first commit

logging/responselogger.go

@@ -0,0 +1,125 @@
+package logging
+
+import (
+	"bufio"
+	"net"
+	"net/http"
+)
+
+// ResponseLogger defines an interface that a responseWrite can implement to
+// support the capture of the status code, the number of bytes written and
+// extra log entry fields.
+type ResponseLogger interface {
+	http.ResponseWriter
+	Size() int
+	StatusCode() int
+	Fields() map[string]interface{}
+	WithFields(map[string]interface{})
+}
+
+// NewResponseLogger wraps the given response writer with methods to capture
+// the status code, the number of bytes written, and methods to add new log
+// entries. It won't wrap the response writer if it's already a
+// ResponseLogger.
+func NewResponseLogger(w http.ResponseWriter) ResponseLogger {
+	if rw, ok := w.(ResponseLogger); ok {
+		return rw
+	}
+	return wrapLogger(w)
+}
+
+func wrapLogger(w http.ResponseWriter) (rw ResponseLogger) {
+	rw = &rwDefault{w, 200, 0, nil}
+	if c, ok := w.(http.CloseNotifier); ok {
+		rw = &rwCloseNotifier{rw, c}
+	}
+	if f, ok := w.(http.Flusher); ok {
+		rw = &rwFlusher{rw, f}
+	}
+	if h, ok := w.(http.Hijacker); ok {
+		rw = &rwHijacker{rw, h}
+	}
+	if p, ok := w.(http.Pusher); ok {
+		rw = &rwPusher{rw, p}
+	}
+	return
+}
+
+type rwDefault struct {
+	http.ResponseWriter
+	code   int
+	size   int
+	fields map[string]interface{}
+}
+
+func (r *rwDefault) Header() http.Header {
+	return r.ResponseWriter.Header()
+}
+
+func (r *rwDefault) Write(p []byte) (n int, err error) {
+	n, err = r.ResponseWriter.Write(p)
+	r.size += n
+	return
+}
+
+func (r *rwDefault) WriteHeader(code int) {
+	r.ResponseWriter.WriteHeader(code)
+	r.code = code
+}
+
+func (r *rwDefault) Size() int {
+	return r.size
+}
+
+func (r *rwDefault) StatusCode() int {
+	return r.code
+}
+
+func (r *rwDefault) Fields() map[string]interface{} {
+	return r.fields
+}
+
+func (r *rwDefault) WithFields(fields map[string]interface{}) {
+	if r.fields == nil {
+		r.fields = make(map[string]interface{}, len(fields))
+	}
+	for k, v := range fields {
+		r.fields[k] = v
+	}
+}
+
+type rwCloseNotifier struct {
+	ResponseLogger
+	c http.CloseNotifier
+}
+
+func (r *rwCloseNotifier) CloseNotify() <-chan bool {
+	return r.CloseNotify()
+}
+
+type rwFlusher struct {
+	ResponseLogger
+	f http.Flusher
+}
+
+func (r *rwFlusher) Flush() {
+	r.f.Flush()
+}
+
+type rwHijacker struct {
+	ResponseLogger
+	h http.Hijacker
+}
+
+func (r *rwHijacker) Hijack() (net.Conn, *bufio.ReadWriter, error) {
+	return r.h.Hijack()
+}
+
+type rwPusher struct {
+	ResponseLogger
+	p http.Pusher
+}
+
+func (rw *rwPusher) Push(target string, opts *http.PushOptions) error {
+	return rw.p.Push(target, opts)
+}