remove `self = this` in torrent.js

1 files changed, 328 insertions, 362 deletions

diff --git a/lib/torrent.js b/lib/torrent.js
index a32326a..5f86228 100644
--- a/lib/torrent.js
+++ b/lib/torrent.js
@@ -179,10 +179,9 @@ class Torrent extends EventEmitter {
   }
 
   get _numConns () {
-    const self = this
     let numConns = 0
-    for (const id in self._peers) {
-      if (self._peers[id].connected) numConns += 1
+    for (const id in this._peers) {
+      if (this._peers[id].connected) numConns += 1
     }
     return numConns
   }
@@ -194,61 +193,59 @@ class Torrent extends EventEmitter {
   }
 
   _onTorrentId (torrentId) {
-    const self = this
-    if (self.destroyed) return
+    if (this.destroyed) return
 
     let parsedTorrent
     try { parsedTorrent = parseTorrent(torrentId) } catch (err) {}
     if (parsedTorrent) {
       // Attempt to set infoHash property synchronously
-      self.infoHash = parsedTorrent.infoHash
-      self._debugId = parsedTorrent.infoHash.toString('hex').substring(0, 7)
+      this.infoHash = parsedTorrent.infoHash
+      this._debugId = parsedTorrent.infoHash.toString('hex').substring(0, 7)
       process.nextTick(() => {
-        if (self.destroyed) return
-        self._onParsedTorrent(parsedTorrent)
+        if (this.destroyed) return
+        this._onParsedTorrent(parsedTorrent)
       })
     } else {
       // If torrentId failed to parse, it could be in a form that requires an async
       // operation, i.e. http/https link, filesystem path, or Blob.
       parseTorrent.remote(torrentId, (err, parsedTorrent) => {
-        if (self.destroyed) return
-        if (err) return self._destroy(err)
-        self._onParsedTorrent(parsedTorrent)
+        if (this.destroyed) return
+        if (err) return this._destroy(err)
+        this._onParsedTorrent(parsedTorrent)
       })
     }
   }
 
   _onParsedTorrent (parsedTorrent) {
-    const self = this
-    if (self.destroyed) return
+    if (this.destroyed) return
 
-    self._processParsedTorrent(parsedTorrent)
+    this._processParsedTorrent(parsedTorrent)
 
-    if (!self.infoHash) {
-      return self._destroy(new Error('Malformed torrent data: No info hash'))
+    if (!this.infoHash) {
+      return this._destroy(new Error('Malformed torrent data: No info hash'))
     }
 
-    if (!self.path) self.path = path.join(TMP, self.infoHash)
+    if (!this.path) this.path = path.join(TMP, this.infoHash)
 
-    self._rechokeIntervalId = setInterval(() => {
-      self._rechoke()
+    this._rechokeIntervalId = setInterval(() => {
+      this._rechoke()
     }, RECHOKE_INTERVAL)
-    if (self._rechokeIntervalId.unref) self._rechokeIntervalId.unref()
+    if (this._rechokeIntervalId.unref) this._rechokeIntervalId.unref()
 
     // Private 'infoHash' event allows client.add to check for duplicate torrents and
     // destroy them before the normal 'infoHash' event is emitted. Prevents user
     // applications from needing to deal with duplicate 'infoHash' events.
-    self.emit('_infoHash', self.infoHash)
-    if (self.destroyed) return
+    this.emit('_infoHash', this.infoHash)
+    if (this.destroyed) return
 
-    self.emit('infoHash', self.infoHash)
-    if (self.destroyed) return // user might destroy torrent in event handler
+    this.emit('infoHash', this.infoHash)
+    if (this.destroyed) return // user might destroy torrent in event handler
 
-    if (self.client.listening) {
-      self._onListening()
+    if (this.client.listening) {
+      this._onListening()
     } else {
-      self.client.once('listening', () => {
-        self._onListening()
+      this.client.once('listening', () => {
+        this._onListening()
       })
     }
   }
@@ -281,24 +278,23 @@ class Torrent extends EventEmitter {
   }
 
   _onListening () {
-    const self = this
-    if (self.discovery || self.destroyed) return
+    if (this.discovery || this.destroyed) return
 
-    let trackerOpts = self.client.tracker
+    let trackerOpts = this.client.tracker
     if (trackerOpts) {
-      trackerOpts = extend(self.client.tracker, {
-        getAnnounceOpts () {
+      trackerOpts = extend(this.client.tracker, {
+        getAnnounceOpts: () => {
           const opts = {
-            uploaded: self.uploaded,
-            downloaded: self.downloaded,
-            left: Math.max(self.length - self.downloaded, 0)
+            uploaded: this.uploaded,
+            downloaded: this.downloaded,
+            left: Math.max(this.length - this.downloaded, 0)
           }
-          if (self.client.tracker.getAnnounceOpts) {
-            extendMutable(opts, self.client.tracker.getAnnounceOpts())
+          if (this.client.tracker.getAnnounceOpts) {
+            extendMutable(opts, this.client.tracker.getAnnounceOpts())
           }
-          if (self._getAnnounceOpts) {
+          if (this._getAnnounceOpts) {
             // TODO: consider deprecating this, as it's redundant with the former case
-            extendMutable(opts, self._getAnnounceOpts())
+            extendMutable(opts, this._getAnnounceOpts())
           }
           return opts
         }
@@ -306,58 +302,54 @@ class Torrent extends EventEmitter {
     }
 
     // begin discovering peers via DHT and trackers
-    self.discovery = new Discovery({
-      infoHash: self.infoHash,
-      announce: self.announce,
-      peerId: self.client.peerId,
-      dht: !self.private && self.client.dht,
+    this.discovery = new Discovery({
+      infoHash: this.infoHash,
+      announce: this.announce,
+      peerId: this.client.peerId,
+      dht: !this.private && this.client.dht,
       tracker: trackerOpts,
-      port: self.client.torrentPort,
+      port: this.client.torrentPort,
       userAgent: USER_AGENT
     })
 
