Perf: Use delete keyword to avoid tons of leftover keys in plain objects

lib/swarm.js

@@ -90,8 +90,7 @@ Object.defineProperty(Swarm.prototype, 'numConns', {
     var self = this
     var numConns = 0
     for (var id in self._peers) {
-      var peer = self._peers[id]
-      if (peer && peer.connected) numConns += 1
+      if (self._peers[id].connected) numConns += 1
     }
     return numConns
   }
@@ -218,7 +217,7 @@ Swarm.prototype.removePeer = function (id) {
 
   debug('removePeer %s', id)
 
-  self._peers[id] = null
+  delete self._peers[id]
   self._peersLength -= 1
 
   peer.destroy()

lib/tcp-pool.js

@@ -64,12 +64,7 @@ TCPPool.removeSwarm = function (swarm, cb) {
   if (!pool) return cb()
   pool.removeSwarm(swarm)
 
-  var numSwarms = 0
-  for (var infoHash in pool.swarms) {
-    var s = pool.swarms[infoHash]
-    if (s) numSwarms += 1
-  }
-  if (numSwarms === 0) pool.destroy(cb)
+  if (Object.keys(pool.swarms).length === 0) pool.destroy(cb)
   else process.nextTick(cb)
 }
 
@@ -85,7 +80,7 @@ TCPPool.removeSwarm = function (swarm, cb) {
 TCPPool.getDefaultListenPort = function (infoHash) {
   for (var port in tcpPools) {
     var pool = tcpPools[port]
-    if (pool && !pool.swarms[infoHash]) return pool.port
+    if (!pool.swarms[infoHash]) return pool.port
   }
   return 0
 }
@@ -125,7 +120,7 @@ TCPPool.prototype.addSwarm = function (swarm) {
 TCPPool.prototype.removeSwarm = function (swarm) {
   var self = this
   debug('remove swarm %s from tcp pool %s', swarm.infoHash, self.port)
-  self.swarms[swarm.infoHash] = null
+  delete self.swarms[swarm.infoHash]
 }
 
 /**
@@ -144,7 +139,7 @@ TCPPool.prototype.destroy = function (cb) {
     conn.destroy()
   })
 
-  tcpPools[self.port] = null
+  delete tcpPools[self.port]
 
   try {
     self.server.close(cb)
@@ -165,16 +160,15 @@ TCPPool.prototype._onListening = function () {
 
   if (port !== self.port) {
     // `port` was 0 when `listen` was called; update to the port that node selected
-    tcpPools[self.port] = null
+    delete tcpPools[self.port]
     self.port = port
     tcpPools[self.port] = self
   }
 
   self.listening = true
 
   for (var infoHash in self.swarms) {
-    var swarm = self.swarms[infoHash]
-    if (swarm) swarm._onListening(self.port)
+    self.swarms[infoHash]._onListening(self.port)
   }
 }
 
@@ -226,10 +220,8 @@ TCPPool.prototype._onError = function (err) {
   self.destroy()
   for (var infoHash in self.swarms) {
     var swarm = self.swarms[infoHash]
-    if (swarm) {
-      self.removeSwarm(swarm)
-      swarm._onError(err)
-    }
+    self.removeSwarm(swarm)
+    swarm._onError(err)
   }
 }