BREAKING: Major cleanup

### Added

- `client.listening` property to signal whether TCP server is listening
for incoming
  connections.

### Changed

- Merged `Swarm` class into `Torrent` object. Properties on
`torrent.swarm` (like
  `torrent.swarm.wires`) now exist on `torrent` (e.g. `torrent.wires`).

- `torrent.addPeer` can no longer be called before the `infoHash` event
has been
  emitted.

- Remove `torrent.on('listening')` event. Use `client.on('listening')`
instead.

- Remove support from `TCPPool` for listening on multiple ports. This
was not used by
  WebTorrent and just added complexity. There is now a single `TCPPool`
instance for the
  whole WebTorrent client.

- Deprecate: Do not use `client.download()` anymore. Use `client.add()`
instead.

- Deprecate: Do not use `torrent.swarm` anymore. Use `torrent` instead.

### Fixed

- When there is a `torrent.on('error')` listener, don't also emit
  `client.on('error')`.

- Do not return existing torrent object when duplicate torrent is
added. Fire an
  `'error'` event instead.

- Memory leak of `Torrent` object caused by `RarityMap`

- Memory leak of `Torrent` object caused by `TCPPool`

- `client.ratio` and `torrent.ratio` are now calculated as `uploaded /
received` instead
  of `uploaded / downloaded`.

1 files changed, 80 insertions, 50 deletions

diff --git a/index.js b/index.js
index 59be529..dc6bedf 100644
--- a/index.js
+++ b/index.js
@@ -1,3 +1,6 @@
+// TODO: cleanup event listeners
+// TODO: set dhtPort to correct port
+
 module.exports = WebTorrent
 
 var createTorrent = require('create-torrent')
@@ -16,10 +19,9 @@ var speedometer = require('speedometer')
 var zeroFill = require('zero-fill')
 
 var concatStream = require('./lib/concat-stream')
+var TCPPool = require('./lib/tcp-pool') // browser exclude
 var Torrent = require('./lib/torrent')
 
-module.exports.WEBRTC_SUPPORT = Peer.WEBRTC_SUPPORT
-
 /**
  * WebTorrent version.
  */
@@ -55,36 +57,44 @@ function WebTorrent (opts) {
 
   if (!opts) opts = {}
 
+  self.peerId = typeof opts.peerId === 'string'
+    ? opts.peerId
+    : (opts.peerId || new Buffer(VERSION_PREFIX + hat(48))).toString('hex')
+  self.peerIdBuffer = new Buffer(self.peerId, 'hex')
+
+  self.nodeId = typeof opts.nodeId === 'string'
+    ? opts.nodeId
+    : (opts.nodeId && opts.nodeId.toString('hex')) || hat(160)
+  self.nodeIdBuffer = new Buffer(self.nodeId, 'hex')
+
   self.destroyed = false
+  self.listening = false
   self.torrentPort = opts.torrentPort || 0
   self.tracker = opts.tracker !== undefined ? opts.tracker : true
+  self.torrents = []
+  self.maxConns = Number(opts.maxConns) || 55
 
   self._rtcConfig = opts.rtcConfig
   self._wrtc = opts.wrtc || global.WRTC // to support `webtorrent-hybrid` package
 
-  self.torrents = []
+  if (typeof TCPPool === 'function') {
+    self._tcpPool = new TCPPool(self)
+  } else {
+    process.nextTick(function () {
+      self._onListening()
+    })
+  }
 
+  // stats
   self._downloadSpeed = speedometer()
   self._uploadSpeed = speedometer()
 
-  self.maxConns = opts.maxConns
-
-  self.peerId = typeof opts.peerId === 'string'
-    ? opts.peerId
-    : (opts.peerId || new Buffer(VERSION_PREFIX + hat(48))).toString('hex')
-  self.peerIdBuffer = new Buffer(self.peerId, 'hex')
-
-  self.nodeId = typeof opts.nodeId === 'string'
-    ? opts.nodeId
-    : (opts.nodeId && opts.nodeId.toString('hex')) || hat(160)
-  self.nodeIdBuffer = new Buffer(self.nodeId, 'hex')
-
   if (opts.dht !== false && typeof DHT === 'function' /* browser exclude */) {
     // use a single DHT instance for all torrents, so the routing table can be reused
     self.dht = new DHT(extend({ nodeId: self.nodeId }, opts.dht))
     self.dht.once('error', function (err) {
       self.emit('error', err)
-      self.destroy()
+      self._destroy()
     })
 
     // Ignore warning when there are > 10 torrents in the client
@@ -114,6 +124,8 @@ function WebTorrent (opts) {
   }
 }
 
