well-goknown/vendor/github.com/rs/zerolog/writer.go

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package zerolog
import (
"bytes"
"io"
"path"
"runtime"
"strconv"
"strings"
"sync"
)
// LevelWriter defines as interface a writer may implement in order
// to receive level information with payload.
type LevelWriter interface {
io.Writer
WriteLevel(level Level, p []byte) (n int, err error)
}
// LevelWriterAdapter adapts an io.Writer to support the LevelWriter interface.
type LevelWriterAdapter struct {
io.Writer
}
// WriteLevel simply writes everything to the adapted writer, ignoring the level.
func (lw LevelWriterAdapter) WriteLevel(l Level, p []byte) (n int, err error) {
return lw.Write(p)
}
// Call the underlying writer's Close method if it is an io.Closer. Otherwise
// does nothing.
func (lw LevelWriterAdapter) Close() error {
if closer, ok := lw.Writer.(io.Closer); ok {
return closer.Close()
}
return nil
}
type syncWriter struct {
mu sync.Mutex
lw LevelWriter
}
// SyncWriter wraps w so that each call to Write is synchronized with a mutex.
// This syncer can be used to wrap the call to writer's Write method if it is
// not thread safe. Note that you do not need this wrapper for os.File Write
// operations on POSIX and Windows systems as they are already thread-safe.
func SyncWriter(w io.Writer) io.Writer {
if lw, ok := w.(LevelWriter); ok {
return &syncWriter{lw: lw}
}
return &syncWriter{lw: LevelWriterAdapter{w}}
}
// Write implements the io.Writer interface.
func (s *syncWriter) Write(p []byte) (n int, err error) {
s.mu.Lock()
defer s.mu.Unlock()
return s.lw.Write(p)
}
// WriteLevel implements the LevelWriter interface.
func (s *syncWriter) WriteLevel(l Level, p []byte) (n int, err error) {
s.mu.Lock()
defer s.mu.Unlock()
return s.lw.WriteLevel(l, p)
}
func (s *syncWriter) Close() error {
s.mu.Lock()
defer s.mu.Unlock()
if closer, ok := s.lw.(io.Closer); ok {
return closer.Close()
}
return nil
}
type multiLevelWriter struct {
writers []LevelWriter
}
func (t multiLevelWriter) Write(p []byte) (n int, err error) {
for _, w := range t.writers {
if _n, _err := w.Write(p); err == nil {
n = _n
if _err != nil {
err = _err
} else if _n != len(p) {
err = io.ErrShortWrite
}
}
}
return n, err
}
func (t multiLevelWriter) WriteLevel(l Level, p []byte) (n int, err error) {
for _, w := range t.writers {
if _n, _err := w.WriteLevel(l, p); err == nil {
n = _n
if _err != nil {
err = _err
} else if _n != len(p) {
err = io.ErrShortWrite
}
}
}
return n, err
}
// Calls close on all the underlying writers that are io.Closers. If any of the
// Close methods return an error, the remainder of the closers are not closed
// and the error is returned.
func (t multiLevelWriter) Close() error {
for _, w := range t.writers {
if closer, ok := w.(io.Closer); ok {
if err := closer.Close(); err != nil {
return err
}
}
}
return nil
}
// MultiLevelWriter creates a writer that duplicates its writes to all the
// provided writers, similar to the Unix tee(1) command. If some writers
// implement LevelWriter, their WriteLevel method will be used instead of Write.
func MultiLevelWriter(writers ...io.Writer) LevelWriter {
lwriters := make([]LevelWriter, 0, len(writers))
for _, w := range writers {
if lw, ok := w.(LevelWriter); ok {
lwriters = append(lwriters, lw)
} else {
lwriters = append(lwriters, LevelWriterAdapter{w})
}
}
return multiLevelWriter{lwriters}
}
// TestingLog is the logging interface of testing.TB.
type TestingLog interface {
Log(args ...interface{})
Logf(format string, args ...interface{})
Helper()
}
// TestWriter is a writer that writes to testing.TB.
type TestWriter struct {
T TestingLog
// Frame skips caller frames to capture the original file and line numbers.
Frame int
}
// NewTestWriter creates a writer that logs to the testing.TB.
func NewTestWriter(t TestingLog) TestWriter {
return TestWriter{T: t}
}
// Write to testing.TB.
func (t TestWriter) Write(p []byte) (n int, err error) {
t.T.Helper()
n = len(p)
// Strip trailing newline because t.Log always adds one.
p = bytes.TrimRight(p, "\n")
// Try to correct the log file and line number to the caller.
if t.Frame > 0 {
_, origFile, origLine, _ := runtime.Caller(1)
_, frameFile, frameLine, ok := runtime.Caller(1 + t.Frame)
if ok {
erase := strings.Repeat("\b", len(path.Base(origFile))+len(strconv.Itoa(origLine))+3)
t.T.Logf("%s%s:%d: %s", erase, path.Base(frameFile), frameLine, p)
return n, err
}
}
t.T.Log(string(p))
return n, err
}
// ConsoleTestWriter creates an option that correctly sets the file frame depth for testing.TB log.
func ConsoleTestWriter(t TestingLog) func(w *ConsoleWriter) {
return func(w *ConsoleWriter) {
w.Out = TestWriter{T: t, Frame: 6}
}
}
// FilteredLevelWriter writes only logs at Level or above to Writer.
