use a nonblocking DatagramChannel for receiving data

android/src/main/java/com/tradle/react/UdpReceiverTask.java

@@ -14,96 +14,106 @@ import java.io.IOException;
 import java.lang.ref.WeakReference;
 import java.net.DatagramPacket;
 import java.net.DatagramSocket;
+import java.net.InetSocketAddress;
+import java.net.SocketAddress;
+import java.nio.ByteBuffer;
+import java.nio.channels.ClosedChannelException;
+import java.nio.channels.DatagramChannel;
+import java.nio.channels.SelectionKey;
+import java.nio.channels.Selector;
 
 /**
  * This is a specialized AsyncTask that receives data from a socket in the background, and
- * notifies it's listener when data is received.
+ * notifies it's listener when data is received.  This is not threadsafe, the listener
+ * should handle synchronicity.
  */
-public class UdpReceiverTask extends AsyncTask<Void, UdpReceiverTask.ReceivedPacket, Void> {
+public class UdpReceiverTask extends AsyncTask<Void, Void, Void> {
     private static final String TAG = "UdpReceiverTask";
     private static final int MAX_UDP_DATAGRAM_LEN = 1024;
 
-    private DatagramSocket mSocket;
+    private DatagramChannel mChannel;
     private WeakReference<OnDataReceivedListener> mReceiverListener;
 
     /**
      * An {@link AsyncTask} that blocks to receive data from a socket.
      * Received data is sent via the {@link OnDataReceivedListener}
      */
-    public UdpReceiverTask(DatagramSocket socket, UdpReceiverTask.OnDataReceivedListener
+    public UdpReceiverTask(DatagramChannel channel, UdpReceiverTask.OnDataReceivedListener
             receiverListener) {
-        this.mSocket = socket;
+        this.mChannel = channel;
         this.mReceiverListener = new WeakReference<>(receiverListener);
     }
 
+    /**
+     * Returns the UdpReceiverTask's DatagramChannel.
+     */
+    public DatagramChannel getChannel() {
+        return mChannel;
+    }
+
     /**
      * An infinite loop to block and read data from the socket.
      */
     @Override
     protected Void doInBackground(Void... a) {
         OnDataReceivedListener receiverListener = mReceiverListener.get();
+
+        Selector selector = null;
         try {
-            byte[] lMsg = new byte[MAX_UDP_DATAGRAM_LEN];
+            selector = Selector.open();
-            DatagramPacket dp = new DatagramPacket(lMsg, lMsg.length);
+            mChannel.register(selector, SelectionKey.OP_READ);
-            while(!isCancelled()){
+        } catch (ClosedChannelException cce) {
-                mSocket.receive(dp);
+            if (receiverListener != null) {
-                publishProgress(new ReceivedPacket(Base64.encodeToString(lMsg, Base64.NO_WRAP),
+                receiverListener.didReceiveError(cce.getMessage());
-                        dp.getAddress().getHostAddress(), dp.getPort()));
             }
         } catch (IOException ioe) {
             if (receiverListener != null) {
                 receiverListener.didReceiveError(ioe.getMessage());
             }
+        }
+
+        final ByteBuffer packet = ByteBuffer.allocate(MAX_UDP_DATAGRAM_LEN);
+        while(!isCancelled()){
+            try {
+                if(selector.selectNow() >= 1){
+                    final InetSocketAddress address = (InetSocketAddress) mChannel.receive(packet);
+                    String base64Data = Base64.encodeToString(packet.array(), Base64.NO_WRAP);
+                    receiverListener.didReceiveData(base64Data, address.getHostName(), address.getPort());
+                    packet.clear();
+                }
+            } catch (IOException ioe) {
+                if (receiverListener != null) {
+                    receiverListener.didReceiveError(ioe.getMessage());
+                }
+                this.cancel(false);
             } catch (RuntimeException rte) {
                 if (receiverListener != null) {
                     receiverListener.didReceiveRuntimeException(rte);
                 }
+                this.cancel(false);
+            }
         }
 
