path: root/internal/debug/api.go

// 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/debug"
    "runtime/pprof"
    "strings"
    "sync"
    "time"

    "github.com/ethereum/go-ethereum/log"
)

// 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 log verbosity ceiling. The verbosity of individual packages
// and source files can be raised using Vmodule.
func (*HandlerT) Verbosity(level int) {
    glogger.Verbosity(log.Lvl(level))
}

// Vmodule sets the log verbosity pattern. See package log for details on the
// pattern syntax.
func (*HandlerT) Vmodule(pattern string) error {
    return glogger.Vmodule(pattern)
}

// BacktraceAt sets the log backtrace location. See package log for details on
// the pattern syntax.
func (*HandlerT) BacktraceAt(location string) error {
    return glogger.BacktraceAt(location)
}

// MemStats returns detailed runtime memory statistics.
func (*HandlerT) MemStats() *runtime.MemStats {
    s := new(runtime.MemStats)
    runtime.ReadMemStats(s)
    return s
}

// GcStats returns GC statistics.
func (*HandlerT) GcStats() *debug.GCStats {
    s := new(debug.GCStats)
    debug.ReadGCStats(s)
    return s
}

// 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
    log.Info("CPU profiling started", "dump", 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")
    }
    log.Info("Done writing CPU profile", "dump", h.cpuFile)
    h.cpuW.Close()
    h.cpuW = nil
    h.cpuFile = ""
    return nil
}

// GoTrace turns on tracing for nsec seconds and writes
// trace data to file.
func (h *HandlerT) GoTrace(file string, nsec uint) error {
    if err := h.StartGoTrace(file); err != nil {
        return err
    }
    time.Sleep(time.Duration(nsec) * time.Second)
    h.StopGoTrace()
    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)
}

// FreeOSMemory returns unused memory to the OS.
func (*HandlerT) FreeOSMemory() {
    debug.FreeOSMemory()
}

// SetGCPercent sets the garbage collection target percentage. It returns the previous
// setting. A negative value disables GC.
func (*HandlerT) SetGCPercent(v int) int {
    return debug.SetGCPercent(v)
}

func writeProfile(name, file string) error {
    p := pprof.Lookup(name)
    log.Info("Writing profile records", "count", p.Count(), "type", name, "dump", 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)
}