I'm looking to use twisted to control communication across Linux pipes (os.pipe()) and fifos (os.mkfifo()) between a master process and a set of slave processes. While I'm positive tat it's possible to use twisted for these types of file descriptors (after all, twisted is great for tcp sockets which *nix abstracts away as file descriptors), I cannot find any examples of this type of usage. Anyone have any links, sample code, or advice?
A:
It does not have anything built-in for asynchronous I/O. Someone wrote a libaio wrapper for it, but it has not been touched for a long time, and I have no idea if it still works.
In the worst case you could use select to see if there's anything available to read, but that won't help you with writing.
Ignacio Vazquez-Abrams
2010-01-15 03:27:50
+2
A:
You can use reactor.spawnProcess to set up arbitrary file descriptor mappings between a parent process and a child process it spawns. For example, to run a program and give it two extra output descriptors (in addition to stdin, stdout, and stderr) with which it can send bytes back to the parent process, you would do something like this:
reactor.spawnProcess(protocol, executable, args,
childFDs={0: 'w', 1: 'r', 2: 'r', 3: 'r', 4: 'r'})
The reactor will take care of creating the pipes for you, and will call childDataReceived on the ProcessProtocol you pass in when data is read from them. See the spawnProcess API docs for details.
If you're also using Twisted on the child end, then you mostly want to be looking at twisted.internet.stdio. stdiodemo.py and stdin.py in the core examples will show you how to use that module.
Jean-Paul Calderone
2010-01-15 13:42:33