Lib/threading.py

   1 """Proposed new threading module, emulating a subset of Java's threading model."""
   2
   3 import sys
   4 import time
   5 import thread
   6 import traceback
   7 import StringIO
   8
   9 # Rename some stuff so "from threading import *" is safe
  10
  11 _sys = sys
  12 del sys
  13
  14 _time = time.time
  15 _sleep = time.sleep
  16 del time
  17
  18 _start_new_thread = thread.start_new_thread
  19 _allocate_lock = thread.allocate_lock
  20 _get_ident = thread.get_ident
  21 ThreadError = thread.error
  22 del thread
  23
  24 _print_exc = traceback.print_exc
  25 del traceback
  26
  27 _StringIO = StringIO.StringIO
  28 del StringIO
  29
  30
  31 # Debug support (adapted from ihooks.py)
  32
  33 _VERBOSE = 0
  34
  35 if __debug__:
  36
  37     class _Verbose:
  38
  39         def __init__(self, verbose=None):
  40             if verbose is None:
  41                 verbose = _VERBOSE
  42             self.__verbose = verbose
  43
  44         def _note(self, format, *args):
  45             if self.__verbose:
  46                 format = format % args
  47                 format = "%s: %s\n" % (
  48                     currentThread().getName(), format)
  49                 _sys.stderr.write(format)
  50
  51 else:
  52     # Disable this when using "python -O"
  53     class _Verbose:
  54         def __init__(self, verbose=None):
  55             pass
  56         def _note(self, *args):
  57             pass
  58
  59
  60 # Synchronization classes
  61
  62 Lock = _allocate_lock
  63
  64 def RLock(*args, **kwargs):
  65     return apply(_RLock, args, kwargs)
  66
  67 class _RLock(_Verbose):
  68
  69     def __init__(self, verbose=None):
  70         _Verbose.__init__(self, verbose)
  71         self.__block = _allocate_lock()
  72         self.__owner = None
  73         self.__count = 0
  74
  75     def __repr__(self):
  76         return "<%s(%s, %d)>" % (
  77                 self.__class__.__name__,
  78                 self.__owner and self.__owner.getName(),
  79                 self.__count)
  80
  81     def acquire(self, blocking=1):
  82         me = currentThread()
  83         if self.__owner is me:
  84             self.__count = self.__count + 1
  85             if __debug__:
  86                 self._note("%s.acquire(%s): recursive success", self, blocking)
  87             return 1
  88         rc = self.__block.acquire(blocking)
  89         if rc:
  90             self.__owner = me
  91             self.__count = 1
  92             if __debug__:
  93                 self._note("%s.acquire(%s): initial succes", self, blocking)
  94         else:
  95             if __debug__:
  96                 self._note("%s.acquire(%s): failure", self, blocking)
  97         return rc
  98
  99     def release(self):
 100         me = currentThread()
 101         assert self.__owner is me, "release() of un-acquire()d lock"
 102         self.__count = count = self.__count - 1
 103         if not count:
 104             self.__owner = None
 105             self.__block.release()
 106             if __debug__:
 107                 self._note("%s.release(): final release", self)
 108         else:
 109             if __debug__:
 110                 self._note("%s.release(): non-final release", self)
 111
 112     # Internal methods used by condition variables
 113
 114     def _acquire_restore(self, (count, owner)):
 115         self.__block.acquire()
 116         self.__count = count
 117         self.__owner = owner
 118         if __debug__:
 119             self._note("%s._acquire_restore()", self)
 120
 121     def _release_save(self):
 122         if __debug__:
 123             self._note("%s._release_save()", self)
 124         count = self.__count
 125         self.__count = 0
 126         owner = self.__owner
 127         self.__owner = None
 128         self.__block.release()
 129         return (count, owner)
 130
 131     def _is_owned(self):
 132         return self.__owner is currentThread()
 133
 134
 135 def Condition(*args, **kwargs):
 136     return apply(_Condition, args, kwargs)
 137
 138 class _Condition(_Verbose):
 139
 140     def __init__(self, lock=None, verbose=None):
 141         _Verbose.__init__(self, verbose)
 142         if lock is None:
 143             lock = RLock()
 144         self.__lock = lock
 145         # Export the lock's acquire() and release() methods
 146         self.acquire = lock.acquire
 147         self.release = lock.release
 148         # If the lock defines _release_save() and/or _acquire_restore(),
 149         # these override the default implementations (which just call
 150         # release() and acquire() on the lock).  Ditto for _is_owned().
