thread constraint

src/main/java/com/github/nkzawa/emitter/Emitter.java

@@ -9,7 +9,7 @@ import java.util.concurrent.ConcurrentMap;
 
 
 /**
- * The event emitter which is ported from the JavaScript module.
+ * The event emitter which is ported from the JavaScript module. This class is thread-safe.
  *
  * @see <a href="https://github.com/component/emitter">https://github.com/component/emitter</a>
  */

src/main/java/com/github/nkzawa/engineio/client/EventThread.java

@@ -0,0 +1,60 @@
+package com.github.nkzawa.engineio.client;
+
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ThreadFactory;
+
+
+/**
+ * The main thread for Engine.IO Client.
+ */
+class EventThread extends Thread {
+
+    private static final ExecutorService service = Executors.newSingleThreadExecutor(new ThreadFactory() {
+        @Override
+        public Thread newThread(Runnable runnable) {
+            thread = new EventThread(runnable);
+            return thread;
+        }
+    });
+
+    private static volatile EventThread thread;
+
+
+    private EventThread(Runnable runnable) {
+        super(runnable);
+    }
+
+    /**
+     * check if the current thread is EventThread.
+     *
+     * @return true if the current thread is EventThread.
+     */
+    public static boolean isCurrent() {
+        return currentThread() == thread;
+    }
+
+    /**
+     * Executes a task in EventThread.
+     *
+     * @param task
+     */
+    public static void exec(Runnable task) {
+        if (isCurrent()) {
+            task.run();
+        } else {
+            service.execute(task);
+        }
+    }
+
+    /**
+     * Executes a task on the next loop in EventThread.
+     *
+     * @param task
+     */
+    public static void nextTick(Runnable task) {
+        service.execute(task);
+    }
+
+}

src/main/java/com/github/nkzawa/engineio/client/Socket.java

@@ -108,8 +108,8 @@ public abstract class Socket extends Emitter {
     private List<String> transports;
     private List<String> upgrades;
     private Map<String, String> query;
-    private ConcurrentLinkedQueue<Packet> writeBuffer = new ConcurrentLinkedQueue<Packet>();
+    private Queue<Packet> writeBuffer = new LinkedList<Packet>();
-    private ConcurrentLinkedQueue<Runnable> callbackBuffer = new ConcurrentLinkedQueue<Runnable>();
+    private Queue<Runnable> callbackBuffer = new LinkedList<Runnable>();
     private Transport transport;
     private Future pingTimeoutTimer;
     private Future pingIntervalTimer;
@@ -176,11 +176,16 @@ public abstract class Socket extends Emitter {
      * Connects the client.
      */
     public void open() {
-        this.readyState = OPENING;
+        EventThread.exec(new Runnable() {
-        Transport transport = this.createTransport(this.transports.get(0));
+            @Override
-        this.setTransport(transport);
+            public void run() {
+                Socket.this.readyState = OPENING;
+                Transport transport = Socket.this.createTransport(Socket.this.transports.get(0));
+                Socket.this.setTransport(transport);
                 transport.open();
             }
+        });
+    }
 
     private Transport createTransport(String name) {
         logger.fine(String.format("creating transport '%s'", name));
@@ -409,7 +414,7 @@ public abstract class Socket extends Emitter {
         }
     };
 
-    private synchronized void onHeartbeat(long timeout) {
+    private void onHeartbeat(long timeout) {
         if (this.pingTimeoutTimer != null) {
             pingTimeoutTimer.cancel(true);
         }
@@ -420,27 +425,37 @@ public abstract class Socket extends Emitter {
 
         final Socket self = this;
         this.pingTimeoutTimer = this.heartbeatScheduler.schedule(new Runnable() {
+            @Override
+            public void run() {
+                EventThread.exec(new Runnable() {
                     @Override
                     public void run() {
                         if (self.readyState == CLOSED) return;
                         self.onClose("ping timeout");
                     }
+                });
+            }
         }, timeout, TimeUnit.MILLISECONDS);
     }
 
-    private synchronized void ping() {
+    private void ping() {
         if (this.pingIntervalTimer != null) {
             pingIntervalTimer.cancel(true);
         }
 
         final Socket self = this;
         this.pingIntervalTimer = this.heartbeatScheduler.schedule(new Runnable() {
+            @Override
+            public void run() {
+                EventThread.exec(new Runnable() {
                     @Override
                     public void run() {
                         logger.fine(String.format("writing ping packet - expecting pong within %sms", self.pingTimeout));
                         self.sendPacket(Packet.PING);
                         self.onHeartbeat(self.pingTimeout);
                     }
+                });
+            }
         }, this.pingInterval, TimeUnit.MILLISECONDS);
     }
 
