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Add posix semaphores support

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There's still some bugs to work out on Windows and OpenBSD.
This commit is contained in:
Justine Tunney 2022-10-14 08:25:47 -07:00
parent f52f65b2e3
commit 8111462789
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GPG key ID: BE714B4575D6E328
36 changed files with 779 additions and 59 deletions
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42
third_party/nsync/futex.c vendored
View file

@ -39,6 +39,7 @@
#include "libc/thread/tls.h"
#include "third_party/nsync/atomic.h"
#include "third_party/nsync/common.internal.h"
#include "third_party/nsync/futex.internal.h"
#include "third_party/nsync/time.h"
// clang-format off
@ -46,7 +47,7 @@
#define FUTEX_WAIT_BITS_ FUTEX_BITSET_MATCH_ANY
int _futex (int *, int, int, const struct timespec *, int *, int);
int _futex (atomic_int *, int, int, const struct timespec *, int *, int);
static int FUTEX_WAIT_;
static int FUTEX_PRIVATE_FLAG_;
@ -54,7 +55,7 @@ static bool FUTEX_IS_SUPPORTED;
bool FUTEX_TIMEOUT_IS_ABSOLUTE;
__attribute__((__constructor__)) static void nsync_futex_init_ (void) {
int x = 0;
atomic_int x;
FUTEX_WAIT_ = FUTEX_WAIT;
@ -87,6 +88,7 @@ __attribute__((__constructor__)) static void nsync_futex_init_ (void) {
// configuring any time synchronization mechanism (like ntp) to
// adjust for leap seconds by adjusting the rate, rather than
// with a backwards step.
atomic_store_explicit (&x, 0, memory_order_relaxed);
if (IsLinux () &&
_futex (&x, FUTEX_WAIT_BITSET | FUTEX_CLOCK_REALTIME,
1, 0, 0, FUTEX_BITSET_MATCH_ANY) == -EAGAIN) {
@ -109,13 +111,11 @@ __attribute__((__constructor__)) static void nsync_futex_init_ (void) {
}
}
static int nsync_futex_polyfill_ (int *p, int expect, struct timespec *timeout) {
static int nsync_futex_polyfill_ (atomic_int *w, int expect, struct timespec *timeout) {
int64_t nanos, maxnanos;
nsync_atomic_uint32_ *w;
struct timespec ts, deadline;
w = (nsync_atomic_uint32_ *)p;
if (ATM_LOAD (p) != expect) {
if (atomic_load_explicit (w, memory_order_relaxed) != expect) {
return -EAGAIN;
}
@ -131,7 +131,7 @@ static int nsync_futex_polyfill_ (int *p, int expect, struct timespec *timeout)
nanos = 100;
maxnanos = __SIG_POLLING_INTERVAL_MS * 1000L * 1000;
while (nsync_time_cmp (deadline, ts) > 0) {
if (ATM_LOAD (p) != expect) {
if (atomic_load_explicit (w, memory_order_relaxed) != expect) {
return 0;
}
ts = nsync_time_add (ts, _timespec_fromnanos (nanos));
@ -152,7 +152,7 @@ static int nsync_futex_polyfill_ (int *p, int expect, struct timespec *timeout)
return -ETIMEDOUT;
}
int nsync_futex_wait_ (int *p, int expect, char pshare, struct timespec *timeout) {
int nsync_futex_wait_ (atomic_int *w, int expect, char pshare, struct timespec *timeout) {
uint32_t ms;
int rc, op, fop;
@ -175,7 +175,7 @@ int nsync_futex_wait_ (int *p, int expect, char pshare, struct timespec *timeout
} else {
ms = -1;
}
if (WaitOnAddress (p, &expect, sizeof(int), ms)) {
if (WaitOnAddress (w, &expect, sizeof(int), ms)) {
rc = 0;
} else {
rc = -GetLastError ();
@ -183,9 +183,9 @@ int nsync_futex_wait_ (int *p, int expect, char pshare, struct timespec *timeout
}
} else if (IsFreebsd ()) {
rc = sys_umtx_timedwait_uint (
p, expect, pshare, timeout);
w, expect, pshare, timeout);
} else {
rc = _futex (p, op, expect, timeout, 0,
rc = _futex (w, op, expect, timeout, 0,
FUTEX_WAIT_BITS_);
if (IsOpenbsd() && rc > 0) {
rc = -rc;
@ -194,19 +194,19 @@ int nsync_futex_wait_ (int *p, int expect, char pshare, struct timespec *timeout
} else {
Polyfill:
__get_tls()->tib_flags |= TIB_FLAG_TIME_CRITICAL;
rc = nsync_futex_polyfill_ (p, expect, timeout);
rc = nsync_futex_polyfill_ (w, expect, timeout);
__get_tls()->tib_flags &= ~TIB_FLAG_TIME_CRITICAL;
}
STRACE ("futex(%t, %s, %#x, %s) → %s",
p, DescribeFutexOp (op), expect,
STRACE ("futex(%t [%d], %s, %#x, %s) → %s",
w, *w, DescribeFutexOp (op), expect,
DescribeTimespec (0, timeout),
DescribeErrnoResult (rc));
return rc;
}
int nsync_futex_wake_ (int *p, int count, char pshare) {
int nsync_futex_wake_ (atomic_int *w, int count, char pshare) {
int e, rc, op, fop;
int wake (void *, int, int) asm ("_futex");
@ -223,9 +223,9 @@ int nsync_futex_wake_ (int *p, int count, char pshare) {
goto Polyfill;
}
if (count == 1) {
WakeByAddressSingle (p);
WakeByAddressSingle (w);
} else {
WakeByAddressAll (p);
WakeByAddressAll (w);
}
rc = 0;
} else if (IsFreebsd ()) {
@ -234,9 +234,9 @@ int nsync_futex_wake_ (int *p, int count, char pshare) {
} else {
fop = UMTX_OP_WAKE_PRIVATE;
}
rc = sys_umtx_op (p, fop, count, 0, 0);
rc = sys_umtx_op (w, fop, count, 0, 0);
} else {
rc = wake (p, op, count);
rc = wake (w, op, count);
}
} else {
Polyfill:
@ -244,8 +244,8 @@ int nsync_futex_wake_ (int *p, int count, char pshare) {
rc = 0;
}
STRACE ("futex(%t, %s, %d) → %s",
p, DescribeFutexOp(op),
STRACE ("futex(%t [%d], %s, %d) → %s",
w, *w, DescribeFutexOp(op),
count, DescribeErrnoResult(rc));
return rc;