Package io.airlift.drift.protocol

Class TCompactProtocol

java.lang.Object

io.airlift.drift.protocol.TCompactProtocol

All Implemented Interfaces:

TProtocol, TProtocolReader, TProtocolWriter

public class TCompactProtocol
extends Object
implements TProtocol

TCompactProtocol2 is the Java implementation of the compact protocol specified in THRIFT-110. The fundamental approach to reducing the overhead of structures is a) use variable-length integers all over the place and b) make use of unused bits wherever possible. Your savings will obviously vary based on the specific makeup of your structs, but in general, the more fields, nested structures, short strings and collections, and low-value i32 and i64 fields you have, the more benefit you'll see.

Constructor Summary

Constructors

Constructor	Description
TCompactProtocol(TTransport transport)	Create a TCompactProtocol.

Method Summary

Modifier and Type	Method	Description
ByteBuffer	readBinary()	Read a byte[] from the wire.
boolean	readBool()	Read a boolean off the wire.
byte	readByte()	Read a single byte off the wire.
double	readDouble()	No magic here - just read a double off the wire.
TField	readFieldBegin()	Read a field header off the wire.
void	readFieldEnd()
float	readFloat()	No magic here - just read a float off the wire.
short	readI16()	Read an i16 from the wire as a zigzag varint.
int	readI32()	Read an i32 from the wire as a zigzag varint.
long	readI64()	Read an i64 from the wire as a zigzag varint.
TList	readListBegin()	Read a list header off the wire.
void	readListEnd()
TMap	readMapBegin()	Read a map header off the wire.
void	readMapEnd()
TMessage	readMessageBegin()	Read a message header.
void	readMessageEnd()
TSet	readSetBegin()	Read a set header off the wire.
void	readSetEnd()
String	readString()	Reads a byte[] (via readBinary), and then UTF-8 decodes it.
TStruct	readStructBegin()	Read a struct begin.
void	readStructEnd()	Doesn't actually consume any wire data, just removes the last field for this struct from the field stack.
void	writeBinary(ByteBuffer value)	Write a byte array, using a varint for the size.
void	writeBool(boolean value)	Write a boolean value.
void	writeByte(byte value)	Write a byte.
void	writeDouble(double value)	Write a double to the wire as 8 bytes.
void	writeFieldBegin(TField field)	Write a field header containing the field id and field type.
void	writeFieldEnd()
void	writeFieldStop()	Write the STOP symbol so we know there are no more fields in this struct.
void	writeFloat(float value)	Write a float to the wire as 4 bytes.
void	writeI16(short value)	Write an I16 as a zigzag varint.
void	writeI32(int value)	Write an i32 as a zigzag varint.
void	writeI64(long value)	Write an i64 as a zigzag varint.
void	writeListBegin(TList list)	Write a list header.
void	writeListEnd()
void	writeMapBegin(TMap map)	Write a map header.
void	writeMapEnd()
void	writeMessageBegin(TMessage message)	Write a message header to the wire.
void	writeMessageEnd()
void	writeSetBegin(TSet set)	Write a set header.
void	writeSetEnd()
void	writeString(String value)	Write a string to the wire with a varint size preceding.
void	writeStructBegin(TStruct struct)	Write a struct begin.
void	writeStructEnd()	Write a struct end.

Methods inherited from class java.lang.Object

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

Constructor Details

TCompactProtocol

public TCompactProtocol(TTransport transport)

Create a TCompactProtocol.

Parameters:

transport - the TTransport object to read from or write to.

Method Details

writeMessageBegin

public void writeMessageBegin(TMessage message)
                       throws TException

Write a message header to the wire. Compact Protocol messages contain the protocol version so we can migrate forwards in the future if need be.

Specified by:

writeMessageBegin in interface TProtocolWriter

Throws:

TException

writeStructBegin

public void writeStructBegin(TStruct struct)

Write a struct begin. This doesn't actually put anything on the wire. We use it as an opportunity to put special placeholder markers on the field stack so we can get the field id deltas correct.

Specified by:

writeStructBegin in interface TProtocolWriter

writeStructEnd

public void writeStructEnd()

Write a struct end. This doesn't actually put anything on the wire. We use this as an opportunity to pop the last field from the current struct off of the field stack.

Specified by:

writeStructEnd in interface TProtocolWriter

writeFieldBegin

public void writeFieldBegin(TField field)
                     throws TException

Write a field header containing the field id and field type. If the difference between the current field id and the last one is small (< 15), then the field id will be encoded in the 4 MSB as a delta. Otherwise, the field id will follow the type header as a zigzag varint.

Specified by:

writeFieldBegin in interface TProtocolWriter

Throws:

TException

writeFieldStop

public void writeFieldStop()
                    throws TException

Write the STOP symbol so we know there are no more fields in this struct.

Specified by:

writeFieldStop in interface TProtocolWriter

Throws:

TException

writeMapBegin

public void writeMapBegin(TMap map)
                   throws TException

Write a map header. If the map is empty, omit the key and value type headers, as we don't need any additional information to skip it.

Specified by:

writeMapBegin in interface TProtocolWriter

Throws:

TException

writeListBegin

public void writeListBegin(TList list)
                    throws TException

Write a list header.

Specified by:

writeListBegin in interface TProtocolWriter

Throws:

TException

writeSetBegin

public void writeSetBegin(TSet set)
                   throws TException

Write a set header.

Specified by:

writeSetBegin in interface TProtocolWriter

Throws:

TException

writeBool

public void writeBool(boolean value)
               throws TException

Write a boolean value. Potentially, this could be a boolean field, in which case the field header info isn't written yet. If so, decide what the right type header is for the value and then write the field header. Otherwise, write a single byte.