-    self.discovery.on('error', onError)
-    self.discovery.on('peer', onPeer)
-    self.discovery.on('trackerAnnounce', onTrackerAnnounce)
-    self.discovery.on('dhtAnnounce', onDHTAnnounce)
-    self.discovery.on('warning', onWarning)
-
-    function onError (err) {
-      self._destroy(err)
-    }
+    this.discovery.on('error', (err) => {
+      this._destroy(err)
+    })
 
-    function onPeer (peer) {
+    this.discovery.on('peer', (peer) => {
       // Don't create new outgoing TCP connections when torrent is done
-      if (typeof peer === 'string' && self.done) return
-      self.addPeer(peer)
-    }
+      if (typeof peer === 'string' && this.done) return
+      this.addPeer(peer)
+    })
 
-    function onTrackerAnnounce () {
-      self.emit('trackerAnnounce')
-      if (self.numPeers === 0) self.emit('noPeers', 'tracker')
-    }
+    this.discovery.on('trackerAnnounce', () => {
+      this.emit('trackerAnnounce')
+      if (this.numPeers === 0) this.emit('noPeers', 'tracker')
+    })
 
-    function onDHTAnnounce () {
-      self.emit('dhtAnnounce')
-      if (self.numPeers === 0) self.emit('noPeers', 'dht')
-    }
+    this.discovery.on('dhtAnnounce', () => {
+      this.emit('dhtAnnounce')
+      if (this.numPeers === 0) this.emit('noPeers', 'dht')
+    })
 
-    function onWarning (err) {
-      self.emit('warning', err)
-    }
+    this.discovery.on('warning', (err) => {
+      this.emit('warning', err)
+    })
 
-    if (self.info) {
+    if (this.info) {
       // if full metadata was included in initial torrent id, use it immediately. Otherwise,
       // wait for torrent-discovery to find peers and ut_metadata to get the metadata.
-      self._onMetadata(self)
-    } else if (self.xs) {
-      self._getMetadataFromServer()
+      this._onMetadata(this)
+    } else if (this.xs) {
+      this._getMetadataFromServer()
     }
   }
 
   _getMetadataFromServer () {
+    // to allow function hoisting
     const self = this
-    const urls = Array.isArray(self.xs) ? self.xs : [ self.xs ]
+
+    const urls = Array.isArray(this.xs) ? this.xs : [ this.xs ]
 
     const tasks = urls.map(url => cb => {
       getMetadataFromURL(url, cb)
@@ -425,14 +417,13 @@ class Torrent extends EventEmitter {
    * Called when the full torrent metadata is received.
    */
   _onMetadata (metadata) {
-    const self = this
-    if (self.metadata || self.destroyed) return
-    self._debug('got metadata')
+    if (this.metadata || this.destroyed) return
+    this._debug('got metadata')
 
-    self._xsRequests.forEach(req => {
+    this._xsRequests.forEach(req => {
       req.abort()
     })
-    self._xsRequests = []
+    this._xsRequests = []
 
     let parsedTorrent
     if (metadata && metadata.infoHash) {
@@ -442,99 +433,99 @@ class Torrent extends EventEmitter {
       try {
         parsedTorrent = parseTorrent(metadata)
       } catch (err) {
-        return self._destroy(err)
+        return this._destroy(err)
       }
     }
 
-    self._processParsedTorrent(parsedTorrent)
-    self.metadata = self.torrentFile
+    this._processParsedTorrent(parsedTorrent)
+    this.metadata = this.torrentFile
 
     // add web seed urls (BEP19)
-    if (self.client.enableWebSeeds) {
-      self.urlList.forEach(url => {
-        self.addWebSeed(url)
+    if (this.client.enableWebSeeds) {
+      this.urlList.forEach(url => {
+        this.addWebSeed(url)
       })
     }
 
-    self._rarityMap = new RarityMap(self)
+    this._rarityMap = new RarityMap(this)
 
-    self.store = new ImmediateChunkStore(
-      new self._store(self.pieceLength, {
+    this.store = new ImmediateChunkStore(
+      new this._store(this.pieceLength, {
         torrent: {
-          infoHash: self.infoHash
+          infoHash: this.infoHash
         },
-        files: self.files.map(file => ({
-          path: path.join(self.path, file.path),
+        files: this.files.map(file => ({
+          path: path.join(this.path, file.path),
           length: file.length,
           offset: file.offset
         })),
-        length: self.length
+        length: this.length
       })
     )
 
-    self.files = self.files.map(file => new File(self, file))
+    this.files = this.files.map(file => new File(this, file))
 
     // Select only specified files (BEP53) http://www.bittorrent.org/beps/bep_0053.html
-    if (self.so) {
-      const selectOnlyFiles = parseRange.parse(self.so)
+    if (this.so) {
+      const selectOnlyFiles = parseRange.parse(this.so)
 
-      self.files.forEach((v, i) => {
-        if (selectOnlyFiles.includes(i)) self.files[i].select(true)
+      this.files.forEach((v, i) => {
+        if (selectOnlyFiles.includes(i)) this.files[i].select(true)
       })
     } else {
       // start off selecting the entire torrent with low priority
-      if (self.pieces.length !== 0) {
-        self.select(0, self.pieces.length - 1, false)
+      if (this.pieces.length !== 0) {
+        this.select(0, this.pieces.length - 1, false)
       }
     }
 
