github.com/AbhinandanKurakure/podman/v3@v3.4.10/pkg/channel/writer.go (about)

     1  package channel
     2  
     3  import (
     4  	"io"
     5  	"sync"
     6  
     7  	"github.com/pkg/errors"
     8  )
     9  
    10  // WriteCloser is an io.WriteCloser that that proxies Write() calls to a channel
    11  // The []byte buffer of the Write() is queued on the channel as one message.
    12  type WriteCloser interface {
    13  	io.WriteCloser
    14  	Chan() <-chan []byte
    15  }
    16  
    17  type writeCloser struct {
    18  	ch  chan []byte
    19  	mux sync.Mutex
    20  }
    21  
    22  // NewWriter initializes a new channel writer
    23  func NewWriter(c chan []byte) WriteCloser {
    24  	return &writeCloser{
    25  		ch: c,
    26  	}
    27  }
    28  
    29  // Chan returns the R/O channel behind WriteCloser
    30  func (w *writeCloser) Chan() <-chan []byte {
    31  	return w.ch
    32  }
    33  
    34  // Write method for WriteCloser
    35  func (w *writeCloser) Write(b []byte) (bLen int, err error) {
    36  	if w == nil {
    37  		return 0, errors.New("use channel.NewWriter() to initialize a WriteCloser")
    38  	}
    39  
    40  	w.mux.Lock()
    41  	defer w.mux.Unlock()
    42  
    43  	if w.ch == nil {
    44  		return 0, errors.New("the channel is closed for Write")
    45  	}
    46  
    47  	buf := make([]byte, len(b))
    48  	copy(buf, b)
    49  	w.ch <- buf
    50  
    51  	return len(b), nil
    52  }
    53  
    54  // Close method for WriteCloser
    55  func (w *writeCloser) Close() error {
    56  	w.mux.Lock()
    57  	defer w.mux.Unlock()
    58  
    59  	close(w.ch)
    60  	w.ch = nil
    61  	return nil
    62  }