 151         try:
 152             self._release_save = lock._release_save
 153         except AttributeError:
 154             pass
 155         try:
 156             self._acquire_restore = lock._acquire_restore
 157         except AttributeError:
 158             pass
 159         try:
 160             self._is_owned = lock._is_owned
 161         except AttributeError:
 162             pass
 163         self.__waiters = []
 164
 165     def __repr__(self):
 166         return "<Condition(%s, %d)>" % (self.__lock, len(self.__waiters))
 167
 168     def _release_save(self):
 169         self.__lock.release()           # No state to save
 170
 171     def _acquire_restore(self, x):
 172         self.__lock.acquire()           # Ignore saved state
 173
 174     def _is_owned(self):
 175         if self.__lock.acquire(0):
 176             self.__lock.release()
 177             return 0
 178         else:
 179             return 1
 180
 181     def wait(self, timeout=None):
 182         me = currentThread()
 183         assert self._is_owned(), "wait() of un-acquire()d lock"
 184         waiter = _allocate_lock()
 185         waiter.acquire()
 186         self.__waiters.append(waiter)
 187         saved_state = self._release_save()
 188         try:    # restore state no matter what (e.g., KeyboardInterrupt)
 189             if timeout is None:
 190                 waiter.acquire()
 191                 if __debug__:
 192                     self._note("%s.wait(): got it", self)
 193             else:
 194                 endtime = _time() + timeout
 195                 delay = 0.000001 # 1 usec
 196                 while 1:
 197                     gotit = waiter.acquire(0)
 198                     if gotit or _time() >= endtime:
 199                         break
 200                     _sleep(delay)
 201                     if delay < 1.0:
 202                         delay = delay * 2.0
 203                 if not gotit:
 204                     if __debug__:
 205                         self._note("%s.wait(%s): timed out", self, timeout)
 206                     try:
 207                         self.__waiters.remove(waiter)
 208                     except ValueError:
 209                         pass
 210                 else:
 211                     if __debug__:
 212                         self._note("%s.wait(%s): got it", self, timeout)
 213         finally:
 214             self._acquire_restore(saved_state)
 215
 216     def notify(self, n=1):
 217         me = currentThread()
 218         assert self._is_owned(), "notify() of un-acquire()d lock"
 219         __waiters = self.__waiters
 220         waiters = __waiters[:n]
 221         if not waiters:
 222             if __debug__:
 223                 self._note("%s.notify(): no waiters", self)
 224             return
 225         self._note("%s.notify(): notifying %d waiter%s", self, n,
 226                    n!=1 and "s" or "")
 227         for waiter in waiters:
 228             waiter.release()
 229             try:
 230                 __waiters.remove(waiter)
 231             except ValueError:
 232                 pass
 233
 234     def notifyAll(self):
 235         self.notify(len(self.__waiters))
 236
 237
 238 def Semaphore(*args, **kwargs):
 239     return apply(_Semaphore, args, kwargs)
 240
 241 class _Semaphore(_Verbose):
 242
 243     # After Tim Peters' semaphore class, but not quite the same (no maximum)
 244
 245     def __init__(self, value=1, verbose=None):
 246         assert value >= 0, "Semaphore initial value must be >= 0"
 247         _Verbose.__init__(self, verbose)
 248         self.__cond = Condition(Lock())
 249         self.__value = value
 250
 251     def acquire(self, blocking=1):
 252         rc = 0
 253         self.__cond.acquire()
 254         while self.__value == 0:
 255             if not blocking:
 256                 break
 257             self.__cond.wait()
 258         else:
 259             self.__value = self.__value - 1
 260             rc = 1
 261         self.__cond.release()
 262         return rc
 263
