"""Thread module emulating a subset of Java's threading model."""

import sys as _sys

import _thread

from time import monotonic as _time

from traceback import format_exc as _format_exc

from _weakrefset import WeakSet

from itertools import islice as _islice, count as _count

try:

    from _collections import deque as _deque

except ImportError:

    from collections import deque as _deque

# Note regarding PEP 8 compliant names

#  This threading model was originally inspired by Java, and inherited

# the convention of camelCase function and method names from that

# language. Those original names are not in any imminent danger of

# being deprecated (even for Py3k),so this module provides them as an

# alias for the PEP 8 compliant names

# Note that using the new PEP 8 compliant names facilitates substitution

# with the multiprocessing module, which doesn't provide the old

# Java inspired names.

__all__ = ['get_ident', 'active_count', 'Condition', 'current_thread',

           'enumerate', 'main_thread', 'TIMEOUT_MAX',

           'Event', 'Lock', 'RLock', 'Semaphore', 'BoundedSemaphore', 'Thread',

           'Barrier', 'BrokenBarrierError', 'Timer', 'ThreadError',

           'setprofile', 'settrace', 'local', 'stack_size']

# Rename some stuff so "from threading import *" is safe

_start_new_thread = _thread.start_new_thread

_allocate_lock = _thread.allocate_lock

_set_sentinel = _thread._set_sentinel

get_ident = _thread.get_ident

ThreadError = _thread.error

try:

    _CRLock = _thread.RLock

except AttributeError:

    _CRLock = None

TIMEOUT_MAX = _thread.TIMEOUT_MAX

del _thread

# Support for profile and trace hooks

_profile_hook = None

_trace_hook = None

def setprofile(func):

    """Set a profile function for all threads started from the threading module.

    The func will be passed to sys.setprofile() for each thread, before its

    run() method is called.

    """

    global _profile_hook

    _profile_hook = func

def settrace(func):

    """Set a trace function for all threads started from the threading module.

    The func will be passed to sys.settrace() for each thread, before its run()

    method is called.

    """

    global _trace_hook

    _trace_hook = func

# Synchronization classes

Lock = _allocate_lock

def RLock(*args, **kwargs):

    """Factory function that returns a new reentrant lock.

    A reentrant lock must be released by the thread that acquired it. Once a

    thread has acquired a reentrant lock, the same thread may acquire it again

    without blocking; the thread must release it once for each time it has

    acquired it.

    """

    if _CRLock is None:

        return _PyRLock(*args, **kwargs)

    return _CRLock(*args, **kwargs)

class _RLock:

    """This class implements reentrant lock objects.

    A reentrant lock must be released by the thread that acquired it. Once a

    thread has acquired a reentrant lock, the same thread may acquire it

    again without blocking; the thread must release it once for each time it

    has acquired it.

    """

    def __init__(self):

        self._block = _allocate_lock()

        self._owner = None

        self._count = 0

    def __repr__(self):

        owner = self._owner

        try:

            owner = _active[owner].name

        except KeyError:

            pass

        return "<%s %s.%s object owner=%r count=%d at %s>" % (

            "locked" if self._block.locked() else "unlocked",

            self.__class__.__module__,

            self.__class__.__qualname__,

            owner,

            self._count,

            hex(id(self))

        )

    def acquire(self, blocking=True, timeout=-1):

        """Acquire a lock, blocking or non-blocking.

        When invoked without arguments: if this thread already owns the lock,

        increment the recursion level by one, and return immediately. Otherwise,

        if another thread owns the lock, block until the lock is unlocked. Once

        the lock is unlocked (not owned by any thread), then grab ownership, set

        the recursion level to one, and return. If more than one thread is

        blocked waiting until the lock is unlocked, only one at a time will be

        able to grab ownership of the lock. There is no return value in this

        case.

        When invoked with the blocking argument set to true, do the same thing

        as when called without arguments, and return true.

        When invoked with the blocking argument set to false, do not block. If a

        call without an argument would block, return false immediately;

        otherwise, do the same thing as when called without arguments, and

        return true.

