纯异步nodejs文件夹(目录)复制

ts2009

　　思路:
　　1、callback 驱动
　　2、递归所有需要复制文件
　　3、在一定阀值下并发复制文件
　　4、运行需要安装 async.js     npm install async
　　代码如下：

var async = require("async");
var fs = require("fs");
var path = require("path");
// cursively make dir
function mkdirs(p, mode, f, made) {
if (typeof mode === 'function' || mode === undefined) {
f = mode;
mode = 0777 & (~process.umask());
}
if (!made)
made = null;
var cb = f || function () {};
if (typeof mode === 'string')
mode = parseInt(mode, 8);
p = path.resolve(p);
fs.mkdir(p, mode, function (er) {
if (!er) {
made = made || p;
return cb(null, made);
}
switch (er.code) {
case 'ENOENT':
mkdirs(path.dirname(p), mode, function (er, made) {
if (er) {
cb(er, made);
} else {
mkdirs(p, mode, cb, made);
}
});
break;
// In the case of any other error, just see if there's a dir
// there already.  If so, then hooray!  If not, then something
// is borked.
default:
fs.stat(p, function (er2, stat) {
// if the stat fails, then that's super weird.
// let the original error be the failure reason.
if (er2 || !stat.isDirectory()) {
cb(er, made);
} else {
cb(null, made)
};
});
break;
}
});
}
// single file copy
function copyFile(file, toDir, cb) {
async.waterfall([
function (callback) {
fs.exists(toDir, function (exists) {
if (exists) {
callback(null, false);
} else {
callback(null, true);
}
});
}, function (need, callback) {
if (need) {
mkdirs(path.dirname(toDir), callback);
} else {
callback(null, true);
}
}, function (p, callback) {
var reads = fs.createReadStream(file);
var writes = fs.createWriteStream(path.join(path.dirname(toDir), path.basename(file)));
reads.pipe(writes);
//don't forget close the  when  all the data are read
reads.on("end", function () {
writes.end();
callback(null);
});
reads.on("error", function (err) {
console.log("error occur in reads");
callback(true, err);
});
}
], cb);
}
// cursively count the  files that need to be copied
function _ccoutTask(from, to, cbw) {
async.waterfall([
function (callback) {
fs.stat(from, callback);
},
function (stats, callback) {
if (stats.isFile()) {
cbw.addFile(from, to);
callback(null, []);
} else if (stats.isDirectory()) {
fs.readdir(from, callback);
}
},
function (files, callback) {
if (files.length) {
for (var i = 0; i < files.length; i++) {
_ccoutTask(path.join(from, files), path.join(to, files), cbw.increase());
}
}
callback(null);
}
], cbw);
}
// wrap the callback before counting
function ccoutTask(from, to, cb) {
var files = [];
var count = 1;
function wrapper(err) {
count--;
if (err || count <= 0) {
cb(err, files)
}
}
wrapper.increase = function () {
count++;
return wrapper;
}
wrapper.addFile = function (file, dir) {
files.push({
file : file,
dir : dir
});
}
_ccoutTask(from, to, wrapper);
}

function copyDir(from, to, cb) {
if(!cb){
cb=function(){};
}
async.waterfall([
function (callback) {
fs.exists(from, function (exists) {
if (exists) {
callback(null, true);
} else {
console.log(from + " not exists");
callback(true);
}
});
},
function (exists, callback) {
fs.stat(from, callback);
},
function (stats, callback) {
if (stats.isFile()) {
// one file copy
copyFile(from, to, function (err) {
if (err) {
// break the waterfall
callback(true);
} else {
callback(null, []);
}
});
} else if (stats.isDirectory()) {
ccoutTask(from, to, callback);
}
},
function (files, callback) {
// prevent reaching to max file open limit   
async.mapLimit(files, 10, function (f, cb) {
copyFile(f.file, f.dir, cb);
}, callback);
}
], cb);
}
var start = new Date().getTime();
copyDir("F:\\gear", "F:\\gear2", function (err) {
if (err) {
console.log("error ocur");
console.dir(err);
} else {
console.log("copy ok");
console.log("consume time:" + (new Date().getTime() - start))
}
});