         return null;
     }
 
-    /**
-     * Send data out to the listener.
-     * @param {@link ReceivedPacket} packet marshalled data
-     */
-    @Override
-    protected void onProgressUpdate(ReceivedPacket... packet) {
-        OnDataReceivedListener receiverListener = mReceiverListener.get();
-        if (receiverListener != null) {
-            receiverListener.didReceiveData(packet[0].base64String, packet[0].address,
-              packet[0].port);
-        }
-    }
-
     /**
      * Close if cancelled.
      */
     @Override
-    protected void onCancelled(){
+    protected void onCancelled() {
-        if (mSocket != null){
+        OnDataReceivedListener receiverListener = mReceiverListener.get();
-            mSocket.close();
-        }
-    }
 
-    /**
+        if (mChannel != null && mChannel.isOpen()){
-     * Internal class used to marshall packet data as a progress update.
+            try {
-     * base64String the data encoded as a base64 string
+                mChannel.close();
-     * address the address of the sender
+            } catch (IOException ioe) {
-     * port the port number of the sender
+                if (receiverListener != null) {
-     */
+                    receiverListener.didReceiveError(ioe.getMessage());
-    class ReceivedPacket {
+                }
-        String base64String;
+            }
-        String address;
-        int port;
-
-        ReceivedPacket(String base64String, String address, int port) {
-            this.base64String = base64String;
-            this.address = address;
-            this.port = port;
         }
     }
-
 
     /**
      * Listener interface for receive events.

android/src/main/java/com/tradle/react/UdpSenderTask.java

@@ -11,29 +11,30 @@ import android.os.AsyncTask;
 
 import java.io.IOException;
 import java.lang.ref.WeakReference;
-import java.net.DatagramPacket;
+import java.net.SocketAddress;
-import java.net.DatagramSocket;
+import java.nio.ByteBuffer;
+import java.nio.channels.DatagramChannel;
 
 /**
  * Specialized AsyncTask that transmits data in the background, and notifies listeners of the result.
  */
-public class UdpSenderTask extends AsyncTask<DatagramPacket, Void, Void> {
+public class UdpSenderTask extends AsyncTask<UdpSenderTask.SenderPacket, Void, Void> {
     private static final String TAG = "UdpSenderTask";
 
-    private DatagramSocket mSocket;
+    private DatagramChannel mChannel;
     private WeakReference<OnDataSentListener> mListener;
 
-    public UdpSenderTask(DatagramSocket socket, OnDataSentListener listener) {
+    public UdpSenderTask(DatagramChannel channel, OnDataSentListener listener) {
-        this.mSocket = socket;
+        this.mChannel = channel;
         this.mListener = new WeakReference<>(listener);
     }
 
     @Override
-    protected Void doInBackground(DatagramPacket... params) {
+    protected Void doInBackground(SenderPacket... params) {
         OnDataSentListener listener = mListener.get();
 
         try {
-            mSocket.send(params[0]);
+            mChannel.send(params[0].data, params[0].socketAddress);
             if (listener != null) {
                 listener.onDataSent(this);
             }
@@ -50,6 +51,14 @@ public class UdpSenderTask extends AsyncTask<DatagramPacket, Void, Void> {
         return null;
     }
 
+    /**
+     * Simple class to marshall outgoing data across to this AsyncTask
+     */
+    public static class SenderPacket {
+        SocketAddress socketAddress;
+        ByteBuffer data;
+    }
+
     /**
      * Callbacks for data send events.
      */

android/src/main/java/com/tradle/react/UdpSocketClient.java

@@ -11,33 +11,35 @@ import android.os.AsyncTask;
 import android.support.annotation.Nullable;
 import android.util.Base64;
 
