Requirements:
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* Linux 2.6.x
* GHC 6.5
* libaio --- the Linux Asynchonrous I/O Library.
* libipq --- the iptables development library (iptables-dev in Debian)
If you wish to try the web server, make sure that the HTML files are
on one of these file systems: ext2, ext3, jfs, xfs. Otherwise, AIO
may not work.
Files and directories:
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IOLib/ : Low-level asynchronous I/O library
Chunk.hs : A type-safe representation of memory buffers
AIO.hs : FFI wrappers for the Linux AIO library
Epoll.hs : FFI wrappers for the Linux epoll interface
NBIO.hs : FFI wrappers for some non-blocking socket primitives
PacketIO.hs : FFI wrappers for sending/receiving IP packets.
TCP.hs : A proof-of-concept, purely functional TCP stack.
ThreadLib/ : The application-level thread library
Thread.hs : CPS Monad and system calls.
Workers.hs : Some standard and reusable event loops for constructing
application-level schedulers.
A default scheduler implementation is also provided.
FileIO.hs : Synchronous disk library, implemented using Linux AIO
SockIO.hs : Synchronous socket library, implemented using standard
non-blocking sockets with epoll.
TCPSockIO.hs : Synchronous socket library, implemented using the
user-level, customized TCP stack.
Mutex.hs : A simple mutex library.
WebClient/ : An HTTP load generator application
WebServer/ : A web server application. It can be linked with
either SockIO or TCPSockIO.
Compile and run:
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First, make sure that libaio is installed on your system and you are
using a development snapshot GHC 6.5. Then, run the shell script
"rebuild.sh" to compile all the sources. This should create three
executable files:
WebServer/Server.bin
WebServer/Server_tcp.bin
WebClient/LoadGen.bin
Run them. They are self-documented. To use Server_tcp.bin, you should
first run "make setup" in the WebServer/ directory to setup iptables.
Read the Makefile for more information.
Programming with threads
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Just use Server.hs and LoadGen.hs as templates to start.
Programming with events
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The scheduler is part of your application. You can use some standard
event loops predefined in Workers.hs, or you can write your own.
FAQ:
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Q: How to use another event source like *poll/*IO/kqueue/whatever?
A: First, wrap up the C function calls using FFI. AIO.hs and
mod_aio.c is a good demo to start with. Then, add system calls and
write your own event loops :-)
Q: How to add system calls?
A: The current setup is not quite modular yet---you will have to add a
line in Thread.hs for each system call you would like to add. In the
future, it is possible to make the Trace interface user-pluggable by
adding an extra level of indirection.
Q: How to write my own event loops?
A: As a demo, LoadGen.hs has a customized event loop. It does not do
anything fancy, though.
Q: How is the TCP stack?
A: The current implementation is purely functional and it is quite
slow. It is roughly 3x-8x slower than the linux kernel TCP stack.
It only implemented server sockets---active TCP connections are
not implemented yet.