Specified by:

writeBool in interface TProtocolWriter

Throws:

TException

writeByte

public void writeByte(byte value)
               throws TException

Write a byte. Nothing to see here!

Specified by:

writeByte in interface TProtocolWriter

Throws:

TException

writeI16

public void writeI16(short value)
              throws TException

Write an I16 as a zigzag varint.

Specified by:

writeI16 in interface TProtocolWriter

Throws:

TException

writeI32

public void writeI32(int value)
              throws TException

Write an i32 as a zigzag varint.

Specified by:

writeI32 in interface TProtocolWriter

Throws:

TException

writeI64

public void writeI64(long value)
              throws TException

Write an i64 as a zigzag varint.

Specified by:

writeI64 in interface TProtocolWriter

Throws:

TException

writeFloat

public void writeFloat(float value)
                throws TException

Write a float to the wire as 4 bytes.

Specified by:

writeFloat in interface TProtocolWriter

Throws:

TException

writeDouble

public void writeDouble(double value)
                 throws TException

Write a double to the wire as 8 bytes.

Specified by:

writeDouble in interface TProtocolWriter

Throws:

TException

writeString

public void writeString(String value)
                 throws TException

Write a string to the wire with a varint size preceding.

Specified by:

writeString in interface TProtocolWriter

Throws:

TException

writeBinary

public void writeBinary(ByteBuffer value)
                 throws TException

Write a byte array, using a varint for the size.

Specified by:

writeBinary in interface TProtocolWriter

Throws:

TException

writeMessageEnd

public void writeMessageEnd()

Specified by:

writeMessageEnd in interface TProtocolWriter

writeMapEnd

public void writeMapEnd()

Specified by:

writeMapEnd in interface TProtocolWriter

writeListEnd

public void writeListEnd()

Specified by:

writeListEnd in interface TProtocolWriter

writeSetEnd

public void writeSetEnd()

Specified by:

writeSetEnd in interface TProtocolWriter

writeFieldEnd

public void writeFieldEnd()

Specified by:

writeFieldEnd in interface TProtocolWriter

readMessageBegin

public TMessage readMessageBegin()
                          throws TException

Read a message header.

Specified by:

readMessageBegin in interface TProtocolReader

Throws:

TException

readStructBegin

public TStruct readStructBegin()

Read a struct begin. There's nothing on the wire for this, but it is our opportunity to push a new struct begin marker onto the field stack.

Specified by:

readStructBegin in interface TProtocolReader

readStructEnd

public void readStructEnd()

Doesn't actually consume any wire data, just removes the last field for this struct from the field stack.

Specified by:

readStructEnd in interface TProtocolReader

readFieldBegin

public TField readFieldBegin()
                      throws TException

Read a field header off the wire.

Specified by:

readFieldBegin in interface TProtocolReader

Throws:

TException

readMapBegin

public TMap readMapBegin()
                  throws TException

Read a map header off the wire. If the size is zero, skip reading the key and value type. This means that 0-length maps will yield TMaps without the "correct" types.

Specified by:

readMapBegin in interface TProtocolReader

Throws:

TException

readListBegin

public TList readListBegin()
                    throws TException

Read a list header off the wire. If the list size is 0-14, the size will be packed into the element type header. If it's a longer list, the 4 MSB of the element type header will be 0xF, and a varint will follow with the true size.

Specified by:

readListBegin in interface TProtocolReader

Throws:

TException

readSetBegin

public TSet readSetBegin()
                  throws TException

Read a set header off the wire. If the set size is 0-14, the size will be packed into the element type header. If it's a longer set, the 4 MSB of the element type header will be 0xF, and a varint will follow with the true size.

Specified by:

readSetBegin in interface TProtocolReader

Throws:

TException

readBool

public boolean readBool()
                 throws TException

Read a boolean off the wire. If this is a boolean field, the value should already have been read during readFieldBegin, so we'll just consume the pre-stored value. Otherwise, read a byte.

Specified by:

readBool in interface TProtocolReader

Throws:

TException

readByte

public byte readByte()
              throws TException

Read a single byte off the wire. Nothing interesting here.

Specified by:

readByte in interface TProtocolReader

Throws:

TException

readI16

public short readI16()
              throws TException

Read an i16 from the wire as a zigzag varint.

Specified by:

readI16 in interface TProtocolReader

Throws:

TException

readI32

public int readI32()
            throws TException

Read an i32 from the wire as a zigzag varint.

Specified by:

readI32 in interface TProtocolReader

Throws:

TException

readI64

public long readI64()
             throws TException

Read an i64 from the wire as a zigzag varint.

Specified by:

readI64 in interface TProtocolReader

Throws:

TException

readFloat

public float readFloat()
                throws TException

No magic here - just read a float off the wire.

Specified by:

readFloat in interface TProtocolReader

Throws:

TException

readDouble

public double readDouble()
                  throws TException

No magic here - just read a double off the wire.

Specified by:

readDouble in interface TProtocolReader

Throws:

TException

readString

public String readString()
                  throws TException

Reads a byte[] (via readBinary), and then UTF-8 decodes it.

Specified by:

readString in interface TProtocolReader

Throws:

TException

readBinary

public ByteBuffer readBinary()
                      throws TException

Read a byte[] from the wire.

Specified by:

readBinary in interface TProtocolReader

Throws:

TException

readMessageEnd

public void readMessageEnd()

Specified by:

readMessageEnd in interface TProtocolReader

readFieldEnd

public void readFieldEnd()

Specified by:

readFieldEnd in interface TProtocolReader

readMapEnd

public void readMapEnd()

Specified by:

readMapEnd in interface TProtocolReader

readListEnd

public void readListEnd()

Specified by:

readListEnd in interface TProtocolReader

readSetEnd

public void readSetEnd()

Specified by:

readSetEnd in interface TProtocolReader