dreemgl/system/server/filewatcher.js

DreemGL is an open-source multi-screen prototyping framework for mediated environments, with a visual editor and shader styling for webGL and DALi runtimes written in JavaScript. As a toolkit for gpu-accelerated multiscreen development, DreemGL includes

/* DreemGL is a collaboration between Teeming Society & Samsung Electronics, sponsored by Samsung and others.
   Copyright 2015-2016 Teeming Society. Licensed under the Apache License, Version 2.0 (the "License"); You may not use this file except in compliance with the License.
   You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing,
   software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and limitations under the License.*/

define.class(function(require, exports){
// internal, Watch file changes

	var fs = require('fs')
	var promisify = require('$system/lib/promisify')

	if (fs) {
		fs.statPromise = promisify(fs.stat)
	}

	var uid = 0
	this.__trace__  = 2
	this.atConstructor = function(delay){
		this.files = {}
		this.timeout = delay || 500
		this.poll = this.poll.bind(this)
		this.itv = setTimeout(this.poll, 0)
		this.lastfire = 0
		this.firelimit = 1000
		this.uid = uid++
	}

	this.atChange = function(changed_file){}

	this.poll = function(file){
		var stats = []
		var names = []
		for(var k in this.files){
			names.push(k)
			stats.push(fs.statPromise(define.expandVariables(k)))
		}
		Promise.all(stats).then(function(results){
			setTimeout(this.poll, this.timeout)
			for(var i = 0;i < results.length; i++){
				var file = names[i]
				var res = results[i]
				res.atime = null
				var str = JSON.stringify(res)
				// lets make sure we dont fire too often
				if(this.files[file] !== null && this.files[file] !== str){

					var now = Date.now()
					if(now - this.lastfire > this.firelimit){
						this.lastfire = now
						try{
							this.atChange(file)
						}
						catch(e){
							//console.log('WATCH EXCEPTION', e, e.stack)
							throw e
						}
					}
				}
				this.files[file] = str
			}
		}.bind(this)).catch(function(err){
			// TODO lets unwatch the files that errored?
			console.log("WATCH ERROR", err.stack)
		})
	}

	this.watch = function(file /*String:path of file to watch*/){
		if(!(file in this.files)) this.files[file] = null
	}
})