Refactor file locking mechanism

The file locking mechanism in both Windows and POSIX systems has been modified. This update restructures the way files are opened for writing and locked. Unnecessary file existence checks have been eliminated, and a more proficient use of the defer statement for file closing is included. On a failure, the file will still be properly closed. This should considerably enhance the efficiency and reliability of the lock function.

Wox/util/single_instance/single_instance_posix.go

@@ -8,28 +8,23 @@ import (
 	"wox/util"
 )
 
-// CreateLockFile tries to create a file with given name and acquire an
-// exclusive lock on it. If the file already exists AND is still locked, it will
-// fail.
 func lock(content string) error {
 	filename := util.GetLocation().GetAppLockFilePath()
 	file, err := os.OpenFile(filename, os.O_WRONLY|os.O_CREATE, 0600)
 	if err != nil {
 		return err
 	}
+	defer file.Close()
 
 	err = syscall.Flock(int(file.Fd()), syscall.LOCK_EX|syscall.LOCK_NB)
 	if err != nil {
-		file.Close()
 		return err
 	}
 
 	if err := file.Truncate(0); err != nil {
-		file.Close()
 		return err
 	}
 	if _, err := file.WriteString(content); err != nil {
-		file.Close()
 		return err
 	}
 

Wox/util/single_instance/single_instance_windows.go

@@ -4,27 +4,25 @@ package single_instance
 
 import (
 	"os"
+	"syscall"
 	"wox/util"
 )
 
 func lock(content string) error {
 	filename := util.GetLocation().GetAppLockFilePath()
-	if _, err := os.Stat(filename); err == nil {
-		// If the files exists, we first try to remove it
-		if err = os.Remove(filename); err != nil {
-			return err
-		}
-	} else if !os.IsNotExist(err) {
+	file, err := os.OpenFile(filename, os.O_RDWR|os.O_CREATE, 0600)
+	if err != nil {
 		return err
 	}
+	defer file.Close()
 
-	file, err := os.OpenFile(filename, os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0600)
+	var overlapped syscall.Overlapped
+	err = syscall.LockFileEx(syscall.Handle(file.Fd()), syscall.LOCKFILE_EXCLUSIVE_LOCK, 0, 1, 0, &overlapped)
 	if err != nil {
 		return err
 	}
 
-	_, err = file.WriteString(content)
-	if err != nil {
+	if _, err := file.WriteString(content); err != nil {
 		return err
 	}