        When invoked with the floating-point timeout argument set to a positive

        value, block for at most the number of seconds specified by timeout

        and as long as the lock cannot be acquired.  Return true if the lock has

        been acquired, false if the timeout has elapsed.

        """

        me = get_ident()

        if self._owner == me:

            self._count += 1

            return 1

        rc = self._block.acquire(blocking, timeout)

        if rc:

            self._owner = me

            self._count = 1

        return rc

    __enter__ = acquire

    def release(self):

        """Release a lock, decrementing the recursion level.

        If after the decrement it is zero, reset the lock to unlocked (not owned

        by any thread), and if any other threads are blocked waiting for the

        lock to become unlocked, allow exactly one of them to proceed. If after

        the decrement the recursion level is still nonzero, the lock remains

        locked and owned by the calling thread.

        Only call this method when the calling thread owns the lock. A

        RuntimeError is raised if this method is called when the lock is

        unlocked.

        There is no return value.

        """

        if self._owner != get_ident():

            raise RuntimeError("cannot release un-acquired lock")

        self._count = count = self._count - 1

        if not count:

            self._owner = None

            self._block.release()

    def __exit__(self, t, v, tb):

        self.release()

    # Internal methods used by condition variables

    def _acquire_restore(self, state):

        self._block.acquire()

        self._count, self._owner = state

    def _release_save(self):

        if self._count == 0:

            raise RuntimeError("cannot release un-acquired lock")

        count = self._count

        self._count = 0

        owner = self._owner

        self._owner = None

        self._block.release()

        return (count, owner)

    def _is_owned(self):

        return self._owner == get_ident()

_PyRLock = _RLock

class Condition:

    """Class that implements a condition variable.

    A condition variable allows one or more threads to wait until they are

    notified by another thread.

    If the lock argument is given and not None, it must be a Lock or RLock

    object, and it is used as the underlying lock. Otherwise, a new RLock object

    is created and used as the underlying lock.

    """

    def __init__(self, lock=None):

        if lock is None:

            lock = RLock()

        self._lock = lock

        # Export the lock's acquire() and release() methods

        self.acquire = lock.acquire

        self.release = lock.release

        # If the lock defines _release_save() and/or _acquire_restore(),

        # these override the default implementations (which just call

        # release() and acquire() on the lock).  Ditto for _is_owned().

        try:

            self._release_save = lock._release_save

        except AttributeError:

            pass

        try:

            self._acquire_restore = lock._acquire_restore

        except AttributeError:

            pass

        try:

            self._is_owned = lock._is_owned

        except AttributeError:

            pass

        self._waiters = _deque()

    def __enter__(self):

        return self._lock.__enter__()

    def __exit__(self, *args):

        return self._lock.__exit__(*args)

    def __repr__(self):

        return "<Condition(%s, %d)>" % (self._lock, len(self._waiters))

    def _release_save(self):

        self._lock.release()           # No state to save

    def _acquire_restore(self, x):

        self._lock.acquire()           # Ignore saved state

    def _is_owned(self):

        # Return True if lock is owned by current_thread.

        # This method is called only if _lock doesn't have _is_owned().

        if self._lock.acquire(0):

            self._lock.release()

            return False

        else:

            return True

    def wait(self, timeout=None):

        """Wait until notified or until a timeout occurs.

        If the calling thread has not acquired the lock when this method is

        called, a RuntimeError is raised.

        This method releases the underlying lock, and then blocks until it is

        awakened by a notify() or notify_all() call for the same condition

        variable in another thread, or until the optional timeout occurs. Once

        awakened or timed out, it re-acquires the lock and returns.

        When the timeout argument is present and not None, it should be a

        floating point number specifying a timeout for the operation in seconds

        (or fractions thereof).

        When the underlying lock is an RLock, it is not released using its

        release() method, since this may not actually unlock the lock when it

        was acquired multiple times recursively. Instead, an internal interface

        of the RLock class is used, which really unlocks it even when it has

        been recursively acquired several times. Another internal interface is

        then used to restore the recursion level when the lock is reacquired.

