ByteBuffers.. *sigh*

Networking & Multiplayer
#1

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.

#2

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.

#3

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

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.