cmd: introduce control socket & subcommand

Move pprof debugging there.

cmd/control.go

@@ -0,0 +1,101 @@
+package cmd
+
+import (
+	"context"
+	"fmt"
+	"github.com/spf13/cobra"
+	"io"
+	golog "log"
+	"net"
+	"net/http"
+	"net/url"
+	"os"
+)
+
+var controlCmd = &cobra.Command{
+	Use:   "control",
+	Short: "control zrepl daemon",
+}
+
+var pprofCmd = &cobra.Command{
+	Use:   "pprof cpu OUTFILE",
+	Short: "pprof CPU of daemon to OUTFILE (- for stdout)",
+	Run:   doControlPProf,
+}
+var pprofCmdArgs struct {
+	seconds int64
+}
+
+func init() {
+	RootCmd.AddCommand(controlCmd)
+	controlCmd.AddCommand(pprofCmd)
+	pprofCmd.Flags().Int64Var(&pprofCmdArgs.seconds, "seconds", 30, "seconds to profile")
+}
+
+func doControlPProf(cmd *cobra.Command, args []string) {
+
+	log := golog.New(os.Stderr, "", 0)
+
+	die := func() {
+		log.Printf("exiting after error")
+		os.Exit(1)
+	}
+
+	ctx := context.WithValue(context.Background(), contextKeyLog, log)
+	conf, err := ParseConfig(ctx, rootArgs.configFile)
+	if err != nil {
+		log.Printf("error parsing config: %s", err)
+		die()
+	}
+
+	if cmd.Flags().Arg(0) != "cpu" {
+		log.Printf("only CPU profiles are supported")
+		log.Printf("%s", cmd.UsageString())
+		die()
+	}
+
+	outfn := cmd.Flags().Arg(1)
+	if outfn == "" {
+		log.Printf("must specify output filename")
+		log.Printf("%s", cmd.UsageString())
+		die()
+	}
+	var out io.Writer
+	if outfn == "-" {
+		out = os.Stdout
+	} else {
+		out, err = os.Create(outfn)
+		if err != nil {
+			log.Printf("error creating output file: %s", err)
+			die()
+		}
+	}
+
+	log.Printf("connecting to daemon")
+	httpc := http.Client{
+		Transport: &http.Transport{
+			DialContext: func(_ context.Context, _, _ string) (net.Conn, error) {
+				return net.Dial("unix", conf.Global.Control.Sockpath)
+			},
+		},
+	}
+
+	log.Printf("profiling...")
+	v := url.Values{}
+	v.Set("seconds", fmt.Sprintf("%d", pprofCmdArgs.seconds))
+	v.Encode()
+	resp, err := httpc.Get("http://unix" + ControlJobEndpointProfile + "?" + v.Encode())
+	if err != nil {
+		log.Printf("error: %s", err)
+		die()
+	}
+
+	_, err = io.Copy(out, resp.Body)
+	if err != nil {
+		log.Printf("error writing profile: %s", err)
+		die()
+	}
+
+	log.Printf("finished")
+
+}