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| 1 | +import { Meteor } from 'meteor/meteor'; |
| 2 | +import { Tracker } from 'meteor/tracker'; |
| 3 | +import { HTTP } from 'meteor/http'; |
| 4 | + |
| 5 | +TimeSync = { |
| 6 | + loggingEnabled: Meteor.isDevelopment, |
| 7 | + forceDDP: false |
| 8 | +}; |
| 9 | + |
| 10 | +function log( /* arguments */ ) { |
| 11 | + if (TimeSync.loggingEnabled) { |
| 12 | + Meteor._debug.apply(this, arguments); |
| 13 | + } |
| 14 | +} |
| 15 | + |
| 16 | +const defaultInterval = 1000; |
| 17 | + |
| 18 | +// Internal values, exported for testing |
| 19 | +SyncInternals = { |
| 20 | + offset: undefined, |
| 21 | + roundTripTime: undefined, |
| 22 | + offsetTracker: new Tracker.Dependency(), |
| 23 | + syncTracker: new Tracker.Dependency(), |
| 24 | + isSynced: false, |
| 25 | + usingDDP: false, |
| 26 | + timeTick: {}, |
| 27 | + getDiscrepancy: function (lastTime, currentTime, interval) { |
| 28 | + return currentTime - (lastTime + interval) |
| 29 | + } |
| 30 | +}; |
| 31 | + |
| 32 | +SyncInternals.timeTick[defaultInterval] = new Tracker.Dependency(); |
| 33 | + |
| 34 | +const maxAttempts = 5; |
| 35 | +let attempts = 0; |
| 36 | + |
| 37 | +/* |
| 38 | + This is an approximation of |
| 39 | + http://en.wikipedia.org/wiki/Network_Time_Protocol |
| 40 | +
|
| 41 | + If this turns out to be more accurate under the connect handlers, |
| 42 | + we should try taking multiple measurements. |
| 43 | + */ |
| 44 | + |
| 45 | +let syncUrl; |
| 46 | + |
| 47 | +TimeSync.setSyncUrl = function (url) { |
| 48 | + if (url) { |
| 49 | + syncUrl = url; |
| 50 | + } else if (Meteor.isCordova || Meteor.isDesktop) { |
| 51 | + // Only use Meteor.absoluteUrl for Cordova and Desktop; see |
| 52 | + // https://github.com/meteor/meteor/issues/4696 |
| 53 | + // https://github.com/mizzao/meteor-timesync/issues/30 |
| 54 | + // Cordova should never be running out of a subdirectory... |
| 55 | + syncUrl = Meteor.absoluteUrl('_timesync'); |
| 56 | + } else { |
| 57 | + // Support Meteor running in relative paths, based on computed root url prefix |
| 58 | + // https://github.com/mizzao/meteor-timesync/pull/40 |
| 59 | + const basePath = __meteor_runtime_config__.ROOT_URL_PATH_PREFIX || ''; |
| 60 | + syncUrl = basePath + '/_timesync'; |
| 61 | + } |
| 62 | +}; |
| 63 | +TimeSync.getSyncUrl = function () { |
| 64 | + return syncUrl; |
| 65 | +} |
| 66 | +TimeSync.setSyncUrl(); |
| 67 | + |
| 68 | +const updateOffset = function () { |
| 69 | + const t0 = Date.now(); |
| 70 | + if (TimeSync.forceDDP || SyncInternals.useDDP) { |
| 71 | + Meteor.call('_timeSync', function (err, res) { |
| 72 | + handleResponse(t0, err, res); |
| 73 | + }); |
| 74 | + } else { |
| 75 | + HTTP.get(syncUrl, function (err, res) { |
| 76 | + handleResponse(t0, err, res); |
| 77 | + }); |
| 78 | + } |
| 79 | +}; |
| 80 | + |
| 81 | +const handleResponse = function (t0, err, res) { |
| 82 | + const t3 = Date.now(); // Grab this now |
| 83 | + if (err) { |
| 84 | + // We'll still use our last computed offset if is defined |
| 85 | + log('Error syncing to server time: ', err); |
| 86 | + if (++attempts <= maxAttempts) { |
| 87 | + Meteor.setTimeout(TimeSync.resync, 1000); |
| 88 | + } else { |
| 89 | + log('Max number of time sync attempts reached. Giving up.'); |
| 90 | + } |
| 91 | + return; |
| 92 | + } |
| 93 | + |
| 94 | + attempts = 0; // It worked |
| 95 | + const response = res.content || res; |
| 96 | + const ts = parseInt(response, 10); |
| 97 | + SyncInternals.isSynced = true; |
| 98 | + SyncInternals.offset = Math.round(((ts - t0) + (ts - t3)) / 2); |
| 99 | + SyncInternals.roundTripTime = t3 - t0; // - (ts - ts) which is 0 |
| 100 | + SyncInternals.offsetTracker.changed(); |
| 101 | +} |
| 102 | + |
| 103 | +// Reactive variable for server time that updates every second. |
| 104 | +TimeSync.serverTime = function (clientTime, interval) { |
| 105 | + check(interval, Match.Optional(Match.Integer)); |
