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[libcxx testing] Remove ALLOW_RETRIES from sleep_until.pass.cpp

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Operating systems are best effort by default, so we cannot assume that
sleep-like APIs return as soon as we'd like.

Even if a sleep-like API returns when we want it to, the potential for
preemption means that attempts to measure time are subject to delays.
This commit is contained in:
David Zarzycki 2020-05-10 05:51:14 -04:00
parent a832fc4b0c
commit 4f4d6c81f8
1 changed files with 9 additions and 11 deletions
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20
libcxx/test/std/thread/thread.threads/thread.thread.this/sleep_until.pass.cpp
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@ -7,7 +7,6 @@
//===----------------------------------------------------------------------===//
//
// UNSUPPORTED: libcpp-has-no-threads
// ALLOW_RETRIES: 2
// <thread>
@ -22,16 +21,15 @@
int main(int, char**)
{
typedef std::chrono::system_clock Clock;
typedef Clock::time_point time_point;
std::chrono::milliseconds ms(500);
time_point t0 = Clock::now();
std::this_thread::sleep_until(t0 + ms);
time_point t1 = Clock::now();
std::chrono::nanoseconds ns = (t1 - t0) - ms;
std::chrono::nanoseconds err = 5 * ms / 100;
// The time slept is within 5% of 500ms
assert(std::abs(ns.count()) < err.count());
typedef std::chrono::system_clock Clock;
typedef Clock::time_point time_point;
std::chrono::milliseconds ms(500);
time_point t0 = Clock::now();
std::this_thread::sleep_until(t0 + ms);
time_point t1 = Clock::now();
// NOTE: Operating systems are (by default) best effort and therefore we may
// have slept longer, perhaps much longer than we requested.
assert(t1 - t0 >= ms);
return 0;
}