 264     def release(self):
 265         self.__cond.acquire()
 266         self.__value = self.__value + 1
 267         self.__cond.notify()
 268         self.__cond.release()
 269
 270
 271 def Event(*args, **kwargs):
 272     return apply(_Event, args, kwargs)
 273
 274 class _Event(_Verbose):
 275
 276     # After Tim Peters' event class (without is_posted())
 277
 278     def __init__(self, verbose=None):
 279         _Verbose.__init__(self, verbose)
 280         self.__cond = Condition(Lock())
 281         self.__flag = 0
 282
 283     def isSet(self):
 284         return self.__flag
 285
 286     def set(self):
 287         self.__cond.acquire()
 288         self.__flag = 1
 289         self.__cond.notifyAll()
 290         self.__cond.release()
 291
 292     def clear(self):
 293         self.__cond.acquire()
 294         self.__flag = 0
 295         self.__cond.release()
 296
 297     def wait(self, timeout=None):
 298         self.__cond.acquire()
 299         if not self.__flag:
 300             self.__cond.wait(timeout)
 301         self.__cond.release()
 302
 303
 304 # Helper to generate new thread names
 305 _counter = 0
 306 def _newname(template="Thread-%d"):
 307     global _counter
 308     _counter = _counter + 1
 309     return template % _counter
 310
 311 # Active thread administration
 312 _active_limbo_lock = _allocate_lock()
 313 _active = {}
 314 _limbo = {}
 315
 316
 317 # Main class for threads
 318
 319 class Thread(_Verbose):
 320
 321     __initialized = 0
 322
 323     def __init__(self, group=None, target=None, name=None,
 324                  args=(), kwargs={}, verbose=None):
 325         assert group is None, "group argument must be None for now"
 326         _Verbose.__init__(self, verbose)
 327         self.__target = target
 328         self.__name = str(name or _newname())
 329         self.__args = args
 330         self.__kwargs = kwargs
 331         self.__daemonic = self._set_daemon()
 332         self.__started = 0
 333         self.__stopped = 0
 334         self.__block = Condition(Lock())
 335         self.__initialized = 1
 336
 337     def _set_daemon(self):
 338         # Overridden in _MainThread and _DummyThread
 339         return currentThread().isDaemon()
 340
 341     def __repr__(self):
 342         assert self.__initialized, "Thread.__init__() was not called"
 343         status = "initial"
 344         if self.__started:
 345             status = "started"
 346         if self.__stopped:
 347             status = "stopped"
 348         if self.__daemonic:
 349             status = status + " daemon"
 350         return "<%s(%s, %s)>" % (self.__class__.__name__, self.__name, status)
 351
 352     def start(self):
 353         assert self.__initialized, "Thread.__init__() not called"
 354         assert not self.__started, "thread already started"
 355         if __debug__:
 356             self._note("%s.start(): starting thread", self)
 357         _active_limbo_lock.acquire()
 358         _limbo[self] = self
 359         _active_limbo_lock.release()
 360         _start_new_thread(self.__bootstrap, ())
 361         self.__started = 1
 362         _sleep(0.000001)    # 1 usec, to let the thread run (Solaris hack)
 363
 364     def run(self):
 365         if self.__target:
 366             apply(self.__target, self.__args, self.__kwargs)
 367
 368     def __bootstrap(self):
 369         try:
 370             self.__started = 1
 371             _active_limbo_lock.acquire()
 372             _active[_get_ident()] = self
 373             del _limbo[self]
 374             _active_limbo_lock.release()
 375             if __debug__:
 376                 self._note("%s.__bootstrap(): thread started", self)
 377             try:
 378                 self.run()
 379             except SystemExit:
 380                 if __debug__:
 381                     self._note("%s.__bootstrap(): raised SystemExit", self)
 382             except:
 383                 if __debug__:
 384                     self._note("%s.__bootstrap(): unhandled exception", self)
 385                 s = _StringIO()
