Merge branch 'use-gzip-pool' of github.com:glefloch/client_golang into beorn7/http
This commit is contained in:
commit
752f50d366
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@ -53,19 +53,16 @@ const (
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acceptEncodingHeader = "Accept-Encoding"
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)
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var bufPool sync.Pool
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func getBuf() *bytes.Buffer {
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buf := bufPool.Get()
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if buf == nil {
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return &bytes.Buffer{}
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}
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return buf.(*bytes.Buffer)
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var gzipPool = sync.Pool{
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New: func() interface{} {
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return gzip.NewWriter(nil)
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},
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}
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func giveBuf(buf *bytes.Buffer) {
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buf.Reset()
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bufPool.Put(buf)
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var bufPool = sync.Pool{
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New: func() interface{} {
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return &bytes.Buffer{}
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},
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}
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// Handler returns an http.Handler for the prometheus.DefaultGatherer, using
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@ -112,7 +109,6 @@ func HandlerFor(reg prometheus.Gatherer, opts HandlerOpts) http.Handler {
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return
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}
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}
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mfs, err := reg.Gather()
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if err != nil {
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if opts.ErrorLog != nil {
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@ -133,10 +129,12 @@ func HandlerFor(reg prometheus.Gatherer, opts HandlerOpts) http.Handler {
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}
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contentType := expfmt.Negotiate(req.Header)
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buf := getBuf()
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defer giveBuf(buf)
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writer, encoding := decorateWriter(req, buf, opts.DisableCompression)
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enc := expfmt.NewEncoder(writer, contentType)
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buf := bufPool.Get().(*bytes.Buffer)
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buf.Reset()
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enc := expfmt.NewEncoder(buf, contentType)
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defer bufPool.Put(buf)
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var lastErr error
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for _, mf := range mfs {
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if err := enc.Encode(mf); err != nil {
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@ -155,9 +153,7 @@ func HandlerFor(reg prometheus.Gatherer, opts HandlerOpts) http.Handler {
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}
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}
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}
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if closer, ok := writer.(io.Closer); ok {
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closer.Close()
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}
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if lastErr != nil && buf.Len() == 0 {
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http.Error(w, "No metrics encoded, last error:\n\n"+lastErr.Error(), http.StatusInternalServerError)
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return
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@ -165,12 +161,20 @@ func HandlerFor(reg prometheus.Gatherer, opts HandlerOpts) http.Handler {
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header := w.Header()
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header.Set(contentTypeHeader, string(contentType))
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header.Set(contentLengthHeader, fmt.Sprint(buf.Len()))
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if encoding != "" {
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header.Set(contentEncodingHeader, encoding)
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}
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if _, err := w.Write(buf.Bytes()); err != nil && opts.ErrorLog != nil {
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opts.ErrorLog.Println("error while sending encoded metrics:", err)
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if !opts.DisableCompression && gzipAccepted(req.Header) {
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header.Set(contentEncodingHeader, "gzip")
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gz := gzipPool.Get().(*gzip.Writer)
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defer gzipPool.Put(gz)
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gz.Reset(w)
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defer gz.Close()
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zipWriter := gzipResponseWriter{gz, w}
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writeResult(zipWriter, buf, opts)
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return
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}
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writeResult(w, buf, opts)
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// TODO(beorn7): Consider streaming serving of metrics.
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})
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@ -292,20 +296,36 @@ type HandlerOpts struct {
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Timeout time.Duration
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}
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// decorateWriter wraps a writer to handle gzip compression if requested. It
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// returns the decorated writer and the appropriate "Content-Encoding" header
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// (which is empty if no compression is enabled).
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func decorateWriter(request *http.Request, writer io.Writer, compressionDisabled bool) (io.Writer, string) {
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if compressionDisabled {
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return writer, ""
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// gzipResponseWriter in charge of wrapping io.Writer and http.ReponseWriter
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// together, allowing to get a single struct which implements both interface.
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type gzipResponseWriter struct {
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io.Writer
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http.ResponseWriter
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}
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func (w gzipResponseWriter) Write(b []byte) (int, error) {
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return w.Writer.Write(b)
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}
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// writeResult to buf using http.ResponseWriter.
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// If ErrorLog is enabled, err is logged in.
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func writeResult(w http.ResponseWriter, buf *bytes.Buffer, opts HandlerOpts) {
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if _, err := w.Write(buf.Bytes()); err != nil && opts.ErrorLog != nil {
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opts.ErrorLog.Println("error while sending encoded metrics:", err)
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}
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header := request.Header.Get(acceptEncodingHeader)
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parts := strings.Split(header, ",")
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}
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// gzipHandler return a http.HandlerFunc in charge of compressing the content
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// of the given http.HandlerFunc
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func gzipAccepted(header http.Header) bool {
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a := header.Get(acceptEncodingHeader)
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parts := strings.Split(a, ",")
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for _, part := range parts {
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part = strings.TrimSpace(part)
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if part == "gzip" || strings.HasPrefix(part, "gzip;") {
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return gzip.NewWriter(writer), "gzip"
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return true
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}
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}
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return writer, ""
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return false
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}
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