com.mysql.cj.protocol.a

Class CompressedPacketSender

java.lang.Object

com.mysql.cj.protocol.a.CompressedPacketSender

All Implemented Interfaces:

MessageSender<NativePacketPayload>

public class CompressedPacketSender
extends java.lang.Object
implements MessageSender<NativePacketPayload>

A MessageSender for the compressed protocol. TODO: add support for pre-allocated buffer for large packets (if there's a demonstrable perf improvement)

Field Summary

Fields

Modifier and Type	Field and Description
static int	COMP_HEADER_LENGTH
private byte[]	compressedPacket Buffer to compress data to.
private int	compressedPayloadLen Length of current compressed packet.
private byte	compressedSequenceId Sequence id of compressed packet.
private java.util.zip.Deflater	deflater
static int	MIN_COMPRESS_LEN
private java.io.BufferedOutputStream	outputStream

Constructor Summary

Constructors

Constructor and Description
CompressedPacketSender(java.io.BufferedOutputStream outputStream)

Method Summary

Modifier and Type	Method and Description
private void	addPayload(byte[] payload, int payloadOffset, int payloadLen) Add and compress the payload into the compressed packet.
private void	addUncompressedHeader(byte packetSequence, int uncompressedPacketLen) Add and compress the header for the raw packet into the compressed packet.
private void	completeCompression() Complete compression of the current payload contents to the compressed packet.
private void	resetPacket()
void	send(byte[] packet, int packetLen, byte packetSequence) Packet sender implementation for the compressed MySQL protocol.
private void	sendCompressedPacket(int uncompressedPayloadLen) Send a compressed packet.
void	stop() Shut down this packet sender and deallocate any resources.
MessageSender<NativePacketPayload>	undecorate() Return the previous PacketSender instance from the decorators chain or the current PacketSender if it is the first entry in a chain.
MessageSender<NativePacketPayload>	undecorateAll() Return a PacketSender instance free of decorators.
private void	writeCompressedHeader(int compLen, byte seq, int uncompLen) Write the compressed packet header.
private void	writeUncompressedHeader(int packetLen, byte packetSequence) Write an uncompressed packet header.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface com.mysql.cj.protocol.MessageSender

send, send, setMaxAllowedPacket

Field Detail

outputStream

private java.io.BufferedOutputStream outputStream

deflater

private java.util.zip.Deflater deflater

compressedPacket

private byte[] compressedPacket

Buffer to compress data to. Used only across one send() invocation.

compressedSequenceId

private byte compressedSequenceId

Sequence id of compressed packet. Used only across one send() invocation.

compressedPayloadLen

private int compressedPayloadLen

Length of current compressed packet.

COMP_HEADER_LENGTH

public static final int COMP_HEADER_LENGTH

See Also:

Constant Field Values

MIN_COMPRESS_LEN

public static final int MIN_COMPRESS_LEN

See Also:

Constant Field Values

Constructor Detail

CompressedPacketSender

public CompressedPacketSender(java.io.BufferedOutputStream outputStream)

Method Detail

stop

public void stop()

Shut down this packet sender and deallocate any resources.

resetPacket

private void resetPacket()

addUncompressedHeader

private void addUncompressedHeader(byte packetSequence,
                                   int uncompressedPacketLen)

Add and compress the header for the raw packet into the compressed packet.

Parameters:

packetSequence - sequence id

uncompressedPacketLen - uncompressed packet length

addPayload

private void addPayload(byte[] payload,
                        int payloadOffset,
                        int payloadLen)

Add and compress the payload into the compressed packet.

Parameters:

payload - payload bytes

payloadOffset - offset

payloadLen - length

completeCompression

private void completeCompression()

Complete compression of the current payload contents to the compressed packet.

writeCompressedHeader

private void writeCompressedHeader(int compLen,
                                   byte seq,
                                   int uncompLen)
                            throws java.io.IOException

Write the compressed packet header.

Parameters:

compLen - compressed data length

seq - sequence id

uncompLen - uncompressed data length

Throws:

java.io.IOException - if write exception occurs

writeUncompressedHeader

private void writeUncompressedHeader(int packetLen,
                                     byte packetSequence)
                              throws java.io.IOException

Write an uncompressed packet header.

Parameters:

packetLen - packet length

packetSequence - sequence id

Throws:

java.io.IOException - if write exception occurs

sendCompressedPacket

private void sendCompressedPacket(int uncompressedPayloadLen)
                           throws java.io.IOException

Send a compressed packet.

Parameters:

uncompressedPayloadLen - uncompressed data length

Throws:

java.io.IOException - if write exception occurs

send

public void send(byte[] packet,
                 int packetLen,
                 byte packetSequence)
          throws java.io.IOException

Packet sender implementation for the compressed MySQL protocol. For compressed transmission of multi-packets, split the packets up in the same way as the uncompressed protocol. We fit up to MAX_PACKET_SIZE bytes of split uncompressed packet, including the header, into an compressed packet. The first packet of the multi-packet is 4 bytes of header and MAX_PACKET_SIZE - 4 bytes of the payload. The next packet must send the remaining four bytes of the payload followed by a new header and payload. If the second split packet is also around MAX_PACKET_SIZE in length, then only MAX_PACKET_SIZE - 4 (from the previous packet) - 4 (for the new header) can be sent. This means the payload will be limited by 8 bytes and this will continue to increase by 4 at every iteration.

Specified by:

send in interface MessageSender<NativePacketPayload>

Parameters:

packet - data bytes

packetLen - packet length

packetSequence - sequence id

Throws:

java.io.IOException - if i/o exception occurs

undecorateAll

public MessageSender<NativePacketPayload> undecorateAll()

Description copied from interface: MessageSender

Return a PacketSender instance free of decorators.

Specified by:

undecorateAll in interface MessageSender<NativePacketPayload>

Returns:

MessageSender instance

undecorate

public MessageSender<NativePacketPayload> undecorate()

Description copied from interface: MessageSender

Return the previous PacketSender instance from the decorators chain or the current PacketSender if it is the first entry in a chain.

Specified by:

undecorate in interface MessageSender<NativePacketPayload>

Returns:

MessageSender instance