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/*
*
* Copyright 2018 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package binarylog
import (
"bufio"
"encoding/binary"
"io"
"sync"
"time"
"github.com/golang/protobuf/proto"
binlogpb "google.golang.org/grpc/binarylog/grpc_binarylog_v1"
)
var (
// DefaultSink is the sink where the logs will be written to. It's exported
// for the binarylog package to update.
DefaultSink Sink = &noopSink{} // TODO(blog): change this default (file in /tmp).
)
// Sink writes log entry into the binary log sink.
//
// sink is a copy of the exported binarylog.Sink, to avoid circular dependency.
type Sink interface {
// Write will be called to write the log entry into the sink.
//
// It should be thread-safe so it can be called in parallel.
Write(*binlogpb.GrpcLogEntry) error
// Close will be called when the Sink is replaced by a new Sink.
Close() error
}
type noopSink struct{}
func (ns *noopSink) Write(*binlogpb.GrpcLogEntry) error { return nil }
func (ns *noopSink) Close() error { return nil }
// newWriterSink creates a binary log sink with the given writer.
//
// Write() marshals the proto message and writes it to the given writer. Each
// message is prefixed with a 4 byte big endian unsigned integer as the length.
//
// No buffer is done, Close() doesn't try to close the writer.
func newWriterSink(w io.Writer) Sink {
return &writerSink{out: w}
}
type writerSink struct {
out io.Writer
}
func (ws *writerSink) Write(e *binlogpb.GrpcLogEntry) error {
b, err := proto.Marshal(e)
if err != nil {
grpclogLogger.Errorf("binary logging: failed to marshal proto message: %v", err)
return err
}
hdr := make([]byte, 4)
binary.BigEndian.PutUint32(hdr, uint32(len(b)))
if _, err := ws.out.Write(hdr); err != nil {
return err
}
if _, err := ws.out.Write(b); err != nil {
return err
}
return nil
}
func (ws *writerSink) Close() error { return nil }
type bufferedSink struct {
mu sync.Mutex
closer io.Closer
out Sink // out is built on buf.
buf *bufio.Writer // buf is kept for flush.
flusherStarted bool
writeTicker *time.Ticker
done chan struct{}
}
func (fs *bufferedSink) Write(e *binlogpb.GrpcLogEntry) error {
fs.mu.Lock()
defer fs.mu.Unlock()
if !fs.flusherStarted {
// Start the write loop when Write is called.
fs.startFlushGoroutine()
fs.flusherStarted = true
}
if err := fs.out.Write(e); err != nil {
return err
}
return nil
}
const (
bufFlushDuration = 60 * time.Second
)
func (fs *bufferedSink) startFlushGoroutine() {
fs.writeTicker = time.NewTicker(bufFlushDuration)
go func() {
for {
select {
case <-fs.done:
return
case <-fs.writeTicker.C:
}
fs.mu.Lock()
if err := fs.buf.Flush(); err != nil {
grpclogLogger.Warningf("failed to flush to Sink: %v", err)
}
fs.mu.Unlock()
}
}()
}
func (fs *bufferedSink) Close() error {
fs.mu.Lock()
defer fs.mu.Unlock()
if fs.writeTicker != nil {
fs.writeTicker.Stop()
}
close(fs.done)
if err := fs.buf.Flush(); err != nil {
grpclogLogger.Warningf("failed to flush to Sink: %v", err)
}
if err := fs.closer.Close(); err != nil {
grpclogLogger.Warningf("failed to close the underlying WriterCloser: %v", err)
}
if err := fs.out.Close(); err != nil {
grpclogLogger.Warningf("failed to close the Sink: %v", err)
}
return nil
}
// NewBufferedSink creates a binary log sink with the given WriteCloser.
//
// Write() marshals the proto message and writes it to the given writer. Each
// message is prefixed with a 4 byte big endian unsigned integer as the length.
//
// Content is kept in a buffer, and is flushed every 60 seconds.
//
// Close closes the WriteCloser.
func NewBufferedSink(o io.WriteCloser) Sink {
bufW := bufio.NewWriter(o)
return &bufferedSink{
closer: o,
out: newWriterSink(bufW),
buf: bufW,
done: make(chan struct{}),
}
}
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