atomic-file

store data in a file, but gaurantee there is never a partial write.

This uses a simple trick to make writes to the file system atomic: first write the file to {filename}~, then mv {filename}~ {filename} although it's possible a program to crash while it's part way through writing a file, the rename operation (mv) can only either succeed or fail.

var AtomicFile = require('atomic-file') //default, json encoding
// var AtomicFile = require('atomic-file/buffer') //binary
 
var af = AtomicFile(filename)
//get the current contents
af.get(function (err, value) {
  //write a new value
  af.set(value, function (err) {
 
  })
})

note, get stores the read value in memory, so subsequent calls to get will be instant. Successful writes will update the value.

af = AtomicFile(filename, suffix='~', codec=json)

create a new atomic-file instance

af.get(cb(err, value))

read the current value. will callback synchronously if the value is already in memory.

af.set(value, cb)

write value to the file atomically. will callback when it's definitely on disk.

af.destroy(cb)

delete the underlying file. callback when definitely deleted.

License

MIT