I need to multiplex communication between threads and sockets

Question

Hello,
I need to implement a server which will have a maximum of 10 clients connected.
I wanted to go for classic blocking I/O because I won't have much clients.
My problem is that even if I accept() some sockets and then create a thread for each socket,
then I still need to communicate some data to the other threads, problem is that I am blocked
on the read() operation, how could I address this problem?
I mean, lets say I am thread1 and blocked on read() on my socket, now thread7 wants to tell
me something like a chat message coming from client he handles, how could thread7 manage
to wake thread1 and send him a message somehow?
I do not want to deal with NIO stuff if possible because I do not need to scale, I just have a
problem because I am stuck on the read.
I will run on Windows.
Thanks for help.
Edited by: Marzullo on Jul 15, 2010 1:05 PM

Answer 1

Marzullo wrote:
Hello,
I need to implement a server which will have a maximum of 10 clients connected.
I wanted to go for classic blocking I/O because I won't have much clients.
My problem is that even if I accept() some sockets and then create a thread for each socket,
then I still need to communicate some data to the other threads, problem is that I am blocked
on the read() operation, how could I address this problem?For small apps like that, I've found it helpful to have two threads per socket: 1 reader and 1 writer. The reader can block on read() 99% of the time, while the writer is blocked on LinkedBlockingQueue.take() 99% of the time (or Object.wait() depending). The writer's queue is populated from the outside with whatever messages are destined to that socket.
I mean, lets say I am thread1 and blocked on read() on my socket, now thread7 wants to tell
me something like a chat message coming from client he handles, how could thread7 manage
to wake thread1 and send him a message somehow?If thread1 is blocked on read() then it will receive any data that was sent to it, there's no need to wake it up because it gets what it's been waiting for (data on the input stream). Thread7 just needs to write data to the socket's output stream and the other end wakes up automatically because read() only blocks until data is available.