Mercurial > templog
annotate py/utils.py @ 299:358c50004679
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| author | Matt Johnston <matt@ucc.asn.au> |
|---|---|
| date | Mon, 27 Feb 2017 23:20:07 +0800 |
| parents | af924d27140f |
| children | 02aff9ff8d24 |
| rev | line source |
|---|---|
| 141 | 1 import os |
| 2 import sys | |
| 265 | 3 import ctypes |
| 141 | 4 import time |
| 5 import select | |
| 6 import logging | |
|
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7 import binascii |
| 259 | 8 import json |
| 265 | 9 import datetime |
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10 import collections |
| 141 | 11 |
|
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12 D = logging.debug |
| 141 | 13 L = logging.info |
| 14 W = logging.warning | |
| 15 E = logging.error | |
| 16 | |
| 17 DEFAULT_TRIES = 3 | |
| 18 READLINE_SELECT_TIMEOUT = 1 | |
| 19 | |
| 144 | 20 def EX(msg, *args, **kwargs): |
| 21 kwargs['exc_info'] = True | |
| 22 logging.error(msg, *args, **kwargs) | |
| 23 | |
| 141 | 24 clock_gettime = None |
| 25 no_clock_gettime = True | |
| 26 def monotonic_time(): | |
| 27 global clock_gettime | |
| 28 global no_clock_gettime | |
| 29 if no_clock_gettime: | |
| 30 return time.time() | |
| 31 | |
| 32 class timespec(ctypes.Structure): | |
| 33 _fields_ = [ | |
| 34 ('tv_sec', ctypes.c_long), | |
| 35 ('tv_nsec', ctypes.c_long) | |
| 36 ] | |
| 37 if not clock_gettime: | |
| 38 try: | |
| 39 librt = ctypes.CDLL('librt.so.0', use_errno=True) | |
| 40 clock_gettime = librt.clock_gettime | |
| 41 clock_gettime.argtypes = [ctypes.c_int, ctypes.POINTER(timespec)] | |
| 42 except: | |
| 43 W("No clock_gettime(), using fake fallback.") | |
| 44 no_clock_gettime = True | |
| 45 return time.time() | |
| 46 | |
| 47 t = timespec() | |
| 48 CLOCK_MONOTONIC = 1 # see <linux/time.h> | |
| 49 | |
| 50 if clock_gettime(CLOCK_MONOTONIC, ctypes.pointer(t)) != 0: | |
| 51 errno_ = ctypes.get_errno() | |
| 52 raise OSError(errno_, os.strerror(errno_)) | |
| 53 return t.tv_sec + t.tv_nsec * 1e-9 | |
| 54 | |
| 55 # decorator, tries a number of times, returns None on failure, sleeps between | |
| 56 # Must be used as "@retry()" if arguments are defaulted | |
| 57 def retry(retries=DEFAULT_TRIES, try_time = 1): | |
| 58 def inner(func): | |
| 59 def new_f(*args, **kwargs): | |
| 60 for i in range(retries): | |
| 61 d = func(*args, **kwargs) | |
| 62 if d is not None: | |
| 63 return d | |
| 64 time.sleep(try_time) | |
| 65 return None | |
| 66 | |
| 230 | 67 new_f.__name__ = func.__name__ |
| 141 | 68 return new_f |
| 69 return inner | |
| 70 | |
| 71 def readline(sock): | |
| 72 timeout = READLINE_SELECT_TIMEOUT | |
| 73 buf = '' | |
| 74 while True: | |
| 75 (rlist, wlist, xlist) = select.select([sock], [], [], timeout) | |
| 76 if sock not in rlist: | |
| 77 # hit timeout | |
| 78 return None | |
| 79 | |
| 80 c = sock.recv(1) | |
| 81 if c == '': | |
| 82 # lightblue timeout | |
| 83 return None | |
| 84 if c == '\r': | |
| 85 continue | |
| 86 | |
| 87 buf += c | |
| 88 if c == '\n': | |
| 89 return buf | |
| 90 | |
| 91 # from http://blog.stalkr.net/2011/04/pctf-2011-32-thats-no-bluetooth.html | |
| 92 def crc16(buff, crc = 0, poly = 0x8408): | |
| 93 l = len(buff) | |
| 94 i = 0 | |
| 95 while i < l: | |
| 96 ch = ord(buff[i]) | |
| 97 uc = 0 | |
| 98 while uc < 8: | |
| 99 if (crc & 1) ^ (ch & 1): | |
| 100 crc = (crc >> 1) ^ poly | |
| 101 else: | |
| 102 crc >>= 1 | |
| 103 ch >>= 1 | |
| 104 uc += 1 | |
| 105 i += 1 | |
| 106 return crc | |
| 107 | |
| 108 def cheap_daemon(): | |
| 109 L("Daemonising.") | |
| 110 sys.stdout.flush() | |
| 111 sys.stderr.flush() | |
| 112 out = file('/dev/null', 'a+') | |
| 113 os.dup2(out.fileno(), sys.stdout.fileno()) | |
| 114 os.dup2(out.fileno(), sys.stderr.fileno()) | |
| 115 | |
| 116 try: | |
| 117 pid = os.fork() | |
| 118 if pid > 0: | |
| 119 sys.exit(0) | |
| 230 | 120 except OSError as e: |
| 141 | 121 E("Bad fork()") |
| 122 sys.exit(1) | |
| 123 | |
| 124 os.setsid() | |
| 125 | |
| 126 try: | |
| 127 pid = os.fork() | |
| 128 if pid > 0: | |
| 129 sys.exit(0) | |
| 230 | 130 except OSError as e: |
| 141 | 131 E("Bad fork()") |
| 132 sys.exit(1) | |
| 133 | |
| 145 | 134 def uptime(): |
| 135 try: | |
| 136 return float(open('/proc/uptime', 'r').read().split(' ', 1)[0]) | |
| 230 | 137 except Exception as e: |
| 145 | 138 return -1 |
| 141 | 139 |
| 259 | 140 |
| 141 def json_load_round_float(s, **args): | |
