ByteBuffers.. *sigh*

[Addictman]

Hi there.

I have a problem with ByteBuffers, and I'm hoping someone can shed some light on what is happening.


I have a ByteBuffer a which is allocated 512 bytes using allocateDirect(512);

This is from now on my "writer". In addition to this, I have Packet classes, which have pack() methods that return a ByteBuffer that is allocated to various sizes depending on the packet data.

Now, when I want to send something, I want to use the writer which has a large capacity, and fill it with the data of differen packets. (I want to be able to fill it with several packets, as this is a turn-based game, and I want to send chunks of larger packets at "end-of-turn" states). (However the following problem occurs if I only try with a single packet as well).

However, when I do writer.put(packet.pack()); nothing seems to happen to the writer's internal values (position(), remaining(), etc). According to the API, the call is equivalent to

while (src.hasRemaining())
        dst.put(src.get());

so I replaced the writer.put(packet.pack()); with this, just to test, but still nothing happens.

Am I missing something really obvious here, or is there some underlying magic that I'm not aware of, going on.

Appreciate any help or advice on this.

Thanks.

[Addictman]

I fixed it. I am dumb.

I was too busy trying to flip the writer buffer, but instead I should have flipped the packet buffer before returning it. Now everything seems to work alright.

[Jeff]

Dotn feel bad.  Flipping Buffers is one of their trickier aspects.  It gets even tricker when you have to start using slice()  

To get all the layers of my protocol working right in my current project I had to trace through with a  debugger and watch what was happenign to those internal fields.  Eactly what state they are expected to be in by the socket code for various operations is definitely under-documented.