Package org.apache.thrift.protocol

Class TCompactProtocol

java.lang.Object

org.apache.thrift.protocol.TProtocol

org.apache.thrift.protocol.TCompactProtocol

All Implemented Interfaces:

TReadProtocol, TWriteProtocol

Direct Known Subclasses:

TTupleProtocol

public class TCompactProtocol
extends 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.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	TCompactProtocol.Factory	TProtocolFactory that produces TCompactProtocols.

Nested classes/interfaces inherited from class org.apache.thrift.protocol.TProtocol

TProtocol.ReadCallback<T,R>, TProtocol.ReadCollectionCallback<R>, TProtocol.ReadMapEntryCallback<K,V>, TProtocol.WriteCallback<T>

Field Summary

Fields inherited from class org.apache.thrift.protocol.TProtocol

skippedBytes, trans_

Constructor Summary

Constructors

Constructor	Description
TCompactProtocol(TTransport transport)	Create a TCompactProtocol.
TCompactProtocol(TTransport transport, long stringLengthLimit)	Deprecated. Use constructor specifying both string limit and container limit instead
TCompactProtocol(TTransport transport, long stringLengthLimit, long containerLengthLimit)	Create a TCompactProtocol.

Method Summary

Modifier and Type	Method	Description
int	getMinSerializedSize(byte type)	Return the minimum number of bytes a type will consume on the wire
ByteBuffer	readBinary()	Read a ByteBuffer 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()
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.
UUID	readUuid()
void	reset()	Reset any internal state back to a blank slate.
protected void	skipBinary()
void	writeBinary(ByteBuffer bin)	Write a byte array, using a varint for the size.
void	writeBool(boolean b)	Write a boolean value.
void	writeByte(byte b)	Write a byte.
protected void	writeCollectionBegin(byte elemType, int size)	Abstract method for writing the start of lists and sets.
void	writeDouble(double dub)	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	writeI16(short i16)	Write an I16 as a zigzag varint.
void	writeI32(int i32)	Write an i32 as a zigzag varint.
void	writeI64(long i64)	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 str)	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.
void	writeUuid(UUID uuid)

Methods inherited from class org.apache.thrift.protocol.TProtocol

checkReadBytesAvailable, checkReadBytesAvailable, checkReadBytesAvailable, getScheme, getTransport, readField, readFieldBeginData, readList, readList, readList, readMap, readMap, readMap, readMessage, readSet, readSet, readSet, readStruct, skip, skip, skipBool, skipByte, skipBytes, skipDouble, skipI16, skipI32, skipI64, writeField, writeList, writeMap, writeMessage, writeSet, writeStruct

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,
 long stringLengthLimit,
 long containerLengthLimit)

Create a TCompactProtocol.

Parameters:

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

stringLengthLimit - the maximum number of bytes to read for variable-length fields.

containerLengthLimit - the maximum number of elements to read for containers.

TCompactProtocol

@Deprecated
public TCompactProtocol(TTransport transport,
 long stringLengthLimit)

Deprecated.

Use constructor specifying both string limit and container limit instead

Create a TCompactProtocol.

Parameters:

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

stringLengthLimit - the maximum number of bytes to read for variable-length fields.

TCompactProtocol

public TCompactProtocol(TTransport transport)

Create a TCompactProtocol.

Parameters:

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

Method Details

reset

public void reset()

Description copied from class: TProtocol

Reset any internal state back to a blank slate. This method only needs to be implemented for stateful protocols.

Overrides:

reset in class TProtocol

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.

Throws:

TException

writeStructBegin

public void writeStructBegin(TStruct struct)
                      throws TException

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.

Throws:

TException

writeStructEnd

public void writeStructEnd()
                    throws TException

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.

Throws:

TException

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.

Throws:

TException

writeFieldStop

public void writeFieldStop()
                    throws TException

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

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.

