swarm.announce() should always call callback

It’s important that calls to swarm.announce() always calls the callback
that it’s passed otherwise http announce/scrape requests
will hang (because res.end() is never called).

Also, since this swarm implementation is in-memory, we can get rid of
the callbacks to internal functions.

Lastly, fixed references to non-existent start() function.

Author: feross

lib/swarm.js

@@ -19,30 +19,27 @@ Swarm.prototype.announce = function (params, cb) {
   if (!params.event || params.event === 'empty') params.event = 'update'
   var fn = '_onAnnounce_' + params.event
   if (self[fn]) {
-    self[fn](params, peer, function (err) {
-      // event processed, prepare response:
+    self[fn](params, peer) // process event
 
-      if (params.left === 0 && peer) peer.complete = true
+    if (params.left === 0 && peer) peer.complete = true
 
-      // send peers
-      var peers = self._getPeers(params.numwant)
-
-      cb(null, {
-        complete: self.complete,
-        incomplete: self.incomplete,
-        peers: peers
-      })
+    cb(null, {
+      complete: self.complete,
+      incomplete: self.incomplete,
+      peers: self._getPeers(params.numwant)
     })
+
   } else {
     cb(new Error('invalid event'))
   }
 }
 
-Swarm.prototype._onAnnounce_started = function (params, peer, cb) {
+Swarm.prototype._onAnnounce_started = function (params, peer) {
   if (peer) {
     debug('unexpected `started` event from peer that is already in swarm')
-    return this._onAnnounce_update() // treat as an update
+    return this._onAnnounce_update(params, peer) // treat as an update
   }
+
   if (params.left === 0) this.complete += 1
   else this.incomplete += 1
   peer = this.peers[params.addr] = {
@@ -51,48 +48,42 @@ Swarm.prototype._onAnnounce_started = function (params, peer, cb) {
     peerId: params.peer_id
   }
   this.emit('start', params.addr)
-
-  cb()
 }
 
-Swarm.prototype._onAnnounce_stopped = function (params, peer, cb) {
+Swarm.prototype._onAnnounce_stopped = function (params, peer) {
   if (!peer) {
     debug('unexpected `stopped` event from peer that is not in swarm')
     return // do nothing
   }
+
   if (peer.complete) this.complete -= 1
   else this.incomplete -= 1
   this.peers[params.addr] = null
   this.emit('stop', params.addr)
-
-  cb()
 }
 
-Swarm.prototype._onAnnounce_completed = function (params, peer, cb) {
+Swarm.prototype._onAnnounce_completed = function (params, peer) {
   if (!peer) {
     debug('unexpected `completed` event from peer that is not in swarm')
-    return start() // treat as a start
+    return this._onAnnounce_started(params, peer) // treat as a start
   }
   if (peer.complete) {
     debug('unexpected `completed` event from peer that is already marked as completed')
     return // do nothing
   }
+
   this.complete += 1
   this.incomplete -= 1
   peer.complete = true
   this.emit('complete', params.addr)
-
-  cb()
 }
 
-Swarm.prototype._onAnnounce_update = function (params, peer, cb) {
+Swarm.prototype._onAnnounce_update = function (params, peer) {
   if (!peer) {
     debug('unexpected `update` event from peer that is not in swarm')
-    return start() // treat as a start
+    return this._onAnnounce_started(params, peer) // treat as a start
   }
   this.emit('update', params.addr)
-
-  cb()
 }
 
 Swarm.prototype._getPeers = function (numwant) {