fix(semaphore): use absolute deadline for POSIX TimedWait#17
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sem_timedwait takes an absolute CLOCK_REALTIME deadline, but the code passed a relative duration, placing the deadline near the epoch so the wait always timed out instantly without blocking on Linux/Android. Compute the deadline from clock_gettime(CLOCK_REALTIME). Add tests covering timeout, already-signaled and signaled-before-timeout cases.
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Problem
CcpSemaphore::TimedWait(generic POSIX path) passed a relative duration tosem_timedwait, which expects anabsolute deadline against
CLOCK_REALTIME. The computedtimespec(tv_sec = timeoutMs/1000, i.e. a few secondsafter the epoch) is always far in the past, so the wait timed out immediately without ever blocking on Linux/Android —
TimedWaitreturnedfalseinstantly regardless of the requested timeout. The pre-existing testCcpSemaphore.DefaultConstructorCreatesNonSignaledSemaphore, which expects a ~1000 ms wait, was already failing onthe generic POSIX path because of this. macOS (mach semaphore) and Windows paths are not affected.
Fix
TimedWaitnow derives an absolute deadline fromclock_gettime(CLOCK_REALTIME), adds the requested timeout, andnormalizes the nanosecond overflow before calling
sem_timedwait. Added#include <time.h>.Tests
Added three tests in
tests/CcpSemaphore.cpp(GoogleTest):TimedWaitWaitsAndReturnsFalseOnTimeoutblocks ~500 msand returns
false(direct regression test for the relative/absolute confusion),TimedWaitReturnsTrueWhenAlreadySignaledreturnstrueimmediately, andTimedWaitReturnsTrueWhenSignaledBeforeTimeoutreturnstruewhen signaled from another thread before the deadline.Reviewed manually; not compiled locally as the vcpkg toolchain is unavailable in this environment.
Scope
Generic POSIX branch only (
#else). macOS and Windows code paths are unchanged. No public API change.