305 lines
10 KiB
Python
305 lines
10 KiB
Python
from __future__ import print_function
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import gc
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import sys
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from functools import partial
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from unittest import skipUnless
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from unittest import skipIf
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from greenlet import greenlet
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from greenlet import getcurrent
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from . import TestCase
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try:
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from contextvars import Context
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from contextvars import ContextVar
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from contextvars import copy_context
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# From the documentation:
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#
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# Important: Context Variables should be created at the top module
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# level and never in closures. Context objects hold strong
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# references to context variables which prevents context variables
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# from being properly garbage collected.
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ID_VAR = ContextVar("id", default=None)
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VAR_VAR = ContextVar("var", default=None)
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ContextVar = None
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except ImportError:
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Context = ContextVar = copy_context = None
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# We don't support testing if greenlet's built-in context var support is disabled.
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@skipUnless(Context is not None, "ContextVar not supported")
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class ContextVarsTests(TestCase):
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def _new_ctx_run(self, *args, **kwargs):
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return copy_context().run(*args, **kwargs)
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def _increment(self, greenlet_id, callback, counts, expect):
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ctx_var = ID_VAR
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if expect is None:
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self.assertIsNone(ctx_var.get())
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else:
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self.assertEqual(ctx_var.get(), expect)
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ctx_var.set(greenlet_id)
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for _ in range(2):
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counts[ctx_var.get()] += 1
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callback()
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def _test_context(self, propagate_by):
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ID_VAR.set(0)
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callback = getcurrent().switch
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counts = dict((i, 0) for i in range(5))
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lets = [
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greenlet(partial(
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partial(
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copy_context().run,
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self._increment
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) if propagate_by == "run" else self._increment,
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greenlet_id=i,
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callback=callback,
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counts=counts,
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expect=(
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i - 1 if propagate_by == "share" else
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0 if propagate_by in ("set", "run") else None
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)
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))
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for i in range(1, 5)
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]
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for let in lets:
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if propagate_by == "set":
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let.gr_context = copy_context()
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elif propagate_by == "share":
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let.gr_context = getcurrent().gr_context
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for i in range(2):
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counts[ID_VAR.get()] += 1
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for let in lets:
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let.switch()
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if propagate_by == "run":
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# Must leave each context.run() in reverse order of entry
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for let in reversed(lets):
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let.switch()
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else:
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# No context.run(), so fine to exit in any order.
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for let in lets:
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let.switch()
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for let in lets:
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self.assertTrue(let.dead)
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# When using run(), we leave the run() as the greenlet dies,
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# and there's no context "underneath". When not using run(),
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# gr_context still reflects the context the greenlet was
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# running in.
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if propagate_by == 'run':
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self.assertIsNone(let.gr_context)
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else:
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self.assertIsNotNone(let.gr_context)
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if propagate_by == "share":
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self.assertEqual(counts, {0: 1, 1: 1, 2: 1, 3: 1, 4: 6})
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else:
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self.assertEqual(set(counts.values()), set([2]))
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def test_context_propagated_by_context_run(self):
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self._new_ctx_run(self._test_context, "run")
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def test_context_propagated_by_setting_attribute(self):
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self._new_ctx_run(self._test_context, "set")
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def test_context_not_propagated(self):
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self._new_ctx_run(self._test_context, None)
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def test_context_shared(self):
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self._new_ctx_run(self._test_context, "share")
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def test_break_ctxvars(self):
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let1 = greenlet(copy_context().run)
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let2 = greenlet(copy_context().run)
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let1.switch(getcurrent().switch)
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let2.switch(getcurrent().switch)
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# Since let2 entered the current context and let1 exits its own, the
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# interpreter emits:
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# RuntimeError: cannot exit context: thread state references a different context object
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let1.switch()
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def test_not_broken_if_using_attribute_instead_of_context_run(self):
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let1 = greenlet(getcurrent().switch)
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let2 = greenlet(getcurrent().switch)
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let1.gr_context = copy_context()
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let2.gr_context = copy_context()
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let1.switch()
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let2.switch()
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let1.switch()
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let2.switch()
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def test_context_assignment_while_running(self):
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# pylint:disable=too-many-statements
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ID_VAR.set(None)
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def target():
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self.assertIsNone(ID_VAR.get())
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self.assertIsNone(gr.gr_context)
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# Context is created on first use
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ID_VAR.set(1)
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self.assertIsInstance(gr.gr_context, Context)
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self.assertEqual(ID_VAR.get(), 1)
