Golang gzip.Writer類代碼示例

func (l *splunkLogger) tryPostMessages(messages []*splunkMessage) error {
	if len(messages) == 0 {
		return nil
	}
	var buffer bytes.Buffer
	var writer io.Writer
	var gzipWriter *gzip.Writer
	var err error
	// If gzip compression is enabled - create gzip writer with specified compression
	// level. If gzip compression is disabled, use standard buffer as a writer
	if l.gzipCompression {
		gzipWriter, err = gzip.NewWriterLevel(&buffer, l.gzipCompressionLevel)
		if err != nil {
			return err
		}
		writer = gzipWriter
	} else {
		writer = &buffer
	}
	for _, message := range messages {
		jsonEvent, err := json.Marshal(message)
		if err != nil {
			return err
		}
		if _, err := writer.Write(jsonEvent); err != nil {
			return err
		}
	}
	// If gzip compression is enabled, tell it, that we are done
	if l.gzipCompression {
		err = gzipWriter.Close()
		if err != nil {
			return err
		}
	}
	req, err := http.NewRequest("POST", l.url, bytes.NewBuffer(buffer.Bytes()))
	if err != nil {
		return err
	}
	req.Header.Set("Authorization", l.auth)
	// Tell if we are sending gzip compressed body
	if l.gzipCompression {
		req.Header.Set("Content-Encoding", "gzip")
	}
	res, err := l.client.Do(req)
	if err != nil {
		return err
	}
	defer res.Body.Close()
	if res.StatusCode != http.StatusOK {
		var body []byte
		body, err = ioutil.ReadAll(res.Body)
		if err != nil {
			return err
		}
		return fmt.Errorf("%s: failed to send event - %s - %s", driverName, res.Status, body)
	}
	io.Copy(ioutil.Discard, res.Body)
	return nil
}

// WriteBytes writes an encrypted/compressed stream to an io.Writer
func writeBytes(out io.Writer, key string, data []byte) error {
	var gzWriter *gzip.Writer  // compressed writer
	var iv [aes.BlockSize]byte // initialization vector
	var cb cipher.Block        // cipher block interface
	var err error              // general error holder

	// init cipher block
	if cb, err = aes.NewCipher(hashKey(key)); err != nil {
		return err
	}

	// init encrypted writer
	encWriter := &cipher.StreamWriter{
		S: cipher.NewOFB(cb, iv[:]),
		W: out,
	}

	// close when done
	defer encWriter.Close()

	// wrap encrypted writer
	gzWriter = gzip.NewWriter(encWriter)

	// close when done
	defer gzWriter.Close()

	// copy data to destination file compressing and encrypting along the way
	_, err = io.Copy(gzWriter, bytes.NewReader(data))

	// return copy error
	return err
}

func NewDscout(waiter *sync.WaitGroup, filename string) *Dscout {
	d := new(Dscout)
	d.Operation.Waiter = waiter
	d.Operation.Waiter.Add(1)
	file, err := os.Create(filename)
	if err != nil {
		return nil
	}
	d.closer = func() {
		file.Close()
	}
	var writer io.WriteCloser = file
	var compressor *gzip.Writer
	if strings.HasSuffix(filename, ".gz") {
		compressor = gzip.NewWriter(file)
		d.closer = func() { compressor.Close(); file.Close() }
		writer = compressor
	}
	uncompressed_name := strings.TrimRight(filename, ".gz")
	switch {
	case strings.HasSuffix(uncompressed_name, ".gob"):
		d.marshaler = new(formats.GobMarshaler)
	case strings.HasSuffix(uncompressed_name, ".xml"):
		d.marshaler = new(formats.XmlMarshaler)
	}
	if d.marshaler != nil {
		d.marshaler.InitFile(writer)
	}
	return d
}

func CreateGobsFile(targetFilePath string, recs *[]interface{}, getRecPtr GobRecPtrMaker, gzipped bool) {
	var file, err = os.Create(targetFilePath)
	var gobber *gob.Encoder
	var gzipper *gzip.Writer
	if file != nil {
		defer file.Close()
	}
	if err != nil {
		panic(err)
	}
	if gzipped {
		if gzipper, err = gzip.NewWriterLevel(file, gzip.BestCompression); gzipper != nil {
			defer gzipper.Close()
			gobber = gob.NewEncoder(gzipper)
		}
		if err != nil {
			panic(err)
		}
	} else {
		gobber = gob.NewEncoder(file)
	}
	for _, rec := range *recs {
		if err = gobber.Encode(coreutil.PtrVal(getRecPtr(rec))); err != nil {
			panic(err)
		}
	}
}

