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87 lines
1.9 KiB
Go
87 lines
1.9 KiB
Go
package logdriver // import "github.com/docker/docker/api/types/plugins/logdriver"
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import (
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"encoding/binary"
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"io"
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)
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const binaryEncodeLen = 4
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// LogEntryEncoder encodes a LogEntry to a protobuf stream
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// The stream should look like:
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//
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// [uint32 binary encoded message size][protobuf message]
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//
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// To decode an entry, read the first 4 bytes to get the size of the entry,
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// then read `size` bytes from the stream.
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type LogEntryEncoder interface {
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Encode(*LogEntry) error
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}
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// NewLogEntryEncoder creates a protobuf stream encoder for log entries.
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// This is used to write out log entries to a stream.
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func NewLogEntryEncoder(w io.Writer) LogEntryEncoder {
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return &logEntryEncoder{
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w: w,
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buf: make([]byte, 1024),
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}
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}
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type logEntryEncoder struct {
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buf []byte
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w io.Writer
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}
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func (e *logEntryEncoder) Encode(l *LogEntry) error {
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n := l.Size()
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total := n + binaryEncodeLen
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if total > len(e.buf) {
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e.buf = make([]byte, total)
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}
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binary.BigEndian.PutUint32(e.buf, uint32(n))
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if _, err := l.MarshalTo(e.buf[binaryEncodeLen:]); err != nil {
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return err
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}
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_, err := e.w.Write(e.buf[:total])
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return err
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}
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// LogEntryDecoder decodes log entries from a stream
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// It is expected that the wire format is as defined by LogEntryEncoder.
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type LogEntryDecoder interface {
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Decode(*LogEntry) error
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}
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// NewLogEntryDecoder creates a new stream decoder for log entries
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func NewLogEntryDecoder(r io.Reader) LogEntryDecoder {
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return &logEntryDecoder{
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lenBuf: make([]byte, binaryEncodeLen),
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buf: make([]byte, 1024),
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r: r,
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}
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}
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type logEntryDecoder struct {
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r io.Reader
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lenBuf []byte
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buf []byte
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}
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func (d *logEntryDecoder) Decode(l *LogEntry) error {
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_, err := io.ReadFull(d.r, d.lenBuf)
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if err != nil {
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return err
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}
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size := int(binary.BigEndian.Uint32(d.lenBuf))
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if len(d.buf) < size {
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d.buf = make([]byte, size)
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}
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if _, err := io.ReadFull(d.r, d.buf[:size]); err != nil {
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return err
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}
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return l.Unmarshal(d.buf[:size])
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}
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