github.com/x-oss-byte/git-lfs@v2.5.2+incompatible/tools/sync_writer.go (about)

     1  package tools
     2  
     3  import "io"
     4  
     5  // closeFn is the type of func Close() in the io.Closer interface.
     6  type closeFn func() error
     7  
     8  // syncFn is the type of func Sync() in the *os.File implementation.
     9  type syncFn func() error
    10  
    11  // SyncWriter provides a wrapper around an io.Writer that synchronizes all
    12  // write after they occur, if the underlying writer supports synchronization.
    13  type SyncWriter struct {
    14  	w io.Writer
    15  
    16  	closeFn closeFn
    17  	syncFn  syncFn
    18  }
    19  
    20  // NewSyncWriter returns a new instance of the *SyncWriter that sends all writes
    21  // to the given io.Writer.
    22  func NewSyncWriter(w io.Writer) *SyncWriter {
    23  	sw := &SyncWriter{
    24  		w: w,
    25  	}
    26  
    27  	if sync, ok := w.(interface {
    28  		Sync() error
    29  	}); ok {
    30  		sw.syncFn = sync.Sync
    31  	} else {
    32  		sw.syncFn = func() error { return nil }
    33  	}
    34  
    35  	if close, ok := w.(io.Closer); ok {
    36  		sw.closeFn = close.Close
    37  	} else {
    38  		sw.closeFn = func() error { return nil }
    39  	}
    40  
    41  	return sw
    42  }
    43  
    44  // Write will write to the file and perform a Sync() if writing succeeds.
    45  func (w *SyncWriter) Write(b []byte) error {
    46  	if _, err := w.w.Write(b); err != nil {
    47  		return err
    48  	}
    49  	return w.syncFn()
    50  }
    51  
    52  // Close will call Close() on the underlying file
    53  func (w *SyncWriter) Close() error {
    54  	return w.closeFn()
    55  }