func newGzipResponseWriter(w http.ResponseWriter) *gzipResponseWriter {
	var gz *gzip.Writer
	if gzI := gzipWriterPool.Get(); gzI == nil {
		gz = gzip.NewWriter(w)
	} else {
		gz = gzI.(*gzip.Writer)
		gz.Reset(w)
	}
	return &gzipResponseWriter{WriteCloser: gz, ResponseWriter: w}
}

func (this *HtmlView) Publish(ctxt *web.Context) (err error) {
	names := mvc.GetMvcMeta(ctxt)
	if names[mvc.MVC_ACTION] == "" {
		names[mvc.MVC_ACTION] = "_"
	}

	var tmpl *template.Template
	tmpl, err = this.getTmpl(names)

	if err == nil {
		var method = ctxt.Method()

		ctxt.SetHeader("Content-Type", "text/html; charset=utf-8")

		if method != "HEAD" {
			var err error
			var tw io.Writer = ctxt.Response
			var gzipwriter *gzip.Writer

			if ctxt.ReqHeaderHas("Accept-Encoding", "gzip") {
				ctxt.SetHeader("Content-Encoding", "gzip")
				gzipwriter, _ = gzip.NewWriterLevel(ctxt.Response, gzip.BestSpeed)
				tw = gzipwriter
			}

			ctxt.SetHeader("Vary", "Accept-Encoding")
			ctxt.Response.WriteHeader(200)

			err = tmpl.Execute(tw, this.VM)

			if err != nil {
				// Header already sent... multiple write headers
				//panic(err)
				log.Println(err)
			}

			if gzipwriter != nil {
				gzipwriter.Close()
			}

			if flushw, ok := ctxt.Response.(http.Flusher); ok {
				flushw.Flush()
			}
		} else {
			ctxt.Response.WriteHeader(200)
		}
	} else {
		log.Println(err)
		ctxt.SetErrorCode(500)
	}

	return
}

func webQuitHandler(diskwriter *csv.Writer, gzipwriter *gzip.Writer, csvfile *os.File) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprintf(w, "flushing to disk and shutting down")
		diskwriter.Flush()
		if gzipwriter != nil {
			gzipwriter.Flush()
			gzipwriter.Close()
		}
		csvfile.Close()
		os.Exit(0)
	}
}

func main() {
	var file *os.File
	var err error
	var writer *gzip.Writer
	var body []byte

	if file, err = os.Create("output/sample.tar.gz"); err != nil {
		log.Fatalln(err)
	}
	defer file.Close()

	// gzip.NewWriter()なら、エラーを返さないので便利
	if writer, err = gzip.NewWriterLevel(file, gzip.BestCompression); err != nil {
		log.Fatalln(err)
	}
	defer writer.Close()

	var filepaths = []string{
		"files/b0044482_1413812.jpg",
		"files/dart_flight_school.png",
		"files/golang.txt",
	}

	// Write()がio.Writerと同じなので、そのまま行ける。
	//	buf := new(bytes.Buffer)
	//	tw := tar.NewWriter(buf)
	tw := tar.NewWriter(writer)
	defer tw.Close()

	for _, filepath := range filepaths {
		if body, err = ioutil.ReadFile(filepath); err != nil {
			log.Fatalln(err)
		}

		if body != nil {
			hdr := &tar.Header{
				Name: path.Base(filepath),
				Size: int64(len(body)),
			}
			if err := tw.WriteHeader(hdr); err != nil {
				println(err)
			}
			if _, err := tw.Write(body); err != nil {
				println(err)
			}
		}
	}

	//	writer.Write(buf.Bytes())
	//	writer.Flush()
}

func (s *server) serveSync(rw http.ResponseWriter, req *http.Request) {
	memberID := s.validateConnection(rw, req)
	if memberID == "" {
		return
	}
	s.logger.Infof("Peer Member %s started synchronization from address %s", memberID, req.RemoteAddr)

	// Create a new channel for the new member synchronization
	syncChan := make(chan []byte)
	s.syncReqChannel <- syncChan

	// Send the response header to client side
	flusher := rw.(http.Flusher)

	gzipped := strings.Contains(req.Header.Get("Accept-Encoding"), "gzip")

	var gzipWriter *gzip.Writer
	var err error

	if gzipped {
		// override the response writer to be a gzipped writer
		if gzipWriter, err = gzip.NewWriterLevel(rw, gzip.DefaultCompression); err == nil {
			rw = gzipResponseWrapper{Writer: gzipWriter, ResponseWriter: rw}
			rw.Header().Set("Content-Encoding", "gzip")
			flusher = rw.(http.Flusher)
			defer func() {
				gzipWriter.Close()
			}()
		} else {
			s.logger.Warnf("Gzip wrapper creation for %s from %s failed: %v. Falling back to uncompressed HTTP", memberID, req.RemoteAddr, err)
		}
	}

