Introduce Tprintf to simplify the current log format

Hypcast previously had a bunch of individual "logf" methods to dump out a log prefixed by a type name and pointer address. This change uses a bit of reflection and a bit of rework on the existing type names to extract that into one shared function. There's an interesting mix of generics and reflection here. I'm using the type parameter to enforce that src is a pointer, which guarantees that "%p" will work right and simplifies getting the type name compared to digging through layers of Elem() that will panic with a wrong move. I'm considering moving Hypcast to log/slog. Even if I throw this away soon, it's nice that I'll be able to search for "log." across the whole codebase to see what needs to change.
ahamlinman · Sep 7, 2024 · 3b669fd · 3b669fd
1 parent 3eb419d
commit 3b669fd
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Showing 4 changed files with 51 additions and 47 deletions.
diff --git a/internal/api/tunerstatus.go b/internal/api/tunerstatus.go
@@ -2,17 +2,17 @@ package api
 
 import (
 	"context"
-	"log"
 	"net/http"
 	"sync"
 
 	"github.com/gorilla/websocket"
 
 	"github.com/ahamlinman/hypcast/internal/atsc/tuner"
+	"github.com/ahamlinman/hypcast/internal/log"
 	"github.com/ahamlinman/hypcast/internal/watch"
 )
 
-type tunerStatusHandler struct {
+type TunerStatusHandler struct {
 	tuner     *tuner.Tuner
 	socket    *websocket.Conn
 	watch     watch.Watch
@@ -23,19 +23,19 @@ type tunerStatusHandler struct {
 
 func (h *Handler) handleSocketTunerStatus(w http.ResponseWriter, r *http.Request) {
 	ctx, shutdown := context.WithCancelCause(r.Context())
-	tsh := &tunerStatusHandler{
+	tsh := &TunerStatusHandler{
 		tuner:    h.tuner,
 		ctx:      ctx,
 		shutdown: shutdown,
 	}
 	tsh.ServeHTTP(w, r)
 }
 
-func (tsh *tunerStatusHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	tsh.logf("Starting new connection")
+func (tsh *TunerStatusHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	log.Tprintf(tsh, "Starting new connection")
 	defer func() {
 		tsh.waitForCleanup()
-		tsh.logf("Connection done: %v", context.Cause(tsh.ctx))
+		log.Tprintf(tsh, "Connection done: %v", context.Cause(tsh.ctx))
 	}()
 
 	var err error
@@ -57,16 +57,16 @@ func (tsh *tunerStatusHandler) ServeHTTP(w http.ResponseWriter, r *http.Request)
 	<-tsh.ctx.Done()
 }
 
-func (tsh *tunerStatusHandler) sendNewTunerStatus(s tuner.Status) {
-	tsh.logf("Received tuner status: %v", s)
+func (tsh *TunerStatusHandler) sendNewTunerStatus(s tuner.Status) {
+	log.Tprintf(tsh, "Received tuner status: %v", s)
 
 	msg := tsh.mapTunerStatusToMessage(s)
 	if err := tsh.socket.WriteJSON(msg); err != nil {
 		tsh.shutdown(err)
 	}
 }
 
-func (tsh *tunerStatusHandler) drainClient() {
+func (tsh *TunerStatusHandler) drainClient() {
 	// Per https://pkg.go.dev/github.com/gorilla/websocket#hdr-Control_Messages,
 	// we have to drain incoming messages ourselves even if we don't care about
 	// them.
@@ -78,7 +78,7 @@ func (tsh *tunerStatusHandler) drainClient() {
 	}
 }
 
-func (tsh *tunerStatusHandler) waitForCleanup() {
+func (tsh *TunerStatusHandler) waitForCleanup() {
 	if tsh.watch != nil {
 		tsh.watch.Wait()
 	}
@@ -97,7 +97,7 @@ var tunerStateStrings = map[tuner.State]string{
 	tuner.StatePlaying:  "Playing",
 }
 
