cluster: allow shared reused dgram sockets

Allow listening on reused dgram ports in cluster workers.

Fix: https://github.com/joyent/node/issues/9261
PR-URL: https://github.com/nodejs/node/pull/2548
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

lib/cluster.js

@@ -57,7 +57,7 @@ Worker.prototype.isConnected = function isConnected() {
 
 // Master/worker specific methods are defined in the *Init() functions.
 
-function SharedHandle(key, address, port, addressType, backlog, fd) {
+function SharedHandle(key, address, port, addressType, backlog, fd, flags) {
   this.key = key;
   this.workers = [];
   this.handle = null;
@@ -66,7 +66,7 @@ function SharedHandle(key, address, port, addressType, backlog, fd) {
   // FIXME(bnoordhuis) Polymorphic return type for lack of a better solution.
   var rval;
   if (addressType === 'udp4' || addressType === 'udp6')
-    rval = dgram._createSocketHandle(address, port, addressType, fd);
+    rval = dgram._createSocketHandle(address, port, addressType, fd, flags);
   else
     rval = net._createServerHandle(address, port, addressType, fd);
 
@@ -438,7 +438,8 @@ function masterInit() {
     var args = [message.address,
                 message.port,
                 message.addressType,
-                message.fd];
+                message.fd,
+                message.index];
     var key = args.join(':');
     var handle = handles[key];
     if (handle === undefined) {
@@ -456,7 +457,8 @@ function masterInit() {
                                               message.port,
                                               message.addressType,
                                               message.backlog,
-                                              message.fd);
+                                              message.fd,
+                                              message.flags);
     }
     if (!handle.data) handle.data = message.data;
 
@@ -485,7 +487,7 @@ function masterInit() {
     cluster.emit('listening', worker, info);
   }
 
-  // Round-robin only. Server in worker is closing, remove from list.
+  // Server in worker is closing, remove from list.
   function close(worker, message) {
     var key = message.key;
     var handle = handles[key];
@@ -500,6 +502,7 @@ function masterInit() {
 
 function workerInit() {
   var handles = {};
+  var indexes = {};
 
   // Called from src/node.js
   cluster._setupWorker = function() {
@@ -528,15 +531,22 @@ function workerInit() {
   };
 
   // obj is a net#Server or a dgram#Socket object.
-  cluster._getServer = function(obj, address, port, addressType, fd, cb) {
+  cluster._getServer = function(obj, options, cb) {
-    var message = {
+    const key = [ options.address,
-      addressType: addressType,
+                options.port,
-      address: address,
+                options.addressType,
-      port: port,
+                options.fd ].join(':');
+    if (indexes[key] === undefined)
+      indexes[key] = 0;
+    else
+      indexes[key]++;
+
+    const message = util._extend({
       act: 'queryServer',
-      fd: fd,
+      index: indexes[key],
       data: null
-    };
+    }, options);
+
     // Set custom data on handle (i.e. tls tickets key)
     if (obj._getServerData) message.data = obj._getServerData();
     send(message, function(reply, handle) {
@@ -549,9 +559,9 @@ function workerInit() {
     });
     obj.once('listening', function() {
       cluster.worker.state = 'listening';
-      var address = obj.address();
+      const address = obj.address();
       message.act = 'listening';
-      message.port = address && address.port || port;
+      message.port = address && address.port || options.port;
       send(message);
     });
   };
@@ -563,6 +573,7 @@ function workerInit() {
     // closed. Avoids resource leaks when the handle is short-lived.
     var close = handle.close;
     handle.close = function() {
+      send({ act: 'close', key: key });
       delete handles[key];
       return close.apply(this, arguments);
     };

lib/dgram.js

@@ -60,14 +60,14 @@ function newHandle(type) {
 }
 
 
-exports._createSocketHandle = function(address, port, addressType, fd) {
+exports._createSocketHandle = function(address, port, addressType, fd, flags) {
   // Opening an existing fd is not supported for UDP handles.
   assert(typeof fd !== 'number' || fd < 0);
 
   var handle = newHandle(addressType);
 
   if (port || address) {
-    var err = handle.bind(address, port || 0, 0);
+    var err = handle.bind(address, port || 0, flags);
     if (err) {
       handle.close();
       return err;
@@ -176,8 +176,12 @@ Socket.prototype.bind = function(port /*, address, callback*/) {
     if (!cluster)
       cluster = require('cluster');
 
+    var flags = 0;
+    if (self._reuseAddr)
+      flags |= constants.UV_UDP_REUSEADDR;
+
     if (cluster.isWorker && !exclusive) {
-      cluster._getServer(self, ip, port, self.type, -1, function(err, handle) {
+      function onHandle(err, handle) {
         if (err) {
           var ex = exceptionWithHostPort(err, 'bind', ip, port);
           self.emit('error', ex);
@@ -191,16 +195,19 @@ Socket.prototype.bind = function(port /*, address, callback*/) {
 
         replaceHandle(self, handle);
         startListening(self);
-      });
+      }
+      cluster._getServer(self, {
+        address: ip,
+        port: port,
+        addressType: self.type,
+        fd: -1,
+        flags: flags
+      }, onHandle);
 
     } else {
       if (!self._handle)
         return; // handle has been closed in the mean time
 
-      var flags = 0;
-      if (self._reuseAddr)
-        flags |= constants.UV_UDP_REUSEADDR;
-
       var err = self._handle.bind(ip, port || 0, flags);
       if (err) {
         var ex = exceptionWithHostPort(err, 'bind', ip, port);

lib/net.js

@@ -1268,7 +1268,13 @@ function listen(self, address, port, addressType, backlog, fd, exclusive) {
     return;
   }
 
-  cluster._getServer(self, address, port, addressType, fd, cb);
+  cluster._getServer(self, {
+    address: address,
+    port: port,
+    addressType: addressType,
+    fd: fd,
+    flags: 0
+  }, cb);
 
   function cb(err, handle) {
     // EADDRINUSE may not be reported until we call listen(). To complicate

test/parallel/test-cluster-dgram-reuse.js

@@ -0,0 +1,40 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const cluster = require('cluster');
+const dgram = require('dgram');
+
+if (common.isWindows) {
+  console.log('1..0 # Skipped: dgram clustering is currently not supported ' +
+              'on windows.');
+  return;
+}
+
+if (cluster.isMaster) {
+  cluster.fork().on('exit', function(code) {
+    assert.equal(code, 0);
+  });
+  return;
+}
+
+const sockets = [];
+function next() {
+  sockets.push(this);
+  if (sockets.length !== 2)
+    return;
+
+  // Work around health check issue
+  process.nextTick(function() {
+    for (var i = 0; i < sockets.length; i++)
+      sockets[i].close(close);
+  });
+}
+
+var waiting = 2;
+function close() {
+  if (--waiting === 0)
+    cluster.worker.disconnect();
+}
+
+for (var i = 0; i < 2; i++)
+  dgram.createSocket({ type: 'udp4', reuseAddr: true }).bind(common.PORT, next);