feat(pprof): add pprof HTTP server (#807)

- `PPROF_ENABLED=no`
- `PPROF_BLOCK_PROFILE_RATE=0`
- `PPROF_MUTEX_PROFILE_RATE=0`
- `PPROF_HTTP_SERVER_ADDRESS=":6060"`

internal/httpserver/run.go

@@ -0,0 +1,66 @@
+package httpserver
+
+import (
+	"context"
+	"errors"
+	"net"
+	"net/http"
+)
+
+// Run runs the HTTP server until ctx is canceled.
+// The done channel has an error written to when the HTTP server
+// is terminated, and can be nil or not nil.
+func (s *Server) Run(ctx context.Context, ready chan<- struct{}, done chan<- struct{}) {
+	server := http.Server{Addr: s.address, Handler: s.handler}
+
+	crashed := make(chan struct{})
+	shutdownDone := make(chan struct{})
+	go func() {
+		defer close(shutdownDone)
+		select {
+		case <-ctx.Done():
+		case <-crashed:
+			return
+		}
+
+		s.logger.Warn(s.name + " http server shutting down: " + ctx.Err().Error())
+		shutdownCtx, cancel := context.WithTimeout(
+			context.Background(), s.shutdownTimeout)
+		defer cancel()
+		if err := server.Shutdown(shutdownCtx); err != nil {
+			s.logger.Error(s.name + " http server failed shutting down within " +
+				s.shutdownTimeout.String())
+		}
+	}()
+
+	listener, err := net.Listen("tcp", s.address)
+	if err != nil {
+		close(s.addressSet)
+		close(crashed) // stop shutdown goroutine
+		<-shutdownDone
+		s.logger.Error(err.Error())
+		close(done)
+		return
+	}
+
+	s.address = listener.Addr().String()
+	close(s.addressSet)
+
+	// note: no further write so no need to mutex
+	s.logger.Info(s.name + " http server listening on " + s.address)
+	close(ready)
+
+	err = server.Serve(listener)
+
+	if err != nil && !errors.Is(ctx.Err(), context.Canceled) {
+		// server crashed
+		close(crashed) // stop shutdown goroutine
+	} else {
+		err = nil
+	}
+	<-shutdownDone
+	if err != nil {
+		s.logger.Error(err.Error())
+	}
+	close(done)
+}