udpate deps

vendor/github.com/theckman/go-flock/flock_windows.go

@@ -8,18 +8,37 @@ import (
 	"syscall"
 )
 
-// Lock is a blocking call to try and take the file lock. It will wait until it
-// is able to obtain the exclusive file lock. It's recommended that TryLock() be
-// used over this function. This function may block the ability to query the
-// current Locked() status due to a RW-mutex lock.
+// ErrorLockViolation is the error code returned from the Windows syscall when a
+// lock would block and you ask to fail immediately.
+const ErrorLockViolation syscall.Errno = 0x21 // 33
+
+// Lock is a blocking call to try and take an exclusive file lock. It will wait
+// until it is able to obtain the exclusive file lock. It's recommended that
+// TryLock() be used over this function. This function may block the ability to
+// query the current Locked() or RLocked() status due to a RW-mutex lock.
 //
-// If we are already locked, this function short-circuits and returns immediately
-// assuming it can take the mutex lock.
+// If we are already locked, this function short-circuits and returns
+// immediately assuming it can take the mutex lock.
 func (f *Flock) Lock() error {
+	return f.lock(&f.l, winLockfileExclusiveLock)
+}
+
+// RLock is a blocking call to try and take a sahred file lock. It will wait
+// until it is able to obtain the shared file lock. It's recommended that
+// TryRLock() be used over this function. This function may block the ability to
+// query the current Locked() or RLocked() status due to a RW-mutex lock.
+//
+// If we are already locked, this function short-circuits and returns
+// immediately assuming it can take the mutex lock.
+func (f *Flock) RLock() error {
+	return f.lock(&f.r, winLockfileSharedLock)
+}
+
+func (f *Flock) lock(locked *bool, flag uint32) error {
 	f.m.Lock()
 	defer f.m.Unlock()
 
-	if f.l {
+	if *locked {
 		return nil
 	}
 
@@ -29,19 +48,19 @@ func (f *Flock) Lock() error {
 		}
 	}
 
-	if _, err := lockFileEx(syscall.Handle(f.fh.Fd()), LOCKFILE_EXCLUSIVE_LOCK, 0, 1, 0, &syscall.Overlapped{}); err != nil {
-		return err
+	if _, errNo := lockFileEx(syscall.Handle(f.fh.Fd()), flag, 0, 1, 0, &syscall.Overlapped{}); errNo > 0 {
+		return errNo
 	}
 
-	f.l = true
+	*locked = true
 	return nil
 }
 
 // Unlock is a function to unlock the file. This file takes a RW-mutex lock, so
-// while it is running the Locked() function will be blocked.
+// while it is running the Locked() and RLocked() functions will be blocked.
 //
 // This function short-circuits if we are unlocked already. If not, it calls
-// syscall.LOCK_UN on the file and closes the file descriptor It does not remove
+// UnlockFileEx() on the file and closes the file descriptor. It does not remove
 // the file from disk. It's up to your application to do.
 func (f *Flock) Unlock() error {
 	f.m.Lock()
@@ -49,36 +68,53 @@ func (f *Flock) Unlock() error {
 
 	// if we aren't locked or if the lockfile instance is nil
 	// just return a nil error because we are unlocked
-	if !f.l || f.fh == nil {
+	if (!f.l && !f.r) || f.fh == nil {
 		return nil
 	}
 
 	// mark the file as unlocked
-	if _, err := unlockFileEx(syscall.Handle(f.fh.Fd()), 0, 1, 0, &syscall.Overlapped{}); err != nil {
-		return err
+	if _, errNo := unlockFileEx(syscall.Handle(f.fh.Fd()), 0, 1, 0, &syscall.Overlapped{}); errNo > 0 {
+		return errNo
 	}
 
 	f.fh.Close()
 
 	f.l = false
+	f.r = false
 	f.fh = nil
 
 	return nil
 }
 
-// TryLock is the preferred function for taking a file lock. This function does
-// take a RW-mutex lock before it tries to lock the file, so there is the
-// possibility that this function may block for a short time if another goroutine
-// is trying to take any action.
+// TryLock is the preferred function for taking an exlusive file lock. This
+// function does take a RW-mutex lock before it tries to lock the file, so there
+// is the possibility that this function may block for a short time if another
+// goroutine is trying to take any action.
 //
 // The actual file lock is non-blocking. If we are unable to get the exclusive
-// file lock, the function will return false instead of waiting for the lock.
-// If we get the lock, we also set the *Flock instance as being locked.
+// file lock, the function will return false instead of waiting for the lock. If
+// we get the lock, we also set the *Flock instance as being exclusive-locked.
 func (f *Flock) TryLock() (bool, error) {
+	return f.try(&f.l, winLockfileExclusiveLock)
+}
+
+// TryRLock is the preferred function for taking a shared file lock. This
+// function does take a RW-mutex lock before it tries to lock the file, so there
+// is the possibility that this function may block for a short time if another
+// goroutine is trying to take any action.
+//
+// The actual file lock is non-blocking. If we are unable to get the shared file
+// lock, the function will return false instead of waiting for the lock. If we
+// get the lock, we also set the *Flock instance as being shared-locked.
+func (f *Flock) TryRLock() (bool, error) {
+	return f.try(&f.r, winLockfileSharedLock)
+}
+
+func (f *Flock) try(locked *bool, flag uint32) (bool, error) {
 	f.m.Lock()
 	defer f.m.Unlock()
 
-	if f.l {
+	if *locked {
 		return true, nil
 	}
 
@@ -88,13 +124,17 @@ func (f *Flock) TryLock() (bool, error) {
 		}
 	}
 
-	_, err := lockFileEx(syscall.Handle(f.fh.Fd()), LOCKFILE_EXCLUSIVE_LOCK|LOCKFILE_FAIL_IMMEDIATELY, 0, 1, 0, &syscall.Overlapped{})
+	_, errNo := lockFileEx(syscall.Handle(f.fh.Fd()), flag|winLockfileFailImmediately, 0, 1, 0, &syscall.Overlapped{})
 
-	switch err {
-	case nil:
-		f.l = true
-		return true, nil
+	if errNo > 0 {
+		if errNo == ErrorLockViolation || errNo == syscall.ERROR_IO_PENDING {
+			return false, nil
+		}
+
+		return false, errNo
 	}
 
-	return false, err
+	*locked = true
+
+	return true, nil
 }