Pull up HTTP changes into deprecated functions

So that also users of those can benefit. Obviously, we will end
updating deprecated functions one day (at latest once v0.10 is out).

Signed-off-by: beorn7 <beorn@soundcloud.com>
This commit is contained in:
beorn7 2018-10-22 12:36:33 +02:00
parent 62361fc0fb
commit fb0f7fe8c2
1 changed files with 52 additions and 53 deletions

View File

@ -15,9 +15,7 @@ package prometheus
import (
"bufio"
"bytes"
"compress/gzip"
"fmt"
"io"
"net"
"net/http"
@ -41,19 +39,10 @@ const (
acceptEncodingHeader = "Accept-Encoding"
)
var bufPool sync.Pool
func getBuf() *bytes.Buffer {
buf := bufPool.Get()
if buf == nil {
return &bytes.Buffer{}
}
return buf.(*bytes.Buffer)
}
func giveBuf(buf *bytes.Buffer) {
buf.Reset()
bufPool.Put(buf)
var gzipPool = sync.Pool{
New: func() interface{} {
return gzip.NewWriter(nil)
},
}
// Handler returns an HTTP handler for the DefaultGatherer. It is
@ -71,58 +60,40 @@ func Handler() http.Handler {
// Deprecated: Use promhttp.HandlerFor(DefaultGatherer, promhttp.HandlerOpts{})
// instead. See there for further documentation.
func UninstrumentedHandler() http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
return http.HandlerFunc(func(rsp http.ResponseWriter, req *http.Request) {
mfs, err := DefaultGatherer.Gather()
if err != nil {
http.Error(w, "An error has occurred during metrics collection:\n\n"+err.Error(), http.StatusInternalServerError)
httpError(rsp, err)
return
}
contentType := expfmt.Negotiate(req.Header)
buf := getBuf()
defer giveBuf(buf)
writer, encoding := decorateWriter(req, buf)
enc := expfmt.NewEncoder(writer, contentType)
var lastErr error
header := rsp.Header()
header.Set(contentTypeHeader, string(contentType))
w := io.Writer(rsp)
if gzipAccepted(req.Header) {
header.Set(contentEncodingHeader, "gzip")
gz := gzipPool.Get().(*gzip.Writer)
defer gzipPool.Put(gz)
gz.Reset(w)
defer gz.Close()
w = gz
}
enc := expfmt.NewEncoder(w, contentType)
for _, mf := range mfs {
if err := enc.Encode(mf); err != nil {
lastErr = err
http.Error(w, "An error has occurred during metrics encoding:\n\n"+err.Error(), http.StatusInternalServerError)
httpError(rsp, err)
return
}
}
if closer, ok := writer.(io.Closer); ok {
closer.Close()
}
if lastErr != nil && buf.Len() == 0 {
http.Error(w, "No metrics encoded, last error:\n\n"+lastErr.Error(), http.StatusInternalServerError)
return
}
header := w.Header()
header.Set(contentTypeHeader, string(contentType))
header.Set(contentLengthHeader, fmt.Sprint(buf.Len()))
if encoding != "" {
header.Set(contentEncodingHeader, encoding)
}
w.Write(buf.Bytes())
})
}
// decorateWriter wraps a writer to handle gzip compression if requested. It
// returns the decorated writer and the appropriate "Content-Encoding" header
// (which is empty if no compression is enabled).
func decorateWriter(request *http.Request, writer io.Writer) (io.Writer, string) {
header := request.Header.Get(acceptEncodingHeader)
parts := strings.Split(header, ",")
for _, part := range parts {
part = strings.TrimSpace(part)
if part == "gzip" || strings.HasPrefix(part, "gzip;") {
return gzip.NewWriter(writer), "gzip"
}
}
return writer, ""
}
var instLabels = []string{"method", "code"}
type nower interface {
@ -503,3 +474,31 @@ func sanitizeCode(s int) string {
return strconv.Itoa(s)
}
}
// gzipAccepted returns whether the client will accept gzip-encoded content.
func gzipAccepted(header http.Header) bool {
a := header.Get(acceptEncodingHeader)
parts := strings.Split(a, ",")
for _, part := range parts {
part = strings.TrimSpace(part)
if part == "gzip" || strings.HasPrefix(part, "gzip;") {
return true
}
}
return false
}
// httpError removes any content-encoding header and then calls http.Error with
// the provided error and http.StatusInternalServerErrer. Error contents is
// supposed to be uncompressed plain text. However, same as with a plain
// http.Error, any header settings will be void if the header has already been
// sent. The error message will still be written to the writer, but it will
// probably be of limited use.
func httpError(rsp http.ResponseWriter, err error) {
rsp.Header().Del(contentEncodingHeader)
http.Error(
rsp,
"An error has occurred while serving metrics:\n\n"+err.Error(),
http.StatusInternalServerError,
)
}