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index.js
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index.js
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var inherits = require('inherits')
var EventEmitter = require('events').EventEmitter
var State = require('./lib/state')
module.exports = Indexer
var Status = {
Indexing: 1,
Ready: 2,
Paused: 3
}
function Indexer (opts) {
if (!(this instanceof Indexer)) return new Indexer(opts)
if (!opts) throw new Error('missing opts param')
if (!opts.log) throw new Error('missing opts param "log"')
if (!opts.batch) throw new Error('missing opts param "batch"')
if (!allOrNone(!!opts.storeState, !!opts.fetchState)) {
throw new Error('either none or all of (opts.storeState, opts.fetchState) must be provided')
}
if (!unset(opts.version) && typeof opts.version !== 'number') throw new Error('opts.version must be a number')
// TODO: support forward & backward indexing from newest
this._version = unset(opts.version) ? 1 : opts.version
this._log = opts.log
this._batch = opts.batch
this._maxBatch = unset(opts.maxBatch) ? 50 : opts.maxBatch
this._state = Status.Indexing
this._at = null
// bind methods to this so we can pass them directly to event listeners
this._run = this._run.bind(this)
this._onNewFeed = this._onNewFeed.bind(this)
if (!opts.storeState && !opts.fetchState && !opts.clearIndex) {
// In-memory storage implementation
var state
this._storeState = function (buf, cb) {
state = buf
process.nextTick(cb)
}
this._fetchState = function (cb) {
process.nextTick(cb, null, state)
}
this._clearIndex = function (cb) {
state = null
process.nextTick(cb)
}
} else {
this._storeState = opts.storeState
this._fetchState = opts.fetchState
this._clearIndex = opts.clearIndex || null
}
var self = this
this._log.ready(function () {
self._fetchState(function (err, state) {
if (err && !err.notFound) {
self.emit('error', err)
return
}
if (!state) {
start()
return
}
try {
state = State.deserialize(state)
} catch (e) {
self.emit('error', e)
return
}
// Wipe existing index if versions don't match (and there's a 'clearIndex' implementation)
var storedVersion = state.version
if (storedVersion !== self._version && self._clearIndex) {
self._clearIndex(function (err) {
if (err) {
self.emit('error', err)
} else {
start()
}
})
} else {
start()
}
})
})
function start () {
self._state = Status.Ready
self._run()
}
this._log.on('feed', this._onNewFeed)
this.setMaxListeners(1024)
}
inherits(Indexer, EventEmitter)
Indexer.prototype._onNewFeed = function (feed, idx) {
var self = this
feed.setMaxListeners(128)
feed.ready(function () {
// It's possible these listeners are already attached. Ensure they are
// removed before attaching them to avoid attaching them twice
feed.removeListener('append', self._run)
feed.removeListener('download', self._run)
feed.on('append', self._run)
feed.on('download', self._run)
if (self._state === Status.Ready) self._run()
})
}
Indexer.prototype.pause = function (cb) {
cb = cb || function () {}
var self = this
if (this._state === Status.Paused || this._wantPause) {
process.nextTick(cb)
} else if (this._state === Status.Ready) {
this._state = Status.Paused
process.nextTick(cb)
} else {
this._wantPause = true
this.once('pause', function () {
self._wantPause = false
self._state = Status.Paused
cb()
})
}
}
Indexer.prototype.resume = function () {
if (this._state !== Status.Paused) return
this._state = Status.Ready
this._run()
}
Indexer.prototype.ready = function (fn) {
if (this._state === Status.Ready) process.nextTick(fn)
else this.once('ready', fn)
}
Indexer.prototype._run = function () {
if (this._wantPause) {
this._wantPause = false
this._pending = true
this.emit('pause')
return
}
if (this._state !== Status.Ready) {
this._pending = true
return
}
var self = this
this._state = Status.Indexing
var didWork = false
var pending = 1
// load state from storage
if (!this._at) {
this._fetchState(function (err, state) {
if (err && !err.notFound) throw err // TODO: how to bubble up errors? eventemitter?
if (!state) {
self._at = {}
self._log.feeds().forEach(function (feed) {
self._at[feed.key.toString('hex')] = {
key: feed.key,
min: 0,
max: 0
}
})
} else {
self._at = State.deserialize(state).keys
}
self._log.feeds().forEach(function (feed) {
feed.setMaxListeners(128)
// The ready() method also adds these events listeners. Try to remove
// them first so that they aren't added twice.
feed.removeListener('append', self._run)
feed.removeListener('download', self._run)
feed.on('append', self._run)
feed.on('download', self._run)
})
work()
})
} else {
work()
}
function work () {
var feeds = self._log.feeds()
var nodes = []
;(function collect (i) {
if (i >= feeds.length) return done()
feeds[i].ready(function () {
var key = feeds[i].key.toString('hex')
if (self._at[key] === undefined) {
self._at[key] = { key: feeds[i].key, min: 0, max: 0 }
}
// prefer to process forward
var at = self._at[key].max
var to = Math.min(feeds[i].length, at + self._maxBatch)
if (!feeds[i].has(at, to)) {
return collect(i + 1)
} else if (at < to) {
// TODO: This waits for all of the blocks to be available, and
// actually blocks ALL indexing until it's ready. The intention is to
// get min(maxBatch, feed.length-at) CONTIGUOUS entries
feeds[i].getBatch(at, to, {wait: false}, function (err, res) {
if (err || !res.length) {
return collect(i + 1)
}
for (var j = 0; j < res.length; j++) {
var node = res[j]
nodes.push({
key: feeds[i].key.toString('hex'),
seq: j + at,
value: node
})
}
didWork = true
self._batch(nodes, function () {
self._at[key].max += nodes.length
self._storeState(State.serialize(self._at, self._version), function () {
self.emit('indexed', nodes)
done()
})
})
})
} else {
collect(i + 1)
}
})
})(0)
function done () {
if (!--pending) {
self._state = Status.Ready
if (didWork || self._pending) {
self._pending = false
self._run()
} else {
self.emit('ready')
}
}
}
}
}
function allOrNone (a, b) {
return (!!a && !!b) || (!a && !b)
}
function unset (x) {
return x === null || x === undefined
}