lib/cpp/src/thrift/protocol/TCompactProtocol.tcc

/*
 * 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.
 */
#ifndef _THRIFT_PROTOCOL_TCOMPACTPROTOCOL_TCC_
#define _THRIFT_PROTOCOL_TCOMPACTPROTOCOL_TCC_ 1

#include <limits>
#include <cstdlib>

#include "thrift/config.h"

/*
 * TCompactProtocol::i*ToZigzag depend on the fact that the right shift
 * operator on a signed integer is an arithmetic (sign-extending) shift.
 * If this is not the case, the current implementation will not work.
 * If anyone encounters this error, we can try to figure out the best
 * way to implement an arithmetic right shift on their platform.
 */
#if !defined(SIGNED_RIGHT_SHIFT_IS) || !defined(ARITHMETIC_RIGHT_SHIFT)
# error "Unable to determine the behavior of a signed right shift"
#endif
#if SIGNED_RIGHT_SHIFT_IS != ARITHMETIC_RIGHT_SHIFT
# error "TCompactProtocol currently only works if a signed right shift is arithmetic"
#endif

#ifdef __GNUC__
#define UNLIKELY(val) (__builtin_expect((val), 0))
#else
#define UNLIKELY(val) (val)
#endif

namespace apache { namespace thrift { namespace protocol {

namespace detail { namespace compact {

enum Types {
  CT_STOP           = 0x00,
  CT_BOOLEAN_TRUE   = 0x01,
  CT_BOOLEAN_FALSE  = 0x02,
  CT_BYTE           = 0x03,
  CT_I16            = 0x04,
  CT_I32            = 0x05,
  CT_I64            = 0x06,
  CT_DOUBLE         = 0x07,
  CT_BINARY         = 0x08,
  CT_LIST           = 0x09,
  CT_SET            = 0x0A,
  CT_MAP            = 0x0B,
  CT_STRUCT         = 0x0C,
  CT_UUID           = 0x0D
};

const int8_t TTypeToCType[17] = {
  CT_STOP, // T_STOP
  0, // unused
  CT_BOOLEAN_TRUE, // T_BOOL
  CT_BYTE, // T_BYTE
  CT_DOUBLE, // T_DOUBLE
  0, // unused
  CT_I16, // T_I16
  0, // unused
  CT_I32, // T_I32
  0, // unused
  CT_I64, // T_I64
  CT_BINARY, // T_STRING
  CT_STRUCT, // T_STRUCT
  CT_MAP, // T_MAP
  CT_SET, // T_SET
  CT_LIST, // T_LIST
  CT_UUID, // T_UUID
};

}} // end detail::compact namespace


template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::writeMessageBegin(
    const std::string& name,
    const TMessageType messageType,
    const int32_t seqid) {
  uint32_t wsize = 0;
  wsize += writeByte(PROTOCOL_ID);
  wsize += writeByte((VERSION_N & VERSION_MASK) | ((static_cast<int32_t>(messageType) << TYPE_SHIFT_AMOUNT) & TYPE_MASK));
  wsize += writeVarint32(seqid);
  wsize += writeString(name);
  return wsize;
}

/**
 * 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.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::writeFieldBegin(const char* name,
                                                        const TType fieldType,
                                                        const int16_t fieldId) {
  if (fieldType == T_BOOL) {
    booleanField_.name = name;
    booleanField_.fieldType = fieldType;
    booleanField_.fieldId = fieldId;
  } else {
    return writeFieldBeginInternal(name, fieldType, fieldId, -1);
  }
  return 0;
}

/**
 * Write the STOP symbol so we know there are no more fields in this struct.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::writeFieldStop() {
  return writeByte(T_STOP);
}

/**
 * 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.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::writeStructBegin(const char* name) {
  (void) name;
  lastField_.push(lastFieldId_);
  lastFieldId_ = 0;
  return 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.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::writeStructEnd() {
  lastFieldId_ = lastField_.top();
  lastField_.pop();
  return 0;
}

/**
 * Write a List header.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::writeListBegin(const TType elemType,
                                                       const uint32_t size) {
  return writeCollectionBegin(elemType, size);
}

/**
 * Write a set header.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::writeSetBegin(const TType elemType,
                                                      const uint32_t size) {
  return writeCollectionBegin(elemType, size);
}

/**
 * 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.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::writeMapBegin(const TType keyType,
                                                      const TType valType,
                                                      const uint32_t size) {
  uint32_t wsize = 0;

  if (size == 0) {
    wsize += writeByte(0);
  } else {
    wsize += writeVarint32(size);
    wsize += writeByte(getCompactType(keyType) << 4 | getCompactType(valType));
  }
  return wsize;
}

