fstorm

writing file like a storm , but always get the expected result

A very very small idea for writing file more 'safe' and 'super fast', inspired by steno, but more efficient and sensible.

fstorm is very suitable to be used when you need to excute frequently writing to same file.

What fstorm do?

Take writeFileSync, writeFile, steno for comparison.

You can also find this benchmark in benchmark folder

RESULT:

10000x

100000x

1000000x

steno will pending without any response, the same as writeFile and writeFileSync

About writeFile

In steno's page. It mentioned that writeFile only take 20ms to writeFile, It is compeletely wrong. In fact, when you run fs.writeFile(..), It is only represent that the code is over, but file haven't been compelete yet. Althought not fast as expected, but it is still much faster than fs.writeFileSync

About steno

steno's setCallback and write(content, callback) are both meanless for hook the content after writting.

About writeFileSync

It is really sloooooooooooooooow..., but it is really reliable, beacuse it execute every file writing one by one..

fstorm!!

Now, There is a more reasonable choice when you need to writing file frequently, only the last one will be kept, and it is dead fast beacuse some trick to avoid unnecessary operation.

source code

var benchmarks = {
  "writeFileSync": function(time, cb){

    var filename = f("writeFileSync.txt");
    var k = 0;

    function compelete(){
      k++
      if( (k >= time) && cb) cb()
    }
    for (var i = 0; i < time; i++) {
      fs.writeFileSync(filename, i)
      compelete()
    }
  },
  "writeFile": function(time, cb){
    var filename = f("writeFile.txt");
    var k = 0;
    function compelete(){
      k++;
      if( (k >= time) && cb) cb()
    }
    for (var i = 0; i < time; i++) {
      fs.writeFile( filename , i, compelete)
    }

  },
  // I try setCallback for steno, it is also fail to get correct content.
  "steno": function(time, cb){
    var filename = f("steno.txt");
    var sfile = steno(filename);
    var k =0;

    function compelete(){
      k++;
      if( (k >= time) && cb) cb()
    }
    for (var i = 0; i < time; i++) {
      sfile.write(i, compelete)
    }
  },

  "fstorm": function( time, cb ){

    var filename = f("fstorm.txt");
    var k =0;
    var fwriter = fstorm(filename);

    fwriter.on('end', cb) // emitted when a squence is over

    for (var i = 0; i < time; i++) {
      fwriter.write(i)
    }
  }

}

Usage

npm install fstorm

var fstorm  = require('fstorm');

var writer = fstorm('./file3.txt');

writer.on('end', function(){
  assert(fs.readFileSync('./file3.txt') === '7')
})

writer
  .write('1')
  .write('2')
  .write('3')
  .write('4')
  .write('5')
  .write('6')

process.nextTick(function(){
  writer
    .write('7')
})

API

fstorm(filename)

return a writer instance

• filename: the dest file's name

var writer = fstorm(filename);

writer.write( content[, options] [, callback])

• content: the content you want to write
• options[Optional]: fstorm use fs.writeFile(filename, options, callback). the options will be passed to it. default is 'utf8'
• callback(err, status):
  • err: follow the 'node-callback-style', if any error is occurred, it will be return.
  • status: if status is 0, mean that this operation will be ignored beacuse of following writing operations . if status is 1, the content has been written successfully.

Example

writer.write('1', function(err, status){
  console.log(status)// ===> 0  
})

writer.write('2', function(err, status){
  console.log(status)// ===> 1  
})

builtin event

__FstormWriter is a SubClass of EventEmitter. __

Temporary， only end and error is emitted by writer, mean that writer is stable (or no new operation is blocked).

• end

writer.on('end', function(content){
  console.log(content === '2') // true
})

writer.write('1')

writer.write('2')

• error

var writer = fstorm('.folder/not/exists/db.json')

writer.on('error', function(err){
  assert(err.code === 'ENOENT')  // true
})

writer.write('2')

Contribution

benchmark

npm run benchmark

test

npm test

License

MITTTTTTTTTTTTTTTTTT.