internal/debug: APIs for profiling and tracing

The debug package provides an RPC wrapper for glog settings and the
debugging facilities of the Go runtime. They can be triggered through
both command line flags and the IPC listener.

4 files changed, 404 insertions, 0 deletions

diff --git a/internal/debug/api.go b/internal/debug/api.go
new file mode 100644
index 000000000..83857eb2e
--- /dev/null
+++ b/internal/debug/api.go
@@ -0,0 +1,192 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+// Package debug interfaces Go runtime debugging facilities.
+// This package is mostly glue code making these facilities available
+// through the CLI and RPC subsystem. If you want to use them from Go code,
+// use package runtime instead.
+package debug
+
+import (
+	"errors"
+	"io"
+	"os"
+	"os/user"
+	"path/filepath"
+	"runtime"
+	"runtime/pprof"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/ethereum/go-ethereum/logger"
+	"github.com/ethereum/go-ethereum/logger/glog"
+)
+
+// Handler is the global debugging handler.
+var Handler = new(HandlerT)
+
+// HandlerT implements the debugging API.
+// Do not create values of this type, use the one
+// in the Handler variable instead.
+type HandlerT struct {
+	mu        sync.Mutex
+	cpuW      io.WriteCloser
+	cpuFile   string
+	traceW    io.WriteCloser
+	traceFile string
+}
+
+// Verbosity sets the glog verbosity floor.
+// The verbosity of individual packages and source files
+// can be raised using Vmodule.
+func (*HandlerT) Verbosity(level int) {
+	glog.SetV(level)
+}
+
+// Vmodule sets the glog verbosity pattern. See package
+// glog for details on pattern syntax.
+func (*HandlerT) Vmodule(pattern string) error {
+	return glog.GetVModule().Set(pattern)
+}
+
+// BacktraceAt sets the glog backtrace location.
+// See package glog for details on pattern syntax.
+func (*HandlerT) BacktraceAt(location string) error {
+	return glog.GetTraceLocation().Set(location)
+}
+
+// CpuProfile turns on CPU profiling for nsec seconds and writes
+// profile data to file.
+func (h *HandlerT) CpuProfile(file string, nsec uint) error {
+	if err := h.StartCPUProfile(file); err != nil {
+		return err
+	}
+	time.Sleep(time.Duration(nsec) * time.Second)
+	h.StopCPUProfile()
+	return nil
+}
+
+// StartCPUProfile turns on CPU profiling, writing to the given file.
+func (h *HandlerT) StartCPUProfile(file string) error {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	if h.cpuW != nil {
+		return errors.New("CPU profiling already in progress")
+	}
+	f, err := os.Create(expandHome(file))
+	if err != nil {
+		return err
+	}
+	if err := pprof.StartCPUProfile(f); err != nil {
+		f.Close()
+		return err
+	}
+	h.cpuW = f
+	h.cpuFile = file
+	glog.V(logger.Info).Infoln("CPU profiling started, writing to", h.cpuFile)
+	return nil
+}
+
+// StopCPUProfile stops an ongoing CPU profile.
+func (h *HandlerT) StopCPUProfile() error {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	pprof.StopCPUProfile()
+	if h.cpuW == nil {
+		return errors.New("CPU profiling not in progress")
+	}
+	glog.V(logger.Info).Infoln("done writing CPU profile to", h.cpuFile)
+	h.cpuW.Close()
+	h.cpuW = nil
+	h.cpuFile = ""
+	return nil
+}
+
+// Trace turns on tracing for nsec seconds and writes
+// trace data to file.
+func (h *HandlerT) Trace(file string, nsec uint) error {
+	if err := h.StartTrace(file); err != nil {
+		return err
+	}
+	time.Sleep(time.Duration(nsec) * time.Second)
+	h.StopTrace()
+	return nil
+}
+
+// BlockProfile turns on CPU profiling for nsec seconds and writes
+// profile data to file. It uses a profile rate of 1 for most accurate
+// information. If a different rate is desired, set the rate
+// and write the profile manually.