-    self._hashes = self.pieces
+    this._hashes = this.pieces
 
-    self.pieces = self.pieces.map((hash, i) => {
-      const pieceLength = (i === self.pieces.length - 1)
-        ? self.lastPieceLength
-        : self.pieceLength
+    this.pieces = this.pieces.map((hash, i) => {
+      const pieceLength = (i === this.pieces.length - 1)
+        ? this.lastPieceLength
+        : this.pieceLength
       return new Piece(pieceLength)
     })
 
-    self._reservations = self.pieces.map(() => [])
+    this._reservations = this.pieces.map(() => [])
 
-    self.bitfield = new BitField(self.pieces.length)
+    this.bitfield = new BitField(this.pieces.length)
 
-    self.wires.forEach(wire => {
+    this.wires.forEach(wire => {
       // If we didn't have the metadata at the time ut_metadata was initialized for this
       // wire, we still want to make it available to the peer in case they request it.
-      if (wire.ut_metadata) wire.ut_metadata.setMetadata(self.metadata)
+      if (wire.ut_metadata) wire.ut_metadata.setMetadata(this.metadata)
 
-      self._onWireWithMetadata(wire)
+      this._onWireWithMetadata(wire)
     })
 
-    if (self.skipVerify) {
+    if (this.skipVerify) {
       // Skip verifying exisitng data and just assume it's correct
-      self._markAllVerified()
-      self._onStore()
+      this._markAllVerified()
+      this._onStore()
     } else {
-      self._debug('verifying existing torrent data')
-      if (self._fileModtimes && self._store === FSChunkStore) {
+      this._debug('verifying existing torrent data')
+      if (this._fileModtimes && this._store === FSChunkStore) {
         // don't verify if the files haven't been modified since we last checked
-        self.getFileModtimes((err, fileModtimes) => {
-          if (err) return self._destroy(err)
+        this.getFileModtimes((err, fileModtimes) => {
+          if (err) return this._destroy(err)
 
-          const unchanged = self.files.map((_, index) => fileModtimes[index] === self._fileModtimes[index]).every(x => x)
+          const unchanged = this.files.map((_, index) => fileModtimes[index] === this._fileModtimes[index]).every(x => x)
 
           if (unchanged) {
-            self._markAllVerified()
-            self._onStore()
+            this._markAllVerified()
+            this._onStore()
           } else {
-            self._verifyPieces()
+            this._verifyPieces()
           }
         })
       } else {
-        self._verifyPieces()
+        this._verifyPieces()
       }
     }
 
-    self.emit('metadata')
+    this.emit('metadata')
   }
 
   /*
@@ -543,46 +534,44 @@ class Torrent extends EventEmitter {
    * Only valid in Node, not in the browser.
    */
   getFileModtimes (cb) {
-    const self = this
     const ret = []
-    parallelLimit(self.files.map((file, index) => cb => {
-      fs.stat(path.join(self.path, file.path), (err, stat) => {
+    parallelLimit(this.files.map((file, index) => cb => {
+      fs.stat(path.join(this.path, file.path), (err, stat) => {
         if (err && err.code !== 'ENOENT') return cb(err)
         ret[index] = stat && stat.mtime.getTime()
         cb(null)
       })
     }), FILESYSTEM_CONCURRENCY, err => {
-      self._debug('done getting file modtimes')
+      this._debug('done getting file modtimes')
       cb(err, ret)
     })
   }
 
   _verifyPieces () {
-    const self = this
-    parallelLimit(self.pieces.map((_, index) => cb => {
-      if (self.destroyed) return cb(new Error('torrent is destroyed'))
+    parallelLimit(this.pieces.map((_, index) => cb => {
+      if (this.destroyed) return cb(new Error('torrent is destroyed'))
 
-      self.store.get(index, (err, buf) => {
-        if (self.destroyed) return cb(new Error('torrent is destroyed'))
+      this.store.get(index, (err, buf) => {
+        if (this.destroyed) return cb(new Error('torrent is destroyed'))
 
         if (err) return process.nextTick(cb, null) // ignore error
         sha1(buf, hash => {
-          if (self.destroyed) return cb(new Error('torrent is destroyed'))
+          if (this.destroyed) return cb(new Error('torrent is destroyed'))
 
-          if (hash === self._hashes[index]) {
-            if (!self.pieces[index]) return
-            self._debug('piece verified %s', index)
-            self._markVerified(index)
+          if (hash === this._hashes[index]) {
+            if (!this.pieces[index]) return
+            this._debug('piece verified %s', index)
+            this._markVerified(index)
           } else {
-            self._debug('piece invalid %s', index)
+            this._debug('piece invalid %s', index)
           }
           cb(null)
         })
       })
     }), FILESYSTEM_CONCURRENCY, err => {
-      if (err) return self._destroy(err)
-      self._debug('done verifying')
-      self._onStore()
+      if (err) return this._destroy(err)
+      this._debug('done verifying')
+      this._onStore()
     })
   }
 
@@ -602,64 +591,61 @@ class Torrent extends EventEmitter {
    * Called when the metadata, listening server, and underlying chunk store is initialized.
    */
   _onStore () {
-    const self = this
-    if (self.destroyed) return
-    self._debug('on store')
+    if (this.destroyed) return
+    this._debug('on store')
 
-    self.ready = true
-    self.emit('ready')
+    this.ready = true
+    this.emit('ready')
 
     // Files may start out done if the file was already in the store
-    self._checkDone()
+    this._checkDone()
 
     // In case any selections were made before torrent was ready
-    self._updateSelections()
+    this._updateSelections()
   }
 
   destroy (cb) {
-    const self = this
-    self._destroy(null, cb)
+    this._destroy(null, cb)
   }
 
   _destroy (err, cb) {
-    const self = this
-    if (self.destroyed) return
-    self.destroyed = true
-    self._debug('destroy')
+    if (this.destroyed) return
+    this.destroyed = true
+    this._debug('destroy')
 
