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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
* limitations under the License.
*/
package io.airlift.drift.protocol;
import io.airlift.drift.TException;
import java.nio.ByteBuffer;
import java.util.ArrayDeque;
import java.util.Deque;
import static java.lang.Double.doubleToLongBits;
import static java.lang.Double.longBitsToDouble;
import static java.nio.charset.StandardCharsets.UTF_8;
import static java.util.Objects.requireNonNull;
/**
* 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.
*/
public class TCompactProtocol
implements TProtocol
{
private static final byte[] EMPTY_BYTE_ARRAY = new byte[0];
private static final TStruct ANONYMOUS_STRUCT = new TStruct("");
private static final TField TSTOP = new TField("", TType.STOP, (short) 0);
private static final byte[] TTYPE_TO_COMPACT_TYPE = new byte[16];
static {
TTYPE_TO_COMPACT_TYPE[TType.STOP] = TType.STOP;
TTYPE_TO_COMPACT_TYPE[TType.BOOL] = Types.BOOLEAN_TRUE;
TTYPE_TO_COMPACT_TYPE[TType.BYTE] = Types.BYTE;
TTYPE_TO_COMPACT_TYPE[TType.I16] = Types.I16;
TTYPE_TO_COMPACT_TYPE[TType.I32] = Types.I32;
TTYPE_TO_COMPACT_TYPE[TType.I64] = Types.I64;
TTYPE_TO_COMPACT_TYPE[TType.DOUBLE] = Types.DOUBLE;
TTYPE_TO_COMPACT_TYPE[TType.STRING] = Types.BINARY;
TTYPE_TO_COMPACT_TYPE[TType.LIST] = Types.LIST;
TTYPE_TO_COMPACT_TYPE[TType.SET] = Types.SET;
TTYPE_TO_COMPACT_TYPE[TType.MAP] = Types.MAP;
TTYPE_TO_COMPACT_TYPE[TType.STRUCT] = Types.STRUCT;
}
private static final byte PROTOCOL_ID = (byte) 0x82;
private static final byte VERSION = 1;
private static final byte VERSION_MASK = 0x1f; // 0001 1111
private static final byte TYPE_MASK = (byte) 0xE0; // 1110 0000
private static final byte TYPE_BITS = 0x07; // 0000 0111
private static final int TYPE_SHIFT_AMOUNT = 5;
/**
* All of the on-wire type codes.
*/
private static final class Types
{
public static final byte BOOLEAN_TRUE = 0x01;
public static final byte BOOLEAN_FALSE = 0x02;
public static final byte BYTE = 0x03;
public static final byte I16 = 0x04;
public static final byte I32 = 0x05;
public static final byte I64 = 0x06;
public static final byte DOUBLE = 0x07;
public static final byte BINARY = 0x08;
public static final byte LIST = 0x09;
public static final byte SET = 0x0A;
public static final byte MAP = 0x0B;
public static final byte STRUCT = 0x0C;
}
/**
* Used to keep track of the last field for the current and previous structs,
* so we can do the delta stuff.
*/
private final Deque lastField = new ArrayDeque<>();
private short lastFieldId;
/**
* If we encounter a boolean field begin, save the TField here so it can
* have the value incorporated.
*/
private TField booleanField;
/**
* If we read a field header, and it's a boolean field, save the boolean
* value here so that readBool can use it.
*/
private Boolean booleanValue;
/**
* The transport for reading from or writing to.
*/
private final TTransport transport;
/**
* Create a TCompactProtocol.
*
* @param transport the TTransport object to read from or write to.
*/
public TCompactProtocol(TTransport transport)
{
this.transport = requireNonNull(transport, "transport is null");
}
//
// Public Writing methods.
//
/**
* 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.
*/
@Override
public void writeMessageBegin(TMessage message)
throws TException
{
writeByteDirect(PROTOCOL_ID);
writeByteDirect((VERSION & VERSION_MASK) | ((message.getType() << TYPE_SHIFT_AMOUNT) & TYPE_MASK));
writeVarint32(message.getSequenceId());
writeString(message.getName());
}
/**
* 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.
