ImageGrid/ui (gen4)/features/recover.js

/**********************************************************************
* 
*
*
**********************************************************************/

define(function(require){ var module = {}

var actions = require('lib/actions')
var features = require('lib/features')

var core = require('features/core')



/*********************************************************************/

var RecoverActions = actions.Actions({
	config: {
		'recover-load-errors-to-previous-location': true,
	},

	// Load index with recovery...
	//
	// This will:
	// 	- save recovery data (.__recover)
	// 	- load
	// 	- clear recovery data (if load successful)
	//
	// NOTE: for more info on the load protocol see: base.BaseActions.load 
	load: [
		function(data){
			// prepare to recover, just in case...
			this.__recover = (this.__recover !== false 
					&& this.config['recover-load-errors-to-previous-location']) ? 
				this.location
				: false

			return function(){

				// all went well clear the recovery data...
				delete this.__recover
			}
		}],

	// Load data and recover on error... 
	//
	// This is the same as .load(..) but will monitor for load errors 
	// and attempt to recover if it fails...
	//
	// NOTE: this avoids load loops by attempting to recover only once...
	// NOTE: this is done as a wrapper because we can't catch errors in
	// 		parent actions at this point...
	loadOrRecover: ['- Location/',
		function(data){
			// this is the critical section, after this point we
			// are doing the actual loading....
			try {

				this.load(data)

			// something bad happened, clear and handle it...
			} catch(err){
				this.clear()

				console.error(err)

				// recover to last location...
				if(this.__recover){
					this.recover()

				// fail...
				} else {
					// clear the recovery data...
					delete this.__recover

					// fail...
					throw err
				}
			}
		}],

	// Recover from load error...
	//
	// This will:
	//	- get recovery data if present
	//	- load recovery data
	//	- clear recovery data
	//
	// NOTE: if no recovery data present (.__recover) this will do nothing.
	recover: ['- File/Recover from load error',
		function(){
			var l = this.__recover

			// nothing to recover...
			if(!l){
				delete this.__recover
				return
			}

			// NOTE: this will prevent us from entering
			// 		a recover attempt loop...
			// 		...if the recovery fails we will just
			// 		clear and stop.
			this.__recover = false

			// do the loading...
			this.location = l
		}],
})

module.Recovery = core.ImageGridFeatures.Feature({
	title: '',
	doc: '',

	tag: 'recover',

	depends: [
		'location',
	],

	actions: RecoverActions,
})



/**********************************************************************
* vim:set ts=4 sw=4 :                                                */
return module })