+WebTorrent.WEBRTC_SUPPORT = Peer.WEBRTC_SUPPORT
+
 Object.defineProperty(WebTorrent.prototype, 'downloadSpeed', {
   get: function () { return this._downloadSpeed() }
 })
@@ -142,10 +154,10 @@ Object.defineProperty(WebTorrent.prototype, 'ratio', {
     var uploaded = this.torrents.reduce(function (total, torrent) {
       return total + torrent.uploaded
     }, 0)
-    var downloaded = this.torrents.reduce(function (total, torrent) {
-      return total + torrent.downloaded
+    var received = this.torrents.reduce(function (total, torrent) {
+      return total + torrent.received
     }, 0) || 1
-    return uploaded / downloaded
+    return uploaded / received
   }
 })
 
@@ -174,14 +186,18 @@ WebTorrent.prototype.get = function (torrentId) {
   return null
 }
 
+WebTorrent.prototype.download = function (torrentId, opts, ontorrent) {
+  console.warn('WebTorrent: client.download() is deprecated. Use client.add() instead')
+  return this.add(torrentId, opts, ontorrent)
+}
+
 /**
  * Start downloading a new torrent. Aliased as `client.download`.
  * @param {string|Buffer|Object} torrentId
  * @param {Object} opts torrent-specific options
  * @param {function=} ontorrent called when the torrent is ready (has metadata)
  */
-WebTorrent.prototype.add =
-WebTorrent.prototype.download = function (torrentId, opts, ontorrent) {
+WebTorrent.prototype.add = function (torrentId, opts, ontorrent) {
   var self = this
   if (self.destroyed) throw new Error('client is destroyed')
   if (typeof opts === 'function') return self.add(torrentId, null, opts)
@@ -189,29 +205,12 @@ WebTorrent.prototype.download = function (torrentId, opts, ontorrent) {
   debug('add')
   opts = opts ? extend(opts) : {}
 
-  var torrent = self.get(torrentId)
-
-  if (torrent) {
-    if (torrent.ready) process.nextTick(onReady)
-    else torrent.once('ready', onReady)
-  } else {
-    torrent = new Torrent(torrentId, self, opts)
-    self.torrents.push(torrent)
+  var torrent = new Torrent(torrentId, self, opts)
+  self.torrents.push(torrent)
 
-    torrent.once('error', function (err) {
-      self.emit('error', err, torrent)
-      self.remove(torrent)
-    })
-
-    torrent.once('listening', function (port) {
-      self.emit('listening', port, torrent)
-    })
-
-    torrent.once('ready', onReady)
-  }
+  torrent.once('ready', onReady)
 
   function onReady () {
-    debug('on torrent')
     if (typeof ontorrent === 'function') ontorrent(torrent)
     self.emit('torrent', torrent)
   }
@@ -303,19 +302,20 @@ WebTorrent.prototype.seed = function (input, opts, onseed) {
  * @param  {function} cb
  */
 WebTorrent.prototype.remove = function (torrentId, cb) {
-  var self = this
   debug('remove')
 
-  var torrent = self.get(torrentId)
+  var torrent = this.get(torrentId)
   if (!torrent) throw new Error('No torrent with id ' + torrentId)
 
-  self.torrents.splice(self.torrents.indexOf(torrent), 1)
+  this.torrents.splice(this.torrents.indexOf(torrent), 1)
   torrent.destroy(cb)
 }
 
 WebTorrent.prototype.address = function () {
-  var self = this
-  return { address: '0.0.0.0', family: 'IPv4', port: self.torrentPort }
+  if (!this.listening) return null
+  return this._tcpPool
+    ? this._tcpPool.server.address()
+    : { address: '0.0.0.0', family: 'IPv4', port: 0 }
 }
 
 /**
@@ -323,18 +323,48 @@ WebTorrent.prototype.address = function () {
  * @param  {function} cb
  */
 WebTorrent.prototype.destroy = function (cb) {
+  if (this.destroyed) throw new Error('client already destroyed')
+  this._destroy(null, cb)
+}
+
+WebTorrent.prototype._destroy = function (err, cb) {
   var self = this
-  if (self.destroyed) throw new Error('client already destroyed')
+  debug('client destroy')
   self.destroyed = true
-  debug('destroy')
 
   var tasks = self.torrents.map(function (torrent) {
-    return function (cb) { self.remove(torrent, cb) }
+    return function (cb) {
+      torrent.destroy(cb)
+    }
   })
 
-  if (self.dht) tasks.push(function (cb) { self.dht.destroy(cb) })
+  if (self._tcpPool) {
+    tasks.push(function (cb) {
+      self._tcpPool.destroy(cb)
+    })
+  }
+
+  if (self.dht) {
+    tasks.push(function (cb) {
+      self.dht.destroy(cb)
+    })
+  }
 
   parallel(tasks, cb)
+
+  if (err) self.emit('error', err)
+}
+
+WebTorrent.prototype._onListening = function () {
+  this.listening = true
+
+  if (this._tcpPool) {
+    // Sometimes server.address() returns `null` in Docker.
+    // WebTorrent issue: https://github.com/feross/bittorrent-swarm/pull/18
+    this.torrentPort = (this._tcpPool.server.address() || { port: 0 }).port
+  }
+
+  this.emit('listening')
 }
 
 /**