼ Show 20 Lines	statics: {
_seenList: [],		_seenList: [],


/**		/**
* Elect a leader, triggering leadership callbacks if they are registered.		* Elect a leader, triggering leadership callbacks if they are registered.
*/		*/
start: function() {		start: function() {
var self = JX.Leader;		var self = JX.Leader;
self.callIfLeader(JX.bag);		self.call(JX.bag);
},		},

/**		/**
* Call a method if this tab is the leader.		* Call a method if this tab is the leader.
*		*
* This is asynchronous because leadership election is asynchronous. If		* This is asynchronous because leadership election is asynchronous. If
* the current tab is not the leader after any election takes place, the		* the current tab is not the leader after any election takes place, the
* callback will not be invoked.		* callback will not be invoked.
▲ Show 20 Lines • Show All 52 Lines • ▼ Show 20 Lines	_callIf: function(leader_callback, follower_callback) {
// tab is closed.		// tab is closed.
if (!self._interval && lease.until > now + 10000) {		if (!self._interval && lease.until > now + 10000) {
self._interval = window.setInterval(self._write, 5000);		self._interval = window.setInterval(self._write, 5000);
}		}

self._becomeLeader();		self._becomeLeader();
leader_callback();		leader_callback();
} else {		} else {

		// Set a callback to try to become the leader shortly after the
		// current lease expires. This lets us recover from cases where the
		// leader goes missing quickly.
		window.setTimeout(self._usurp, (lease.until - now) + 50);

follower_callback();		follower_callback();
}		}

return;		return;
}		}

// If the lease isn't good, try to become the leader. We don't have		// If the lease isn't good, try to become the leader. We don't have
// proper locking primitives for this, but can do a relatively good		// proper locking primitives for this, but can do a relatively good
// job. The algorithm here is:		// job. The algorithm here is:
//		//
// - Write our ID, trying to acquire the lease.		// - Write our ID, trying to acquire the lease.
▲ Show 20 Lines • Show All 135 Lines • ▼ Show 20 Lines	_becomeLeader: function() {
if (self._isLeader) {		if (self._isLeader) {
return;		return;
}		}

self._isLeader = true;		self._isLeader = true;
new JX.Leader().invoke('onBecomeLeader');		new JX.Leader().invoke('onBecomeLeader');
},		},


		/**
		* Try to usurp leadership position after a lease expiration.
		*/
		_usurp: function() {
		var self = JX.Leader;
		self.call(JX.bag);
		},


/**		/**
* Mark a message as seen.		* Mark a message as seen.
*		*
* We keep a fixed-sized list of recent messages, and let old ones fall		* We keep a fixed-sized list of recent messages, and let old ones fall
* off the end after a while.		* off the end after a while.
*/		*/
_markSeen: function(id) {		_markSeen: function(id) {
var self = JX.Leader;		var self = JX.Leader;
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