-    self.client._remove(self)
+    this.client._remove(this)
 
-    clearInterval(self._rechokeIntervalId)
+    clearInterval(this._rechokeIntervalId)
 
-    self._xsRequests.forEach(req => {
+    this._xsRequests.forEach(req => {
       req.abort()
     })
 
-    if (self._rarityMap) {
-      self._rarityMap.destroy()
+    if (this._rarityMap) {
+      this._rarityMap.destroy()
     }
 
-    for (const id in self._peers) {
-      self.removePeer(id)
+    for (const id in this._peers) {
+      this.removePeer(id)
     }
 
-    self.files.forEach(file => {
+    this.files.forEach(file => {
       if (file instanceof File) file._destroy()
     })
 
-    const tasks = self._servers.map(server => cb => {
+    const tasks = this._servers.map(server => cb => {
       server.destroy(cb)
     })
 
-    if (self.discovery) {
+    if (this.discovery) {
       tasks.push(cb => {
-        self.discovery.destroy(cb)
+        this.discovery.destroy(cb)
       })
     }
 
-    if (self.store) {
+    if (this.store) {
       tasks.push(cb => {
-        self.store.close(cb)
+        this.store.close(cb)
       })
     }
 
@@ -673,39 +659,38 @@ class Torrent extends EventEmitter {
       // errors versus torrent errors. Torrent errors are not fatal, and the client
       // is still usable afterwards. Therefore, always listen for errors in both
       // places (`client.on('error')` and `torrent.on('error')`).
-      if (self.listenerCount('error') === 0) {
-        self.client.emit('error', err)
+      if (this.listenerCount('error') === 0) {
+        this.client.emit('error', err)
       } else {
-        self.emit('error', err)
+        this.emit('error', err)
       }
     }
 
-    self.emit('close')
+    this.emit('close')
 
-    self.client = null
-    self.files = []
-    self.discovery = null
-    self.store = null
-    self._rarityMap = null
-    self._peers = null
-    self._servers = null
-    self._xsRequests = null
+    this.client = null
+    this.files = []
+    this.discovery = null
+    this.store = null
+    this._rarityMap = null
+    this._peers = null
+    this._servers = null
+    this._xsRequests = null
   }
 
   addPeer (peer) {
-    const self = this
-    if (self.destroyed) throw new Error('torrent is destroyed')
-    if (!self.infoHash) throw new Error('addPeer() must not be called before the `infoHash` event')
+    if (this.destroyed) throw new Error('torrent is destroyed')
+    if (!this.infoHash) throw new Error('addPeer() must not be called before the `infoHash` event')
 
-    if (self.client.blocked) {
+    if (this.client.blocked) {
       let host
       if (typeof peer === 'string') {
         let parts
         try {
           parts = addrToIPPort(peer)
         } catch (e) {
-          self._debug('ignoring peer: invalid %s', peer)
-          self.emit('invalidPeer', peer)
+          this._debug('ignoring peer: invalid %s', peer)
+          this.emit('invalidPeer', peer)
           return false
         }
         host = parts[0]
@@ -713,65 +698,64 @@ class Torrent extends EventEmitter {
         host = peer.remoteAddress
       }
 
-      if (host && self.client.blocked.contains(host)) {
-        self._debug('ignoring peer: blocked %s', peer)
+      if (host && this.client.blocked.contains(host)) {
+        this._debug('ignoring peer: blocked %s', peer)
         if (typeof peer !== 'string') peer.destroy()
-        self.emit('blockedPeer', peer)
+        this.emit('blockedPeer', peer)
         return false
       }
     }
 
-    const wasAdded = !!self._addPeer(peer)
+    const wasAdded = !!this._addPeer(peer)
     if (wasAdded) {
-      self.emit('peer', peer)
+      this.emit('peer', peer)
     } else {
-      self.emit('invalidPeer', peer)
+      this.emit('invalidPeer', peer)
     }
     return wasAdded
   }
 
   _addPeer (peer) {
-    const self = this
-    if (self.destroyed) {
+    if (this.destroyed) {
       if (typeof peer !== 'string') peer.destroy()
       return null
     }
-    if (typeof peer === 'string' && !self._validAddr(peer)) {
-      self._debug('ignoring peer: invalid %s', peer)
+    if (typeof peer === 'string' && !this._validAddr(peer)) {
+      this._debug('ignoring peer: invalid %s', peer)
       return null
     }
 
     const id = (peer && peer.id) || peer
-    if (self._peers[id]) {
-      self._debug('ignoring peer: duplicate (%s)', id)
+    if (this._peers[id]) {
+      this._debug('ignoring peer: duplicate (%s)', id)
       if (typeof peer !== 'string') peer.destroy()
       return null
     }
 
-    if (self.paused) {
-      self._debug('ignoring peer: torrent is paused')
+    if (this.paused) {
+      this._debug('ignoring peer: torrent is paused')
       if (typeof peer !== 'string') peer.destroy()
       return null
     }
 
-    self._debug('add peer %s', id)
+    this._debug('add peer %s', id)
 
     let newPeer
     if (typeof peer === 'string') {
       // `peer` is an addr ("ip:port" string)
-      newPeer = Peer.createTCPOutgoingPeer(peer, self)
+      newPeer = Peer.createTCPOutgoingPeer(peer, this)
     } else {
       // `peer` is a WebRTC connection (simple-peer)
-      newPeer = Peer.createWebRTCPeer(peer, self)
+      newPeer = Peer.createWebRTCPeer(peer, this)
     }
 