*/
@Override
public void writeStructBegin(TStruct struct)
{
lastField.push(lastFieldId);
lastFieldId = 0;
}
/**
* 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.
*/
@Override
public void writeStructEnd()
{
lastFieldId = lastField.pop();
}
/**
* 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.
*/
@Override
public void writeFieldBegin(TField field)
throws TException
{
if (field.getType() == TType.BOOL) {
// we want to possibly include the value, so we'll wait.
booleanField = field;
}
else {
writeFieldBeginInternal(field, (byte) -1);
}
}
/**
* The workhorse of writeFieldBegin. It has the option of doing a
* 'type override' of the type header. This is used specifically in the
* boolean field case.
*/
private void writeFieldBeginInternal(TField field, byte typeOverride)
throws TException
{
// short lastField = lastField_.pop();
// if there's a type override, use that.
byte typeToWrite = typeOverride == -1 ? getCompactType(field.getType()) : typeOverride;
// check if we can use delta encoding for the field id
if (field.getId() > lastFieldId && field.getId() - lastFieldId <= 15) {
// write them together
writeByteDirect((field.getId() - lastFieldId) << 4 | typeToWrite);
}
else {
// write them separate
writeByteDirect(typeToWrite);
writeI16(field.getId());
}
lastFieldId = field.getId();
}
/**
* Write the STOP symbol so we know there are no more fields in this struct.
*/
@Override
public void writeFieldStop()
throws TException
{
writeByteDirect(TType.STOP);
}
/**
* 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.
*/
@Override
public void writeMapBegin(TMap map)
throws TException
{
if (map.getSize() == 0) {
writeByteDirect(0);
}
else {
writeVarint32(map.getSize());
writeByteDirect(getCompactType(map.getKeyType()) << 4 | getCompactType(map.getValueType()));
}
}
/**
* Write a list header.
*/
@Override
public void writeListBegin(TList list)
throws TException
{
writeCollectionBegin(list.getType(), list.getSize());
}
/**
* Write a set header.
*/
@Override
public void writeSetBegin(TSet set)
throws TException
{
writeCollectionBegin(set.getType(), set.getSize());
}
/**
* 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.
*/
@Override
public void writeBool(boolean value)
throws TException
{
if (booleanField != null) {
// we haven't written the field header yet
writeFieldBeginInternal(booleanField, value ? Types.BOOLEAN_TRUE : Types.BOOLEAN_FALSE);
booleanField = null;
}
else {
// we're not part of a field, so just write the value.
writeByteDirect(value ? Types.BOOLEAN_TRUE : Types.BOOLEAN_FALSE);
}
}
/**
* Write a byte. Nothing to see here!
*/
@Override
public void writeByte(byte value)
throws TException
{
writeByteDirect(value);
}
/**
* Write an I16 as a zigzag varint.
*/
@Override
public void writeI16(short value)
throws TException
{
writeVarint32(intToZigZag(value));
}
/**
* Write an i32 as a zigzag varint.
*/
@Override
public void writeI32(int value)
throws TException
{
writeVarint32(intToZigZag(value));
}
/**
* Write an i64 as a zigzag varint.
*/
@Override
public void writeI64(long value)
throws TException
{
writeVarint64(longToZigzag(value));
}
/**
* Write a double to the wire as 8 bytes.
*/
@Override
public void writeDouble(double value)
throws TException
{
byte[] data = {0, 0, 0, 0, 0, 0, 0, 0};
fixedLongToBytes(doubleToLongBits(value), data);
transport.write(data);
}
/**
* Write a string to the wire with a varint size preceding.
*/
@Override
public void writeString(String value)
throws TException
{
byte[] bytes = value.getBytes(UTF_8);
writeBinary(bytes, 0, bytes.length);
}
/**
* Write a byte array, using a varint for the size.
*/
@Override
public void writeBinary(ByteBuffer value)
throws TException
{
int length = value.limit() - value.position();
writeBinary(value.array(), value.position() + value.arrayOffset(), length);
}
private void writeBinary(byte[] buf, int offset, int length)
throws TException
{
writeVarint32(length);
transport.write(buf, offset, length);
}
//
// These methods are called by structs, but don't actually have any wire
// output or purpose.