        """

        if not self._is_owned():

            raise RuntimeError("cannot wait on un-acquired lock")

        waiter = _allocate_lock()

        waiter.acquire()

        self._waiters.append(waiter)

        saved_state = self._release_save()

        gotit = False

        try:    # restore state no matter what (e.g., KeyboardInterrupt)

            if timeout is None:

                waiter.acquire()

                gotit = True

            else:

                if timeout > 0:

                    gotit = waiter.acquire(True, timeout)

                else:

                    gotit = waiter.acquire(False)

            return gotit

        finally:

            self._acquire_restore(saved_state)

            if not gotit:

                try:

                    self._waiters.remove(waiter)

                except ValueError:

                    pass

    def wait_for(self, predicate, timeout=None):

        """Wait until a condition evaluates to True.

        predicate should be a callable which result will be interpreted as a

        boolean value.  A timeout may be provided giving the maximum time to

        wait.

        """

        endtime = None

        waittime = timeout

        result = predicate()

        while not result:

            if waittime is not None:

                if endtime is None:

                    endtime = _time() + waittime

                else:

                    waittime = endtime - _time()

                    if waittime <= 0:

                        break

            self.wait(waittime)

            result = predicate()

        return result

    def notify(self, n=1):

        """Wake up one or more threads waiting on this condition, if any.

        If the calling thread has not acquired the lock when this method is

        called, a RuntimeError is raised.

        This method wakes up at most n of the threads waiting for the condition

        variable; it is a no-op if no threads are waiting.

        """

        if not self._is_owned():

            raise RuntimeError("cannot notify on un-acquired lock")

        all_waiters = self._waiters

        waiters_to_notify = _deque(_islice(all_waiters, n))

        if not waiters_to_notify:

            return

        for waiter in waiters_to_notify:

            waiter.release()

            try:

                all_waiters.remove(waiter)

            except ValueError:

                pass

    def notify_all(self):

        """Wake up all threads waiting on this condition.

        If the calling thread has not acquired the lock when this method

        is called, a RuntimeError is raised.

        """

        self.notify(len(self._waiters))

    notifyAll = notify_all

class Semaphore:

    """This class implements semaphore objects.

    Semaphores manage a counter representing the number of release() calls minus

    the number of acquire() calls, plus an initial value. The acquire() method

    blocks if necessary until it can return without making the counter

    negative. If not given, value defaults to 1.

    """

    # After Tim Peters' semaphore class, but not quite the same (no maximum)

    def __init__(self, value=1):

        if value < 0:

            raise ValueError("semaphore initial value must be >= 0")

        self._cond = Condition(Lock())

        self._value = value

    def acquire(self, blocking=True, timeout=None):

        """Acquire a semaphore, decrementing the internal counter by one.

        When invoked without arguments: if the internal counter is larger than

        zero on entry, decrement it by one and return immediately. If it is zero

        on entry, block, waiting until some other thread has called release() to

        make it larger than zero. This is done with proper interlocking so that

        if multiple acquire() calls are blocked, release() will wake exactly one

        of them up. The implementation may pick one at random, so the order in

        which blocked threads are awakened should not be relied on. There is no

        return value in this case.

        When invoked with blocking set to true, do the same thing as when called

        without arguments, and return true.

        When invoked with blocking set to false, do not block. If a call without

        an argument would block, return false immediately; otherwise, do the

        same thing as when called without arguments, and return true.

        When invoked with a timeout other than None, it will block for at

        most timeout seconds.  If acquire does not complete successfully in

        that interval, return false.  Return true otherwise.

        """

        if not blocking and timeout is not None:

            raise ValueError("can't specify timeout for non-blocking acquire")

        rc = False

        endtime = None

        with self._cond:

            while self._value == 0:

                if not blocking:

                    break

                if timeout is not None:

                    if endtime is None:

                        endtime = _time() + timeout

                    else:

                        timeout = endtime - _time()

                        if timeout <= 0:

                            break

                self._cond.wait(timeout)

            else:

                self._value -= 1

                rc = True

        return rc

    __enter__ = acquire

    def release(self):

        """Release a semaphore, incrementing the internal counter by one.

        When the counter is zero on entry and another thread is waiting for it

        to become larger than zero again, wake up that thread.