| 106 | + // If a client time is provided, we don't need to depend on the tick. |
| 107 | + if (!clientTime) getTickDependency(interval || defaultInterval).depend(); |
| 108 | + |
| 109 | + SyncInternals.offsetTracker.depend(); // depend on offset to enable reactivity |
| 110 | + // Convert Date argument to epoch as necessary |
| 111 | + return (+clientTime || Date.now()) + SyncInternals.offset; |
| 112 | +}; |
| 113 | + |
| 114 | +// Reactive variable for the difference between server and client time. |
| 115 | +TimeSync.serverOffset = function () { |
| 116 | + SyncInternals.offsetTracker.depend(); |
| 117 | + return SyncInternals.offset; |
| 118 | +}; |
| 119 | + |
| 120 | +TimeSync.roundTripTime = function () { |
| 121 | + SyncInternals.offsetTracker.depend(); |
| 122 | + return SyncInternals.roundTripTime; |
| 123 | +}; |
| 124 | + |
| 125 | +TimeSync.isSynced = function () { |
| 126 | + SyncInternals.offsetTracker.depend(); |
| 127 | + return SyncInternals.isSynced; |
| 128 | +}; |
| 129 | + |
| 130 | +let resyncIntervalId = null; |
| 131 | + |
| 132 | +TimeSync.resync = function () { |
| 133 | + if (resyncIntervalId !== null) Meteor.clearInterval(resyncIntervalId); |
| 134 | + |
| 135 | + updateOffset(); |
| 136 | + resyncIntervalId = Meteor.setInterval(updateOffset, (SyncInternals.useDDP) ? 300000 : 600000); |
| 137 | +}; |
| 138 | + |
| 139 | +// Run this as soon as we load, even before Meteor.startup() |
| 140 | +// Run again whenever we reconnect after losing connection |
| 141 | +let wasConnected = false; |
| 142 | + |
| 143 | +Tracker.autorun(function () { |
| 144 | + const connected = Meteor.status().connected; |
| 145 | + if (connected && !wasConnected) TimeSync.resync(); |
| 146 | + wasConnected = connected; |
| 147 | + SyncInternals.useDDP = connected; |
| 148 | +}); |
| 149 | + |
| 150 | +// Resync if unexpected change by more than a few seconds. This needs to be |
| 151 | +// somewhat lenient, or a CPU-intensive operation can trigger a re-sync even |
| 152 | +// when the offset is still accurate. In any case, we're not going to be able to |
| 153 | +// catch very small system-initiated NTP adjustments with this, anyway. |
| 154 | +const tickCheckTolerance = 5000; |
| 155 | + |
| 156 | +let lastClientTime = Date.now(); |
| 157 | + |
| 158 | +// Set up a new interval for any amount of reactivity. |
| 159 | +function getTickDependency(interval) { |
| 160 | + |
| 161 | + if (!SyncInternals.timeTick[interval]) { |
| 162 | + const dep = new Tracker.Dependency(); |
| 163 | + |
| 164 | + Meteor.setInterval(function () { |
| 165 | + dep.changed(); |
| 166 | + }, interval); |
| 167 | + |
| 168 | + SyncInternals.timeTick[interval] = dep; |
| 169 | + } |
| 170 | + |
| 171 | + return SyncInternals.timeTick[interval]; |
| 172 | +} |
| 173 | + |
| 174 | +// Set up special interval for the default tick, which also watches for re-sync |
| 175 | +Meteor.setInterval(function () { |
| 176 | + const currentClientTime = Date.now(); |
| 177 | + const discrepancy = SyncInternals.getDiscrepancy(lastClientTime, currentClientTime, defaultInterval); |
| 178 | + |
| 179 | + if (Math.abs(discrepancy) < tickCheckTolerance) { |
| 180 | + // No problem here, just keep ticking along |
| 181 | + SyncInternals.timeTick[defaultInterval].changed(); |
| 182 | + } else { |
| 183 | + // resync on major client clock changes |
| 184 | + // based on http://stackoverflow.com/a/3367542/1656818 |
| 185 | + log('Clock discrepancy detected. Attempting re-sync.'); |
| 186 | + // Refuse to compute server time and try to guess new server offset. Guessing only works if the server time hasn't changed. |
| 187 | + SyncInternals.offset = SyncInternals.offset - discrepancy; |
| 188 | + SyncInternals.isSynced = false; |
| 189 | + SyncInternals.offsetTracker.changed(); |
| 190 | + TimeSync.resync(); |
| 191 | + } |
| 192 | + |
| 193 | + lastClientTime = currentClientTime; |
| 194 | +}, defaultInterval); |
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