-    self._peers[newPeer.id] = newPeer
-    self._peersLength += 1
+    this._peers[newPeer.id] = newPeer
+    this._peersLength += 1
 
     if (typeof peer === 'string') {
       // `peer` is an addr ("ip:port" string)
-      self._queue.push(newPeer)
-      self._drain()
+      this._queue.push(newPeer)
+      this._drain()
     }
 
     return newPeer
@@ -806,46 +790,43 @@ class Torrent extends EventEmitter {
    * peer that has already sent a handshake.
    */
   _addIncomingPeer (peer) {
-    const self = this
-    if (self.destroyed) return peer.destroy(new Error('torrent is destroyed'))
-    if (self.paused) return peer.destroy(new Error('torrent is paused'))
+    if (this.destroyed) return peer.destroy(new Error('torrent is destroyed'))
+    if (this.paused) return peer.destroy(new Error('torrent is paused'))
 
     this._debug('add incoming peer %s', peer.id)
 
-    self._peers[peer.id] = peer
-    self._peersLength += 1
+    this._peers[peer.id] = peer
+    this._peersLength += 1
   }
 
   removePeer (peer) {
-    const self = this
     const id = (peer && peer.id) || peer
-    peer = self._peers[id]
+    peer = this._peers[id]
 
     if (!peer) return
 
     this._debug('removePeer %s', id)
 
-    delete self._peers[id]
-    self._peersLength -= 1
+    delete this._peers[id]
+    this._peersLength -= 1
 
     peer.destroy()
 
     // If torrent swarm was at capacity before, try to open a new connection now
-    self._drain()
+    this._drain()
   }
 
   select (start, end, priority, notify) {
-    const self = this
-    if (self.destroyed) throw new Error('torrent is destroyed')
+    if (this.destroyed) throw new Error('torrent is destroyed')
 
-    if (start < 0 || end < start || self.pieces.length <= end) {
+    if (start < 0 || end < start || this.pieces.length <= end) {
       throw new Error('invalid selection ', start, ':', end)
     }
     priority = Number(priority) || 0
 
-    self._debug('select %s-%s (priority %s)', start, end, priority)
+    this._debug('select %s-%s (priority %s)', start, end, priority)
 
-    self._selections.push({
+    this._selections.push({
       from: start,
       to: end,
       offset: 0,
@@ -853,65 +834,62 @@ class Torrent extends EventEmitter {
       notify: notify || noop
     })
 
-    self._selections.sort((a, b) => b.priority - a.priority)
+    this._selections.sort((a, b) => b.priority - a.priority)
 
-    self._updateSelections()
+    this._updateSelections()
   }
 
   deselect (start, end, priority) {
-    const self = this
-    if (self.destroyed) throw new Error('torrent is destroyed')
+    if (this.destroyed) throw new Error('torrent is destroyed')
 
     priority = Number(priority) || 0
-    self._debug('deselect %s-%s (priority %s)', start, end, priority)
+    this._debug('deselect %s-%s (priority %s)', start, end, priority)
 
-    for (let i = 0; i < self._selections.length; ++i) {
-      const s = self._selections[i]
+    for (let i = 0; i < this._selections.length; ++i) {
+      const s = this._selections[i]
       if (s.from === start && s.to === end && s.priority === priority) {
-        self._selections.splice(i, 1)
+        this._selections.splice(i, 1)
         break
       }
     }
 
-    self._updateSelections()
+    this._updateSelections()
   }
 
   critical (start, end) {
-    const self = this
-    if (self.destroyed) throw new Error('torrent is destroyed')
+    if (this.destroyed) throw new Error('torrent is destroyed')
 
-    self._debug('critical %s-%s', start, end)
+    this._debug('critical %s-%s', start, end)
 
     for (let i = start; i <= end; ++i) {
-      self._critical[i] = true
+      this._critical[i] = true
     }
 
-    self._updateSelections()
+    this._updateSelections()
   }
 
   _onWire (wire, addr) {
-    const self = this
-    self._debug('got wire %s (%s)', wire._debugId, addr || 'Unknown')
+    this._debug('got wire %s (%s)', wire._debugId, addr || 'Unknown')
 
     wire.on('download', downloaded => {
-      if (self.destroyed) return
-      self.received += downloaded
-      self._downloadSpeed(downloaded)
-      self.client._downloadSpeed(downloaded)
-      self.emit('download', downloaded)
-      self.client.emit('download', downloaded)
+      if (this.destroyed) return
+      this.received += downloaded
+      this._downloadSpeed(downloaded)
+      this.client._downloadSpeed(downloaded)
+      this.emit('download', downloaded)
+      this.client.emit('download', downloaded)
     })
 
     wire.on('upload', uploaded => {
-      if (self.destroyed) return
-      self.uploaded += uploaded
-      self._uploadSpeed(uploaded)
-      self.client._uploadSpeed(uploaded)
-      self.emit('upload', uploaded)
-      self.client.emit('upload', uploaded)
+      if (this.destroyed) return
+      this.uploaded += uploaded
+      this._uploadSpeed(uploaded)
+      this.client._uploadSpeed(uploaded)
+      this.emit('upload', uploaded)
+      this.client.emit('upload', uploaded)
     })
 
-    self.wires.push(wire)
+    this.wires.push(wire)
 
     if (addr) {
       // Sometimes RTCPeerConnection.getStats() doesn't return an ip:port for peers
@@ -921,25 +899,25 @@ class Torrent extends EventEmitter {
     }
 
     // When peer sends PORT message, add that DHT node to routing table
-    if (self.client.dht && self.client.dht.listening) {
+    if (this.client.dht && this.client.dht.listening) {
       wire.on('port', port => {
-        if (self.destroyed || self.client.dht.destroyed) {
+        if (this.destroyed || this.client.dht.destroyed) {
           return
         }
         if (!wire.remoteAddress) {
-          return self._debug('ignoring PORT from peer with no address')
+          return this._debug('ignoring PORT from peer with no address')
         }
         if (port === 0 || port > 65536) {
-          return self._debug('ignoring invalid PORT from peer')
+          return this._debug('ignoring invalid PORT from peer')
         }
 