//
@Override
public void writeMessageEnd() {}
@Override
public void writeMapEnd() {}
@Override
public void writeListEnd() {}
@Override
public void writeSetEnd() {}
@Override
public void writeFieldEnd() {}
//
// Internal writing methods
//
/**
* Abstract method for writing the start of lists and sets. List and sets on
* the wire differ only by the type indicator.
*/
private void writeCollectionBegin(byte elemType, int size)
throws TException
{
if (size <= 14) {
writeByteDirect(size << 4 | getCompactType(elemType));
}
else {
writeByteDirect(0xf0 | getCompactType(elemType));
writeVarint32(size);
}
}
private final byte[] i32buf = new byte[5];
/**
* Write an i32 as a varint. Results in 1-5 bytes on the wire.
*/
@SuppressWarnings("ValueOfIncrementOrDecrementUsed")
private void writeVarint32(int n)
throws TException
{
int idx = 0;
while (true) {
if ((n & ~0x7F) == 0) {
i32buf[idx++] = (byte) n;
break;
}
i32buf[idx++] = (byte) ((n & 0x7F) | 0x80);
n >>>= 7;
}
transport.write(i32buf, 0, idx);
}
private final byte[] varint64out = new byte[10];
/**
* Write an i64 as a varint. Results in 1-10 bytes on the wire.
*/
@SuppressWarnings("ValueOfIncrementOrDecrementUsed")
private void writeVarint64(long n)
throws TException
{
int idx = 0;
while (true) {
if ((n & ~0x7FL) == 0) {
varint64out[idx++] = (byte) n;
break;
}
varint64out[idx++] = ((byte) ((n & 0x7F) | 0x80));
n >>>= 7;
}
transport.write(varint64out, 0, idx);
}
/**
* Convert l into a zigzag long. This allows negative numbers to be
* represented compactly as a varint.
*/
private static long longToZigzag(long l)
{
return (l << 1) ^ (l >> 63);
}
/**
* Convert n into a zigzag int. This allows negative numbers to be
* represented compactly as a varint.
*/
private static int intToZigZag(int n)
{
return (n << 1) ^ (n >> 31);
}
/**
* Convert a long into little-endian bytes in buf
*/
private static void fixedLongToBytes(long n, byte[] buf)
{
buf[0] = (byte) (n & 0xff);
buf[1] = (byte) ((n >> 8) & 0xff);
buf[2] = (byte) ((n >> 16) & 0xff);
buf[3] = (byte) ((n >> 24) & 0xff);
buf[4] = (byte) ((n >> 32) & 0xff);
buf[5] = (byte) ((n >> 40) & 0xff);
buf[6] = (byte) ((n >> 48) & 0xff);
buf[7] = (byte) ((n >> 56) & 0xff);
}
private final byte[] byteDirectBuffer = new byte[1];
/**
* Writes a byte without any possibility of all that field header nonsense.
* Used internally by other writing methods that know they need to write a byte.
*/
private void writeByteDirect(byte b)
throws TException
{
byteDirectBuffer[0] = b;
transport.write(byteDirectBuffer);
}
/**
* Writes a byte without any possibility of all that field header nonsense.
*/
private void writeByteDirect(int n)
throws TException
{
writeByteDirect((byte) n);
}
//
// Reading methods.
//
/**
* Read a message header.
*/
@Override
public TMessage readMessageBegin()
throws TException
{
byte protocolId = readByte();
if (protocolId != PROTOCOL_ID) {
throw new TProtocolException("Expected protocol id " + Integer.toHexString(PROTOCOL_ID) + " but got " + Integer.toHexString(protocolId));
}
byte versionAndType = readByte();
byte version = (byte) (versionAndType & VERSION_MASK);
if (version != VERSION) {
throw new TProtocolException("Expected version " + VERSION + " but got " + version);
}
byte type = (byte) ((versionAndType >> TYPE_SHIFT_AMOUNT) & TYPE_BITS);
int seqid = readVarint32();
String messageName = readString();
return new TMessage(messageName, type, seqid);
}
/**
* 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.
