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| 1 | +"""Drop-in replacement for the thread module. |
| 2 | +
|
| 3 | +Meant to be used as a brain-dead substitute so that threaded code does |
| 4 | +not need to be rewritten for when the thread module is not present. |
| 5 | +
|
| 6 | +Suggested usage is:: |
| 7 | +
|
| 8 | + try: |
| 9 | + import _thread |
| 10 | + except ImportError: |
| 11 | + import _dummy_thread as _thread |
| 12 | +
|
| 13 | +""" |
| 14 | +# Exports only things specified by thread documentation; |
| 15 | +# skipping obsolete synonyms allocate(), start_new(), exit_thread(). |
| 16 | +__all__ = ['error', 'start_new_thread', 'exit', 'get_ident', 'allocate_lock', |
| 17 | + 'interrupt_main', 'LockType'] |
| 18 | + |
| 19 | +# A dummy value |
| 20 | +TIMEOUT_MAX = 2**31 |
| 21 | + |
| 22 | +# NOTE: this module can be imported early in the extension building process, |
| 23 | +# and so top level imports of other modules should be avoided. Instead, all |
| 24 | +# imports are done when needed on a function-by-function basis. Since threads |
| 25 | +# are disabled, the import lock should not be an issue anyway (??). |
| 26 | + |
| 27 | +error = RuntimeError |
| 28 | + |
| 29 | +def start_new_thread(function, args, kwargs={}): |
| 30 | + """Dummy implementation of _thread.start_new_thread(). |
| 31 | +
|
| 32 | + Compatibility is maintained by making sure that ``args`` is a |
| 33 | + tuple and ``kwargs`` is a dictionary. If an exception is raised |
| 34 | + and it is SystemExit (which can be done by _thread.exit()) it is |
| 35 | + caught and nothing is done; all other exceptions are printed out |
| 36 | + by using traceback.print_exc(). |
| 37 | +
|
| 38 | + If the executed function calls interrupt_main the KeyboardInterrupt will be |
| 39 | + raised when the function returns. |
| 40 | +
|
| 41 | + """ |
| 42 | + if type(args) != type(tuple()): |
| 43 | + raise TypeError("2nd arg must be a tuple") |
| 44 | + if type(kwargs) != type(dict()): |
| 45 | + raise TypeError("3rd arg must be a dict") |
| 46 | + global _main |
| 47 | + _main = False |
| 48 | + try: |
| 49 | + function(*args, **kwargs) |
| 50 | + except SystemExit: |
| 51 | + pass |
| 52 | + except: |
| 53 | + import traceback |
| 54 | + traceback.print_exc() |
| 55 | + _main = True |
| 56 | + global _interrupt |
| 57 | + if _interrupt: |
| 58 | + _interrupt = False |
| 59 | + raise KeyboardInterrupt |
| 60 | + |
| 61 | +def exit(): |
| 62 | + """Dummy implementation of _thread.exit().""" |
| 63 | + raise SystemExit |
| 64 | + |
| 65 | +def get_ident(): |
| 66 | + """Dummy implementation of _thread.get_ident(). |
| 67 | +
|
| 68 | + Since this module should only be used when _threadmodule is not |
| 69 | + available, it is safe to assume that the current process is the |
| 70 | + only thread. Thus a constant can be safely returned. |
| 71 | + """ |
| 72 | + return 1 |
| 73 | + |
| 74 | +def allocate_lock(): |
| 75 | + """Dummy implementation of _thread.allocate_lock().""" |
| 76 | + return LockType() |
| 77 | + |
| 78 | +def stack_size(size=None): |
| 79 | + """Dummy implementation of _thread.stack_size().""" |
| 80 | + if size is not None: |
| 81 | + raise error("setting thread stack size not supported") |
| 82 | + return 0 |
| 83 | + |
| 84 | +def _set_sentinel(): |
| 85 | + """Dummy implementation of _thread._set_sentinel().""" |
| 86 | + return LockType() |
| 87 | + |
| 88 | +class LockType(object): |
| 89 | + """Class implementing dummy implementation of _thread.LockType. |
| 90 | +
|
| 91 | + Compatibility is maintained by maintaining self.locked_status |
| 92 | + which is a boolean that stores the state of the lock. Pickling of |
| 93 | + the lock, though, should not be done since if the _thread module is |
| 94 | + then used with an unpickled ``lock()`` from here problems could |
| 95 | + occur from this class not having atomic methods. |
| 96 | +
|
| 97 | + """ |
| 98 | + |
| 99 | + def __init__(self): |
| 100 | + self.locked_status = False |
| 101 | + |
| 102 | + def acquire(self, waitflag=None, timeout=-1): |
| 103 | + """Dummy implementation of acquire(). |
| 104 | +
|
| 105 | + For blocking calls, self.locked_status is automatically set to |
| 106 | + True and returned appropriately based on value of |
| 107 | + ``waitflag``. If it is non-blocking, then the value is |
| 108 | + actually checked and not set if it is already acquired. This |
| 109 | + is all done so that threading.Condition's assert statements |
| 110 | + aren't triggered and throw a little fit. |
| 111 | +
|
| 112 | + """ |
| 113 | + if waitflag is None or waitflag: |
| 114 | + self.locked_status = True |
| 115 | + return True |
| 116 | + else: |
| 117 | + if not self.locked_status: |
| 118 | + self.locked_status = True |
| 119 | + return True |
| 120 | + else: |
| 121 | + if timeout > 0: |
| 122 | + import time |
| 123 | + time.sleep(timeout) |
| 124 | + return False |
| 125 | + |
| 126 | + __enter__ = acquire |
| 127 | + |
| 128 | + def __exit__(self, typ, val, tb): |
| 129 | + self.release() |
| 130 | + |
| 131 | + def release(self): |
| 132 | + """Release the dummy lock.""" |
| 133 | + # XXX Perhaps shouldn't actually bother to test? Could lead |
| 134 | + # to problems for complex, threaded code. |
| 135 | + if not self.locked_status: |
| 136 | + raise error |
| 137 | + self.locked_status = False |
| 138 | + return True |
| 139 | + |
| 140 | + def locked(self): |
| 141 | + return self.locked_status |
| 142 | + |
| 143 | + def __repr__(self): |
| 144 | + return "<%s %s.%s object at %s>" % ( |
| 145 | + "locked" if self.locked_status else "unlocked", |
| 146 | + self.__class__.__module__, |
| 147 | + self.__class__.__qualname__, |
| 148 | + hex(id(self)) |
| 149 | + ) |
| 150 | + |
| 151 | +# Used to signal that interrupt_main was called in a "thread" |
| 152 | +_interrupt = False |
| 153 | +# True when not executing in a "thread" |
| 154 | +_main = True |
| 155 | + |
| 156 | +def interrupt_main(): |
| 157 | + """Set _interrupt flag to True to have start_new_thread raise |
| 158 | + KeyboardInterrupt upon exiting.""" |
| 159 | + if _main: |
| 160 | + raise KeyboardInterrupt |
| 161 | + else: |
| 162 | + global _interrupt |
| 163 | + _interrupt = True |
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