uquic/integrationtests/tools/testlog/testlog.go

package testlog

import (
	"bytes"
	"flag"
	"log"
	"os"
	"sync"

	"github.com/lucas-clemente/quic-go/internal/utils"

	//nolint:stylecheck
	. "github.com/onsi/ginkgo"
	//nolint:stylecheck
	. "github.com/onsi/gomega"
)

const logBufSize = 100 * 1 << 20 // initial size of the log buffer: 100 MB

type syncedBuffer struct {
	mutex sync.Mutex

	*bytes.Buffer
}

func (b *syncedBuffer) Write(p []byte) (int, error) {
	b.mutex.Lock()
	n, err := b.Buffer.Write(p)
	b.mutex.Unlock()
	return n, err
}

func (b *syncedBuffer) Bytes() []byte {
	b.mutex.Lock()
	p := b.Buffer.Bytes()
	b.mutex.Unlock()
	return p
}

func (b *syncedBuffer) Reset() {
	b.mutex.Lock()
	b.Buffer.Reset()
	b.mutex.Unlock()
}

var (
	logFileName string // the log file set in the ginkgo flags
	logBufOnce  sync.Once
	logBuf      *syncedBuffer
)

// read the logfile command line flag
// to set call ginkgo -- -logfile=log.txt
func init() {
	flag.StringVar(&logFileName, "logfile", "", "log file")
}

var _ = BeforeEach(func() {
	log.SetFlags(log.Ldate | log.Ltime | log.Lmicroseconds)

	if Debug() {
		logBufOnce.Do(func() {
			logBuf = &syncedBuffer{Buffer: bytes.NewBuffer(make([]byte, 0, logBufSize))}
		})
		utils.DefaultLogger.SetLogLevel(utils.LogLevelDebug)
		log.SetOutput(logBuf)
	}
})

var _ = AfterEach(func() {
	if Debug() {
		logFile, err := os.Create(logFileName)
		Expect(err).ToNot(HaveOccurred())
		logFile.Write(logBuf.Bytes())
		logFile.Close()
		logBuf.Reset()
	}
})

// Debug says if this test is being logged
func Debug() bool {
	return len(logFileName) > 0
}