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Implement waitable_atomic for FreeBSD #1607

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Implement waitable_atomic for FreeBSD #1607

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b7ae3b9
Implement waitable_atomic for FreeBSD
ronaldklop Jan 9, 2025
5daa46f
Reimplement waitable_atomic.cpp to use absolute times.
ronaldklop Feb 4, 2025
50f7e84
Merge branch 'mongodb:master' into master
ronaldklop Feb 4, 2025
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42 changes: 42 additions & 0 deletions src/mongo/platform/waitable_atomic.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,9 @@
#ifdef __linux__
#include <linux/futex.h>
#include <sys/syscall.h>
#elif defined(__FreeBSD__)
#include <sys/types.h>
#include <sys/umtx.h>
#elif defined(_WIN32)
#include <synchapi.h>
#endif
Expand Down Expand Up @@ -235,6 +238,45 @@ bool waitUntil(const void* uaddr,
return timeoutOverflow || errno != ETIMEDOUT;
}

#elif defined(__FreeBSD__)

void notifyOne(const void* uaddr) {
_umtx_op(const_cast<void*>(uaddr), UMTX_OP_WAKE_PRIVATE, 1, NULL, NULL);
}

void notifyMany(const void* uaddr, int nToWake) {
_umtx_op(const_cast<void*>(uaddr), UMTX_OP_WAKE_PRIVATE, nToWake, NULL, NULL);
}

void notifyAll(const void* uaddr) {
_umtx_op(const_cast<void*>(uaddr), UMTX_OP_WAKE_PRIVATE, INT_MAX, NULL, NULL);
}

bool waitUntil(const void* uaddr,
uint32_t old,
boost::optional<system_clock::time_point> deadline) {
struct _umtx_time umtx_deadline;
void* uaddr2 = nullptr;

if (deadline) {
umtx_deadline._timeout.tv_sec = durationCount<Seconds>(deadline->time_since_epoch());
umtx_deadline._timeout.tv_nsec = durationCount<Nanoseconds>(
deadline->time_since_epoch() - stdx::chrono::seconds(umtx_deadline._timeout.tv_sec));
umtx_deadline._flags = UMTX_ABSTIME;
umtx_deadline._clockid = CLOCK_REALTIME_FAST;
uaddr2 = &umtx_deadline;
}

int umtxOpRet;
if ((umtxOpRet = _umtx_op(const_cast<void*>(uaddr), UMTX_OP_WAIT_UINT_PRIVATE, old, (void*)sizeof(struct _umtx_time), uaddr2)) != 0) {
if (errno == ETIMEDOUT) {
Comment on lines +270 to +272
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The umtxOpRet error check is incorrect. The function returns -1 on error and sets errno, but the code checks if umtxOpRet != 0 which will trigger the invariant even for expected errors.

Comment on lines +270 to +272
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The umtxOpRet error check is incorrect. The function returns -1 on error and sets errno, but the code checks if umtxOpRet != 0 which will trigger the invariant even for successful returns.

return false;
}
invariant(umtxOpRet == 0, errorMessage(lastSystemError()));
}
return true;
}

#else
#error "Need an implementation of waitUntil(), notifyOne(), notifyMany(), notifyAll() for this OS"
#endif
Expand Down