Throws:

TException

writeListBegin

public void writeListBegin(TList list)
                    throws TException

Write a list header.

Throws:

TException

writeSetBegin

public void writeSetBegin(TSet set)
                   throws TException

Write a set header.

Throws:

TException

writeBool

public void writeBool(boolean b)
               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.

Throws:

TException

writeByte

public void writeByte(byte b)
               throws TException

Write a byte. Nothing to see here!

Throws:

TException

writeI16

public void writeI16(short i16)
              throws TException

Write an I16 as a zigzag varint.

Throws:

TException

writeI32

public void writeI32(int i32)
              throws TException

Write an i32 as a zigzag varint.

Throws:

TException

writeI64

public void writeI64(long i64)
              throws TException

Write an i64 as a zigzag varint.

Throws:

TException

writeDouble

public void writeDouble(double dub)
                 throws TException

Write a double to the wire as 8 bytes.

Throws:

TException

writeUuid

public void writeUuid(UUID uuid)
               throws TException

Throws:

TException

writeString

public void writeString(String str)
                 throws TException

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

Throws:

TException

writeBinary

public void writeBinary(ByteBuffer bin)
                 throws TException

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

Throws:

TException

writeMessageEnd

public void writeMessageEnd()
                     throws TException

Throws:

TException

writeMapEnd

public void writeMapEnd()
                 throws TException

Throws:

TException

writeListEnd

public void writeListEnd()
                  throws TException

Throws:

TException

writeSetEnd

public void writeSetEnd()
                 throws TException

Throws:

TException

writeFieldEnd

public void writeFieldEnd()
                   throws TException

Throws:

TException

writeCollectionBegin

protected void writeCollectionBegin(byte elemType,
 int size)
                             throws TException

Abstract method for writing the start of lists and sets. List and sets on the wire differ only by the type indicator.

Throws:

TException

readMessageBegin

public TMessage readMessageBegin()
                          throws TException

Read a message header.

Throws:

TException

readStructBegin

public TStruct readStructBegin()
                        throws TException

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.

Throws:

TException

readStructEnd

public void readStructEnd()
                   throws TException

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

Throws:

TException

readFieldBegin

public TField readFieldBegin()
                      throws TException

Read a field header off the wire.

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.

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.

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.

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.

Throws:

TException

readByte

public byte readByte()
              throws TException

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

Throws:

TException

readI16

public short readI16()
              throws TException

Read an i16 from the wire as a zigzag varint.

Throws:

TException

readI32

public int readI32()
            throws TException

Read an i32 from the wire as a zigzag varint.

Throws:

TException

readI64

public long readI64()
             throws TException

Read an i64 from the wire as a zigzag varint.

Throws:

TException

readDouble

public double readDouble()
                  throws TException

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

Throws:

TException

readUuid

public UUID readUuid()
              throws TException

Throws:

TException

readString

public String readString()
                  throws TException

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

Throws:

TException

readBinary

public ByteBuffer readBinary()
                      throws TException

Read a ByteBuffer from the wire.

Throws:

TException

readMessageEnd

public void readMessageEnd()
                    throws TException

Throws:

TException

readFieldEnd

public void readFieldEnd()
                  throws TException

Throws:

TException

readMapEnd

public void readMapEnd()
                throws TException

Throws:

TException

readListEnd

public void readListEnd()
                 throws TException

Throws:

TException

readSetEnd

public void readSetEnd()
                throws TException

Throws:

TException

getMinSerializedSize

public int getMinSerializedSize(byte type)
                         throws TTransportException

Return the minimum number of bytes a type will consume on the wire

Specified by:

getMinSerializedSize in class TProtocol

Parameters:

type - Returns the minimum amount of bytes needed to store the smallest possible instance of TType.

Returns:

min serialized size

Throws:

TTransportException

skipBinary

protected void skipBinary()
                   throws TException

Overrides:

skipBinary in class TProtocol

Throws:

TException