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webroot/rsrc/externals/javelin/lib/Leader.js
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| * leading tab, by listening for `onBecomeLeader`. | * leading tab, by listening for `onBecomeLeader`. | ||||
| */ | */ | ||||
| JX.install('Leader', { | JX.install('Leader', { | ||||
| events: ['onBecomeLeader', 'onReceiveBroadcast'], | events: ['onBecomeLeader', 'onReceiveBroadcast'], | ||||
| statics: { | statics: { | ||||
| _leaseDuration: 1500, | |||||
| _interval: null, | _interval: null, | ||||
| _timeout: null, | _timeout: null, | ||||
| _broadcastKey: 'JX.Leader.broadcast', | _broadcastKey: 'JX.Leader.broadcast', | ||||
| _leaderKey: 'JX.Leader.id', | _leaderKey: 'JX.Leader.id', | ||||
| /** | /** | ||||
| * Tracks leadership state. Since leadership election is asynchronous, | * Tracks leadership state. Since leadership election is asynchronous, | ||||
| ▲ Show 20 Lines • Show All 81 Lines • ▼ Show 20 Lines | _callIf: function(leader_callback, follower_callback) { | ||||
| // If the lease is good, we're all set. | // If the lease is good, we're all set. | ||||
| var now = +new Date(); | var now = +new Date(); | ||||
| if (lease.until > now) { | if (lease.until > now) { | ||||
| if (lease.id === self._id) { | if (lease.id === self._id) { | ||||
| // If we haven't installed an update timer yet, do so now. This will | // If we haven't installed an update timer yet, do so now. This will | ||||
| // renew our lease every 5 seconds, making sure we hold it until the | // renew our lease every 5 seconds, making sure we hold it until the | ||||
| // tab is closed. | // tab is closed. | ||||
| if (!self._interval && lease.until > now + 10000) { | var interval = parseInt(self._leaseDuration / 3, 10); | ||||
| self._interval = window.setInterval(self._write, 5000); | |||||
| if (!self._interval && lease.until > now + (interval * 2)) { | |||||
| self._interval = window.setInterval(self._write, interval); | |||||
| } | } | ||||
| self._becomeLeader(); | self._becomeLeader(); | ||||
| leader_callback(); | leader_callback(); | ||||
| } else { | } else { | ||||
| // Set a callback to try to become the leader shortly after the | // Set a callback to try to become the leader shortly after the | ||||
| // current lease expires. This lets us quickly recover from cases | // current lease expires. This lets us quickly recover from cases | ||||
| ▲ Show 20 Lines • Show All 79 Lines • ▼ Show 20 Lines | statics: { | ||||
| /** | /** | ||||
| * Write a lease which names us as the leader. | * Write a lease which names us as the leader. | ||||
| */ | */ | ||||
| _write: function() { | _write: function() { | ||||
| var self = JX.Leader; | var self = JX.Leader; | ||||
| var str = [self._id, ((+new Date()) + 16000)].join(':'); | var str = [self._id, ((+new Date()) + self._leaseDuration)].join(':'); | ||||
| window.localStorage.setItem(self._leaderKey, str); | window.localStorage.setItem(self._leaderKey, str); | ||||
| }, | }, | ||||
| /** | /** | ||||
| * Read the current lease. | * Read the current lease. | ||||
| */ | */ | ||||
| _read: function() { | _read: function() { | ||||
| ▲ Show 20 Lines • Show All 67 Lines • ▼ Show 20 Lines | statics: { | ||||
| }, | }, | ||||
| /** | /** | ||||
| * Try to usurp leadership position after a lease expiration. | * Try to usurp leadership position after a lease expiration. | ||||
| */ | */ | ||||
| _usurp: function() { | _usurp: function() { | ||||
| var self = JX.Leader; | var self = JX.Leader; | ||||
| self.call(JX.bag); | |||||
| self._timeout = null; | self._timeout = null; | ||||
| 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. | ||||
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