git ssb

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'use strict';
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var hash = require('ssb-keys').hash
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// make a validation stream?
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// read the latest record in the database
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// check it against the incoming data,
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// and then read through
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function isString (s) {
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  return 'string' === typeof s
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}
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function isInteger (n) {
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  return ~~n === n
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}
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function isObject (o) {
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  return o && 'object' === typeof o
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}
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var util = require('./util')
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var encode = util.encode
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module.exports = function (ssb) {
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  var write = util.BatchQueue(ssb)
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  function getLatest (id, cb) {
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    ssb.getLatest(id, function (err, data) {
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      if(err) return cb(null, {key: null, value: null, type: 'put', public: null, ready: true})
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      cb(null, {
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        key: data.key, value: data.value, type: 'put',
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        public: data.value && data.value.author, ready: true
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      })
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    })
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  }
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  var latest = {}
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  function setLatest(id) {
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    if(latest[id].ready)
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      throw new Error('setLatest should only be called once')
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    ssb.getLatest(id, function (err, data) {
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      latest[id].ready = true
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      if(data) {
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        latest[id].key = data.key
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        latest[id].value = data.value
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      }
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      validate(id)
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    })
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  }
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  function validate(id) {
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    var feed = latest[id]
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    if(!feed.queue.length) return
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    if(!feed.ready) return
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    while(feed.queue.length) {
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      var op = feed.queue.shift()
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      if('function' == typeof op.create) {
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        op.value = op.create(feed.key, feed.value)
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        op.key = '%'+hash(encode(op.value))
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      }
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      var err =
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        util.isInvalidShape(op.value) ||
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        util.isInvalid(id, op.value, feed)
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      if(err)
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        op.cb(err)
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      else {
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        feed.key = op.key
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        feed.value = op.value
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        feed.ts = Date.now()
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        write(op)
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      }
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    }
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  }
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  function queue (id, job) {
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    if(!latest[id]) {
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      latest[id] = {
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        key:null, value: null,
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        ready: false, queue: [],
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        ts: Date.now()
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      }
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      latest[id].queue.push(job)
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      setLatest(id)
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    }
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    else
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      latest[id].queue.push(job)
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    validate(id)
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  }
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  function add (msg, cb) {
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    var err = util.isInvalidShape(msg)
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    if(err) return cb(err)
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    queue(msg.author, {
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        key: '%'+hash(encode(msg)),
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        value: msg, cb: cb,
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        create: null
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      })
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  }
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  add.queue = function (id, create, cb) {
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    queue(id, {
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        key: null, value: null,
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        create: create, cb: cb
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      })
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  }
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  return add
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}
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