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// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package runtime
import (
"runtime/internal/atomic"
"runtime/internal/sys"
"unsafe"
)
type mOS struct {
waitsemacount uint32
}
//go:noescape
//extern thrsleep
func thrsleep(ident uintptr, clock_id int32, tsp *timespec, lock uintptr, abort *uint32) int32
//go:noescape
//extern thrwakeup
func thrwakeup(ident uintptr, n int32) int32
//go:nosplit
func semacreate(mp *m) {
}
//go:nosplit
func semasleep(ns int64) int32 {
_g_ := getg()
// Compute sleep deadline.
var tsp *timespec
if ns >= 0 {
var ts timespec
var nsec int32
ns += nanotime()
ts.set_sec(int64(timediv(ns, 1000000000, &nsec)))
ts.set_nsec(nsec)
tsp = &ts
}
for {
v := atomic.Load(&_g_.m.mos.waitsemacount)
if v > 0 {
if atomic.Cas(&_g_.m.mos.waitsemacount, v, v-1) {
return 0 // semaphore acquired
}
continue
}
// Sleep until woken by semawakeup or timeout; or abort if waitsemacount != 0.
//
// From OpenBSD's __thrsleep(2) manual:
// "The abort argument, if not NULL, points to an int that will
// be examined [...] immediately before blocking. If that int
// is non-zero then __thrsleep() will immediately return EINTR
// without blocking."
ret := thrsleep(uintptr(unsafe.Pointer(&_g_.m.mos.waitsemacount)), _CLOCK_MONOTONIC, tsp, 0, &_g_.m.mos.waitsemacount)
if ret == _EWOULDBLOCK {
return -1
}
}
}
//go:nosplit
func semawakeup(mp *m) {
atomic.Xadd(&mp.mos.waitsemacount, 1)
ret := thrwakeup(uintptr(unsafe.Pointer(&mp.mos.waitsemacount)), 1)
if ret != 0 && ret != _ESRCH {
// semawakeup can be called on signal stack.
systemstack(func() {
print("thrwakeup addr=", &mp.mos.waitsemacount, " sem=", mp.mos.waitsemacount, " ret=", ret, "\n")
})
}
}
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