 386                 _print_exc(file=s)
 387                 _sys.stderr.write("Exception in thread %s:\n%s\n" %
 388                                  (self.getName(), s.getvalue()))
 389             else:
 390                 if __debug__:
 391                     self._note("%s.__bootstrap(): normal return", self)
 392         finally:
 393             self.__stop()
 394             try:
 395                 self.__delete()
 396             except:
 397                 pass
 398
 399     def __stop(self):
 400         self.__block.acquire()
 401         self.__stopped = 1
 402         self.__block.notifyAll()
 403         self.__block.release()
 404
 405     def __delete(self):
 406         _active_limbo_lock.acquire()
 407         del _active[_get_ident()]
 408         _active_limbo_lock.release()
 409
 410     def join(self, timeout=None):
 411         assert self.__initialized, "Thread.__init__() not called"
 412         assert self.__started, "cannot join thread before it is started"
 413         assert self is not currentThread(), "cannot join current thread"
 414         if __debug__:
 415             if not self.__stopped:
 416                 self._note("%s.join(): waiting until thread stops", self)
 417         self.__block.acquire()
 418         if timeout is None:
 419             while not self.__stopped:
 420                 self.__block.wait()
 421             if __debug__:
 422                 self._note("%s.join(): thread stopped", self)
 423         else:
 424             deadline = _time() + timeout
 425             while not self.__stopped:
 426                 delay = deadline - _time()
 427                 if delay <= 0:
 428                     if __debug__:
 429                         self._note("%s.join(): timed out", self)
 430                     break
 431                 self.__block.wait(delay)
 432             else:
 433                 if __debug__:
 434                     self._note("%s.join(): thread stopped", self)
 435         self.__block.release()
 436
 437     def getName(self):
 438         assert self.__initialized, "Thread.__init__() not called"
 439         return self.__name
 440
 441     def setName(self, name):
 442         assert self.__initialized, "Thread.__init__() not called"
 443         self.__name = str(name)
 444
 445     def isAlive(self):
 446         assert self.__initialized, "Thread.__init__() not called"
 447         return self.__started and not self.__stopped
 448
 449     def isDaemon(self):
 450         assert self.__initialized, "Thread.__init__() not called"
 451         return self.__daemonic
 452
 453     def setDaemon(self, daemonic):
 454         assert self.__initialized, "Thread.__init__() not called"
 455         assert not self.__started, "cannot set daemon status of active thread"
 456         self.__daemonic = daemonic
 457
 458
 459 # Special thread class to represent the main thread
 460 # This is garbage collected through an exit handler
 461
 462 class _MainThread(Thread):
 463
 464     def __init__(self):
 465         Thread.__init__(self, name="MainThread")
 466         self._Thread__started = 1
 467         _active_limbo_lock.acquire()
 468         _active[_get_ident()] = self
 469         _active_limbo_lock.release()
 470         import atexit
 471         atexit.register(self.__exitfunc)
 472
 473     def _set_daemon(self):
 474         return 0
 475
 476     def __exitfunc(self):
 477         self._Thread__stop()
 478         t = _pickSomeNonDaemonThread()
 479         if t:
 480             if __debug__:
 481                 self._note("%s: waiting for other threads", self)
 482         while t:
 483             t.join()
 484             t = _pickSomeNonDaemonThread()
 485         if __debug__:
 486             self._note("%s: exiting", self)
 487         self._Thread__delete()
 488
 489 def _pickSomeNonDaemonThread():
 490     for t in enumerate():
 491         if not t.isDaemon() and t.isAlive():
 492             return t
 493     return None
 494
 495
 496 # Dummy thread class to represent threads not started here.