+func (*HandlerT) BlockProfile(file string, nsec uint) error {
+	runtime.SetBlockProfileRate(1)
+	time.Sleep(time.Duration(nsec) * time.Second)
+	defer runtime.SetBlockProfileRate(0)
+	return writeProfile("block", file)
+}
+
+// SetBlockProfileRate sets the rate of goroutine block profile data collection.
+// rate 0 disables block profiling.
+func (*HandlerT) SetBlockProfileRate(rate int) {
+	runtime.SetBlockProfileRate(rate)
+}
+
+// WriteBlockProfile writes a goroutine blocking profile to the given file.
+func (*HandlerT) WriteBlockProfile(file string) error {
+	return writeProfile("block", file)
+}
+
+// WriteMemProfile writes an allocation profile to the given file.
+// Note that the profiling rate cannot be set through the API,
+// it must be set on the command line.
+func (*HandlerT) WriteMemProfile(file string) error {
+	return writeProfile("heap", file)
+}
+
+// Stacks returns a printed representation of the stacks of all goroutines.
+func (*HandlerT) Stacks() string {
+	buf := make([]byte, 1024*1024)
+	buf = buf[:runtime.Stack(buf, true)]
+	return string(buf)
+}
+
+func writeProfile(name, file string) error {
+	p := pprof.Lookup(name)
+	glog.V(logger.Info).Infof("writing %d %s profile records to %s", p.Count(), name, file)
+	f, err := os.Create(expandHome(file))
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	return p.WriteTo(f, 0)
+}
+
+// expands home directory in file paths.
+// ~someuser/tmp will not be expanded.
+func expandHome(p string) string {
+	if strings.HasPrefix(p, "~/") || strings.HasPrefix(p, "~\\") {
+		home := os.Getenv("HOME")
+		if home == "" {
+			if usr, err := user.Current(); err == nil {
+				home = usr.HomeDir
+			}
+		}
+		if home != "" {
+			p = home + p[1:]
+		}
+	}
+	return filepath.Clean(p)
+}
diff --git a/internal/debug/flags.go b/internal/debug/flags.go
new file mode 100644
index 000000000..22e524cd6
--- /dev/null
+++ b/internal/debug/flags.go
@@ -0,0 +1,117 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package debug
+
+import (
+	"fmt"
+	"net/http"
+	_ "net/http/pprof"
+	"runtime"
+
+	"github.com/codegangsta/cli"
+	"github.com/ethereum/go-ethereum/logger"
+	"github.com/ethereum/go-ethereum/logger/glog"
+)
+
+var (
+	verbosityFlag = cli.GenericFlag{
+		Name:  "verbosity",
+		Usage: "Logging verbosity: 0=silent, 1=error, 2=warn, 3=info, 4=core, 5=debug, 6=detail",
+		Value: glog.GetVerbosity(),
+	}
+	vmoduleFlag = cli.GenericFlag{
+		Name:  "vmodule",
+		Usage: "Per-module verbosity: comma-separated list of <pattern>=<level> (e.g. eth/*=6,p2p=5)",
+		Value: glog.GetVModule(),
+	}
+	backtraceAtFlag = cli.GenericFlag{
+		Name:  "backtrace",
+		Usage: "Request a stack trace at a specific logging statement (e.g. \"block.go:271\")",
+		Value: glog.GetTraceLocation(),
+	}
+	pprofFlag = cli.BoolFlag{
+		Name:  "pprof",
+		Usage: "Enable the pprof HTTP server",
+	}
+	pprofPortFlag = cli.IntFlag{
+		Name:  "pprofport",
+		Usage: "pprof HTTP server listening port",
+		Value: 6060,
+	}
+	memprofilerateFlag = cli.IntFlag{
+		Name:  "memprofilerate",
+		Usage: "Turn on memory profiling with the given rate",
+	}
+	blockprofilerateFlag = cli.IntFlag{
+		Name:  "blockprofilerate",
+		Usage: "Turn on block profiling with the given rate",
+	}
+	cpuprofileFlag = cli.StringFlag{
+		Name:  "cpuprofile",
+		Usage: "Write CPU profile to the given file",
+	}
+	traceFlag = cli.StringFlag{
+		Name:  "trace",
+		Usage: "Write execution trace to the given file",
+	}
+)
+
+// Flags holds all command-line flags required for debugging.