| 142 return json.loads(s,parse_float = lambda f: round(float(f), 2), **args) | |
| 265 | 143 |
| 144 class NotTooOften(object): | |
| 145 """ prevents things happening more than once per limit. | |
| 146 Isn't monotonic, good enough for logging. eg | |
| 147 self.logfailure = NotTooOften(180) # 3 minutes | |
| 148 ... | |
| 149 if self.logfailure(): | |
| 150 L("blah") | |
| 151 """ | |
| 152 def __init__(self, limit): | |
| 153 """ limit is a delay in seconds or TimeDelta """ | |
| 154 if type(limit) is datetime.timedelta: | |
| 155 self.limit = limit | |
| 156 else: | |
| 157 self.limit = datetime.timedelta(seconds=limit) | |
| 158 | |
| 159 # must be positive | |
| 160 assert self.limit > datetime.timedelta(0) | |
| 161 self.last = datetime.datetime(10, 1, 1) | |
| 162 | |
| 163 def __call__(self): | |
| 164 if datetime.datetime.now() - self.last > self.limit: | |
| 165 self.last = datetime.datetime.now() | |
| 166 return True | |
| 167 | |
| 168 def log(self, msg): | |
| 169 """ calls L(msg) if it isn't too often, otherwise D(msg) | |
| 170 """ | |
| 171 if self(): | |
| 172 L(msg + " (log interval %s)" % str(self.limit)) | |
| 173 else: | |
| 174 D(msg) | |
| 270 | 175 |
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176 Period = collections.namedtuple('Period', 'start end') |
| 270 | 177 class StepIntegrator(object): |
| 178 """ | |
| 271 | 179 Takes on/off events and a monotonically increasing timefn. Returns the integral |
| 180 of (now-limittime, now) over those events. | |
| 181 | |
| 270 | 182 >>> s = StepIntegrator(lambda: t, 40) |
| 183 >>> t = 1 | |
| 184 >>> s.turn(1) | |
| 185 >>> t = 10 | |
| 186 >>> s.turn(0) | |
| 187 >>> t = 20 | |
| 188 >>> s.turn(1) | |
| 189 >>> t = 30 | |
| 190 >>> print(s.integrate()) | |
| 191 19 | |
| 192 >>> s.turn(0) | |
| 193 >>> print(s.integrate()) | |
| 194 19 | |
| 195 >>> t = 35 | |
| 196 >>> print(s.integrate()) | |
| 197 19 | |
| 198 >>> t = 42 | |
| 199 >>> print(s.integrate()) | |
| 200 18 | |
| 201 >>> t = 52 | |
| 202 >>> print(s.integrate()) | |
| 203 10 | |
| 204 >>> t = 69 | |
| 205 >>> print(s.integrate()) | |
| 206 1 | |
| 207 >>> t = 70 | |
| 208 >>> print(s.integrate()) | |
| 209 0 | |
| 210 >>> t = 170 | |
| 211 >>> print(s.integrate()) | |
| 212 0 | |
| 213 """ | |
| 214 def __init__(self, timefn, limittime): | |
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215 # _on_periods is a list of [period]. End is None if still on |
| 270 | 216 self._on_periods = [] |
| 217 self._timefn = timefn | |
| 218 self._limittime = limittime | |
| 219 | |
| 271 | 220 def set_limit(self, limittime): |
| 221 if self._limittime == limittime: | |
| 222 return | |
| 223 self._limittime = limittime | |
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224 self._trim() |
| 271 | 225 |
| 270 | 226 def turn(self, value): |
| 227 if not self._on_periods: | |
| 228 if value: | |
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229 self._on_periods.append(Period(self._timefn(), None)) |
| 270 | 230 return |
| 231 | |
| 232 # state hasn't changed | |
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233 on_now = (self._on_periods[-1].end is None) |
| 270 | 234 if value == on_now: |
| 235 return | |
| 236 | |
| 237 if value: | |
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238 self._on_periods.append(Period(self._timefn(), None)) |
| 270 | 239 else: |
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240 self._on_periods[-1] = self._on_periods[-1]._replace(end = self._timefn()) |
| 270 | 241 |
| 242 def _trim(self): | |
| 243 begin = self._timefn() - self._limittime | |
| 244 # shortcut, first start is after begin | |
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245 if not self._on_periods or self._on_periods[0].start >= begin: |
| 270 | 246 return |
| 247 | |
| 248 new_periods = [] | |
| 249 for s, e in self._on_periods: | |
| 250 if s == e: | |
| 251 continue | |
| 252 elif s >= begin: | |
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253 new_periods.append(Period(s,e)) |
| 270 | 254 elif e is not None and e < begin: |
| 255 continue | |
| 256 else: | |
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257 new_periods.append(Period(begin, e)) |
| 270 | 258 self._on_periods = new_periods |
| 259 | |
| 260 def integrate(self): | |
| 261 self._trim() | |
| 262 tot = 0 | |
| 263 for s, e in self._on_periods: | |
| 264 if e is None: | |
| 265 e = self._timefn() | |
| 266 tot += (e-s) | |
| 267 return tot | |
| 268 | |
| 269 | |
| 270 | |
| 271 | |
| 272 | |
| 273 | |
| 274 |