| |
| """ |
| Utilities for the OpenFlow test framework |
| """ |
| |
| import random |
| import time |
| import os |
| import fcntl |
| import logging |
| |
| default_timeout = None # set by oft |
| |
| def gen_xid(): |
| return random.randrange(1,0xffffffff) |
| |
| """ |
| Wait on a condition variable until the given function returns non-None or a timeout expires. |
| The condition variable must already be acquired. |
| The timeout value -1 means use the default timeout. |
| There is deliberately no support for an infinite timeout. |
| TODO: get the default timeout from configuration |
| """ |
| def timed_wait(cv, fn, timeout=-1): |
| if timeout == -1: |
| # TODO make this configurable |
| timeout = default_timeout |
| |
| end_time = time.time() + timeout |
| while True: |
| val = fn() |
| if val != None: |
| return val |
| |
| remaining_time = end_time - time.time() |
| cv.wait(remaining_time) |
| |
| if time.time() > end_time: |
| return None |
| |
| class EventDescriptor(): |
| """ |
| Similar to a condition variable, but can be passed to select(). |
| Only supports one waiter. |
| """ |
| |
| def __init__(self): |
| self.pipe_rd, self.pipe_wr = os.pipe() |
| fcntl.fcntl(self.pipe_wr, fcntl.F_SETFL, os.O_NONBLOCK) |
| |
| def __del__(self): |
| os.close(self.pipe_rd) |
| os.close(self.pipe_wr) |
| |
| def notify(self): |
| try: |
| os.write(self.pipe_wr, "x") |
| except OSError as e: |
| logging.warn("Failed to notify EventDescriptor: %s", e) |
| |
| def wait(self): |
| os.read(self.pipe_rd, 1) |
| |
| def fileno(self): |
| return self.pipe_rd |