/
sys.go
56 lines (50 loc) · 1.25 KB
/
sys.go
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package hybridlog
import (
"errors"
"syscall"
"time"
"unsafe"
)
func mmap(fd uintptr, sz int) ([]byte, error) {
b, err := syscall.Mmap(int(fd), 0, sz, syscall.PROT_READ, syscall.MAP_SHARED)
if err != nil {
return nil, err
}
return b, nil
}
func munmap(b []byte) error {
return syscall.Munmap(b)
}
func flock(fd uintptr, timeout time.Duration) error {
var t time.Time
for {
// If we're beyond our timeout then return an error.
// This can only occur after we've attempted a flock once.
if t.IsZero() {
t = time.Now()
} else if timeout > 0 && time.Since(t) > timeout {
return errors.New("failed to acquire file lock")
}
// Only 1 process can acquire the lock
flag := syscall.LOCK_EX
// Otherwise attempt to obtain an exclusive lock.
err := syscall.Flock(int(fd), flag|syscall.LOCK_NB)
if err == nil {
return nil
} else if err != syscall.EWOULDBLOCK {
return err
}
// Wait for a bit and try again.
time.Sleep(50 * time.Millisecond)
}
}
func funlock(fd uintptr) error {
return syscall.Flock(int(fd), syscall.LOCK_UN)
}
func madvise(b []byte) error {
_, _, e1 := syscall.Syscall(syscall.SYS_MADVISE, uintptr(unsafe.Pointer(&b[0])), uintptr(len(b)), uintptr(syscall.MADV_RANDOM))
if e1 != 0 {
return e1
}
return nil
}