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package httpfs
// Utility functions on top of standard httpfs protocol
import (
"bufio"
"bytes"
"io"
)
const BUFSIZE = 16 * 1024 * 1024 // bufio buffer size
// create a file for writing, clobbers previous content if any.
func Create(URL string) (WriteCloseFlusher, error) {
_ = Remove(URL)
err := Touch(URL)
if err != nil {
return nil, err
}
return &bufWriter{bufio.NewWriterSize(&appendWriter{URL, 0}, BUFSIZE)}, nil
}
func MustCreate(URL string) WriteCloseFlusher {
f, err := Create(URL)
if err != nil {
panic(err)
}
return f
}
type WriteCloseFlusher interface {
io.WriteCloser
Flush() error
}
// open a file for reading
func Open(URL string) (io.ReadCloser, error) {
data, err := Read(URL)
if err != nil {
return nil, err
}
return io.NopCloser(bytes.NewReader(data)), nil
}
func MustOpen(URL string) io.ReadCloser {
f, err := Open(URL)
if err != nil {
panic(err)
}
return f
}
type bufWriter struct {
buf *bufio.Writer
}
func (w *bufWriter) Write(p []byte) (int, error) { return w.buf.Write(p) }
func (w *bufWriter) Close() error {
err := w.buf.Flush()
w.buf = nil // Dangling pointer somewhere?
if err != nil {
return err
}
return nil
}
func (w *bufWriter) Flush() error { return w.buf.Flush() }
type appendWriter struct {
URL string
byteCount int64
}
func (w *appendWriter) Write(p []byte) (int, error) {
err := AppendSize(w.URL, p, w.byteCount)
if err != nil {
return 0, err // don't know how many bytes written
}
w.byteCount += int64(len(p))
return len(p), nil
}
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