	encoder := newEncoder(rw)
	var msgID uint64
	for data := range syncChan {
		ev := &sse{id: strconv.FormatUint(msgID, 10), event: "SYNC", data: string(data)}
		// Write to the ResponseWriter
		// Server Sent Events compatible
		if err := encoder.Encode(ev); err != nil {
			s.logger.WithFields(log.Fields{
				"error": err,
			}).Errorf("Failed to encode sync message to peer member %s", memberID)
			return
		}
		msgID++
	}
	flusher.Flush()
	s.logger.Infof("Peer Member %s synchronization has been completed successfully", memberID)
}

func createInvoiceFile(filename string) (io.WriteCloser, func(), error) {
	file, err := os.Create(filename)
	if err != nil {
		return nil, nil, err
	}
	closer := func() { file.Close() }
	var writer io.WriteCloser = file
	var compressor *gzip.Writer
	if strings.HasSuffix(filename, ".gz") {
		compressor = gzip.NewWriter(file)
		closer = func() { compressor.Close(); file.Close() }
		writer = compressor
	}
	return writer, closer, nil
}

func getPubmedRecords(urlFetcher *gopubmed.Fetcher, first bool, meshWriter *gzip.Writer, xmlWriter *gzip.Writer, transport *http.Transport, pmids []string) {
	preUrlTime := time.Now()

	articles, raw, err := urlFetcher.GetArticlesAndRaw(pmids)
	if err != nil {
		log.Fatal(err)
	}
	s := string(raw[:len(raw)])

	for i := 0; i < len(articles); i++ {
		pubmedArticle := articles[i]
		if pubmedArticle.MedlineCitation != nil && pubmedArticle.MedlineCitation.MeshHeadingList != nil && pubmedArticle.MedlineCitation.MeshHeadingList.MeshHeading != nil {
			fmt.Fprint(meshWriter, articles[i].MedlineCitation.PMID.Text)
			for j := 0; j < len(pubmedArticle.MedlineCitation.MeshHeadingList.MeshHeading); j++ {
				fmt.Fprint(meshWriter, "|")
				fmt.Fprint(meshWriter, pubmedArticle.MedlineCitation.MeshHeadingList.MeshHeading[j].DescriptorName.Attr_UI)
				fmt.Fprint(meshWriter, "::"+pubmedArticle.MedlineCitation.MeshHeadingList.MeshHeading[j].DescriptorName.Text)

				if len(pubmedArticle.MedlineCitation.MeshHeadingList.MeshHeading[j].QualifierName) > 0 {
					fmt.Fprint(meshWriter, "=")
					for q := 0; q < len(pubmedArticle.MedlineCitation.MeshHeadingList.MeshHeading[j].QualifierName); q++ {
						if q != 0 {
							fmt.Fprint(meshWriter, "&")
						}

						fmt.Fprint(meshWriter, pubmedArticle.MedlineCitation.MeshHeadingList.MeshHeading[j].QualifierName[q].Attr_UI)
						fmt.Fprint(meshWriter, "::"+pubmedArticle.MedlineCitation.MeshHeadingList.MeshHeading[j].QualifierName[q].Text)
					}
				}
			}
			fmt.Fprintln(meshWriter, "")
		}
	}
	meshWriter.Flush()
	if !first {
		s = strings.Replace(s, startXml, "", -1)
		s = strings.Replace(s, docType, "", -1)
		s = strings.Replace(s, startPubmedArticleSet, "", -1)
	}
	s = strings.Replace(s, endPubmedArticleSet, "<!-- breakset -->", -1)

	xmlWriter.Write([]byte(s))
	postUrlTime := time.Now()
	log.Println("Total request time:", postUrlTime.Sub(preUrlTime))
}

func (e *Engine) gzip() error {
	var buf bytes.Buffer
	var level int
	var err error
	level, err = e.stack.PopInt()
	if err == nil {
		var w *gzip.Writer
		w, err = gzip.NewWriterLevel(&buf, level)
		if err == nil {
			_, err = w.Write(e.stack.Pop())
			w.Close()
		}
	}
	if err == nil {
		e.stack.Push(buf.Bytes())
	}
	return err
}

func writeSure(path string, info DirWalker) (err error) {
	file, err := os.Create(path)
	if err != nil {
		return
	}
	defer file.Close()

	var zfile io.Writer
	if strings.HasSuffix(path, ".gz") {
		var tmp *gzip.Writer
		tmp = gzip.NewWriter(file)
		defer tmp.Close()
		zfile = tmp
	} else {
		zfile = file
	}

