BREAKING: opts.filter function is async; add createSwarm

- The expected signature for opts.filter is now:

function myFilterFn (infoHash, params, cb) {
  cb(infoHash === 'blah)
}

This allows interfacing with a database and fixes #80.

Also, swarm.getSwarm() is no longer responsible for creating a Swarm
instance, only returning an instance if there is already one. Creating
a swarm happens in swarm.createSwarm(). This change only affects users
who were override swarm.getSwarm().

server.js

@@ -175,19 +175,19 @@ Server.prototype.close = function (cb) {
   else cb(null)
 }
 
-Server.prototype.getSwarm = function (infoHash, params) {
+Server.prototype.createSwarm = function (infoHash) {
   var self = this
-  if (!params) params = {}
   if (Buffer.isBuffer(infoHash)) infoHash = infoHash.toString('hex')
-
+  var swarm = self.torrents[infoHash] = new Swarm(infoHash, self)
-  if (self._filter && !self._filter(infoHash, params)) return null
-
-  var swarm = self.torrents[infoHash]
-  if (!swarm) swarm = self.torrents[infoHash] = new Swarm(infoHash, self)
-
   return swarm
 }
 
+Server.prototype.getSwarm = function (infoHash) {
+  var self = this
+  if (Buffer.isBuffer(infoHash)) infoHash = infoHash.toString('hex')
+  return self.torrents[infoHash]
+}
+
 Server.prototype.onHttpRequest = function (req, res, opts) {
   var self = this
   if (!opts) opts = {}
@@ -334,7 +334,10 @@ 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, params)
+      var swarm = self.getSwarm(params.info_hash)
+      if (!swarm) {
+        return self.emit('warning', new Error('no swarm with that `info_hash`'))
+      }
       var toPeer = swarm.peers[params.to_peer_id]
       if (!toPeer) {
         return self.emit('warning', new Error('no peer with that `to_peer_id`'))
@@ -370,8 +373,28 @@ Server.prototype._onRequest = function (params, cb) {
 
 Server.prototype._onAnnounce = function (params, cb) {
   var self = this
-  var swarm = self.getSwarm(params.info_hash, params)
+
-  if (swarm === null) return cb(new Error('disallowed info_hash'))
+  var swarm = self.getSwarm(params.info_hash)
+  if (swarm) announce()
+  else createSwarm()
+
+  function createSwarm () {
+    if (self._filter) {
+      self._filter(params.info_hash, params, function (allowed) {
+        if (allowed) {
+          swarm = self.createSwarm(params.info_hash)
+          announce()
+        } else {
+          cb(new Error('disallowed info_hash'))
+        }
+      })
+    } else {
+      swarm = self.createSwarm(params.info_hash)
+      announce()
+    }
+  }
+
+  function announce () {
     if (!params.event || params.event === 'empty') params.event = 'update'
     swarm.announce(params, function (err, response) {
       if (err) return cb(err)
@@ -409,6 +432,8 @@ Server.prototype._onAnnounce = function (params, cb) {
     })
   }
 
+}
+
 Server.prototype._onScrape = function (params, cb) {
   var self = this
 
@@ -419,15 +444,20 @@ Server.prototype._onScrape = function (params, cb) {
   }
 
   series(params.info_hash.map(function (infoHash) {
-    var swarm = self.getSwarm(infoHash)
     return function (cb) {
+      var swarm = self.getSwarm(infoHash)
+      if (swarm) {
         swarm.scrape(params, function (err, scrapeInfo) {
-        cb(err, scrapeInfo && {
+          if (err) return cb(err)
+          cb(null, {
             infoHash: infoHash,
-          complete: scrapeInfo.complete || 0,
+            complete: (scrapeInfo && scrapeInfo.complete) || 0,
-          incomplete: scrapeInfo.incomplete || 0
+            incomplete: (scrapeInfo && scrapeInfo.incomplete) || 0
           })
         })
+      } else {
+        cb(null, { infoHash: infoHash, complete: 0, incomplete: 0 })
+      }
     }
   }), function (err, results) {
     if (err) return cb(err)
@@ -440,9 +470,9 @@ Server.prototype._onScrape = function (params, cb) {
 
     results.forEach(function (result) {
       response.files[common.hexToBinary(result.infoHash)] = {
-        complete: result.complete,
+        complete: result.complete || 0,
-        incomplete: result.incomplete,
+        incomplete: result.incomplete || 0,
-        downloaded: result.complete // TODO: this only provides a lower-bound
+        downloaded: result.complete || 0 // TODO: this only provides a lower-bound
       }
     })
 

test/filter.js

@@ -15,8 +15,10 @@ var peerId = new Buffer('01234567890123456789')
 function testFilterOption (t, serverType) {
   t.plan(6)
   var opts = serverType === 'http' ? { udp: false } : { http: false }
-  opts.filter = function (infoHash) {
+  opts.filter = function (infoHash, params, cb) {
-    return infoHash !== parsedBitlove.infoHash
+    process.nextTick(function () {
+      cb(infoHash !== parsedBitlove.infoHash)
+    })
   }
   var server = new Server(opts)