-func (tsh *tunerStatusHandler) mapTunerStatusToMessage(s tuner.Status) tunerStatusMsg {
+func (tsh *TunerStatusHandler) mapTunerStatusToMessage(s tuner.Status) tunerStatusMsg {
 	msg := tunerStatusMsg{
 		State:       tunerStateStrings[s.State],
 		ChannelName: s.ChannelName,
@@ -107,11 +107,3 @@ func (tsh *tunerStatusHandler) mapTunerStatusToMessage(s tuner.Status) tunerStat
 	}
 	return msg
 }
-
-func (tsh *tunerStatusHandler) logf(format string, v ...any) {
-	joinFmt := "TunerStatusHandler(%p): " + format
-	joinArgs := make([]any, len(v)+1)
-	joinArgs[0] = tsh
-	copy(joinArgs[1:], v)
-	log.Printf(joinFmt, joinArgs...)
-}
diff --git a/internal/api/webrtc.go b/internal/api/webrtc.go
@@ -4,14 +4,14 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
-	"log"
 	"net/http"
 	"sync"
 
 	"github.com/gorilla/websocket"
 	"github.com/pion/webrtc/v3"
 
 	"github.com/ahamlinman/hypcast/internal/atsc/tuner"
+	"github.com/ahamlinman/hypcast/internal/log"
 	"github.com/ahamlinman/hypcast/internal/watch"
 )
 
@@ -43,7 +43,7 @@ func init() {
 	webrtcAPI = webrtc.NewAPI(webrtc.WithMediaEngine(&me))
 }
 
-type webrtcHandler struct {
+type WebRTCHandler struct {
 	tuner     *tuner.Tuner
 	socket    *websocket.Conn
 	rtcPeer   *webrtc.PeerConnection
@@ -55,19 +55,19 @@ type webrtcHandler struct {
 
 func (h *Handler) handleSocketWebRTCPeer(w http.ResponseWriter, r *http.Request) {
 	ctx, shutdown := context.WithCancelCause(r.Context())
-	wh := &webrtcHandler{
+	wh := &WebRTCHandler{
 		tuner:    h.tuner,
 		ctx:      ctx,
 		shutdown: shutdown,
 	}
 	wh.ServeHTTP(w, r)
 }
 
-func (wh *webrtcHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	wh.logf("Starting new connection")
+func (wh *WebRTCHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	log.Tprintf(wh, "Starting new connection")
 	defer func() {
 		wh.waitForCleanup()
-		wh.logf("Connection done: %v", context.Cause(wh.ctx))
+		log.Tprintf(wh, "Connection done: %v", context.Cause(wh.ctx))
 	}()
 
 	var err error
@@ -95,7 +95,7 @@ func (wh *webrtcHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	<-wh.ctx.Done()
 }
 
-func (wh *webrtcHandler) handleClientSessionAnswers() {
+func (wh *WebRTCHandler) handleClientSessionAnswers() {
 	for {
 		_, r, err := wh.socket.NextReader()
 		if err != nil {
@@ -116,8 +116,8 @@ func (wh *webrtcHandler) handleClientSessionAnswers() {
 	}
 }
 
-func (wh *webrtcHandler) handleTrackUpdate(ts tuner.Tracks) {
-	wh.logf("Received tracks: %v", ts)
+func (wh *WebRTCHandler) handleTrackUpdate(ts tuner.Tracks) {
+	log.Tprintf(wh, "Received tracks: %v", ts)
 	if err := wh.replaceTracks(ts); err != nil {
 		wh.shutdown(err)
 		return
@@ -128,7 +128,7 @@ func (wh *webrtcHandler) handleTrackUpdate(ts tuner.Tracks) {
 	}
 }
 
-func (wh *webrtcHandler) replaceTracks(ts tuner.Tracks) error {
+func (wh *WebRTCHandler) replaceTracks(ts tuner.Tracks) error {
 	if err := wh.removeTracks(); err != nil {
 		return err
 	}
@@ -138,7 +138,7 @@ func (wh *webrtcHandler) replaceTracks(ts tuner.Tracks) error {
 	return wh.addTracks(ts)
 }
 
-func (wh *webrtcHandler) renegotiateSession() error {
+func (wh *WebRTCHandler) renegotiateSession() error {
 	if !wh.hasTransceivers() {
 		// Skip negotiation until we've had a chance to properly define video and
 		// audio transceivers based on Tuner tracks.
@@ -163,7 +163,7 @@ func (wh *webrtcHandler) renegotiateSession() error {
 	return wh.socket.WriteJSON(msg)
 }
 
-func (wh *webrtcHandler) removeTracks() error {
+func (wh *WebRTCHandler) removeTracks() error {
 	for _, sender := range wh.rtcPeer.GetSenders() {
 		if err := wh.rtcPeer.RemoveTrack(sender); err != nil {
 			return err
@@ -172,14 +172,14 @@ func (wh *webrtcHandler) removeTracks() error {
 	return nil
 }
 
