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Use golang.org/x/sys/windows for FileLockEx/UnlockFileEx #283

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Jul 2, 2021
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Use golang.org/x/sys/windows for FileLockEx/UnlockFileEx #283

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43 changes: 6 additions & 37 deletions bolt_windows.go
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Original file line number Diff line number Diff line change
Expand Up @@ -6,40 +6,10 @@ import (
"syscall"
"time"
"unsafe"
)

// LockFileEx code derived from golang build filemutex_windows.go @ v1.5.1
var (
modkernel32 = syscall.NewLazyDLL("kernel32.dll")
procLockFileEx = modkernel32.NewProc("LockFileEx")
procUnlockFileEx = modkernel32.NewProc("UnlockFileEx")
)

const (
// see https://msdn.microsoft.com/en-us/library/windows/desktop/aa365203(v=vs.85).aspx
flagLockExclusive = 2
flagLockFailImmediately = 1

// see https://msdn.microsoft.com/en-us/library/windows/desktop/ms681382(v=vs.85).aspx
errLockViolation syscall.Errno = 0x21
"golang.org/x/sys/windows"
)

func lockFileEx(h syscall.Handle, flags, reserved, locklow, lockhigh uint32, ol *syscall.Overlapped) (err error) {
r, _, err := procLockFileEx.Call(uintptr(h), uintptr(flags), uintptr(reserved), uintptr(locklow), uintptr(lockhigh), uintptr(unsafe.Pointer(ol)))
if r == 0 {
return err
}
return nil
}

func unlockFileEx(h syscall.Handle, reserved, locklow, lockhigh uint32, ol *syscall.Overlapped) (err error) {
r, _, err := procUnlockFileEx.Call(uintptr(h), uintptr(reserved), uintptr(locklow), uintptr(lockhigh), uintptr(unsafe.Pointer(ol)), 0)
if r == 0 {
return err
}
return nil
}

// fdatasync flushes written data to a file descriptor.
func fdatasync(db *DB) error {
return db.file.Sync()
Expand All @@ -51,22 +21,22 @@ func flock(db *DB, exclusive bool, timeout time.Duration) error {
if timeout != 0 {
t = time.Now()
}
var flag uint32 = flagLockFailImmediately
var flags uint32 = windows.LOCKFILE_FAIL_IMMEDIATELY
if exclusive {
flag |= flagLockExclusive
flags |= windows.LOCKFILE_EXCLUSIVE_LOCK
}
for {
// Fix for https://github.com/etcd-io/bbolt/issues/121. Use byte-range
// -1..0 as the lock on the database file.
var m1 uint32 = (1 << 32) - 1 // -1 in a uint32
err := lockFileEx(syscall.Handle(db.file.Fd()), flag, 0, 1, 0, &syscall.Overlapped{
err := windows.LockFileEx(windows.Handle(db.file.Fd()), flags, 0, 1, 0, &windows.Overlapped{
Offset: m1,
OffsetHigh: m1,
})

if err == nil {
return nil
} else if err != errLockViolation {
} else if err != windows.ERROR_LOCK_VIOLATION {
return err
}

Expand All @@ -83,11 +53,10 @@ func flock(db *DB, exclusive bool, timeout time.Duration) error {
// funlock releases an advisory lock on a file descriptor.
func funlock(db *DB) error {
var m1 uint32 = (1 << 32) - 1 // -1 in a uint32
err := unlockFileEx(syscall.Handle(db.file.Fd()), 0, 1, 0, &syscall.Overlapped{
return windows.UnlockFileEx(windows.Handle(db.file.Fd()), 0, 1, 0, &windows.Overlapped{
Offset: m1,
OffsetHigh: m1,
})
return err
}

// mmap memory maps a DB's data file.
Expand Down