//
// It should be used only in combination with MultiLevelWriter when you
// want to write to multiple destinations at different levels. Otherwise
// you should just set the level on the logger and filter events early.
// When using MultiLevelWriter then you set the level on the logger to
// the lowest of the levels you use for writers.
type FilteredLevelWriter struct {
Writer LevelWriter
Level Level
}
// Write writes to the underlying Writer.
func (w *FilteredLevelWriter) Write(p []byte) (int, error) {
return w.Writer.Write(p)
}
// WriteLevel calls WriteLevel of the underlying Writer only if the level is equal
// or above the Level.
func (w *FilteredLevelWriter) WriteLevel(level Level, p []byte) (int, error) {
if level >= w.Level {
return w.Writer.WriteLevel(level, p)
}
return len(p), nil
}
var triggerWriterPool = &sync.Pool{
New: func() interface{} {
return bytes.NewBuffer(make([]byte, 0, 1024))
},
}
// TriggerLevelWriter buffers log lines at the ConditionalLevel or below
// until a trigger level (or higher) line is emitted. Log lines with level
// higher than ConditionalLevel are always written out to the destination
// writer. If trigger never happens, buffered log lines are never written out.
//
// It can be used to configure "log level per request".
type TriggerLevelWriter struct {
// Destination writer. If LevelWriter is provided (usually), its WriteLevel is used
// instead of Write.
io.Writer
// ConditionalLevel is the level (and below) at which lines are buffered until
// a trigger level (or higher) line is emitted. Usually this is set to DebugLevel.
ConditionalLevel Level
// TriggerLevel is the lowest level that triggers the sending of the conditional
// level lines. Usually this is set to ErrorLevel.
TriggerLevel Level
buf *bytes.Buffer
triggered bool
mu sync.Mutex
}
func (w *TriggerLevelWriter) WriteLevel(l Level, p []byte) (n int, err error) {
w.mu.Lock()
defer w.mu.Unlock()
// At first trigger level or above log line, we flush the buffer and change the
// trigger state to triggered.
if !w.triggered && l >= w.TriggerLevel {
err := w.trigger()
if err != nil {
return 0, err
}
}
// Unless triggered, we buffer everything at and below ConditionalLevel.
if !w.triggered && l <= w.ConditionalLevel {
if w.buf == nil {
w.buf = triggerWriterPool.Get().(*bytes.Buffer)
}
// We prefix each log line with a byte with the level.
// Hopefully we will never have a level value which equals a newline
// (which could interfere with reconstruction of log lines in the trigger method).
w.buf.WriteByte(byte(l))
w.buf.Write(p)
return len(p), nil
}
// Anything above ConditionalLevel is always passed through.
// Once triggered, everything is passed through.
if lw, ok := w.Writer.(LevelWriter); ok {
return lw.WriteLevel(l, p)
}
return w.Write(p)
}
// trigger expects lock to be held.
func (w *TriggerLevelWriter) trigger() error {
if w.triggered {
return nil
}
w.triggered = true
if w.buf == nil {
return nil
}
p := w.buf.Bytes()
for len(p) > 0 {
// We do not use bufio.Scanner here because we already have full buffer
// in the memory and we do not want extra copying from the buffer to
// scanner's token slice, nor we want to hit scanner's token size limit,
// and we also want to preserve newlines.
i := bytes.IndexByte(p, '\n')
line := p[0 : i+1]
p = p[i+1:]
// We prefixed each log line with a byte with the level.
level := Level(line[0])
line = line[1:]
var err error
if lw, ok := w.Writer.(LevelWriter); ok {
_, err = lw.WriteLevel(level, line)
} else {
_, err = w.Write(line)
}
if err != nil {
return err
}
}
return nil
}
// Trigger forces flushing the buffer and change the trigger state to
// triggered, if the writer has not already been triggered before.
func (w *TriggerLevelWriter) Trigger() error {
w.mu.Lock()
defer w.mu.Unlock()
return w.trigger()
}
// Close closes the writer and returns the buffer to the pool.
func (w *TriggerLevelWriter) Close() error {
w.mu.Lock()
defer w.mu.Unlock()
if w.buf == nil {
return nil
}
// We return the buffer only if it has not grown above the limit.
// This prevents accumulation of large buffers in the pool just
// because occasionally a large buffer might be needed.
if w.buf.Cap() <= TriggerLevelWriterBufferReuseLimit {
w.buf.Reset()
triggerWriterPool.Put(w.buf)
}
w.buf = nil
return nil
}