	io.WriteString(zfile, magic)
	dumpDir(zfile, "__root__", info)
	return
}

func (nf *Netflow) NewFileWriter(filename string, mode int, compress bool) error {
	log.Debugln("NewFileWriter")
	if _, ok := nf.writers[filename]; ok {
		return fmt.Errorf("netflow writer %v already exists", filename)
	}

	f, err := os.Create(filename)
	if err != nil {
		return err
	}

	c := make(chan *Packet, BUFFER_DEPTH)
	go func() {
		var w *gzip.Writer
		if compress {
			log.Debugln("using compression")
			w = gzip.NewWriter(f)
		}
		for {
			d := <-c
			if d == nil {
				break
			}
			if mode == ASCII {
				if compress {
					w.Write([]byte(d.GoString()))
				} else {
					f.Write([]byte(d.GoString()))
				}
			} else {
				if compress {
					w.Write(d.Raw)
				} else {
					f.Write(d.Raw)
				}
			}
		}
		if compress {
			w.Close()
		}
		f.Close()
	}()

	nf.registerWriter(filename, c)
	return nil
}

func calcFileInfo(fi *FileInfo) {
	fmt.Printf("calcFileInfo: '%s'\n", fi.Path)
	const BufSize = 16 * 1024
	var buf [BufSize]byte
	r, err := os.Open(fi.Path)
	fataliferr(err)
	defer r.Close()
	sha1 := sha1.New()
	md5Hash := md5.New()
	fi.ShouldCompress = false
	tryCompressFirsBlock := shouldTryCompressFile(fi.Path)
	var gzw *gzip.Writer
	compressedData := &bytes.Buffer{}
	fi.Size = 0
	fi.CompressedData = nil
	for {
		n, err := r.Read(buf[:])
		if err == io.EOF {
			break
		}
		d := buf[:n]
		fataliferr(err)
		fatalif(n == 0, "n is 0")
		fi.Size += n
		_, err = sha1.Write(d)
		fataliferr(err)
		_, err = md5Hash.Write(d)
		fataliferr(err)
		if tryCompressFirsBlock {
			tryCompressFirsBlock = false
			gz, err := gzip.NewWriterLevel(compressedData, gzip.BestCompression)
			fataliferr(err)
			_, err = gz.Write(d)
			fataliferr(err)
			gz.Close()
			compressedSize := compressedData.Len()
			saved := n - compressedSize
			// relatively high threshold of 20% savings on compression
			fi.ShouldCompress = saved > 0 && perc(compressedSize, saved) > 20
			diff := n - compressedSize
			fmt.Printf("  should compress: %v, %d => %d (%d %.2f%%)\n", fi.ShouldCompress, n, compressedSize, diff, perc(n, diff))
			if fi.ShouldCompress {
				compressedData = &bytes.Buffer{}
				gzw, err = gzip.NewWriterLevel(compressedData, gzip.BestCompression)
				fataliferr(err)
			}
		}
		if gzw != nil {
			_, err = gzw.Write(d)
			fataliferr(err)
		}
	}
	sha1Sum := sha1.Sum(nil)
	fi.Sha1Hex = fmt.Sprintf("%x", sha1Sum)

	if gzw != nil {
		gzw.Close()
		compressedSize := compressedData.Len()
		// only use compressed if compressed by at least 5%
		if compressedSize+(compressedSize/20) < fi.Size {
			fi.CompressedData = compressedData.Bytes()
		}
	}

	md5Sum := md5Hash.Sum(nil)
	fi.Md5Hex = fmt.Sprintf("%x", md5Sum)
	// if compressed, md5 is of the compressed content
	if fi.CompressedData != nil {
		md5Sum2 := md5.Sum(fi.CompressedData)
		fi.Md5Hex = fmt.Sprintf("%x", md5Sum2[:])
	}

	fi.S3PathSha1Part = sha1HexToS3Path(fi.Sha1Hex)
	ext := strings.ToLower(filepath.Ext(fi.Path))
	if fi.CompressedData != nil {
		fi.S3FullPath = fi.S3PathSha1Part + ".gz" + ext
	} else {
		fi.S3FullPath = fi.S3PathSha1Part + ext
	}
	fmt.Printf("  sha1: %s\n", fi.Sha1Hex)
	fmt.Printf("   md5: %s\n", fi.Md5Hex)
	fmt.Printf("    s3: %s\n", fi.S3FullPath)
	fmt.Printf("  size: %d\n", fi.Size)
	if fi.CompressedData != nil {
		sizedCompressed := len(fi.CompressedData)
		saved := fi.Size - sizedCompressed
		fmt.Printf("  size compressed: %d (saves %d %.2f%%)\n", sizedCompressed, saved, perc(fi.Size, saved))
	}
}