@@ -502,8 +517,13 @@ public abstract class Socket extends Emitter {
      * @param msg
      * @param fn callback to be called on drain
      */
-    public void send(String msg, Runnable fn) {
+    public void send(final String msg, final Runnable fn) {
-        this.sendPacket(Packet.MESSAGE, msg, fn);
+        EventThread.exec(new Runnable() {
+            @Override
+            public void run() {
+                Socket.this.sendPacket(Packet.MESSAGE, msg, fn);
+            }
+        });
     }
 
     private void sendPacket(String type) {
@@ -529,13 +549,18 @@ public abstract class Socket extends Emitter {
      * @return a reference to to this object.
      */
     public Socket close() {
-        if (this.readyState == OPENING || this.readyState == OPEN) {
+        EventThread.exec(new Runnable() {
-            this.onClose("forced close");
+            @Override
+            public void run() {
+                if (Socket.this.readyState == OPENING || Socket.this.readyState == OPEN) {
+                    Socket.this.onClose("forced close");
                     logger.fine("socket closing - telling transport to close");
-            this.transport.close();
+                    Socket.this.transport.close();
-            this.transport.off();
+                    Socket.this.transport.off();
                 }
 
+            }
+        });
         return this;
     }
 
@@ -558,18 +583,16 @@ public abstract class Socket extends Emitter {
             if (this.pingTimeoutTimer != null) {
                 this.pingTimeoutTimer.cancel(true);
             }
+            EventThread.nextTick(new Runnable() {
+                @Override
+                public void run() {
+                    Socket.this.writeBuffer.clear();
+                    Socket.this.callbackBuffer.clear();
+                }
+            });
             this.readyState = CLOSED;
             this.emit(EVENT_CLOSE, reason, desc);
             this.onclose();
-            // TODO:
-            // clean buffer in next tick, so developers can still
-            // grab the buffers on `close` event
-            // setTimeout(function() {}
-            //   self.writeBuffer = [];
-            //   self.callbackBuffer = [];
-            // );
-            this.writeBuffer.clear();
-            this.callbackBuffer.clear();
             this.id = null;
         }
     }

src/main/java/com/github/nkzawa/engineio/client/Transport.java

@@ -58,28 +58,43 @@ public abstract class Transport extends Emitter {
     }
 
     public Transport open() {
-        if (this.readyState == CLOSED || this.readyState < 0) {
+        exec(new Runnable() {
-            this.readyState = OPENING;
+            @Override
-            this.doOpen();
+            public void run() {
+                if (Transport.this.readyState == CLOSED || Transport.this.readyState < 0) {
+                    Transport.this.readyState = OPENING;
+                    Transport.this.doOpen();
                 }
+            }
+        });
         return this;
     }
 
     public Transport close() {
-        if (this.readyState == OPENING || this.readyState == OPEN) {
+        exec(new Runnable() {
-            this.doClose();
+            @Override
-            this.onClose();
+            public void run() {
+                if (Transport.this.readyState == OPENING || Transport.this.readyState == OPEN) {
+                    Transport.this.doClose();
+                    Transport.this.onClose();
                 }
+            }
+        });
         return this;
     }
 
-    public void send(Packet[] packets) {
+    public void send(final Packet[] packets) {
-        if (this.readyState == OPEN) {
+        exec(new Runnable() {
-            this.write(packets);
+            @Override
+            public void run() {
+                if (Transport.this.readyState == OPEN) {
+                    Transport.this.write(packets);
                 } else {
                     throw new RuntimeException("Transport not open");
                 }
             }
+        });
+    }
 
     protected void onOpen() {
         this.readyState = OPEN;
@@ -106,6 +121,14 @@ public abstract class Transport extends Emitter {
 
     abstract protected void doClose();
 
+    protected static void exec(Runnable task) {
+        EventThread.exec(task);
+    }
+
+    protected static void nextTick(Runnable task) {
+        EventThread.nextTick(task);
+    }
+
 
     public static class Options {
 

src/main/java/com/github/nkzawa/engineio/client/transports/Polling.java

@@ -33,10 +33,12 @@ abstract public class Polling extends Transport {
     }
 
     public void pause(final Runnable onPause) {
-        int pending = 0;
+        exec(new Runnable() {
-        final Polling self = this;
+            @Override
+            public void run() {
+                final Polling self = Polling.this;
 
-        this.readyState = PAUSED;
+                Polling.this.readyState = PAUSED;
 
                 final Runnable pause = new Runnable() {
                     @Override
@@ -47,13 +49,13 @@ abstract public class Polling extends Transport {
                     }
                 };
 
-        if (this.polling || !this.writable) {
+                if (Polling.this.polling || !Polling.this.writable) {
                     final int[] total = new int[] {0};
 
-            if (this.polling) {
+                    if (Polling.this.polling) {
                         logger.fine("we are currently polling - waiting to pause");
                         total[0]++;
-                this.once(EVENT_POLL_COMPLETE, new Listener() {
+                        Polling.this.once(EVENT_POLL_COMPLETE, new Listener() {
                             @Override
                             public void call(Object... args) {
                                 logger.fine("pre-pause polling complete");
@@ -64,10 +66,10 @@ abstract public class Polling extends Transport {
                         });
                     }
 
