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package crawl
import (
"fmt"
"io"
"time"
"compress/gzip"
"code.google.com/p/go-uuid/uuid"
)
var (
warcTimeFmt = time.RFC3339
warcVersion = "WARC/1.0"
warcContentTypes = map[string]string{
"warcinfo": "application/warc-fields",
"response": "application/http; msgtype=response",
"request": "application/http; msgtype=request",
"metadata": "application/warc-fields",
}
)
// A Warc header. Header field names are case-sensitive.
type WarcHeader map[string]string
// Set a header to the specified value. Multiple values are not
// supported.
func (h WarcHeader) Set(key, value string) {
h[key] = value
// Keep Content-Type in sync with WARC-Type.
if key == "WARC-Type" {
if ct, ok := warcContentTypes[value]; ok {
h["Content-Type"] = ct
} else {
h["Content-Type"] = "application/octet-stream"
}
}
}
// Get the value of a header. If not found, returns an empty string.
func (h WarcHeader) Get(key string) string {
return h[key]
}
// Encode the header to a Writer.
func (h WarcHeader) Encode(w io.Writer) {
fmt.Fprintf(w, "%s\r\n", warcVersion)
for hdr, value := range h {
fmt.Fprintf(w, "%s: %s\r\n", hdr, value)
}
fmt.Fprintf(w, "\r\n")
}
// NewWarcHeader returns a WarcHeader with its own unique ID and the
// current timestamp.
func NewWarcHeader() WarcHeader {
h := make(WarcHeader)
h.Set("WARC-Record-ID", fmt.Sprintf("<%s>", uuid.NewUUID().URN()))
h.Set("WARC-Date", time.Now().Format(warcTimeFmt))
h.Set("Content-Type", "application/octet-stream")
return h
}
// WarcWriter can write records to a file in WARC format.
type WarcWriter struct {
writer io.WriteCloser
}
type recordWriter struct {
io.Writer
}
func (rw *recordWriter) Close() error {
// Add the end-of-record marker.
fmt.Fprintf(rw, "\r\n\r\n")
return nil
}
// NewRecord starts a new WARC record with the provided header. The
// caller must call Close on the returned writer before creating the
// next record.
func (w *WarcWriter) NewRecord(hdr WarcHeader) io.WriteCloser {
hdr.Encode(w.writer)
return &recordWriter{w.writer}
}
// Close the WARC writer and flush all buffers.
func (w *WarcWriter) Close() error {
return w.writer.Close()
}
func NewWarcWriter(w io.WriteCloser) *WarcWriter {
return &WarcWriter{gzip.NewWriter(w)}
}
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