Mercurial > templog
view server/utils.py @ 487:931408ce71d9
working OK
author | Matt Johnston <matt@ucc.asn.au> |
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date | Fri, 07 Feb 2014 23:32:08 +0800 |
parents | f0ddb75bcf04 |
children |
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import os import sys #import ctypes import time import select import logging L = logging.info W = logging.warning E = logging.error DEFAULT_TRIES = 3 READLINE_SELECT_TIMEOUT = 1 __all__ = ('monotonic_time', 'retry') clock_gettime = None no_clock_gettime = True def monotonic_time(): global clock_gettime global no_clock_gettime if no_clock_gettime: return time.time() class timespec(ctypes.Structure): _fields_ = [ ('tv_sec', ctypes.c_long), ('tv_nsec', ctypes.c_long) ] if not clock_gettime: try: librt = ctypes.CDLL('librt.so.0', use_errno=True) clock_gettime = librt.clock_gettime clock_gettime.argtypes = [ctypes.c_int, ctypes.POINTER(timespec)] except: W("No clock_gettime(), using fake fallback.") no_clock_gettime = True return time.time() t = timespec() CLOCK_MONOTONIC = 1 # see <linux/time.h> if clock_gettime(CLOCK_MONOTONIC, ctypes.pointer(t)) != 0: errno_ = ctypes.get_errno() raise OSError(errno_, os.strerror(errno_)) return t.tv_sec + t.tv_nsec * 1e-9 # decorator, tries a number of times, returns None on failure, sleeps between # Must be used as "@retry()" if arguments are defaulted def retry(retries=DEFAULT_TRIES, try_time = 1): def inner(func): def new_f(*args, **kwargs): for i in range(retries): d = func(*args, **kwargs) if d is not None: return d time.sleep(try_time) return None new_f.func_name = func.func_name return new_f return inner def readline(sock): timeout = READLINE_SELECT_TIMEOUT buf = '' while True: (rlist, wlist, xlist) = select.select([sock], [], [], timeout) if sock not in rlist: # hit timeout return None c = sock.recv(1) if c == '': # lightblue timeout return None if c == '\r': continue buf += c if c == '\n': return buf # from http://blog.stalkr.net/2011/04/pctf-2011-32-thats-no-bluetooth.html def crc16(buff, crc = 0, poly = 0x8408): l = len(buff) i = 0 while i < l: ch = ord(buff[i]) uc = 0 while uc < 8: if (crc & 1) ^ (ch & 1): crc = (crc >> 1) ^ poly else: crc >>= 1 ch >>= 1 uc += 1 i += 1 return crc def cheap_daemon(): L("Daemonising.") sys.stdout.flush() sys.stderr.flush() out = file('/dev/null', 'a+') os.dup2(out.fileno(), sys.stdout.fileno()) os.dup2(out.fileno(), sys.stderr.fileno()) try: pid = os.fork() if pid > 0: sys.exit(0) except OSError, e: E("Bad fork()") sys.exit(1) os.setsid() try: pid = os.fork() if pid > 0: sys.exit(0) except OSError, e: E("Bad fork()") sys.exit(1)