        """

        with self._cond:

            self._value += 1

            self._cond.notify()

    def __exit__(self, t, v, tb):

        self.release()

class BoundedSemaphore(Semaphore):

    """Implements a bounded semaphore.

    A bounded semaphore checks to make sure its current value doesn't exceed its

    initial value. If it does, ValueError is raised. In most situations

    semaphores are used to guard resources with limited capacity.

    If the semaphore is released too many times it's a sign of a bug. If not

    given, value defaults to 1.

    Like regular semaphores, bounded semaphores manage a counter representing

    the number of release() calls minus the number of acquire() calls, plus an

    initial value. The acquire() method blocks if necessary until it can return

    without making the counter negative. If not given, value defaults to 1.

    """

    def __init__(self, value=1):

        Semaphore.__init__(self, value)

        self._initial_value = value

    def release(self):

        """Release a semaphore, incrementing the internal counter by one.

        When the counter is zero on entry and another thread is waiting for it

        to become larger than zero again, wake up that thread.

        If the number of releases exceeds the number of acquires,

        raise a ValueError.

        """

        with self._cond:

            if self._value >= self._initial_value:

                raise ValueError("Semaphore released too many times")

            self._value += 1

            self._cond.notify()

class Event:

    """Class implementing event objects.

    Events manage a flag that can be set to true with the set() method and reset

    to false with the clear() method. The wait() method blocks until the flag is

    true.  The flag is initially false.

    """

    # After Tim Peters' event class (without is_posted())

    def __init__(self):

        self._cond = Condition(Lock())

        self._flag = False

    def _reset_internal_locks(self):

        # private!  called by Thread._reset_internal_locks by _after_fork()

        self._cond.__init__(Lock())

    def is_set(self):

        """Return true if and only if the internal flag is true."""

        return self._flag

    isSet = is_set

    def set(self):

        """Set the internal flag to true.

        All threads waiting for it to become true are awakened. Threads

        that call wait() once the flag is true will not block at all.

        """

        with self._cond:

            self._flag = True

            self._cond.notify_all()

    def clear(self):

        """Reset the internal flag to false.

        Subsequently, threads calling wait() will block until set() is called to

        set the internal flag to true again.

        """

        with self._cond:

            self._flag = False

    def wait(self, timeout=None):

        """Block until the internal flag is true.

        If the internal flag is true on entry, return immediately. Otherwise,

        block until another thread calls set() to set the flag to true, or until

        the optional timeout occurs.

        When the timeout argument is present and not None, it should be a

        floating point number specifying a timeout for the operation in seconds

        (or fractions thereof).

        This method returns the internal flag on exit, so it will always return

        True except if a timeout is given and the operation times out.

        """

        with self._cond:

            signaled = self._flag

            if not signaled:

                signaled = self._cond.wait(timeout)

            return signaled

# A barrier class.  Inspired in part by the pthread_barrier_* api and

# the CyclicBarrier class from Java.  See

# http://sourceware.org/pthreads-win32/manual/pthread_barrier_init.html and

# http://java.sun.com/j2se/1.5.0/docs/api/java/util/concurrent/

#        CyclicBarrier.html

# for information.

# We maintain two main states, 'filling' and 'draining' enabling the barrier

# to be cyclic.  Threads are not allowed into it until it has fully drained

# since the previous cycle.  In addition, a 'resetting' state exists which is

# similar to 'draining' except that threads leave with a BrokenBarrierError,

# and a 'broken' state in which all threads get the exception.

class Barrier:

    """Implements a Barrier.

    Useful for synchronizing a fixed number of threads at known synchronization

    points.  Threads block on 'wait()' and are simultaneously once they have all

    made that call.

    """

    def __init__(self, parties, action=None, timeout=None):

        """Create a barrier, initialised to 'parties' threads.

        'action' is a callable which, when supplied, will be called by one of

        the threads after they have all entered the barrier and just prior to

        releasing them all. If a 'timeout' is provided, it is uses as the

        default for all subsequent 'wait()' calls.

        """

        self._cond = Condition(Lock())

        self._action = action

        self._timeout = timeout

        self._parties = parties

        self._state = 0 #0 filling, 1, draining, -1 resetting, -2 broken

        self._count = 0

    def wait(self, timeout=None):

        """Wait for the barrier.