+import com.facebook.common.logging.FLog;
 import com.facebook.react.bridge.Callback;
 
 import java.io.IOException;
-import java.net.DatagramPacket;
 import java.net.DatagramSocket;
-import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.net.SocketAddress;
 import java.net.SocketException;
 import java.net.UnknownHostException;
+import java.nio.ByteBuffer;
 import java.nio.channels.DatagramChannel;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
+import static com.tradle.react.UdpSenderTask.OnDataSentListener;
+
 /**
  * Client class that wraps a sender and a receiver for UDP data.
  */
-public final class UdpSocketClient implements UdpReceiverTask.OnDataReceivedListener, UdpSenderTask.OnDataSentListener {
+public final class UdpSocketClient implements UdpReceiverTask.OnDataReceivedListener, OnDataSentListener {
     private final OnDataReceivedListener mReceiverListener;
     private final OnRuntimeExceptionListener mExceptionListener;
     private final boolean mReuseAddress;
-    private final Map<UdpSenderTask, Callback> mPendingSends;
 
-    private DatagramChannel mChannel;
-    private DatagramSocket mSocket;
     private UdpReceiverTask mReceiverTask;
 
+    private final Map<UdpSenderTask, Callback> mPendingSends;
+    private DatagramChannel mSenderChannel;
+
     private UdpSocketClient(Builder builder) {
         this.mReceiverListener = builder.receiverListener;
         this.mExceptionListener = builder.exceptionListener;
@@ -58,20 +60,20 @@ public final class UdpSocketClient implements UdpReceiverTask.OnDataReceivedList
      *             binding.
      */
     public void bind(Integer port, @Nullable String address) throws IOException {
-        mChannel = DatagramChannel.open();
+        DatagramChannel receiverChannel = DatagramChannel.open();
-        mChannel.configureBlocking(true);
+        receiverChannel.configureBlocking(false);
-        mSocket = mChannel.socket();
+        mReceiverTask = new UdpReceiverTask(receiverChannel, this);
-        mReceiverTask = new UdpReceiverTask(mSocket, this);
 
-        SocketAddress socketAddress = null;
+        SocketAddress socketAddress;
         if (address != null) {
             socketAddress = new InetSocketAddress(address, port);
         } else {
             socketAddress = new InetSocketAddress(port);
         }
 
-        mSocket.setReuseAddress(mReuseAddress);
+        DatagramSocket socket = receiverChannel.socket();
-        mSocket.bind(socketAddress);
+        socket.setReuseAddress(mReuseAddress);
+        socket.bind(socketAddress);
 
         // begin listening for data in the background
         mReceiverTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
@@ -86,16 +88,25 @@ public final class UdpSocketClient implements UdpReceiverTask.OnDataReceivedList
      * @param callback callback for results
      * @throws UnknownHostException
      */
-    public void send(String base64String, Integer port, String address, @Nullable Callback callback) throws UnknownHostException {
+    public void send(String base64String, Integer port, String address, @Nullable Callback callback) throws UnknownHostException, IOException {
+        if (null == mSenderChannel || !mSenderChannel.isOpen()) {
+            mSenderChannel = DatagramChannel.open();
+            mSenderChannel.configureBlocking(true);
+        }
+
         byte[] data = Base64.decode(base64String, Base64.NO_WRAP);
-        DatagramPacket packet = new DatagramPacket(data, data.length,
+
-                InetAddress.getByName(address), port);
+        UdpSenderTask task = new UdpSenderTask(mSenderChannel, this);
-        UdpSenderTask task = new UdpSenderTask(mSocket, this);
+        UdpSenderTask.SenderPacket packet = new UdpSenderTask.SenderPacket();
+        packet.data = ByteBuffer.wrap(data);
+        packet.socketAddress = new InetSocketAddress(address, port);
+
         if (callback != null) {
             synchronized (mPendingSends) {
                 mPendingSends.put(task, callback);
             }
         }
+
         task.execute(packet);
     }
 
