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Significant refactor of membership change paths in prep for smaller
damping pull request
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,131 @@ | ||
| // Copyright (c) 2015 Uber Technologies, Inc. | ||
| // | ||
| // Permission is hereby granted, free of charge, to any person obtaining a copy | ||
| // of this software and associated documentation files (the "Software"), to deal | ||
| // in the Software without restriction, including without limitation the rights | ||
| // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | ||
| // copies of the Software, and to permit persons to whom the Software is | ||
| // furnished to do so, subject to the following conditions: | ||
| // | ||
| // The above copyright notice and this permission notice shall be included in | ||
| // all copies or substantial portions of the Software. | ||
| // | ||
| // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | ||
| // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | ||
| // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | ||
| // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | ||
| // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | ||
| // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN | ||
| // THE SOFTWARE. | ||
|
|
||
| 'use strict'; | ||
|
|
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| var MembershipUpdateRules = require('./membership-update-rules.js'); | ||
|
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| var LOG_10 = Math.log(10); | ||
|
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| function Dissemination(ringpop) { | ||
| this.ringpop = ringpop; | ||
| this.ringpop.on('changed', this.onRingChanged.bind(this)); | ||
|
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| this.changes = {}; | ||
| this.maxPiggybackCount = 1; | ||
| this.piggybackFactor = 15; // A lower piggyback factor leads to more full-syncs | ||
| } | ||
|
|
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| Dissemination.prototype.adjustMaxPiggybackCount = function adjustMaxPiggybackCount() { | ||
| var serverCount = this.ringpop.ring.getServerCount(); | ||
| var prevPiggybackCount = this.maxPiggybackCount; | ||
| var newPiggybackCount = this.piggybackFactor * Math.ceil(Math.log(serverCount + 1) / LOG_10); | ||
|
|
||
| if (this.maxPiggybackCount !== newPiggybackCount) { | ||
| this.maxPiggybackCount = newPiggybackCount; | ||
| this.ringpop.stat('gauge', 'max-piggyback', this.maxPiggybackCount); | ||
| this.ringpop.logger.debug('adjusted max piggyback count', { | ||
| newPiggybackCount: this.maxPiggybackCount, | ||
| oldPiggybackCount: prevPiggybackCount, | ||
| piggybackFactor: this.piggybackFactor, | ||
| serverCount: serverCount | ||
| }); | ||
| } | ||
| }; | ||
|
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| Dissemination.prototype.fullSync = function fullSync() { | ||
| var changes = []; | ||
|
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| for (var i = 0; i < this.ringpop.membership.members; i++) { | ||
| var member = this.ringpop.membership.members[i]; | ||
|
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| changes.push({ | ||
| source: this.ringpop.whoami(), | ||
| address: member.address, | ||
| status: member.status, | ||
| incarnationNumber: member.incarnationNumber | ||
| }); | ||
| } | ||
|
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| return changes; | ||
| }; | ||
|
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| Dissemination.prototype.issueChanges = function issueChanges(checksum, source) { | ||
| var changesToDisseminate = []; | ||
|
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| var changedNodes = Object.keys(this.changes); | ||
|
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| for (var i = 0; i < changedNodes.length; i++) { | ||
| var address = changedNodes[i]; | ||
| var change = this.changes[address]; | ||
|
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| // TODO We're bumping the piggyback count even though | ||
| // we don't know whether the change successfully made | ||
| // it over to the other side. This can result in undesired | ||
| // full-syncs. | ||
| if (typeof change.piggybackCount === 'undefined') { | ||
| change.piggybackCount = 0; | ||
| } | ||
|
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| change.piggybackCount += 1; | ||
|
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| if (change.piggybackCount > this.maxPiggybackCount) { | ||
| delete this.changes[address]; | ||
| continue; | ||
| } | ||
|
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| // TODO Compute change ID | ||
| // TODO Include change timestamp | ||
| changesToDisseminate.push({ | ||
| source: change.source, | ||
| address: change.address, | ||
| status: change.status, | ||
| incarnationNumber: change.incarnationNumber | ||
| }); | ||
| } | ||
|
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| this.ringpop.stat('gauge', 'changes.disseminate', changesToDisseminate.length); | ||
|
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| if (changesToDisseminate.length) { | ||
| return changesToDisseminate; | ||
| } else if (checksum && this.ringpop.membership.checksum !== checksum) { | ||
| this.ringpop.stat('increment', 'full-sync'); | ||
| this.ringpop.logger.info('full sync', { | ||
| localChecksum: this.ringpop.membership.checksum, | ||
| remoteChecksum: checksum, | ||
| remoteNode: source | ||
| }); | ||
|
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| // TODO Somehow send back indication of isFullSync | ||
| return this.fullSync(); | ||
| } else { | ||
| return []; | ||
| } | ||
| }; | ||
|
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| Dissemination.prototype.onRingChanged = function onRingChanged() { | ||
| this.adjustMaxPiggybackCount(); | ||
| }; | ||
|
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| Dissemination.prototype.recordChange = function recordChange(change) { | ||
| this.changes[change.address] = change; | ||
| }; | ||
|
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| module.exports = Dissemination; |
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