+var Flags = []cli.Flag{
+	verbosityFlag, vmoduleFlag, backtraceAtFlag,
+	pprofFlag, pprofPortFlag,
+	memprofilerateFlag, blockprofilerateFlag, cpuprofileFlag, traceFlag,
+}
+
+// Setup initializes profiling and logging based on the CLI flags.
+// It should be called as early as possible in the program.
+func Setup(ctx *cli.Context) error {
+	// logging
+	glog.CopyStandardLogTo("INFO")
+	glog.SetToStderr(true)
+
+	// profiling, tracing
+	runtime.MemProfileRate = ctx.GlobalInt(memprofilerateFlag.Name)
+	Handler.SetBlockProfileRate(ctx.GlobalInt(blockprofilerateFlag.Name))
+	if traceFile := ctx.GlobalString(traceFlag.Name); traceFile != "" {
+		if err := Handler.StartTrace(traceFile); err != nil {
+			return err
+		}
+	}
+	if cpuFile := ctx.GlobalString(cpuprofileFlag.Name); cpuFile != "" {
+		if err := Handler.StartCPUProfile(cpuFile); err != nil {
+			return err
+		}
+	}
+
+	// pprof server
+	if ctx.GlobalBool(pprofFlag.Name) {
+		address := fmt.Sprintf("127.0.0.1:%d", ctx.GlobalInt(pprofPortFlag.Name))
+		go func() {
+			glog.V(logger.Info).Infof("starting pprof server at http://%s/debug/pprof", address)
+			glog.Errorln(http.ListenAndServe(address, nil))
+		}()
+	}
+	return nil
+}
+
+// Exit stops all running profiles, flushing their output to the
+// respective file.
+func Exit() {
+	Handler.StopCPUProfile()
+	Handler.StopTrace()
+}
diff --git a/internal/debug/trace.go b/internal/debug/trace.go
new file mode 100644
index 000000000..45637977a
--- /dev/null
+++ b/internal/debug/trace.go
@@ -0,0 +1,64 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+//+build go1.5
+
+package debug
+
+import (
+	"errors"
+	"os"
+	"runtime/trace"
+
+	"github.com/ethereum/go-ethereum/logger"
+	"github.com/ethereum/go-ethereum/logger/glog"
+)
+
+// StartTrace turns on tracing, writing to the given file.
+func (h *HandlerT) StartTrace(file string) error {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	if h.traceW != nil {
+		return errors.New("trace already in progress")
+	}
+	f, err := os.Create(expandHome(file))
+	if err != nil {
+		return err
+	}
+	if err := trace.Start(f); err != nil {
+		f.Close()
+		return err
+	}
+	h.traceW = f
+	h.traceFile = file
+	glog.V(logger.Info).Infoln("trace started, writing to", h.traceFile)
+	return nil
+}
+
+// StopTrace stops an ongoing trace.
+func (h *HandlerT) StopTrace() error {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	trace.Stop()
+	if h.traceW == nil {
+		return errors.New("trace not in progress")
+	}
+	glog.V(logger.Info).Infoln("done writing trace to", h.traceFile)
+	h.traceW.Close()
+	h.traceW = nil
+	h.traceFile = ""
+	return nil
+}
diff --git a/internal/debug/trace_fallback.go b/internal/debug/trace_fallback.go
new file mode 100644
index 000000000..319945925
--- /dev/null
+++ b/internal/debug/trace_fallback.go
@@ -0,0 +1,31 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+//+build !go1.5
+
+// no-op implementation of tracing methods for Go < 1.5.
+
+package debug
+
+import "errors"
+
+func (*HandlerT) StartTrace(string) error {
+	return errors.New("tracing is not supported on Go < 1.5")
+}
+
+func (*HandlerT) StopTrace() error {
+	return errors.New("tracing is not supported on Go < 1.5")
+}