refactor: restore "First stage of access logging middleware."

This reverts commit 82651985c4.

middlewares/accesslog/save_backend.go

@@ -0,0 +1,90 @@
+package accesslog
+
+import (
+	"fmt"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/codegangsta/negroni"
+	"github.com/vulcand/oxy/utils"
+)
+
+// SaveBackend sends the backend name to the logger. These are always used with a corresponding
+// SaveFrontend handler.
+type SaveBackend struct {
+	next        http.Handler
+	backendName string
+}
+
+// NewSaveBackend creates a SaveBackend handler.
+func NewSaveBackend(next http.Handler, backendName string) http.Handler {
+	return &SaveBackend{next, backendName}
+}
+
+func (sb *SaveBackend) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
+	table := GetLogDataTable(r)
+	table.Core[BackendName] = sb.backendName
+	table.Core[BackendURL] = r.URL // note that this is *not* the original incoming URL
+	table.Core[BackendAddr] = r.URL.Host
+
+	crw := &captureResponseWriter{rw: rw}
+	start := time.Now().UTC()
+
+	sb.next.ServeHTTP(crw, r)
+
+	// use UTC to handle switchover of daylight saving correctly
+	table.Core[OriginDuration] = time.Now().UTC().Sub(start)
+	table.Core[OriginStatus] = crw.Status()
+	table.Core[OriginStatusLine] = fmt.Sprintf("%03d %s", crw.Status(), http.StatusText(crw.Status()))
+	// make copy of headers so we can ensure there is no subsequent mutation during response processing
+	table.OriginResponse = make(http.Header)
+	utils.CopyHeaders(table.OriginResponse, crw.Header())
+	table.Core[OriginContentSize] = crw.Size()
+}
+
+//-------------------------------------------------------------------------------------------------
+
+// SaveFrontend sends the frontend name to the logger. These are sometimes used with a corresponding
+// SaveBackend handler, but not always. For example, redirected requests don't reach a backend.
+type SaveFrontend struct {
+	next         http.Handler
+	frontendName string
+}
+
+// NewSaveFrontend creates a SaveFrontend handler.
+func NewSaveFrontend(next http.Handler, frontendName string) http.Handler {
+	return &SaveFrontend{next, frontendName}
+}
+
+func (sb *SaveFrontend) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
+	table := GetLogDataTable(r)
+	table.Core[FrontendName] = strings.TrimPrefix(sb.frontendName, "frontend-")
+
+	sb.next.ServeHTTP(rw, r)
+}
+
+//-------------------------------------------------------------------------------------------------
+// the next 3 function (SaveNegroniFrontend, NewSaveNegroniFrontend, ServeHTTP) are temporary,
+// DON'T USE THIS FUNCTION, MUST BE SUPPRESS BEFORE MERGING #1485
+
+// SaveNegroniFrontend sends the frontend name to the logger. These are sometimes used with a corresponding
+// SaveBackend handler, but not always. For example, redirected requests don't reach a backend.
+type SaveNegroniFrontend struct {
+	next         negroni.Handler
+	frontendName string
+}
+
+// NewSaveNegroniFrontend creates a SaveFrontend handler.
+func NewSaveNegroniFrontend(next negroni.Handler, frontendName string) negroni.Handler {
+	return &SaveNegroniFrontend{next, frontendName}
+}
+
+func (sb *SaveNegroniFrontend) ServeHTTP(rw http.ResponseWriter, r *http.Request, next http.HandlerFunc) {
+	table := GetLogDataTable(r)
+	table.Core[FrontendName] = strings.TrimPrefix(sb.frontendName, "frontend-")
+
+	sb.next.ServeHTTP(rw, r, next)
+}
+
+//-------------------------------------------------------------------------------------------------