45 lines
956 B
Python
45 lines
956 B
Python
"""
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Uses a trace function to switch greenlets at unexpected times.
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In the trace function, we switch from the current greenlet to another
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greenlet, which switches
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"""
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import greenlet
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g1 = None
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g2 = None
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switch_to_g2 = False
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def tracefunc(*args):
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print('TRACE', *args)
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global switch_to_g2
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if switch_to_g2:
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switch_to_g2 = False
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g2.switch()
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print('\tLEAVE TRACE', *args)
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def g1_run():
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print('In g1_run')
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global switch_to_g2
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switch_to_g2 = True
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from_parent = greenlet.getcurrent().parent.switch()
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print('Return to g1_run')
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print('From parent', from_parent)
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def g2_run():
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#g1.switch()
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greenlet.getcurrent().parent.switch()
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greenlet.settrace(tracefunc)
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g1 = greenlet.greenlet(g1_run)
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g2 = greenlet.greenlet(g2_run)
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# This switch didn't actually finish!
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# And if it did, it would raise TypeError
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# because g1_run() doesn't take any arguments.
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g1.switch(1)
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print('Back in main')
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g1.switch(2)
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