/
messages.go
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/
messages.go
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/* Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements. See the NOTICE file distributed with
this work for additional information regarding copyright ownership.
The ASF licenses this file to You 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 siesta
import (
"bytes"
"compress/gzip"
"io/ioutil"
)
type CompressionCodec int
const (
CompressionNone CompressionCodec = 0
CompressionGZip CompressionCodec = 1
CompressionSnappy CompressionCodec = 2
CompressionLZ4 CompressionCodec = 3
)
const compressionCodecMask int8 = 3
type MessageAndOffset struct {
Offset int64
Message *MessageData
}
func (this *MessageAndOffset) Read(decoder Decoder) *DecodingError {
offset, err := decoder.GetInt64()
if err != nil {
return NewDecodingError(err, reason_InvalidMessageAndOffsetOffset)
}
this.Offset = offset
_, err = decoder.GetInt32()
if err != nil {
return NewDecodingError(err, reason_InvalidMessageLength)
}
message := new(MessageData)
decodingErr := message.Read(decoder)
if decodingErr != nil {
return decodingErr
}
this.Message = message
return nil
}
func (this *MessageAndOffset) Write(encoder Encoder) {
encoder.WriteInt64(this.Offset)
encoder.Reserve(&LengthSlice{})
this.Message.Write(encoder)
encoder.UpdateReserved()
}
func ReadMessageSet(decoder Decoder) ([]*MessageAndOffset, *DecodingError) {
messages := make([]*MessageAndOffset, 0)
for decoder.Remaining() > 0 {
messageAndOffset := new(MessageAndOffset)
err := messageAndOffset.Read(decoder)
if err != nil {
if err.Error() != EOF {
return nil, err
}
continue
}
messages = append(messages, messageAndOffset)
}
return messages, nil
}
type MessageData struct {
Crc int32
MagicByte int8
Attributes int8
Key []byte
Value []byte
Nested []*MessageAndOffset
}
func (this *MessageData) Read(decoder Decoder) *DecodingError {
crc, err := decoder.GetInt32()
if err != nil {
return NewDecodingError(err, reason_InvalidMessageCRC)
}
this.Crc = crc
magic, err := decoder.GetInt8()
if err != nil {
return NewDecodingError(err, reason_InvalidMessageMagicByte)
}
this.MagicByte = magic
attributes, err := decoder.GetInt8()
if err != nil {
return NewDecodingError(err, reason_InvalidMessageAttributes)
}
this.Attributes = attributes
key, err := decoder.GetBytes()
if err != nil {
return NewDecodingError(err, reason_InvalidMessageKey)
}
this.Key = key
value, err := decoder.GetBytes()
if err != nil {
return NewDecodingError(err, reason_InvalidMessageValue)
}
this.Value = value
compressionCodec := CompressionCodec(this.Attributes & compressionCodecMask)
switch compressionCodec {
case CompressionNone:
case CompressionGZip:
{
if this.Value == nil {
return NewDecodingError(NoDataToUncompress, reason_NoGzipData)
}
reader, err := gzip.NewReader(bytes.NewReader(this.Value))
if err != nil {
return NewDecodingError(err, reason_MalformedGzipData)
}
if this.Value, err = ioutil.ReadAll(reader); err != nil {
return NewDecodingError(err, reason_MalformedGzipData)
}
messages, decodingErr := ReadMessageSet(NewBinaryDecoder(this.Value))
if decodingErr != nil {
return decodingErr
}
this.Nested = messages
}
case CompressionSnappy:
panic("Not implemented yet")
case CompressionLZ4:
panic("Not implemented yet")
}
return nil
}
//TODO compress and write if needed
func (this *MessageData) Write(encoder Encoder) {
encoder.Reserve(&CrcSlice{})
encoder.WriteInt8(this.MagicByte)
encoder.WriteInt8(this.Attributes)
encoder.WriteBytes(this.Key)
encoder.WriteBytes(this.Value)
encoder.UpdateReserved()
}
type Message struct {
Topic string
Partition int32
Offset int64
Key []byte
Value []byte
}
var (
reason_InvalidMessageAndOffsetOffset = "Invalid offset in MessageAndOffset"
reason_InvalidMessageLength = "Invalid Message length"
reason_InvalidMessageCRC = "Invalid Message CRC"
reason_InvalidMessageMagicByte = "Invalid Message magic byte"
reason_InvalidMessageAttributes = "Invalid Message attributes"
reason_InvalidMessageKey = "Invalid Message key"
reason_InvalidMessageValue = "Invalid Message value"
reason_NoGzipData = "No data to uncompress for GZip encoded message"
reason_MalformedGzipData = "Malformed GZip encoded message"
)