feat(diagnostics): add pprof profiling (#1627)

* feat(tracing): enable tracing

* of course the squash didn't work.

* gah. always nice when there's 40 csets.

* might as well.

* refactor: tracing to diagnostics

* feat: add note about the magic methods from pprof

---------

Co-authored-by: ze0s <ze0s@riseup.net>

internal/diagnostics/profiling.go

@@ -0,0 +1,30 @@
+// Copyright (c) 2021 - 2024, Ludvig Lundgren and the autobrr contributors.
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package diagnostics
+
+import (
+	"fmt"
+	"net/http"
+	_ "net/http/pprof"
+
+	"github.com/rs/zerolog/log"
+)
+
+// SetupProfiling pprof profiling
+func SetupProfiling(enabled bool, host string, port int) {
+	if enabled {
+		go func() {
+			// pprof has an init method which adds the following endpoints
+			// http.HandleFunc(prefix+"/debug/pprof/", Index)
+			// http.HandleFunc(prefix+"/debug/pprof/cmdline", Cmdline)
+			// http.HandleFunc(prefix+"/debug/pprof/profile", Profile)
+			// http.HandleFunc(prefix+"/debug/pprof/symbol", Symbol)
+			// http.HandleFunc(prefix+"/debug/pprof/trace", Trace)
+			err := http.ListenAndServe(fmt.Sprintf("%s:%d", host, port), nil)
+			if err != nil {
+				log.Printf("Error starting profiling server: %v", err)
+			}
+		}()
+	}
+}