52 lines
1.1 KiB
Go
52 lines
1.1 KiB
Go
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package tools
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import "io"
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// closeFn is the type of func Close() in the io.Closer interface.
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type closeFn func() error
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// syncFn is the type of func Sync() in the *os.File implementation.
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type syncFn func() error
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// SyncWriter provides a wrapper around an io.Writer that synchronizes all
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// write after they occur, if the underlying writer supports synchronization.
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type SyncWriter struct {
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w io.Writer
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closeFn closeFn
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syncFn syncFn
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}
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// NewSyncWriter returns a new instance of the *SyncWriter that sends all writes
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// to the given io.Writer.
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func NewSyncWriter(w io.Writer) *SyncWriter {
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sw := &SyncWriter{
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w: w,
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}
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if sync, ok := w.(interface {
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Sync() error
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}); ok {
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sw.syncFn = sync.Sync
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}
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if close, ok := w.(io.Closer); ok {
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sw.closeFn = close.Close
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}
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return sw
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}
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// Write will write to the file and perform a Sync() if writing succeeds.
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func (w *SyncWriter) Write(b []byte) error {
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if _, err := w.w.Write(b); err != nil {
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return err
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}
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return w.syncFn()
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}
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// Close will call Close() on the underlying file
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func (w *SyncWriter) Close() error {
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return w.closeFn()
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}
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