go-ethereum/internal/debug/trace.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/>.

//+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
}