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//go:build !(sqlite3_flock || sqlite3_nosys)
package vfs
import (
"math/rand"
"os"
"time"
"golang.org/x/sys/unix"
)
func osSync(file *os.File, _ /*fullsync*/, _ /*dataonly*/ bool) error {
// SQLite trusts Linux's fdatasync for all fsync's.
return unix.Fdatasync(int(file.Fd()))
}
func osAllocate(file *os.File, size int64) error {
if size == 0 {
return nil
}
return unix.Fallocate(int(file.Fd()), 0, 0, size)
}
func osUnlock(file *os.File, start, len int64) _ErrorCode {
err := unix.FcntlFlock(file.Fd(), unix.F_OFD_SETLK, &unix.Flock_t{
Type: unix.F_UNLCK,
Start: start,
Len: len,
})
if err != nil {
return _IOERR_UNLOCK
}
return _OK
}
func osLock(file *os.File, typ int16, start, len int64, timeout time.Duration, def _ErrorCode) _ErrorCode {
lock := unix.Flock_t{
Type: typ,
Start: start,
Len: len,
}
var err error
switch {
case timeout == 0:
err = unix.FcntlFlock(file.Fd(), unix.F_OFD_SETLK, &lock)
case timeout < 0:
err = unix.FcntlFlock(file.Fd(), unix.F_OFD_SETLKW, &lock)
default:
before := time.Now()
for {
err = unix.FcntlFlock(file.Fd(), unix.F_OFD_SETLK, &lock)
if errno, _ := err.(unix.Errno); errno != unix.EAGAIN {
break
}
if time.Since(before) > timeout {
break
}
const sleepIncrement = 1024*1024 - 1 // power of two, ~1ms
time.Sleep(time.Duration(rand.Int63() & sleepIncrement))
}
}
return osLockErrorCode(err, def)
}
func osReadLock(file *os.File, start, len int64, timeout time.Duration) _ErrorCode {
return osLock(file, unix.F_RDLCK, start, len, timeout, _IOERR_RDLOCK)
}
func osWriteLock(file *os.File, start, len int64, timeout time.Duration) _ErrorCode {
return osLock(file, unix.F_WRLCK, start, len, timeout, _IOERR_LOCK)
}
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