        When the specified number of threads have started waiting, they are all

        simultaneously awoken. If an 'action' was provided for the barrier, one

        of the threads will have executed that callback prior to returning.

        Returns an individual index number from 0 to 'parties-1'.

        """

        if timeout is None:

            timeout = self._timeout

        with self._cond:

            self._enter() # Block while the barrier drains.

            index = self._count

            self._count += 1

            try:

                if index + 1 == self._parties:

                    # We release the barrier

                    self._release()

                else:

                    # We wait until someone releases us

                    self._wait(timeout)

                return index

            finally:

                self._count -= 1

                # Wake up any threads waiting for barrier to drain.

                self._exit()

    # Block until the barrier is ready for us, or raise an exception

    # if it is broken.

    def _enter(self):

        while self._state in (-1, 1):

            # It is draining or resetting, wait until done

            self._cond.wait()

        #see if the barrier is in a broken state

        if self._state < 0:

            raise BrokenBarrierError

        assert self._state == 0

    # Optionally run the 'action' and release the threads waiting

    # in the barrier.

    def _release(self):

        try:

            if self._action:

                self._action()

            # enter draining state

            self._state = 1

            self._cond.notify_all()

        except:

            #an exception during the _action handler.  Break and reraise

            self._break()

            raise

    # Wait in the barrier until we are released.  Raise an exception

    # if the barrier is reset or broken.

    def _wait(self, timeout):

        if not self._cond.wait_for(lambda : self._state != 0, timeout):

            #timed out.  Break the barrier

            self._break()

            raise BrokenBarrierError

        if self._state < 0:

            raise BrokenBarrierError

        assert self._state == 1

    # If we are the last thread to exit the barrier, signal any threads

    # waiting for the barrier to drain.

    def _exit(self):

        if self._count == 0:

            if self._state in (-1, 1):

                #resetting or draining

                self._state = 0

                self._cond.notify_all()

    def reset(self):

        """Reset the barrier to the initial state.

        Any threads currently waiting will get the BrokenBarrier exception

        raised.

        """

        with self._cond:

            if self._count > 0:

                if self._state == 0:

                    #reset the barrier, waking up threads

                    self._state = -1

                elif self._state == -2:

                    #was broken, set it to reset state

                    #which clears when the last thread exits

                    self._state = -1

            else:

                self._state = 0

            self._cond.notify_all()

    def abort(self):

        """Place the barrier into a 'broken' state.

        Useful in case of error.  Any currently waiting threads and threads

        attempting to 'wait()' will have BrokenBarrierError raised.

        """

        with self._cond:

            self._break()

    def _break(self):

        # An internal error was detected.  The barrier is set to

        # a broken state all parties awakened.

        self._state = -2

        self._cond.notify_all()

    @property

    def parties(self):

        """Return the number of threads required to trip the barrier."""

        return self._parties

    @property

    def n_waiting(self):

        """Return the number of threads currently waiting at the barrier."""

        # We don't need synchronization here since this is an ephemeral result

        # anyway.  It returns the correct value in the steady state.

        if self._state == 0:

            return self._count

        return 0

    @property

    def broken(self):

        """Return True if the barrier is in a broken state."""

        return self._state == -2

# exception raised by the Barrier class

class BrokenBarrierError(RuntimeError):

    pass

# Helper to generate new thread names

_counter = _count().__next__

_counter() # Consume 0 so first non-main thread has id 1.

def _newname(template="Thread-%d"):

    return template % _counter()

# Active thread administration

_active_limbo_lock = _allocate_lock()

_active = {}    # maps thread id to Thread object

_limbo = {}

_dangling = WeakSet()

# Main class for threads

class Thread:

    """A class that represents a thread of control.

    This class can be safely subclassed in a limited fashion. There are two ways

    to specify the activity: by passing a callable object to the constructor, or

    by overriding the run() method in a subclass.

