73 lines
2.1 KiB
JavaScript
73 lines
2.1 KiB
JavaScript
'use strict';
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var assert = require('assert'),
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debug = require('debug')('box:locker'),
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EventEmitter = require('events').EventEmitter,
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util = require('util');
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function Locker() {
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this._operation = null;
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this._timestamp = null;
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this._watcherId = -1;
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this._lockDepth = 0; // recursive locks
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}
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util.inherits(Locker, EventEmitter);
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// these are mutually exclusive operations
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Locker.prototype.OP_BOX_UPDATE = 'box_update';
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Locker.prototype.OP_PLATFORM_START = 'platform_start';
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Locker.prototype.OP_FULL_BACKUP = 'full_backup';
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Locker.prototype.OP_APPTASK = 'apptask';
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Locker.prototype.OP_MIGRATE = 'migrate';
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Locker.prototype.lock = function (operation) {
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assert.strictEqual(typeof operation, 'string');
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if (this._operation !== null) return new Error('Already locked for ' + this._operation);
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this._operation = operation;
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++this._lockDepth;
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this._timestamp = new Date();
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var that = this;
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this._watcherId = setInterval(function () { debug('Lock unreleased %s', that._operation); }, 1000 * 60 * 5);
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debug('Acquired : %s', this._operation);
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this.emit('locked', this._operation);
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return null;
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};
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Locker.prototype.recursiveLock = function (operation) {
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if (this._operation === operation) {
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++this._lockDepth;
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debug('Re-acquired : %s Depth : %s', this._operation, this._lockDepth);
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return null;
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}
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return this.lock(operation);
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};
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Locker.prototype.unlock = function (operation) {
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assert.strictEqual(typeof operation, 'string');
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if (this._operation !== operation) throw new Error('Mismatched unlock. Current lock is for ' + this._operation); // throw because this is a programming error
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if (--this._lockDepth === 0) {
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debug('Released : %s', this._operation);
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this._operation = null;
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this._timestamp = null;
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clearInterval(this._watcherId);
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this._watcherId = -1;
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} else {
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debug('Recursive lock released : %s. Depth : %s', this._operation, this._lockDepth);
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}
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this.emit('unlocked', operation);
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return null;
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};
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exports = module.exports = new Locker();
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