163 lines
		
	
	
		
			3.8 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
			
		
		
	
	
			163 lines
		
	
	
		
			3.8 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
/*
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 *
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 * Copyright 2018 gRPC authors.
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 *
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 * Licensed under the Apache License, Version 2.0 (the "License");
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 * you may not use this file except in compliance with the License.
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 * You may obtain a copy of the License at
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 *
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 *     http://www.apache.org/licenses/LICENSE-2.0
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 *
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 * Unless required by applicable law or agreed to in writing, software
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 * distributed under the License is distributed on an "AS IS" BASIS,
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 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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 * See the License for the specific language governing permissions and
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 * limitations under the License.
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 *
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 */
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package binarylog
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import (
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	"bufio"
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	"encoding/binary"
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	"fmt"
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	"io"
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	"io/ioutil"
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	"sync"
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	"time"
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	"github.com/golang/protobuf/proto"
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	pb "google.golang.org/grpc/binarylog/grpc_binarylog_v1"
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	"google.golang.org/grpc/grpclog"
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)
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var (
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	defaultSink Sink = &noopSink{} // TODO(blog): change this default (file in /tmp).
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)
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// SetDefaultSink sets the sink where binary logs will be written to.
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//
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// Not thread safe. Only set during initialization.
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func SetDefaultSink(s Sink) {
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	if defaultSink != nil {
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		defaultSink.Close()
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	}
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	defaultSink = s
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}
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// Sink writes log entry into the binary log sink.
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type Sink interface {
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	// Write will be called to write the log entry into the sink.
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	//
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	// It should be thread-safe so it can be called in parallel.
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	Write(*pb.GrpcLogEntry) error
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	// Close will be called when the Sink is replaced by a new Sink.
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	Close() error
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}
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type noopSink struct{}
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func (ns *noopSink) Write(*pb.GrpcLogEntry) error { return nil }
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func (ns *noopSink) Close() error                 { return nil }
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// newWriterSink creates a binary log sink with the given writer.
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//
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// Write() marshals the proto message and writes it to the given writer. Each
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// message is prefixed with a 4 byte big endian unsigned integer as the length.
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//
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// No buffer is done, Close() doesn't try to close the writer.
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func newWriterSink(w io.Writer) *writerSink {
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	return &writerSink{out: w}
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}
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type writerSink struct {
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	out io.Writer
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}
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func (ws *writerSink) Write(e *pb.GrpcLogEntry) error {
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	b, err := proto.Marshal(e)
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	if err != nil {
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		grpclog.Infof("binary logging: failed to marshal proto message: %v", err)
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	}
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	hdr := make([]byte, 4)
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	binary.BigEndian.PutUint32(hdr, uint32(len(b)))
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	if _, err := ws.out.Write(hdr); err != nil {
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		return err
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	}
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	if _, err := ws.out.Write(b); err != nil {
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		return err
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	}
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	return nil
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}
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func (ws *writerSink) Close() error { return nil }
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type bufWriteCloserSink struct {
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	mu     sync.Mutex
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	closer io.Closer
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	out    *writerSink   // out is built on buf.
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	buf    *bufio.Writer // buf is kept for flush.
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	writeStartOnce sync.Once
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	writeTicker    *time.Ticker
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}
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func (fs *bufWriteCloserSink) Write(e *pb.GrpcLogEntry) error {
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	// Start the write loop when Write is called.
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	fs.writeStartOnce.Do(fs.startFlushGoroutine)
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	fs.mu.Lock()
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	if err := fs.out.Write(e); err != nil {
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		fs.mu.Unlock()
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		return err
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	}
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	fs.mu.Unlock()
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	return nil
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}
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const (
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	bufFlushDuration = 60 * time.Second
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)
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func (fs *bufWriteCloserSink) startFlushGoroutine() {
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	fs.writeTicker = time.NewTicker(bufFlushDuration)
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	go func() {
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		for range fs.writeTicker.C {
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			fs.mu.Lock()
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			fs.buf.Flush()
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			fs.mu.Unlock()
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		}
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	}()
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}
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func (fs *bufWriteCloserSink) Close() error {
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	if fs.writeTicker != nil {
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		fs.writeTicker.Stop()
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	}
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	fs.mu.Lock()
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	fs.buf.Flush()
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	fs.closer.Close()
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	fs.out.Close()
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	fs.mu.Unlock()
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	return nil
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}
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func newBufWriteCloserSink(o io.WriteCloser) Sink {
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	bufW := bufio.NewWriter(o)
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	return &bufWriteCloserSink{
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		closer: o,
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		out:    newWriterSink(bufW),
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		buf:    bufW,
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	}
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}
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// NewTempFileSink creates a temp file and returns a Sink that writes to this
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// file.
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func NewTempFileSink() (Sink, error) {
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	tempFile, err := ioutil.TempFile("/tmp", "grpcgo_binarylog_*.txt")
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	if err != nil {
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		return nil, fmt.Errorf("failed to create temp file: %v", err)
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	}
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	return newBufWriteCloserSink(tempFile), nil
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}
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