Support async createSwarm() and getSwarm()

Fix #95.

Make server.getSwarm() and server.createSwarm() into async functions
that take a callback.

lib/server/swarm.js

@@ -4,7 +4,7 @@ var debug = require('debug')('bittorrent-tracker')
 var randomIterate = require('random-iterate')
 
 // Regard this as the default implementation of an interface that you
-// need to support when overriding Server.getSwarm()
+// need to support when overriding Server.createSwarm() and Server.getSwarm()
 function Swarm (infoHash, server) {
   this.peers = {}
   this.complete = 0

server.js

@@ -196,17 +196,23 @@ Server.prototype.close = function (cb) {
   else cb(null)
 }
 
-Server.prototype.createSwarm = function (infoHash) {
+Server.prototype.createSwarm = function (infoHash, cb) {
   var self = this
   if (Buffer.isBuffer(infoHash)) infoHash = infoHash.toString('hex')
+
+  process.nextTick(function () {
     var swarm = self.torrents[infoHash] = new Swarm(infoHash, self)
-  return swarm
+    cb(null, swarm)
+  })
 }
 
-Server.prototype.getSwarm = function (infoHash) {
+Server.prototype.getSwarm = function (infoHash, cb) {
   var self = this
   if (Buffer.isBuffer(infoHash)) infoHash = infoHash.toString('hex')
-  return self.torrents[infoHash]
+
+  process.nextTick(function () {
+    cb(null, self.torrents[infoHash])
+  })
 }
 
 Server.prototype.onHttpRequest = function (req, res, opts) {
@@ -358,7 +364,8 @@ Server.prototype._onWebSocketRequest = function (socket, params) {
     if (params.answer) {
       debug('got answer %s from %s', JSON.stringify(params.answer), params.peer_id)
 
-      var swarm = self.getSwarm(params.info_hash)
+      self.getSwarm(params.info_hash, function (err, swarm) {
+        if (err) return self.emit('warning', err)
         if (!swarm) {
           return self.emit('warning', new Error('no swarm with that `info_hash`'))
         }
@@ -374,11 +381,19 @@ Server.prototype._onWebSocketRequest = function (socket, params) {
           info_hash: common.hexToBinary(params.info_hash)
         }), toPeer.socket.onSend)
         debug('sent answer to %s from %s', toPeer.peerId, params.peer_id)
+
+        done()
+      })
+    } else {
+      done()
     }
 
+    function done () {
+      // emit event once the announce is fully "processed"
       if (params.action === common.ACTIONS.ANNOUNCE) {
         self.emit(common.EVENT_NAMES[params.event], params.peer_id, params)
       }
+    }
   })
 }
 
@@ -398,9 +413,14 @@ Server.prototype._onRequest = function (params, cb) {
 Server.prototype._onAnnounce = function (params, cb) {
   var self = this
 
-  var swarm = self.getSwarm(params.info_hash)
+  self.getSwarm(params.info_hash, function (err, swarm) {
-  if (swarm) announce()
+    if (err) return cb(err)
-  else createSwarm()
+    if (swarm) {
+      announce(swarm)
+    } else {
+      createSwarm()
+    }
+  })
 
   function createSwarm () {
     if (self._filter) {
@@ -410,17 +430,21 @@ Server.prototype._onAnnounce = function (params, cb) {
         } else if (!allowed) {
           cb(new Error('disallowed info_hash'))
         } else {
-          swarm = self.createSwarm(params.info_hash)
+          self.createSwarm(params.info_hash, function (err, swarm) {
-          announce()
+            if (err) return cb(err)
+            announce(swarm)
+          })
         }
       })
     } else {
-      swarm = self.createSwarm(params.info_hash)
+      self.createSwarm(params.info_hash, function (err, swarm) {
-      announce()
+        if (err) return cb(err)
+        announce(swarm)
+      })
     }
   }
 
-  function announce () {
+  function announce (swarm) {
     if (!params.event || params.event === 'empty') params.event = 'update'
     swarm.announce(params, function (err, response) {
       if (err) return cb(err)
@@ -470,7 +494,8 @@ Server.prototype._onScrape = function (params, cb) {
 
   series(params.info_hash.map(function (infoHash) {
     return function (cb) {
-      var swarm = self.getSwarm(infoHash)
+      self.getSwarm(infoHash, function (err, swarm) {
+        if (err) return cb(err)
         if (swarm) {
           swarm.scrape(params, function (err, scrapeInfo) {
             if (err) return cb(err)
@@ -483,6 +508,7 @@ Server.prototype._onScrape = function (params, cb) {
         } else {
           cb(null, { infoHash: infoHash, complete: 0, incomplete: 0 })
         }
+      })
     }
   }), function (err, results) {
     if (err) return cb(err)

test/server.js

@@ -8,7 +8,7 @@ var peerId2 = new Buffer('12345678901234567890')
 var torrentLength = 50000
 
 function serverTest (t, serverType, serverFamily) {
-  t.plan(25)
+  t.plan(26)
 
   var opts = serverType === 'http' ? { udp: false, ws: false } : { http: false, ws: false }
   var server = new Server(opts)
@@ -49,7 +49,8 @@ function serverTest (t, serverType, serverFamily) {
       t.equal(data.complete, 0)
       t.equal(data.incomplete, 1)
 
-      var swarm = server.getSwarm(infoHash)
+      server.getSwarm(infoHash, function (err, swarm) {
+        t.error(err)
 
         t.equal(Object.keys(server.torrents).length, 1)
         t.equal(swarm.complete, 0)
@@ -115,6 +116,7 @@ function serverTest (t, serverType, serverFamily) {
         })
       })
     })
+  })
 }
 
 test('http ipv4 server', function (t) {