 497 # These aren't garbage collected when they die,
 498 # nor can they be waited for.
 499 # Their purpose is to return *something* from currentThread().
 500 # They are marked as daemon threads so we won't wait for them
 501 # when we exit (conform previous semantics).
 502
 503 class _DummyThread(Thread):
 504
 505     def __init__(self):
 506         Thread.__init__(self, name=_newname("Dummy-%d"))
 507         self._Thread__started = 1
 508         _active_limbo_lock.acquire()
 509         _active[_get_ident()] = self
 510         _active_limbo_lock.release()
 511
 512     def _set_daemon(self):
 513         return 1
 514
 515     def join(self):
 516         assert 0, "cannot join a dummy thread"
 517
 518
 519 # Global API functions
 520
 521 def currentThread():
 522     try:
 523         return _active[_get_ident()]
 524     except KeyError:
 525         ##print "currentThread(): no current thread for", _get_ident()
 526         return _DummyThread()
 527
 528 def activeCount():
 529     _active_limbo_lock.acquire()
 530     count = len(_active) + len(_limbo)
 531     _active_limbo_lock.release()
 532     return count
 533
 534 def enumerate():
 535     _active_limbo_lock.acquire()
 536     active = _active.values() + _limbo.values()
 537     _active_limbo_lock.release()
 538     return active
 539
 540
 541 # Create the main thread object
 542
 543 _MainThread()
 544
 545
 546 # Self-test code
 547
 548 def _test():
 549
 550     import random
 551
 552     class BoundedQueue(_Verbose):
 553
 554         def __init__(self, limit):
 555             _Verbose.__init__(self)
 556             self.mon = RLock()
 557             self.rc = Condition(self.mon)
 558             self.wc = Condition(self.mon)
 559             self.limit = limit
 560             self.queue = []
 561
 562         def put(self, item):
 563             self.mon.acquire()
 564             while len(self.queue) >= self.limit:
 565                 self._note("put(%s): queue full", item)
 566                 self.wc.wait()
 567             self.queue.append(item)
 568             self._note("put(%s): appended, length now %d",
 569                        item, len(self.queue))
 570             self.rc.notify()
 571             self.mon.release()
 572
 573         def get(self):
 574             self.mon.acquire()
 575             while not self.queue:
 576                 self._note("get(): queue empty")
 577                 self.rc.wait()
 578             item = self.queue[0]
 579             del self.queue[0]
 580             self._note("get(): got %s, %d left", item, len(self.queue))
 581             self.wc.notify()
 582             self.mon.release()
 583             return item
 584
 585     class ProducerThread(Thread):
 586
 587         def __init__(self, queue, quota):
 588             Thread.__init__(self, name="Producer")
 589             self.queue = queue
 590             self.quota = quota
 591
 592         def run(self):
 593             from random import random
 594             counter = 0
 595             while counter < self.quota:
 596                 counter = counter + 1
 597                 self.queue.put("%s.%d" % (self.getName(), counter))
 598                 _sleep(random() * 0.00001)
 599
 600
 601     class ConsumerThread(Thread):
 602
 603         def __init__(self, queue, count):
 604             Thread.__init__(self, name="Consumer")
 605             self.queue = queue
 606             self.count = count
 607
 608         def run(self):
 609             while self.count > 0:
 610                 item = self.queue.get()
 611                 print item
 612                 self.count = self.count - 1
 613
 614     import time
 615
 616     NP = 3
 617     QL = 4
 618     NI = 5
 619
 620     Q = BoundedQueue(QL)
 621     P = []
 622     for i in range(NP):
 623         t = ProducerThread(Q, NI)
 624         t.setName("Producer-%d" % (i+1))
 625         P.append(t)
 626     C = ConsumerThread(Q, NI*NP)
 627     for t in P:
 628         t.start()
 629         _sleep(0.000001)
 630     C.start()
 631     for t in P:
 632         t.join()
 633     C.join()
 634
 635 if __name__ == '__main__':
 636     _test()