A module for storing the ever-increasing sequence files when following couchdb _changes feeds.
Saves the sequence ID in an atomic way, so that it doesn't clobber the file if it crashes mid-save. Only does a single save at a time, so you can bang on it repeatedy, and it'll avoid doing unnecessary file IO or weird cases where two writes cross paths in odd ways.
var SF = require('seq-file')
var s = new SF('sequence.seq')
s.save(10)
console.log(s.seq) // 10
s.save(11) // won't actually save, because still saving the 10
console.log(s.seq) // 11. You get the idea.
// some time in the future, another change comes in
s.save(21)
// oh no! crash while saving!
s.save(34)
throw 'pwn' // file now contains "21", not ""- frequency: modify how frequently a sequence number is saved.
var SF = require('seq-file', {
frequency: 4
})
var s = new SF('sequence.seq')
s.save(11) // this won't save (we only save every 4 increments).
s.save(12) // this will totally save.