-            if (!this.writable) {
+                    if (!Polling.this.writable) {
                         logger.fine("we are currently writing - waiting to pause");
                         total[0]++;
-                this.once(EVENT_DRAIN, new Listener() {
+                        Polling.this.once(EVENT_DRAIN, new Listener() {
                             @Override
                             public void call(Object... args) {
                                 logger.fine("pre-pause writing complete");
@@ -81,6 +83,8 @@ abstract public class Polling extends Transport {
                     pause.run();
                 }
             }
+        });
+    }
 
     private void poll() {
         logger.fine("polling");

src/main/java/com/github/nkzawa/engineio/client/transports/PollingXHR.java

@@ -42,16 +42,26 @@ public class PollingXHR extends Polling {
         req.on(Request.EVENT_SUCCESS, new Listener() {
             @Override
             public void call(Object... args) {
+                exec(new Runnable() {
+                    @Override
+                    public void run() {
                         fn.run();
                     }
                 });
+            }
+        });
         req.on(Request.EVENT_ERROR, new Listener() {
             @Override
-            public void call(Object... args) {
+            public void call(final Object... args) {
+                exec(new Runnable() {
+                    @Override
+                    public void run() {
                         Exception err = args.length > 0 && args[0] instanceof Exception ? (Exception)args[0] : null;
                         self.onError("xhr post error", err);
                     }
                 });
+            }
+        });
         req.create();
         this.sendXhr = req;
     }
@@ -62,18 +72,28 @@ public class PollingXHR extends Polling {
         final PollingXHR self = this;
         req.on(Request.EVENT_DATA, new Listener() {
             @Override
-            public void call(Object... args) {
+            public void call(final Object... args) {
+                exec(new Runnable() {
+                    @Override
+                    public void run() {
                         String data = args.length > 0 ? (String) args[0] : null;
                         self.onData(data);
                     }
                 });
+            }
+        });
         req.on(Request.EVENT_ERROR, new Listener() {
             @Override
-            public void call(Object... args) {
+            public void call(final Object... args) {
+                exec(new Runnable() {
+                    @Override
+                    public void run() {
                         Exception err = args.length > 0 && args[0] instanceof Exception ? (Exception) args[0] : null;
                         self.onError("xhr poll error", err);
                     }
                 });
+            }
+        });
         req.create();
         this.pollXhr = req;
     }

src/main/java/com/github/nkzawa/engineio/client/transports/WebSocket.java

@@ -44,20 +44,40 @@ public class WebSocket extends Transport {
             this.socket = new WebSocketClient(new URI(this.uri()), new Draft_17()) {
                 @Override
                 public void onOpen(ServerHandshake serverHandshake) {
+                    exec(new Runnable() {
+                        @Override
+                        public void run() {
                             self.onOpen();
                         }
+                    });
+                }
                 @Override
                 public void onClose(int i, String s, boolean b) {
+                    exec(new Runnable() {
+                        @Override
+                        public void run() {
                             self.onClose();
                         }
-                @Override
+                    });
-                public void onMessage(String s) {
-                    self.onData(s);
                 }
                 @Override
-                public void onError(Exception e) {
+                public void onMessage(final String s) {
+                    exec(new Runnable() {
+                        @Override
+                        public void run() {
+                            self.onData(s);
+                        }
+                    });
+                }
+                @Override
+                public void onError(final Exception e) {
+                    exec(new Runnable() {
+                        @Override
+                        public void run() {
                             self.onError("websocket error", e);
                         }
+                    });
+                }
             };
             this.socket.connect();
         } catch (URISyntaxException e) {
@@ -82,6 +102,9 @@ public class WebSocket extends Transport {
 
         if (this.socket.getConnection().hasBufferedData()) {
             this.bufferedAmountId = this.drainScheduler.scheduleAtFixedRate(new Runnable() {
+                @Override
+                public void run() {
+                    exec(new Runnable() {
                         @Override
                         public void run() {
                             if (!self.socket.getConnection().hasBufferedData()) {
@@ -89,9 +112,11 @@ public class WebSocket extends Transport {
                                 ondrain.run();
                             }
                         }
+                    });
+                }
             }, 50, 50, TimeUnit.MILLISECONDS);
         } else {
-            this.drainScheduler.schedule(ondrain, 0, TimeUnit.MILLISECONDS);
+            nextTick(ondrain);
         }
     }
 

src/test/java/com/github/nkzawa/engineio/client/ServerConnectionTest.java

@@ -80,8 +80,8 @@ public class ServerConnectionTest {
     public void stopServer() throws InterruptedException {
         System.out.println("Stopping server ...");
         serverProcess.destroy();
-        serverOutout.cancel(false);
+        serverOutout.cancel(true);
-        serverError.cancel(false);
+        serverError.cancel(true);
         serverService.shutdown();
         serverService.awaitTermination(3000, TimeUnit.MILLISECONDS);
     }