2132a74321
When exiting, the state's `is_initialized` flag is unset. Noticeable on Windows, when a thread tried to access the state's `exit_event` property to check whether it had been set, it would complain that the state was no longer initialized. Now, even when no longer initialized, if the `exit_event` is set, it will not raise an error when accessing this attribute. ref: N25B-119
53 lines
1.8 KiB
Python
53 lines
1.8 KiB
Python
import signal
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import threading
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class State(object):
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"""
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Do not create an instance of this class directly: use the instance `state` below. This state must be initiated once,
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probably when your program starts.
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This class is used to share state between threads. For example, when the program is quit, that all threads can
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detect this via the `exit_event` property being set.
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"""
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def __init__(self):
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self.is_initialized = False
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self.exit_event = None
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def initialize(self):
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if self.is_initialized:
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print("Already initialized")
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return
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self.exit_event = threading.Event()
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def handle_exit(_, __):
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print("Exiting.")
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self.exit_event.set()
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signal.signal(signal.SIGINT, handle_exit)
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signal.signal(signal.SIGTERM, handle_exit)
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self.is_initialized = True
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def deinitialize(self):
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if not self.is_initialized: return
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self.is_initialized = False
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def __getattribute__(self, name):
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# Enforce that the state is initialized before accessing any property (aside from the basic ones)
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if name in ("initialize", "deinitialize", "is_initialized", "__dict__", "__class__"):
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return object.__getattribute__(self, name)
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if not object.__getattribute__(self, "is_initialized"):
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# Special case for the exit_event: if the event is set, return it without an error
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if name == "exit_event":
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exit_event = object.__getattribute__(self, "exit_event")
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if exit_event and exit_event.is_set(): return exit_event
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raise RuntimeError("State must be initialized before accessing '%s'" % name)
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return object.__getattribute__(self, name)
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# Must call `.initialize` before use
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state = State()
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