github.com/mutagen-io/mutagen@v0.18.0-rc1/pkg/daemon/lock.go (about)

     1  package daemon
     2  
     3  import (
     4  	"fmt"
     5  
     6  	"github.com/mutagen-io/mutagen/pkg/filesystem/locking"
     7  )
     8  
     9  // Lock represents the global daemon lock. It is held by a single daemon
    10  // instance at a time.
    11  type Lock struct {
    12  	// locker is the underlying file locker.
    13  	locker *locking.Locker
    14  }
    15  
    16  // AcquireLock attempts to acquire the global daemon lock.
    17  func AcquireLock() (*Lock, error) {
    18  	// Compute the lock path.
    19  	lockPath, err := subpath(lockName)
    20  	if err != nil {
    21  		return nil, fmt.Errorf("unable to compute daemon lock path: %w", err)
    22  	}
    23  
    24  	// Create the locker and attempt to acquire the lock.
    25  	locker, err := locking.NewLocker(lockPath, 0600)
    26  	if err != nil {
    27  		return nil, fmt.Errorf("unable to create daemon file locker: %w", err)
    28  	} else if err = locker.Lock(false); err != nil {
    29  		locker.Close()
    30  		return nil, err
    31  	}
    32  
    33  	// Create the lock.
    34  	return &Lock{
    35  		locker: locker,
    36  	}, nil
    37  }
    38  
    39  // Release releases the daemon lock.
    40  func (l *Lock) Release() error {
    41  	// Release the lock.
    42  	if err := l.locker.Unlock(); err != nil {
    43  		l.locker.Close()
    44  		return err
    45  	}
    46  
    47  	// Close the locker.
    48  	if err := l.locker.Close(); err != nil {
    49  		return fmt.Errorf("unable to close locker: %w", err)
    50  	}
    51  
    52  	// Success.
    53  	return nil
    54  }