*/
@Override
public TStruct readStructBegin()
{
lastField.push(lastFieldId);
lastFieldId = 0;
return ANONYMOUS_STRUCT;
}
/**
* Doesn't actually consume any wire data, just removes the last field for
* this struct from the field stack.
*/
@Override
public void readStructEnd()
{
// consume the last field we read off the wire.
lastFieldId = lastField.pop();
}
/**
* Read a field header off the wire.
*/
@Override
public TField readFieldBegin()
throws TException
{
byte type = readByte();
// if it's a stop, then we can return immediately, as the struct is over.
if (type == TType.STOP) {
return TSTOP;
}
short fieldId;
// mask off the 4 MSB of the type header. it could contain a field id delta.
short modifier = (short) ((type & 0xf0) >> 4);
if (modifier == 0) {
// not a delta. look ahead for the zigzag varint field id.
fieldId = readI16();
}
else {
// has a delta. add the delta to the last read field id.
fieldId = (short) (lastFieldId + modifier);
}
TField field = new TField("", getTType((byte) (type & 0x0f)), fieldId);
// if this happens to be a boolean field, the value is encoded in the type
if (isBoolType(type)) {
// save the boolean value in a special instance variable.
booleanValue = (byte) (type & 0x0f) == Types.BOOLEAN_TRUE ? Boolean.TRUE : Boolean.FALSE;
}
// push the new field onto the field stack so we can keep the deltas going.
lastFieldId = field.getId();
return field;
}
/**
* 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.
*/
@Override
public TMap readMapBegin()
throws TException
{
int size = checkSize(readVarint32());
byte keyAndValueType = size == 0 ? 0 : readByte();
return new TMap(getTType((byte) (keyAndValueType >> 4)), getTType((byte) (keyAndValueType & 0xf)), size);
}
/**
* 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.
*/
@Override
public TList readListBegin()
throws TException
{
byte sizeAndType = readByte();
int size = (sizeAndType >> 4) & 0x0f;
if (size == 15) {
size = readVarint32();
}
checkSize(size);
byte type = getTType(sizeAndType);
return new TList(type, size);
}
/**
* 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.
*/
@Override
public TSet readSetBegin()
throws TException
{
return new TSet(readListBegin());
}
/**
* 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.
*/
@Override
public boolean readBool()
throws TException
{
if (booleanValue != null) {
boolean result = booleanValue;
booleanValue = null;
return result;
}
return readByte() == Types.BOOLEAN_TRUE;
}
private final byte[] byteRawBuf = new byte[1];
/**
* Read a single byte off the wire. Nothing interesting here.
*/
@Override
public byte readByte()
throws TException
{
transport.read(byteRawBuf, 0, 1);
return byteRawBuf[0];
}
/**
* Read an i16 from the wire as a zigzag varint.
*/
@Override
public short readI16()
throws TException
{
return (short) zigzagToInt(readVarint32());
}
/**
* Read an i32 from the wire as a zigzag varint.
*/
@Override
public int readI32()
throws TException
{
return zigzagToInt(readVarint32());
}
/**
* Read an i64 from the wire as a zigzag varint.
*/
@Override
public long readI64()
throws TException
{
return zigzagToLong(readVarint64());
}
private final byte[] doubleBuf = new byte[8];
/**
* No magic here - just read a double off the wire.
*/
@Override
public double readDouble()
throws TException
{
transport.read(doubleBuf, 0, 8);
return longBitsToDouble(bytesToLong(doubleBuf));
}
/**
* Reads a byte[] (via readBinary), and then UTF-8 decodes it.
*/
@Override
public String readString()
throws TException
{
int length = checkSize(readVarint32());
if (length == 0) {
return "";
}
return new String(readBinary(length), UTF_8);
}
/**
* Read a byte[] from the wire.
