transaction.js
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// Copyright IBM Corp. 2015,2016. All Rights Reserved.
// Node module: loopback-connector
// This file is licensed under the MIT License.
// License text available at https://opensource.org/licenses/MIT
var assert = require('assert');
var util = require('util');
var EventEmitter = require('events').EventEmitter;
var debug = require('debug')('loopback:connector:transaction');
module.exports = Transaction;
/**
* Create a new Transaction object
* @param {Connector} connector The connector instance
* @param {*} connection A connection to the DB
* @constructor
*/
function Transaction(connector, connection) {
this.connector = connector;
this.connection = connection;
EventEmitter.call(this);
}
util.inherits(Transaction, EventEmitter);
// Isolation levels
Transaction.SERIALIZABLE = 'SERIALIZABLE';
Transaction.REPEATABLE_READ = 'REPEATABLE READ';
Transaction.READ_COMMITTED = 'READ COMMITTED';
Transaction.READ_UNCOMMITTED = 'READ UNCOMMITTED';
Transaction.hookTypes = {
BEFORE_COMMIT: 'before commit',
AFTER_COMMIT: 'after commit',
BEFORE_ROLLBACK: 'before rollback',
AFTER_ROLLBACK: 'after rollback',
TIMEOUT: 'timeout',
};
/**
* Commit a transaction and release it back to the pool
* @param cb
* @returns {*}
*/
Transaction.prototype.commit = function(cb) {
return this.connector.commit(this.connection, cb);
};
/**
* Rollback a transaction and release it back to the pool
* @param cb
* @returns {*|boolean}
*/
Transaction.prototype.rollback = function(cb) {
return this.connector.rollback(this.connection, cb);
};
/**
* Begin a new transaction
* @param {Connector} connector The connector instance
* @param {Object} [options] Options {isolationLevel: '...', timeout: 1000}
* @param cb
*/
Transaction.begin = function(connector, options, cb) {
if (typeof options === 'function' && cb === undefined) {
cb = options;
options = {};
}
if (typeof options === 'string') {
options = { isolationLevel: options };
}
var isolationLevel = options.isolationLevel || Transaction.READ_COMMITTED;
assert(isolationLevel === Transaction.SERIALIZABLE ||
isolationLevel === Transaction.REPEATABLE_READ ||
isolationLevel === Transaction.READ_COMMITTED ||
isolationLevel === Transaction.READ_UNCOMMITTED, 'Invalid isolationLevel');
debug('Starting a transaction with options: %j', options);
assert(typeof connector.beginTransaction === 'function',
'beginTransaction must be function implemented by the connector');
connector.beginTransaction(isolationLevel, function(err, connection) {
if (err) {
return cb(err);
}
var tx = connection;
if (!(connection instanceof Transaction)) {
tx = new Transaction(connector, connection);
}
cb(err, tx);
});
};