Commitf9b0d51

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Fix Gather.cancel() to return True when there were active child tasks.

Patch by Johannes Ebke.

1 parentf5ab2bb commitf9b0d51Copy full SHA for f9b0d51

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+34

-2

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+34

-2

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Lines changed: 4 additions & 2 deletions

Original file line number	Diff line number	Diff line change
`@@ -592,9 +592,11 @@ def __init__(self, children, *, loop=None):`
`592`	`592`	`defcancel(self):`
`593`	`593`	`ifself.done():`
`594`	`594`	`returnFalse`
	`595`	`+ret=False`
`595`	`596`	`forchildinself._children:`
`596`		`-child.cancel()`
`597`		`-returnTrue`
	`597`	`+ifchild.cancel():`
	`598`	`+ret=True`
	`599`	`+returnret`
`598`	`600`
`599`	`601`
`600`	`602`	`defgather(*coros_or_futures,loop=None,return_exceptions=False):`

Lines changed: 30 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -1899,6 +1899,36 @@ def test_cancel_blocking_wait_for(self):`
`1899`	`1899`	`deftest_cancel_wait_for(self):`
`1900`	`1900`	`self._test_cancel_wait_for(60.0)`
`1901`	`1901`
	`1902`	`+deftest_cancel_gather(self):`
	`1903`	`+"""Ensure that a gathering future refuses to be cancelled once all`
	`1904`	`+ children are done"""`
	`1905`	`+loop=asyncio.new_event_loop()`
	`1906`	`+self.addCleanup(loop.close)`
	`1907`	`+`
	`1908`	`+fut=asyncio.Future(loop=loop)`
	`1909`	`+# The indirection fut->child_coro is needed since otherwise the`
	`1910`	`+# gathering task is done at the same time as the child future`
	`1911`	`+defchild_coro():`
	`1912`	`+return (yieldfromfut)`
	`1913`	`+gather_future=asyncio.gather(child_coro(),loop=loop)`
	`1914`	`+gather_task=asyncio.ensure_future(gather_future,loop=loop)`
	`1915`	`+`
	`1916`	`+cancel_result=None`
	`1917`	`+defcancelling_callback(_):`
	`1918`	`+nonlocalcancel_result`
	`1919`	`+cancel_result=gather_task.cancel()`
	`1920`	`+fut.add_done_callback(cancelling_callback)`
	`1921`	`+`
	`1922`	`+fut.set_result(42)# calls the cancelling_callback after fut is done()`
	`1923`	`+`
	`1924`	`+# At this point the task should complete.`
	`1925`	`+loop.run_until_complete(gather_task)`
	`1926`	`+`
	`1927`	`+# Python issue #26923: asyncio.gather drops cancellation`
	`1928`	`+self.assertEqual(cancel_result,False)`
	`1929`	`+self.assertFalse(gather_task.cancelled())`
	`1930`	`+self.assertEqual(gather_task.result(), [42])`
	`1931`	`+`
`1902`	`1932`
`1903`	`1933`	`classGatherTestsBase:`
`1904`	`1934`

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