    """

    _initialized = False

    # Need to store a reference to sys.exc_info for printing

    # out exceptions when a thread tries to use a global var. during interp.

    # shutdown and thus raises an exception about trying to perform some

    # operation on/with a NoneType

    _exc_info = _sys.exc_info

    # Keep sys.exc_clear too to clear the exception just before

    # allowing .join() to return.

    #XXX __exc_clear = _sys.exc_clear

    def __init__(self, group=None, target=None, name=None,

                 args=(), kwargs=None, *, daemon=None):

        """This constructor should always be called with keyword arguments. Arguments are:

        *group* should be None; reserved for future extension when a ThreadGroup

        class is implemented.

        *target* is the callable object to be invoked by the run()

        method. Defaults to None, meaning nothing is called.

        *name* is the thread name. By default, a unique name is constructed of

        the form "Thread-N" where N is a small decimal number.

        *args* is the argument tuple for the target invocation. Defaults to ().

        *kwargs* is a dictionary of keyword arguments for the target

        invocation. Defaults to {}.

        If a subclass overrides the constructor, it must make sure to invoke

        the base class constructor (Thread.__init__()) before doing anything

        else to the thread.

        """

        assert group is None, "group argument must be None for now"

        if kwargs is None:

            kwargs = {}

        self._target = target

        self._name = str(name or _newname())

        self._args = args

        self._kwargs = kwargs

        if daemon is not None:

            self._daemonic = daemon

        else:

            self._daemonic = current_thread().daemon

        self._ident = None

        self._tstate_lock = None

        self._started = Event()

        self._is_stopped = False

        self._initialized = True

        # sys.stderr is not stored in the class like

        # sys.exc_info since it can be changed between instances

        self._stderr = _sys.stderr

        # For debugging and _after_fork()

        _dangling.add(self)

    def _reset_internal_locks(self, is_alive):

        # private!  Called by _after_fork() to reset our internal locks as

        # they may be in an invalid state leading to a deadlock or crash.

        self._started._reset_internal_locks()

        if is_alive:

            self._set_tstate_lock()

        else:

            # The thread isn't alive after fork: it doesn't have a tstate

            # anymore.

            self._is_stopped = True

            self._tstate_lock = None

    def __repr__(self):

        assert self._initialized, "Thread.__init__() was not called"

        status = "initial"

        if self._started.is_set():

            status = "started"

        self.is_alive() # easy way to get ._is_stopped set when appropriate

        if self._is_stopped:

            status = "stopped"

        if self._daemonic:

            status += " daemon"

        if self._ident is not None:

            status += " %s" % self._ident

        return "<%s(%s, %s)>" % (self.__class__.__name__, self._name, status)

    def start(self):

        """Start the thread's activity.

        It must be called at most once per thread object. It arranges for the

        object's run() method to be invoked in a separate thread of control.

        This method will raise a RuntimeError if called more than once on the

        same thread object.

        """

        if not self._initialized:

            raise RuntimeError("thread.__init__() not called")

        if self._started.is_set():

            raise RuntimeError("threads can only be started once")

        with _active_limbo_lock:

            _limbo[self] = self

        try:

            _start_new_thread(self._bootstrap, ())

        except Exception:

            with _active_limbo_lock:

                del _limbo[self]

            raise

        self._started.wait()

    def run(self):

        """Method representing the thread's activity.

        You may override this method in a subclass. The standard run() method

        invokes the callable object passed to the object's constructor as the

        target argument, if any, with sequential and keyword arguments taken

        from the args and kwargs arguments, respectively.

        """

        try:

            if self._target:

                self._target(*self._args, **self._kwargs)

        finally:

            # Avoid a refcycle if the thread is running a function with

            # an argument that has a member that points to the thread.

            del self._target, self._args, self._kwargs

    def _bootstrap(self):

        # Wrapper around the real bootstrap code that ignores

        # exceptions during interpreter cleanup.  Those typically

        # happen when a daemon thread wakes up at an unfortunate

        # moment, finds the world around it destroyed, and raises some

        # random exception *** while trying to report the exception in

        # _bootstrap_inner() below ***.  Those random exceptions

        # don't help anybody, and they confuse users, so we suppress

        # them.  We suppress them only when it appears that the world

        # indeed has already been destroyed, so that exceptions in

        # _bootstrap_inner() during normal business hours are properly