server.go

package server

import (
	"encoding/json"
	"net/http"
	"runtime/debug"
	"time"

	"github.com/ethereum-optimism/optimism/indexer/metrics"

	"github.com/ethereum/go-ethereum/log"
)

// RespondWithError writes the given error code and message to the writer.
func RespondWithError(w http.ResponseWriter, code int, message string) {
	RespondWithJSON(w, code, map[string]string{"error": message})
}

// RespondWithJSON writes the given payload marshalled as JSON to the writer.
func RespondWithJSON(w http.ResponseWriter, code int, payload interface{}) {
	response, _ := json.Marshal(payload)

	w.WriteHeader(code)
	w.Header().Set("Content-Type", "application/json")
	_, _ = w.Write(response)
}

// responseWriter is a minimal wrapper for http.ResponseWriter that allows the
// written HTTP status code to be captured for logging.
type responseWriter struct {
	http.ResponseWriter
	status      int
	wroteHeader bool
}

func wrapResponseWriter(w http.ResponseWriter) *responseWriter {
	return &responseWriter{ResponseWriter: w}
}

func (rw *responseWriter) Status() int {
	return rw.status
}

func (rw *responseWriter) WriteHeader(code int) {
	if rw.wroteHeader {
		return
	}

	rw.status = code
	rw.ResponseWriter.WriteHeader(code)
	rw.wroteHeader = true
}

// LoggingMiddleware logs the incoming HTTP request & its duration.
func LoggingMiddleware(metrics *metrics.Metrics, logger log.Logger) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		fn := func(w http.ResponseWriter, r *http.Request) {
			defer func() {
				if err := recover(); err != nil {
					w.WriteHeader(http.StatusInternalServerError)
					logger.Error(
						"server panicked",
						"err", err,
						"trace", debug.Stack(),
					)
				}
			}()

			metrics.RecordHTTPRequest()
			start := time.Now()
			wrapped := wrapResponseWriter(w)
			next.ServeHTTP(wrapped, r)
			dur := time.Since(start)
			logger.Info(
				"served request",
				"status", wrapped.status,
				"method", r.Method,
				"path", r.URL.EscapedPath(),
				"duration", dur,
			)
			metrics.RecordHTTPResponse(wrapped.status, dur)
		}

		return http.HandlerFunc(fn)
	}
}