title: ReadableByteChannel hangs on read(bytebuffer)
body: <p>Im working on Instant messenger using java 1.6. IM uses multithreading - main thread, receiving, and ping. For tcp/ip communication I used SocketChannel. And it seems there is a problem with receiving bigger packages from server. Server instead of one sends a couple of packages and thats where the problem begins. Every first 8 bytes is telling what is the type of package and how big it is. This is how I managed reading:</p>
  
  <pre><code>public void run(){
      while(true){
          try{
          Headbuffer.clear();
          bytes = readChannel.read(Headbuffer); //ReadableByteChannel
          Headbuffer.flip();
          if(bytes != -1){
              int head = Headbuffer.getInt();
              int size = Headbuffer.getInt();
              System.out.println("received pkg: 0x" + Integer.toHexString(head)+" with size "+ size+" bytes);
              switch(head){
              case incoming.Pkg1: ReadWelcome(); break;
              case incoming.Pkg2: ReadLoginFail();break;
              case incoming.Pkg3: ReadLoginOk();break;
              case incoming.Pkg4: ReadUserList();break;
              case incoming.Pkg5: ReadUserData();break;
              case incoming.Pkg6: ReadMessage();break;
              case incoming.Pkg7: ReadTypingNotify();break;
              case incoming.Pkg8: ReadListStatus();break;
              case incoming.Pkg9: ChangeStatus();break;
              }
          }
          }catch(Exception e){
              e.printStackTrace();
          }
      }   
  }
  </code></pre>
  
  <p>And during the tests everything was fine until i logged on my account and import my buddylist. I send request to server for statuses and he send me back about 10 out of 80 contacts. So I came up with something like this: </p>
  
  <pre><code>public synchronized void readInStatus(ByteBuffer headBuffer){
  
      byteArray.add(headBuffer); //Store every buffer in ArrayList
      int buddies = MainController.controler.getContacts().getSize();
      while(buddies&gt;0){
  
            readStuff();
            readDescription();
          --buddies; 
      }       
  }
  </code></pre>
  
  <p>and each readStuff() and readDescription() are checking each parameter size with remaining bytes in the buffer:</p>
  
  <pre><code> if(byteArray.get(current).remaining() &gt;= 4){
  
        uin = byteArray.get(current).getInt();
        }else{
            byteArray.add(Receiver.receiver.read());
            current = current +1;
            uin = byteArray.get(current).getInt(); 
        }
  </code></pre>
  
  <p>and Receiver.receiver.read() is:</p>
  
  <pre><code>public ByteBuffer read(){
      try {
          ByteBuffer bb = ByteBuffer.allocate(40000);
          bb.order(ByteOrder.LITTLE_ENDIAN);
          bytes = readChannel.read(bb);
          bb.flip();
          return bb;
      } catch (Exception e) {
          e.printStackTrace();
      }
      return null;
  }
  </code></pre>
  
  <p>So application is lunched, logged and then sends contacts. Server send me back just a piece of my list. But in the method <strong>readInStatus(ByteBuffer headBuffer)</strong> I try to force the rest of the list. And now the fun part - after some time it gets to the <strong>Receiver.receiver.read()</strong> and on <strong>bytes = readChannel.read(bb)</strong> it just stops and I dont know why , no errors no nothing even after some time and Im out of the ideas. Im fighting with this whole week and i dont get anywhere near the solution. I will appreciate any suggestions. Thanks.</p>
  
  <hr>
  
  <p>Thanks for response. Yes, I'm using blocking SocketChannel, I tried non-blocking but it goes wild and out of control so I skipped the idea. About the bytes I expect - this is kind of weird, because its giving me size only once in head but its size of the first part not the whole package, other parts is not containing header bytes at all. I can't predict how much bytes it would be, the reason is - descriptions with 255 bytes capacity. This is exactly why I've created variable <strong>buddies</strong> in : <code>public synchronized void readInStatus(ByteBuffer headBuffer)</code>
  wich is basically length of my buddy list and before reading each field I'm checking if there is enough bytes left if its not, I do <strong>read()</strong>. But last field before description is integer with the length of the incoming description. But its impossible to determine how long package is, until some processing is done. @robert do you think I should try again switching to non-blocking SocketChannel in that situation ?</p>