-        self._debug('port: %s (from %s)', port, addr)
-        self.client.dht.addNode({ host: wire.remoteAddress, port })
+        this._debug('port: %s (from %s)', port, addr)
+        this.client.dht.addNode({ host: wire.remoteAddress, port })
       })
     }
 
     wire.on('timeout', () => {
-      self._debug('wire timeout (%s)', addr)
+      this._debug('wire timeout (%s)', addr)
       // TODO: this might be destroying wires too eagerly
       wire.destroy()
     })
@@ -951,38 +929,38 @@ class Torrent extends EventEmitter {
     wire.setKeepAlive(true)
 
     // use ut_metadata extension
-    wire.use(utMetadata(self.metadata))
+    wire.use(utMetadata(this.metadata))
 
     wire.ut_metadata.on('warning', err => {
-      self._debug('ut_metadata warning: %s', err.message)
+      this._debug('ut_metadata warning: %s', err.message)
     })
 
-    if (!self.metadata) {
+    if (!this.metadata) {
       wire.ut_metadata.on('metadata', metadata => {
-        self._debug('got metadata via ut_metadata')
-        self._onMetadata(metadata)
+        this._debug('got metadata via ut_metadata')
+        this._onMetadata(metadata)
       })
       wire.ut_metadata.fetch()
     }
 
     // use ut_pex extension if the torrent is not flagged as private
-    if (typeof utPex === 'function' && !self.private) {
+    if (typeof utPex === 'function' && !this.private) {
       wire.use(utPex())
 
       wire.ut_pex.on('peer', peer => {
         // Only add potential new peers when we're not seeding
-        if (self.done) return
-        self._debug('ut_pex: got peer: %s (from %s)', peer, addr)
-        self.addPeer(peer)
+        if (this.done) return
+        this._debug('ut_pex: got peer: %s (from %s)', peer, addr)
+        this.addPeer(peer)
       })
 
       wire.ut_pex.on('dropped', peer => {
         // the remote peer believes a given peer has been dropped from the torrent swarm.
         // if we're not currently connected to it, then remove it from the queue.
-        const peerObj = self._peers[peer]
+        const peerObj = this._peers[peer]
         if (peerObj && !peerObj.connected) {
-          self._debug('ut_pex: dropped peer: %s (from %s)', peer, addr)
-          self.removePeer(peer)
+          this._debug('ut_pex: dropped peer: %s (from %s)', peer, addr)
+          this.removePeer(peer)
         }
       })
 
@@ -994,25 +972,24 @@ class Torrent extends EventEmitter {
 
     // Hook to allow user-defined `bittorrent-protocol` extensions
     // More info: https://github.com/webtorrent/bittorrent-protocol#extension-api
-    self.emit('wire', wire, addr)
+    this.emit('wire', wire, addr)
 
-    if (self.metadata) {
+    if (this.metadata) {
       process.nextTick(() => {
         // This allows wire.handshake() to be called (by Peer.onHandshake) before any
         // messages get sent on the wire
-        self._onWireWithMetadata(wire)
+        this._onWireWithMetadata(wire)
       })
     }
   }
 
   _onWireWithMetadata (wire) {
-    const self = this
     let timeoutId = null
 
-    function onChokeTimeout () {
-      if (self.destroyed || wire.destroyed) return
+    const onChokeTimeout = () => {
+      if (this.destroyed || wire.destroyed) return
 
-      if (self._numQueued > 2 * (self._numConns - self.numPeers) &&
+      if (this._numQueued > 2 * (this._numConns - this.numPeers) &&
         wire.amInterested) {
         wire.destroy()
       } else {
@@ -1022,9 +999,9 @@ class Torrent extends EventEmitter {
     }
 
     let i
-    function updateSeedStatus () {
-      if (wire.peerPieces.buffer.length !== self.bitfield.buffer.length) return
-      for (i = 0; i < self.pieces.length; ++i) {
+    const updateSeedStatus = () => {
+      if (wire.peerPieces.buffer.length !== this.bitfield.buffer.length) return
+      for (i = 0; i < this.pieces.length; ++i) {
         if (!wire.peerPieces.get(i)) return
       }
       wire.isSeeder = true
@@ -1033,12 +1010,12 @@ class Torrent extends EventEmitter {
 
     wire.on('bitfield', () => {
       updateSeedStatus()
-      self._update()
+      this._update()
     })
 
     wire.on('have', () => {
       updateSeedStatus()
-      self._update()
+      this._update()
     })
 
     wire.once('interested', () => {
@@ -1057,7 +1034,7 @@ class Torrent extends EventEmitter {
 
     wire.on('unchoke', () => {
       clearTimeout(timeoutId)
-      self._update()
+      this._update()
     })
 
     wire.on('request', (index, offset, length, cb) => {
@@ -1065,16 +1042,16 @@ class Torrent extends EventEmitter {
         // Per spec, disconnect from peers that request >128KB
         return wire.destroy()
       }
-      if (self.pieces[index]) return
-      self.store.get(index, { offset, length }, cb)
+      if (this.pieces[index]) return
+      this.store.get(index, { offset, length }, cb)
     })
 
-    wire.bitfield(self.bitfield) // always send bitfield (required)
+    wire.bitfield(this.bitfield) // always send bitfield (required)
     wire.uninterested() // always start out uninterested (as per protocol)
 
