| 1 | """Drop-in replacement for the thread module.
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| 2 |
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| 3 | Meant to be used as a brain-dead substitute so that threaded code does
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| 4 | not need to be rewritten for when the thread module is not present.
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| 5 |
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| 6 | Suggested usage is::
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| 7 |
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| 8 | try:
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| 9 | import thread
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| 10 | except ImportError:
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| 11 | import dummy_thread as thread
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| 12 |
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| 13 | """
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| 14 | # Exports only things specified by thread documentation;
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| 15 | # skipping obsolete synonyms allocate(), start_new(), exit_thread().
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| 16 | __all__ = ['error', 'start_new_thread', 'exit', 'get_ident', 'allocate_lock',
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| 17 | 'interrupt_main', 'LockType']
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| 18 |
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| 19 | import traceback as _traceback
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| 20 |
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| 21 | class error(Exception):
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| 22 | """Dummy implementation of thread.error."""
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| 23 |
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| 24 | def __init__(self, *args):
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| 25 | self.args = args
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| 26 |
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| 27 | def start_new_thread(function, args, kwargs={}):
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| 28 | """Dummy implementation of thread.start_new_thread().
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| 29 |
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| 30 | Compatibility is maintained by making sure that ``args`` is a
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| 31 | tuple and ``kwargs`` is a dictionary. If an exception is raised
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| 32 | and it is SystemExit (which can be done by thread.exit()) it is
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| 33 | caught and nothing is done; all other exceptions are printed out
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| 34 | by using traceback.print_exc().
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| 35 |
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| 36 | If the executed function calls interrupt_main the KeyboardInterrupt will be
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| 37 | raised when the function returns.
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| 38 |
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| 39 | """
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| 40 | if type(args) != type(tuple()):
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| 41 | raise TypeError("2nd arg must be a tuple")
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| 42 | if type(kwargs) != type(dict()):
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| 43 | raise TypeError("3rd arg must be a dict")
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| 44 | global _main
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| 45 | _main = False
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| 46 | try:
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| 47 | function(*args, **kwargs)
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| 48 | except SystemExit:
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| 49 | pass
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| 50 | except:
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| 51 | _traceback.print_exc()
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| 52 | _main = True
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| 53 | global _interrupt
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| 54 | if _interrupt:
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| 55 | _interrupt = False
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| 56 | raise KeyboardInterrupt
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| 57 |
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| 58 | def exit():
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| 59 | """Dummy implementation of thread.exit()."""
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| 60 | raise SystemExit
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| 61 |
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| 62 | def get_ident():
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| 63 | """Dummy implementation of thread.get_ident().
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| 64 |
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| 65 | Since this module should only be used when threadmodule is not
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| 66 | available, it is safe to assume that the current process is the
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| 67 | only thread. Thus a constant can be safely returned.
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| 68 | """
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| 69 | return -1
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| 70 |
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| 71 | def allocate_lock():
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| 72 | """Dummy implementation of thread.allocate_lock()."""
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| 73 | return LockType()
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| 74 |
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| 75 | def stack_size(size=None):
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| 76 | """Dummy implementation of thread.stack_size()."""
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| 77 | if size is not None:
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| 78 | raise error("setting thread stack size not supported")
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| 79 | return 0
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| 80 |
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| 81 | class LockType(object):
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| 82 | """Class implementing dummy implementation of thread.LockType.
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| 83 |
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| 84 | Compatibility is maintained by maintaining self.locked_status
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| 85 | which is a boolean that stores the state of the lock. Pickling of
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| 86 | the lock, though, should not be done since if the thread module is
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| 87 | then used with an unpickled ``lock()`` from here problems could
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| 88 | occur from this class not having atomic methods.
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| 89 |
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| 90 | """
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| 91 |
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| 92 | def __init__(self):
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| 93 | self.locked_status = False
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| 94 |
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| 95 | def acquire(self, waitflag=None):
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| 96 | """Dummy implementation of acquire().
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| 97 |
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| 98 | For blocking calls, self.locked_status is automatically set to
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| 99 | True and returned appropriately based on value of
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| 100 | ``waitflag``. If it is non-blocking, then the value is
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| 101 | actually checked and not set if it is already acquired. This
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| 102 | is all done so that threading.Condition's assert statements
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| 103 | aren't triggered and throw a little fit.
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| 104 |
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| 105 | """
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| 106 | if waitflag is None or waitflag:
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| 107 | self.locked_status = True
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| 108 | return True
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| 109 | else:
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| 110 | if not self.locked_status:
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| 111 | self.locked_status = True
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| 112 | return True
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| 113 | else:
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| 114 | return False
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| 115 |
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| 116 | __enter__ = acquire
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| 117 |
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| 118 | def __exit__(self, typ, val, tb):
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| 119 | self.release()
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| 120 |
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| 121 | def release(self):
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| 122 | """Release the dummy lock."""
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| 123 | # XXX Perhaps shouldn't actually bother to test? Could lead
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| 124 | # to problems for complex, threaded code.
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| 125 | if not self.locked_status:
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| 126 | raise error
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| 127 | self.locked_status = False
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| 128 | return True
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| 129 |
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| 130 | def locked(self):
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| 131 | return self.locked_status
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| 132 |
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| 133 | # Used to signal that interrupt_main was called in a "thread"
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| 134 | _interrupt = False
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| 135 | # True when not executing in a "thread"
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| 136 | _main = True
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| 137 |
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| 138 | def interrupt_main():
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| 139 | """Set _interrupt flag to True to have start_new_thread raise
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| 140 | KeyboardInterrupt upon exiting."""
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| 141 | if _main:
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| 142 | raise KeyboardInterrupt
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| 143 | else:
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| 144 | global _interrupt
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| 145 | _interrupt = True
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