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.
Take writeFileSync, writeFile, steno for comparison.
You can also find this benchmark in benchmark folder
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)
}
}
}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')
})
return a writer instance
- filename: the dest file's name
var writer = fstorm(filename);- 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
})__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')benchmark
npm run benchmark
test
npm test
MITTTTTTTTTTTTTTTTTT.