-func (wh *webrtcHandler) addTracks(ts tuner.Tracks) error {
+func (wh *WebRTCHandler) addTracks(ts tuner.Tracks) error {
 	if wh.hasTransceivers() {
 		return wh.addTracksWithExistingTransceivers(ts)
 	}
 	return wh.addTracksWithNewTransceivers(ts)
 }
 
-func (wh *webrtcHandler) addTracksWithExistingTransceivers(ts tuner.Tracks) error {
+func (wh *WebRTCHandler) addTracksWithExistingTransceivers(ts tuner.Tracks) error {
 	if _, err := wh.rtcPeer.AddTrack(ts.Video); err != nil {
 		return err
 	}
@@ -189,7 +189,7 @@ func (wh *webrtcHandler) addTracksWithExistingTransceivers(ts tuner.Tracks) erro
 	return nil
 }
 
-func (wh *webrtcHandler) addTracksWithNewTransceivers(ts tuner.Tracks) error {
+func (wh *WebRTCHandler) addTracksWithNewTransceivers(ts tuner.Tracks) error {
 	init := webrtc.RTPTransceiverInit{
 		Direction: webrtc.RTPTransceiverDirectionSendonly,
 	}
@@ -202,21 +202,13 @@ func (wh *webrtcHandler) addTracksWithNewTransceivers(ts tuner.Tracks) error {
 	return nil
 }
 
-func (wh *webrtcHandler) hasTransceivers() bool {
+func (wh *WebRTCHandler) hasTransceivers() bool {
 	return len(wh.rtcPeer.GetTransceivers()) > 0
 }
 
-func (wh *webrtcHandler) waitForCleanup() {
+func (wh *WebRTCHandler) waitForCleanup() {
 	if wh.watch != nil {
 		wh.watch.Wait()
 	}
 	wh.waitGroup.Wait()
 }
-
-func (wh *webrtcHandler) logf(format string, v ...any) {
-	joinFmt := "WebRTCHandler(%p): " + format
-	joinArgs := make([]any, len(v)+1)
-	joinArgs[0] = wh
-	copy(joinArgs[1:], v)
-	log.Printf(joinFmt, joinArgs...)
-}
diff --git a/internal/atsc/tuner/tuner.go b/internal/atsc/tuner/tuner.go
@@ -5,7 +5,6 @@ package tuner
 import (
 	"errors"
 	"fmt"
-	"log"
 	"strings"
 	"sync"
 	"text/template"
@@ -16,6 +15,7 @@ import (
 
 	"github.com/ahamlinman/hypcast/internal/atsc"
 	"github.com/ahamlinman/hypcast/internal/gst"
+	"github.com/ahamlinman/hypcast/internal/log"
 	"github.com/ahamlinman/hypcast/internal/watch"
 )
 
@@ -194,12 +194,12 @@ func (t *Tuner) Tune(channelName string) (err error) {
 	t.pipeline.SetSink(sinkNameVideo, createTrackSink(vt))
 	t.pipeline.SetSink(sinkNameAudio, createTrackSink(at))
 
-	log.Printf("Tuner(%p): Starting pipeline", t)
+	log.Tprintf(t, "Starting pipeline")
 	err = t.pipeline.Start()
 	if err != nil {
 		return err
 	}
-	log.Printf("Tuner(%p): Started pipeline", t)
+	log.Tprintf(t, "Started pipeline")
 
 	t.status.Set(Status{
 		State:       StatePlaying,

diff --git a/internal/log/log.go b/internal/log/log.go
@@ -0,0 +1,20 @@
+// Package log provides special log formatting features for Hypcast.
+package log
+
+import (
+	"log"
+	"reflect"
+)
+
+// Tprintf prints its arguments in the manner of [log.Printf], with a prefix of
+// the form "Type(0xabcd...)" indicating the element type and address of the src
+// pointer. This can be a convenient way to differentiate instances of the same
+// type, though addresses are somewhat opaque as identifiers, and revealing them
+// might even be a security concern (albeit a far-fetched one).
+func Tprintf[T any](src *T, fmt string, v ...any) {
+	tfmt := "%s(%p): " + fmt
+	tval := make([]any, len(v)+2)
+	tval[0], tval[1] = reflect.TypeFor[T]().Name(), src
+	copy(tval[2:], v)
+	log.Printf(tfmt, tval...)
+}