improve performance by using less goroutines

- get rid of command channel in Client
- get rid of loginTimer; use other timers instead
- move debugging code to debug.go

irc/debug.go

@@ -0,0 +1,68 @@
+package irc
+
+import (
+	"os"
+	"runtime"
+	"runtime/debug"
+	"runtime/pprof"
+	"time"
+)
+
+func (msg *DebugCommand) HandleServer(server *Server) {
+	client := msg.Client()
+	if !client.flags[Operator] {
+		return
+	}
+
+	switch msg.subCommand {
+	case "GCSTATS":
+		stats := debug.GCStats{
+			Pause:          make([]time.Duration, 10),
+			PauseQuantiles: make([]time.Duration, 5),
+		}
+		debug.ReadGCStats(&stats)
+
+		server.Replyf(client, "last GC:     %s", stats.LastGC.Format(time.RFC1123))
+		server.Replyf(client, "num GC:      %d", stats.NumGC)
+		server.Replyf(client, "pause total: %s", stats.PauseTotal)
+		server.Replyf(client, "pause quantiles min%%: %s", stats.PauseQuantiles[0])
+		server.Replyf(client, "pause quantiles 25%%:  %s", stats.PauseQuantiles[1])
+		server.Replyf(client, "pause quantiles 50%%:  %s", stats.PauseQuantiles[2])
+		server.Replyf(client, "pause quantiles 75%%:  %s", stats.PauseQuantiles[3])
+		server.Replyf(client, "pause quantiles max%%: %s", stats.PauseQuantiles[4])
+
+	case "NUMGOROUTINE":
+		count := runtime.NumGoroutine()
+		server.Replyf(client, "num goroutines: %d", count)
+
+	case "PROFILEHEAP":
+		profFile := "ergonomadic.mprof"
+		file, err := os.Create(profFile)
+		if err != nil {
+			server.Replyf(client, "error: %s", err)
+			break
+		}
+		defer file.Close()
+		pprof.Lookup("heap").WriteTo(file, 0)
+		server.Replyf(client, "written to %s", profFile)
+
+	case "STARTCPUPROFILE":
+		profFile := "ergonomadic.prof"
+		file, err := os.Create(profFile)
+		if err != nil {
+			server.Replyf(client, "error: %s", err)
+			break
+		}
+		if err := pprof.StartCPUProfile(file); err != nil {
+			defer file.Close()
+			server.Replyf(client, "error: %s", err)
+			break
+		}
+
+		server.Replyf(client, "CPU profile writing to %s", profFile)
+
+	case "STOPCPUPROFILE":
+		pprof.StopCPUProfile()
+		server.Reply(client, "CPU profiling stopped")
+	}
+}