@@ -103,8 +114,11 @@ public final class UdpSocketClient implements UdpReceiverTask.OnDataReceivedList
      * Sets the socket to enable broadcasts.
      */
     public void setBroadcast(boolean flag) throws SocketException {
-        if (mSocket != null) {
+        if (mReceiverTask != null) {
-            mSocket.setBroadcast(flag);
+            DatagramChannel channel = mReceiverTask.getChannel();
+            if (channel != null) {
+                channel.socket().setBroadcast(flag);
+            }
         }
     }
 
@@ -113,9 +127,12 @@ public final class UdpSocketClient implements UdpReceiverTask.OnDataReceivedList
      */
     public void close() throws IOException {
         if (mReceiverTask != null && !mReceiverTask.isCancelled()) {
-            mReceiverTask.cancel(false);
+            // stop the receiving task, and close the channel
-        } else if (mChannel.isOpen()) {
+            mReceiverTask.cancel(true);
-            mChannel.close();
+        }
+
+        if (mSenderChannel != null && mSenderChannel.isOpen()) {
+            mSenderChannel.close();
         }
     }
 

android/src/main/java/com/tradle/react/UdpSockets.java

@@ -70,10 +70,10 @@ public final class UdpSockets extends ReactContextBaseJavaModule
                     mClients.clear();
                 }
             }.execute().get();
-        } catch (InterruptedException e) {
+        } catch (InterruptedException ioe) {
-            FLog.e(TAG, "onCatalystInstanceDestroy", e);
+            FLog.e(TAG, "onCatalystInstanceDestroy", ioe);
-        } catch (ExecutionException e) {
+        } catch (ExecutionException ee) {
-            FLog.e(TAG, "onCatalystInstanceDestroy", e);
+            FLog.e(TAG, "onCatalystInstanceDestroy", ee);
         }
     }
 
@@ -140,15 +140,15 @@ public final class UdpSockets extends ReactContextBaseJavaModule
                     result.putInt("port", port);
 
                     callback.invoke(null, result);
-                } catch (SocketException exception) {
+                } catch (SocketException se) {
                     // Socket is already bound or a problem occurred during binding
-                    callback.invoke(UdpErrorUtil.getError(null, exception.getMessage()));
+                    callback.invoke(UdpErrorUtil.getError(null, se.getMessage()));
-                } catch (IllegalArgumentException exception) {
+                } catch (IllegalArgumentException iae) {
                     // SocketAddress is not supported
-                    callback.invoke(UdpErrorUtil.getError(null, exception.getMessage()));
+                    callback.invoke(UdpErrorUtil.getError(null, iae.getMessage()));
-                } catch (IOException exception) {
+                } catch (IOException ioe) {
                     // an exception occurred
-                    callback.invoke(UdpErrorUtil.getError(null, exception.getMessage()));
+                    callback.invoke(UdpErrorUtil.getError(null, ioe.getMessage()));
                 }
             }
         }.execute();
@@ -170,8 +170,11 @@ public final class UdpSockets extends ReactContextBaseJavaModule
 
                 try {
                     client.send(base64String, port, address, callback);
-                } catch (UnknownHostException e) {
+                } catch (UnknownHostException uhe) {
-                    callback.invoke(UdpErrorUtil.getError(null, e.getMessage()));
+                    callback.invoke(UdpErrorUtil.getError(null, uhe.getMessage()));
+                } catch (IOException ioe) {
+                    // an exception occurred
+                    callback.invoke(UdpErrorUtil.getError(null, ioe.getMessage()));
                 }
             }
         }.execute();
@@ -193,8 +196,8 @@ public final class UdpSockets extends ReactContextBaseJavaModule
                 try {
                     client.close();
                     callback.invoke();
-                } catch (IOException e) {
+                } catch (IOException ioe) {
-                    callback.invoke(UdpErrorUtil.getError(null, e.getMessage()));
+                    callback.invoke(UdpErrorUtil.getError(null, ioe.getMessage()));
                 }
 
                 mClients.remove(cId);