Only close websocket when it's not participating in any more swarms

lib/server/swarm.js

@@ -7,19 +7,29 @@ var randomIterate = require('random-iterate')
 // Regard this as the default implementation of an interface that you
 // need to support when overriding Server.createSwarm() and Server.getSwarm()
 function Swarm (infoHash, server) {
+  this.infoHash = infoHash
   this.complete = 0
   this.incomplete = 0
+
   this.peers = new LRU({
     max: server.peersCacheLength || 1000,
     maxAge: server.peersCacheTtl || 20 * 60 * 1000 // 20 minutes
   })
 
-  // When a websocket peer is evicted from the LRU cache, close the websocket
-  // after a short timeout period. We wait 1s so the server has a chance to send
-  // a response to 'stopped' events, which remove the peer and cause an eviction.
+  // When a peer is evicted from the LRU store, send a synthetic 'stopped' event
+  // so the stats get updated correctly.
   this.peers.on('evict', function (data) {
     var peer = data.value
-    if (peer.socket) {
+    this.announce({
+      type: peer.type,
+      event: 'stopped',
+      numwant: 0,
+      peer_id: peer.peerId
+    }, noop)
+
+    // When a websocket peer is evicted, and it's not in any other swarms, close
+    // the websocket to conserve server resources.
+    if (peer.socket && peer.socket.infoHashes.length === 0) {
       try {
         peer.socket.close()
         peer.socket = null
@@ -86,6 +96,14 @@ Swarm.prototype._onAnnounceStopped = function (params, peer, id) {
 
   if (peer.complete) this.complete -= 1
   else this.incomplete -= 1
+
+  // If it's a websocket, remove this swarm's infohash from the list of active
+  // swarms that this peer is participating in.
+  if (peer.socket) {
+    var index = peer.socket.infoHashes.indexOf(this.infoHash)
+    peer.socket.infoHashes.splice(index, 1)
+  }
+
   this.peers.remove(id)
 }
 
@@ -133,3 +151,5 @@ Swarm.prototype._getPeers = function (numwant, ownPeerId, isWebRTC) {
   }
   return peers
 }
+
+function noop () {}

server.js

@@ -585,7 +585,7 @@ Server.prototype._onWebSocketClose = function (socket) {
   debug('websocket close %s', socket.peerId)
 
   if (socket.peerId) {
-    socket.infoHashes.forEach(function (infoHash) {
+    socket.infoHashes.slice(0).forEach(function (infoHash) {
       var swarm = self.torrents[infoHash]
       if (swarm) {
         swarm.announce({