On Thu, 2005-07-07 at 13:48 -0400, Tom Cocagne wrote:

I was wondering if anyone has suggestions for a good way to go about setting up a message-passing communication channel between one or more C threads and a single thread dedicated to running Python/Twisted. I already have functional Python bindings accessing the contents of the messages (basically C structures) but need some way to exchange the messages between the C threads and the Python thread.

Any reason you're using threads? You can run Twisted directly on the glib event loop, so your whole program could run on the same loop. In any case, Switching data from Twisted to C is just like passing data from any Python program to C code: call a C extension function from Python that calls into C code, and for reverse call a Python function from C code. Thread safety is mostly orthogonal, so you can probably use the standard Twisted reactor.callFromThread to have code run in the Twisted thread.

On Jul 7, 2005, at 7:48 AM, Tom Cocagne wrote:

I was wondering if anyone has suggestions for a good way to go about setting up a message-passing communication channel between one or more C threads and a single thread dedicated to running Python/Twisted. I already have functional Python bindings accessing the contents of the messages (basically C structures) but need some way to exchange the messages between the C threads and the Python thread.

All I really need is a means by which to inform Twisted's reactor that a C thread has sent a message. My original plan was to use a pair of pipes (via os.pipe()) to send pointers back and forth but it didn't seem to work on Windows . I'm pretty sure this will work fine for posix systems but it definitely didn't work on my first attempt with Windows (though the problem may have been due to my library configuration).

I would imagine that something along these lines has been done before. Does anyone know of an existing approach or have suggestions for a better solution?

Acquire the GIL, call reactor.callFromThread, release the GIL. -bob

On Thu, Jul 07, 2005 at 01:48:57PM -0400, Tom Cocagne wrote:

All I really need is a means by which to inform Twisted's reactor that a C thread has sent a message. My original plan was to use a pair of pipes (via os.pipe()) to send pointers back and forth but it didn't seem to work on Windows . I'm pretty sure this will work fine for posix systems but it definitely didn't work on my first attempt with Windows (though the problem may have been due to my library configuration).

#define MY_MODULE "foo.bar" #define MY_FUNCTION "handle_message" void send_message_to_python(message_t *message) { PyObject *module_name, *module, *dict, *func, *args, *pymessage; module_name = PyString_FromString(MY_MODULE); module = PyImport_Import(module_name); dict = PyModule_GetDict(module) func = PyDict_GetItemString(MY_FUNCTION); args = PyTuple_New(1) pymessage = MyPythonWrappedMessage_New(message); PyTuple_SetItem(args, 0, pymessage); PyObject_CallObject(func, args); } (with appropriate error checking, of course) This has the effect of doing from foo.bar import handle_message handle_message(m) I'm not at all sure what would happen on Windows. I suppose this would work there too. But you also need to run the reactor, I guess which might be easier or harder depending on the behaviour of the C program. The simplest way is just to start a C thread and do the equivalent of the above for from twisted.internet import reactor reactor.run() -w