mirror of
https://github.com/prometheus/prometheus.git
synced 2024-12-28 06:59:40 -08:00
82 lines
2.3 KiB
Go
82 lines
2.3 KiB
Go
package log
|
|
|
|
import (
|
|
"io"
|
|
"sync"
|
|
"sync/atomic"
|
|
)
|
|
|
|
// SwapLogger wraps another logger that may be safely replaced while other
|
|
// goroutines use the SwapLogger concurrently. The zero value for a SwapLogger
|
|
// will discard all log events without error.
|
|
//
|
|
// SwapLogger serves well as a package global logger that can be changed by
|
|
// importers.
|
|
type SwapLogger struct {
|
|
logger atomic.Value
|
|
}
|
|
|
|
type loggerStruct struct {
|
|
Logger
|
|
}
|
|
|
|
// Log implements the Logger interface by forwarding keyvals to the currently
|
|
// wrapped logger. It does not log anything if the wrapped logger is nil.
|
|
func (l *SwapLogger) Log(keyvals ...interface{}) error {
|
|
s, ok := l.logger.Load().(loggerStruct)
|
|
if !ok || s.Logger == nil {
|
|
return nil
|
|
}
|
|
return s.Log(keyvals...)
|
|
}
|
|
|
|
// Swap replaces the currently wrapped logger with logger. Swap may be called
|
|
// concurrently with calls to Log from other goroutines.
|
|
func (l *SwapLogger) Swap(logger Logger) {
|
|
l.logger.Store(loggerStruct{logger})
|
|
}
|
|
|
|
// SyncWriter synchronizes concurrent writes to an io.Writer.
|
|
type SyncWriter struct {
|
|
mu sync.Mutex
|
|
w io.Writer
|
|
}
|
|
|
|
// NewSyncWriter returns a new SyncWriter. The returned writer is safe for
|
|
// concurrent use by multiple goroutines.
|
|
func NewSyncWriter(w io.Writer) *SyncWriter {
|
|
return &SyncWriter{w: w}
|
|
}
|
|
|
|
// Write writes p to the underlying io.Writer. If another write is already in
|
|
// progress, the calling goroutine blocks until the SyncWriter is available.
|
|
func (w *SyncWriter) Write(p []byte) (n int, err error) {
|
|
w.mu.Lock()
|
|
n, err = w.w.Write(p)
|
|
w.mu.Unlock()
|
|
return n, err
|
|
}
|
|
|
|
// syncLogger provides concurrent safe logging for another Logger.
|
|
type syncLogger struct {
|
|
mu sync.Mutex
|
|
logger Logger
|
|
}
|
|
|
|
// NewSyncLogger returns a logger that synchronizes concurrent use of the
|
|
// wrapped logger. When multiple goroutines use the SyncLogger concurrently
|
|
// only one goroutine will be allowed to log to the wrapped logger at a time.
|
|
// The other goroutines will block until the logger is available.
|
|
func NewSyncLogger(logger Logger) Logger {
|
|
return &syncLogger{logger: logger}
|
|
}
|
|
|
|
// Log logs keyvals to the underlying Logger. If another log is already in
|
|
// progress, the calling goroutine blocks until the syncLogger is available.
|
|
func (l *syncLogger) Log(keyvals ...interface{}) error {
|
|
l.mu.Lock()
|
|
err := l.logger.Log(keyvals...)
|
|
l.mu.Unlock()
|
|
return err
|
|
}
|