     // Send PORT message to peers that support DHT
-    if (wire.peerExtensions.dht && self.client.dht && self.client.dht.listening) {
-      wire.port(self.client.dht.address().port)
+    if (wire.peerExtensions.dht && this.client.dht && this.client.dht.listening) {
+      wire.port(this.client.dht.address().port)
     }
 
     if (wire.type !== 'webSeed') { // do not choke on webseeds
@@ -1090,58 +1067,53 @@ class Torrent extends EventEmitter {
    * Called on selection changes.
    */
   _updateSelections () {
-    const self = this
-    if (!self.ready || self.destroyed) return
+    if (!this.ready || this.destroyed) return
 
     process.nextTick(() => {
-      self._gcSelections()
+      this._gcSelections()
     })
-    self._updateInterest()
-    self._update()
+    this._updateInterest()
+    this._update()
   }
 
   /**
    * Garbage collect selections with respect to the store's current state.
    */
   _gcSelections () {
-    const self = this
-
-    for (let i = 0; i < self._selections.length; ++i) {
-      const s = self._selections[i]
+    for (let i = 0; i < this._selections.length; ++i) {
+      const s = this._selections[i]
       const oldOffset = s.offset
 
       // check for newly downloaded pieces in selection
-      while (self.bitfield.get(s.from + s.offset) && s.from + s.offset < s.to) {
+      while (this.bitfield.get(s.from + s.offset) && s.from + s.offset < s.to) {
         s.offset += 1
       }
 
       if (oldOffset !== s.offset) s.notify()
       if (s.to !== s.from + s.offset) continue
-      if (!self.bitfield.get(s.from + s.offset)) continue
+      if (!this.bitfield.get(s.from + s.offset)) continue
 
-      self._selections.splice(i, 1) // remove fully downloaded selection
+      this._selections.splice(i, 1) // remove fully downloaded selection
       i -= 1 // decrement i to offset splice
 
       s.notify()
-      self._updateInterest()
+      this._updateInterest()
     }
 
-    if (!self._selections.length) self.emit('idle')
+    if (!this._selections.length) this.emit('idle')
   }
 
   /**
    * Update interested status for all peers.
    */
   _updateInterest () {
-    const self = this
+    const prev = this._amInterested
+    this._amInterested = !!this._selections.length
 
-    const prev = self._amInterested
-    self._amInterested = !!self._selections.length
-
-    self.wires.forEach(wire => {
+    this.wires.forEach(wire => {
       let interested = false
-      for (let index = 0; index < self.pieces.length; ++index) {
-        if (self.pieces[index] && wire.peerPieces.get(index)) {
+      for (let index = 0; index < this.pieces.length; ++index) {
+        if (this.pieces[index] && wire.peerPieces.get(index)) {
           interested = true
           break
         }
@@ -1151,23 +1123,22 @@ class Torrent extends EventEmitter {
       else wire.uninterested()
     })
 
-    if (prev === self._amInterested) return
-    if (self._amInterested) self.emit('interested')
-    else self.emit('uninterested')
+    if (prev === this._amInterested) return
+    if (this._amInterested) this.emit('interested')
+    else this.emit('uninterested')
   }
 
   /**
    * Heartbeat to update all peers and their requests.
    */
   _update () {
-    const self = this
-    if (self.destroyed) return
+    if (this.destroyed) return
 
     // update wires in random order for better request distribution
-    const ite = randomIterate(self.wires)
+    const ite = randomIterate(this.wires)
     let wire
     while ((wire = ite())) {
-      self._updateWire(wire)
+      this._updateWire(wire)
     }
   }
 
@@ -1175,6 +1146,7 @@ class Torrent extends EventEmitter {
    * Attempts to update a peer's requests
    */
   _updateWire (wire) {
+    // to allow function hoisting
     const self = this
 
     if (wire.peerChoking) return
@@ -1321,16 +1293,15 @@ class Torrent extends EventEmitter {
    * unchoking as described in BEP3.
    */
   _rechoke () {
-    const self = this
-    if (!self.ready) return
+    if (!this.ready) return
 
-    if (self._rechokeOptimisticTime > 0) self._rechokeOptimisticTime -= 1
-    else self._rechokeOptimisticWire = null
+    if (this._rechokeOptimisticTime > 0) this._rechokeOptimisticTime -= 1
+    else this._rechokeOptimisticWire = null
 
     const peers = []
 
-    self.wires.forEach(wire => {
-      if (!wire.isSeeder && wire !== self._rechokeOptimisticWire) {
+    this.wires.forEach(wire => {
+      if (!wire.isSeeder && wire !== this._rechokeOptimisticWire) {
         peers.push({
           wire,
           downloadSpeed: wire.downloadSpeed(),
@@ -1345,20 +1316,20 @@ class Torrent extends EventEmitter {
 
     let unchokeInterested = 0
     let i = 0
-    for (; i < peers.length && unchokeInterested < self._rechokeNumSlots; ++i) {
+    for (; i < peers.length && unchokeInterested < this._rechokeNumSlots; ++i) {
       peers[i].isChoked = false
       if (peers[i].wire.peerInterested) unchokeInterested += 1
     }
 
     // Optimistically unchoke a peer
-    if (!self._rechokeOptimisticWire && i < peers.length && self._rechokeNumSlots) {
+    if (!this._rechokeOptimisticWire && i < peers.length && this._rechokeNumSlots) {
       const candidates = peers.slice(i).filter(peer => peer.wire.peerInterested)
       const optimistic = candidates[randomInt(candidates.length)]
 
       if (optimistic) {
         optimistic.isChoked = false
-        self._rechokeOptimisticWire = optimistic.wire
-        self._rechokeOptimisticTime = RECHOKE_OPTIMISTIC_DURATION
+        this._rechokeOptimisticWire = optimistic.wire
+        this._rechokeOptimisticTime = RECHOKE_OPTIMISTIC_DURATION
       }
     }
 
