77 lines
2.5 KiB
JavaScript
77 lines
2.5 KiB
JavaScript
// Copyright IBM Corp. 2014,2018. All Rights Reserved.
|
|
// Node module: loopback
|
|
// This file is licensed under the MIT License.
|
|
// License text available at https://opensource.org/licenses/MIT
|
|
|
|
/**
|
|
* Module Dependencies.
|
|
*/
|
|
|
|
'use strict';
|
|
var assert = require('assert');
|
|
|
|
/**
|
|
* Checkpoint list entry.
|
|
*
|
|
* @property id {Number} the sequencial identifier of a checkpoint
|
|
* @property time {Number} the time when the checkpoint was created
|
|
* @property sourceId {String} the source identifier
|
|
*
|
|
* @class Checkpoint
|
|
* @inherits {PersistedModel}
|
|
*/
|
|
|
|
module.exports = function(Checkpoint) {
|
|
// Workaround for https://github.com/strongloop/loopback/issues/292
|
|
Checkpoint.definition.rawProperties.time.default =
|
|
Checkpoint.definition.properties.time.default = function() {
|
|
return new Date();
|
|
};
|
|
|
|
/**
|
|
* Get the current checkpoint id
|
|
* @callback {Function} callback
|
|
* @param {Error} err
|
|
* @param {Number} checkpoint The current checkpoint seq
|
|
*/
|
|
Checkpoint.current = function(cb) {
|
|
var Checkpoint = this;
|
|
Checkpoint._getSingleton(function(err, cp) {
|
|
cb(err, cp.seq);
|
|
});
|
|
};
|
|
|
|
Checkpoint._getSingleton = function(cb) {
|
|
var query = {limit: 1}; // match all instances, return only one
|
|
var initialData = {seq: 1};
|
|
this.findOrCreate(query, initialData, cb);
|
|
};
|
|
|
|
/**
|
|
* Increase the current checkpoint if it already exists otherwise initialize it
|
|
* @callback {Function} callback
|
|
* @param {Error} err
|
|
* @param {Object} checkpoint The current checkpoint
|
|
*/
|
|
Checkpoint.bumpLastSeq = function(cb) {
|
|
var Checkpoint = this;
|
|
Checkpoint._getSingleton(function(err, cp) {
|
|
if (err) return cb(err);
|
|
var originalSeq = cp.seq;
|
|
cp.seq++;
|
|
// Update the checkpoint but only if it was not changed under our hands
|
|
Checkpoint.updateAll({id: cp.id, seq: originalSeq}, {seq: cp.seq}, function(err, info) {
|
|
if (err) return cb(err);
|
|
// possible outcomes
|
|
// 1) seq was updated to seq+1 - exactly what we wanted!
|
|
// 2) somebody else already updated seq to seq+1 and our call was a no-op.
|
|
// That should be ok, checkpoints are time based, so we reuse the one created just now
|
|
// 3) seq was bumped more than once, so we will be using a value that is behind the latest seq.
|
|
// @bajtos is not entirely sure if this is ok, but since it wasn't handled by the current implementation either,
|
|
// he thinks we can keep it this way.
|
|
cb(null, cp);
|
|
});
|
|
});
|
|
};
|
|
};
|