*/
@Override
public ByteBuffer readBinary()
throws TException
{
int length = checkSize(readVarint32());
if (length == 0) {
return ByteBuffer.wrap(EMPTY_BYTE_ARRAY);
}
byte[] buf = new byte[length];
transport.read(buf, 0, length);
return ByteBuffer.wrap(buf);
}
/**
* Read a byte[] of a known length from the wire.
*/
private byte[] readBinary(int length)
throws TException
{
if (length == 0) {
return EMPTY_BYTE_ARRAY;
}
byte[] buf = new byte[length];
transport.read(buf, 0, length);
return buf;
}
private static int checkSize(int length)
throws TProtocolException
{
if (length < 0) {
throw new TProtocolException("Negative length: " + length);
}
return length;
}
//
// These methods are here for the struct to call, but don't have any wire
// encoding.
//
@Override
public void readMessageEnd() {}
@Override
public void readFieldEnd() {}
@Override
public void readMapEnd() {}
@Override
public void readListEnd() {}
@Override
public void readSetEnd() {}
//
// Internal reading methods
//
/**
* Read an i32 from the wire as a varint. The MSB of each byte is set
* if there is another byte to follow. This can read up to 5 bytes.
*/
private int readVarint32()
throws TException
{
int result = 0;
int shift = 0;
while (true) {
byte b = readByte();
result |= (b & 0x7f) << shift;
if ((b & 0x80) != 0x80) {
break;
}
shift += 7;
}
return result;
}
/**
* Read an i64 from the wire as a proper varint. The MSB of each byte is set
* if there is another byte to follow. This can read up to 10 bytes.
*/
private long readVarint64()
throws TException
{
int shift = 0;
long result = 0;
while (true) {
byte b = readByte();
result |= (long) (b & 0x7f) << shift;
if ((b & 0x80) != 0x80) {
break;
}
shift += 7;
}
return result;
}
//
// encoding helpers
//
/**
* Convert from zigzag int to int.
*/
private static int zigzagToInt(int n)
{
return (n >>> 1) ^ -(n & 1);
}
/**
* Convert from zigzag long to long.
*/
private static long zigzagToLong(long n)
{
return (n >>> 1) ^ -(n & 1);
}
/**
* Note that it's important that the mask bytes are long literals,
* otherwise they'll default to ints, and when you shift an int left 56 bits,
* you just get a messed up int.
*/
private static long bytesToLong(byte[] bytes)
{
return ((bytes[7] & 0xffL) << 56) |
((bytes[6] & 0xffL) << 48) |
((bytes[5] & 0xffL) << 40) |
((bytes[4] & 0xffL) << 32) |
((bytes[3] & 0xffL) << 24) |
((bytes[2] & 0xffL) << 16) |
((bytes[1] & 0xffL) << 8) |
((bytes[0] & 0xffL));
}
//
// type testing and converting
//
private static boolean isBoolType(byte b)
{
int lowerNibble = b & 0x0f;
return lowerNibble == Types.BOOLEAN_TRUE || lowerNibble == Types.BOOLEAN_FALSE;
}
/**
* Given a TCompactProtocol.Types constant, convert it to its corresponding
* TType value.
*/
private static byte getTType(byte type)
throws TProtocolException
{
switch ((byte) (type & 0x0f)) {
case TType.STOP:
return TType.STOP;
case Types.BOOLEAN_FALSE:
case Types.BOOLEAN_TRUE:
return TType.BOOL;
case Types.BYTE:
return TType.BYTE;
case Types.I16:
return TType.I16;
case Types.I32:
return TType.I32;
case Types.I64:
return TType.I64;
case Types.DOUBLE:
return TType.DOUBLE;
case Types.BINARY:
return TType.STRING;
case Types.LIST:
return TType.LIST;
case Types.SET:
return TType.SET;
case Types.MAP:
return TType.MAP;
case Types.STRUCT:
return TType.STRUCT;
default:
throw new TProtocolException("don't know what type: " + (byte) (type & 0x0f));
}
}
/**
* Given a TType value, find the appropriate TCompactProtocol.Types constant.
*/
private static byte getCompactType(byte ttype)
{
return TTYPE_TO_COMPACT_TYPE[ttype];
}
}