@@ -1396,13 +1367,11 @@ class Torrent extends EventEmitter {
    * given wire may effectively swap out the request for one of its own.
    */
   _hotswap (wire, index) {
-    const self = this
-
     const speed = wire.downloadSpeed()
     if (speed < Piece.BLOCK_LENGTH) return false
-    if (!self._reservations[index]) return false
+    if (!this._reservations[index]) return false
 
-    const r = self._reservations[index]
+    const r = this._reservations[index]
     if (!r) {
       return false
     }
@@ -1433,10 +1402,10 @@ class Torrent extends EventEmitter {
       const req = minWire.requests[i]
       if (req.piece !== index) continue
 
-      self.pieces[index].cancel((req.offset / Piece.BLOCK_LENGTH) | 0)
+      this.pieces[index].cancel((req.offset / Piece.BLOCK_LENGTH) | 0)
     }
 
-    self.emit('hotswap', minWire, wire, index)
+    this.emit('hotswap', minWire, wire, index)
     return true
   }
 
@@ -1545,58 +1514,56 @@ class Torrent extends EventEmitter {
   }
 
   _checkDone () {
-    const self = this
-    if (self.destroyed) return
+    if (this.destroyed) return
 
     // are any new files done?
-    self.files.forEach(file => {
+    this.files.forEach(file => {
       if (file.done) return
       for (let i = file._startPiece; i <= file._endPiece; ++i) {
-        if (!self.bitfield.get(i)) return
+        if (!this.bitfield.get(i)) return
       }
       file.done = true
       file.emit('done')
-      self._debug(`file done: ${file.name}`)
+      this._debug(`file done: ${file.name}`)
     })
 
     // is the torrent done? (if all current selections are satisfied, or there are
     // no selections, then torrent is done)
     let done = true
-    for (let i = 0; i < self._selections.length; i++) {
-      const selection = self._selections[i]
+    for (let i = 0; i < this._selections.length; i++) {
+      const selection = this._selections[i]
       for (let piece = selection.from; piece <= selection.to; piece++) {
-        if (!self.bitfield.get(piece)) {
+        if (!this.bitfield.get(piece)) {
           done = false
           break
         }
       }
       if (!done) break
     }
-    if (!self.done && done) {
-      self.done = true
-      self._debug(`torrent done: ${self.infoHash}`)
-      self.emit('done')
+    if (!this.done && done) {
+      this.done = true
+      this._debug(`torrent done: ${this.infoHash}`)
+      this.emit('done')
     }
-    self._gcSelections()
+    this._gcSelections()
 
     return done
   }
 
   load (streams, cb) {
-    const self = this
-    if (self.destroyed) throw new Error('torrent is destroyed')
-    if (!self.ready) return self.once('ready', () => { self.load(streams, cb) })
+    if (this.destroyed) throw new Error('torrent is destroyed')
+    if (!this.ready) return this.once('ready', () => { this.load(streams, cb) })
 
     if (!Array.isArray(streams)) streams = [ streams ]
     if (!cb) cb = noop
 
     const readable = new MultiStream(streams)
-    const writable = new ChunkStoreWriteStream(self.store, self.pieceLength)
+    const writable = new ChunkStoreWriteStream(this.store, this.pieceLength)
 
     pump(readable, writable, err => {
       if (err) return cb(err)
-      self._markAllVerified()
-      self._checkDone()
+      this._markAllVerified()
+      this._checkDone()
       cb(null)
     })
   }
@@ -1635,15 +1602,14 @@ class Torrent extends EventEmitter {
    * queue until another connection closes.
    */
   _drain () {
-    const self = this
-    this._debug('_drain numConns %s maxConns %s', self._numConns, self.client.maxConns)
-    if (typeof net.connect !== 'function' || self.destroyed || self.paused ||
-        self._numConns >= self.client.maxConns) {
+    this._debug('_drain numConns %s maxConns %s', this._numConns, this.client.maxConns)
+    if (typeof net.connect !== 'function' || this.destroyed || this.paused ||
+        this._numConns >= this.client.maxConns) {
       return
     }
-    this._debug('drain (%s queued, %s/%s peers)', self._numQueued, self.numPeers, self.client.maxConns)
+    this._debug('drain (%s queued, %s/%s peers)', this._numQueued, this.numPeers, this.client.maxConns)
 
-    const peer = self._queue.shift()
+    const peer = this._queue.shift()
     if (!peer) return // queue could be empty
 
     this._debug('tcp connect attempt to %s', peer.addr)
@@ -1662,12 +1628,12 @@ class Torrent extends EventEmitter {
 
     // When connection closes, attempt reconnect after timeout (with exponential backoff)
     conn.on('close', () => {
-      if (self.destroyed) return
+      if (this.destroyed) return
 
       // TODO: If torrent is done, do not try to reconnect after a timeout
 
       if (peer.retries >= RECONNECT_WAIT.length) {
-        self._debug(
+        this._debug(
           'conn %s closed: will not re-add (max %s attempts)',
           peer.addr, RECONNECT_WAIT.length
         )
@@ -1675,13 +1641,13 @@ class Torrent extends EventEmitter {
       }
 
       const ms = RECONNECT_WAIT[peer.retries]
-      self._debug(
+      this._debug(
         'conn %s closed: will re-add to queue in %sms (attempt %s)',
         peer.addr, ms, peer.retries + 1
       )
 
-      const reconnectTimeout = setTimeout(function reconnectTimeout () {
-        const newPeer = self._addPeer(peer.addr)
+      const reconnectTimeout = setTimeout(() => {
+        const newPeer = this._addPeer(peer.addr)
         if (newPeer) newPeer.retries = peer.retries + 1
       }, ms)
       if (reconnectTimeout.unref) reconnectTimeout.unref()