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self.assertEqual(gr.gr_context[ID_VAR], 1)
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# Clearing the context makes it get re-created as another
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# empty context when next used
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old_context = gr.gr_context
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gr.gr_context = None # assign None while running
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self.assertIsNone(ID_VAR.get())
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self.assertIsNone(gr.gr_context)
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ID_VAR.set(2)
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self.assertIsInstance(gr.gr_context, Context)
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self.assertEqual(ID_VAR.get(), 2)
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self.assertEqual(gr.gr_context[ID_VAR], 2)
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new_context = gr.gr_context
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getcurrent().parent.switch((old_context, new_context))
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# parent switches us back to old_context
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self.assertEqual(ID_VAR.get(), 1)
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gr.gr_context = new_context # assign non-None while running
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self.assertEqual(ID_VAR.get(), 2)
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getcurrent().parent.switch()
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# parent switches us back to no context
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self.assertIsNone(ID_VAR.get())
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self.assertIsNone(gr.gr_context)
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gr.gr_context = old_context
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self.assertEqual(ID_VAR.get(), 1)
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getcurrent().parent.switch()
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# parent switches us back to no context
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self.assertIsNone(ID_VAR.get())
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self.assertIsNone(gr.gr_context)
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gr = greenlet(target)
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with self.assertRaisesRegex(AttributeError, "can't delete context attribute"):
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del gr.gr_context
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self.assertIsNone(gr.gr_context)
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old_context, new_context = gr.switch()
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self.assertIs(new_context, gr.gr_context)
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self.assertEqual(old_context[ID_VAR], 1)
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self.assertEqual(new_context[ID_VAR], 2)
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self.assertEqual(new_context.run(ID_VAR.get), 2)
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gr.gr_context = old_context # assign non-None while suspended
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gr.switch()
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self.assertIs(gr.gr_context, new_context)
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gr.gr_context = None # assign None while suspended
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gr.switch()
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self.assertIs(gr.gr_context, old_context)
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gr.gr_context = None
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gr.switch()
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self.assertIsNone(gr.gr_context)
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# Make sure there are no reference leaks
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gr = None
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gc.collect()
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self.assertEqual(sys.getrefcount(old_context), 2)
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self.assertEqual(sys.getrefcount(new_context), 2)
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def test_context_assignment_different_thread(self):
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import threading
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VAR_VAR.set(None)
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ctx = Context()
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is_running = threading.Event()
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should_suspend = threading.Event()
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did_suspend = threading.Event()
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should_exit = threading.Event()
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holder = []
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def greenlet_in_thread_fn():
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VAR_VAR.set(1)
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is_running.set()
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should_suspend.wait(10)
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VAR_VAR.set(2)
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getcurrent().parent.switch()
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holder.append(VAR_VAR.get())
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def thread_fn():
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gr = greenlet(greenlet_in_thread_fn)
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gr.gr_context = ctx
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holder.append(gr)
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gr.switch()
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did_suspend.set()
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should_exit.wait(10)
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gr.switch()
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del gr
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greenlet() # trigger cleanup
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thread = threading.Thread(target=thread_fn, daemon=True)
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thread.start()
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is_running.wait(10)
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gr = holder[0]
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# Can't access or modify context if the greenlet is running
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# in a different thread
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with self.assertRaisesRegex(ValueError, "running in a different"):
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getattr(gr, 'gr_context')
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with self.assertRaisesRegex(ValueError, "running in a different"):
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gr.gr_context = None
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should_suspend.set()
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did_suspend.wait(10)
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# OK to access and modify context if greenlet is suspended
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self.assertIs(gr.gr_context, ctx)
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self.assertEqual(gr.gr_context[VAR_VAR], 2)
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gr.gr_context = None
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should_exit.set()
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thread.join(10)
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self.assertEqual(holder, [gr, None])
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# Context can still be accessed/modified when greenlet is dead:
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self.assertIsNone(gr.gr_context)
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gr.gr_context = ctx
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self.assertIs(gr.gr_context, ctx)
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# Otherwise we leak greenlets on some platforms.
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# XXX: Should be able to do this automatically
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del holder[:]
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gr = None
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thread = None
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def test_context_assignment_wrong_type(self):
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g = greenlet()
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with self.assertRaisesRegex(TypeError,
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"greenlet context must be a contextvars.Context or None"):
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g.gr_context = self
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@skipIf(Context is not None, "ContextVar supported")
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class NoContextVarsTests(TestCase):
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def test_contextvars_errors(self):
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let1 = greenlet(getcurrent().switch)
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self.assertFalse(hasattr(let1, 'gr_context'))
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with self.assertRaises(AttributeError):
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getattr(let1, 'gr_context')
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with self.assertRaises(AttributeError):
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let1.gr_context = None
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let1.switch()
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with self.assertRaises(AttributeError):
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getattr(let1, 'gr_context')
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with self.assertRaises(AttributeError):
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let1.gr_context = None
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del let1
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