/**
 * 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.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::writeBool(const bool value) {
  uint32_t wsize = 0;

  if (booleanField_.name != nullptr) {
    // we haven't written the field header yet
    wsize
      += writeFieldBeginInternal(booleanField_.name,
                                 booleanField_.fieldType,
                                 booleanField_.fieldId,
                                 static_cast<int8_t>(value
                                                     ? detail::compact::CT_BOOLEAN_TRUE
                                                     : detail::compact::CT_BOOLEAN_FALSE));
    booleanField_.name = nullptr;
  } else {
    // we're not part of a field, so just write the value
    wsize
      += writeByte(static_cast<int8_t>(value
                                       ? detail::compact::CT_BOOLEAN_TRUE
                                       : detail::compact::CT_BOOLEAN_FALSE));
  }
  return wsize;
}

template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::writeByte(const int8_t byte) {
  trans_->write(reinterpret_cast<const uint8_t*>(&byte), 1);
  return 1;
}

/**
 * Write an i16 as a zigzag varint.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::writeI16(const int16_t i16) {
  return writeVarint32(i32ToZigzag(i16));
}

/**
 * Write an i32 as a zigzag varint.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::writeI32(const int32_t i32) {
  return writeVarint32(i32ToZigzag(i32));
}

/**
 * Write an i64 as a zigzag varint.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::writeI64(const int64_t i64) {
  return writeVarint64(i64ToZigzag(i64));
}

/**
 * Write a double to the wire as 8 bytes.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::writeDouble(const double dub) {
  static_assert(sizeof(double) == sizeof(uint64_t), "sizeof(double) == sizeof(uint64_t)");
  static_assert(std::numeric_limits<double>::is_iec559, "std::numeric_limits<double>::is_iec559");

  auto bits = bitwise_cast<uint64_t>(dub);
  bits = THRIFT_htolell(bits);
  trans_->write(reinterpret_cast<const uint8_t*>(&bits), 8);
  return 8;
}

/**
 * Write a string to the wire with a varint size preceding.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::writeString(const std::string& str) {
  return writeBinary(str);
}

template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::writeBinary(const std::string& str) {
  if(str.size() > (std::numeric_limits<uint32_t>::max)())
    throw TProtocolException(TProtocolException::SIZE_LIMIT);
  auto ssize = static_cast<uint32_t>(str.size());
  uint32_t wsize = writeVarint32(ssize) ;
  // checking ssize + wsize > uint_max, but we don't want to overflow while checking for overflows.
  // transforming the check to ssize > uint_max - wsize
  if(ssize > (std::numeric_limits<uint32_t>::max)() - wsize)
    throw TProtocolException(TProtocolException::SIZE_LIMIT);
  wsize += ssize;
  trans_->write(reinterpret_cast<const uint8_t*>(str.data()), ssize);
  return wsize;
}

/**
 * Write a TUuid to the wire
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::writeUUID(const TUuid& uuid) {
  trans_->write(uuid.data(), uuid.size());
  return uuid.size();
}

//
// Internal Writing methods
//

/**
 * 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.
 */
template <class Transport_>
int32_t TCompactProtocolT<Transport_>::writeFieldBeginInternal(
    const char* name,
    const TType fieldType,
    const int16_t fieldId,
    int8_t typeOverride) {
  (void) name;
  uint32_t wsize = 0;

  // if there's a type override, use that.
  int8_t typeToWrite = (typeOverride == -1 ? getCompactType(fieldType) : typeOverride);

  // check if we can use delta encoding for the field id
  if (fieldId > lastFieldId_ && fieldId - lastFieldId_ <= 15) {
    // write them together
    wsize += writeByte(static_cast<int8_t>((fieldId - lastFieldId_)
                                           << 4 | typeToWrite));
  } else {
    // write them separate
    wsize += writeByte(typeToWrite);
    wsize += writeI16(fieldId);
  }

  lastFieldId_ = fieldId;
  return wsize;
}

/**
 * Abstract method for writing the start of lists and sets. List and sets on
 * the wire differ only by the type indicator.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::writeCollectionBegin(const TType elemType,
                                                             int32_t size) {
  uint32_t wsize = 0;
  if (size <= 14) {
    wsize += writeByte(static_cast<int8_t>(size
                                           << 4 | getCompactType(elemType)));
  } else {
    wsize += writeByte(0xf0 | getCompactType(elemType));
    wsize += writeVarint32(size);
  }
  return wsize;
}

/**
 * Write an i32 as a varint. Results in 1-5 bytes on the wire.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::writeVarint32(uint32_t n) {
  uint8_t buf[5];
  uint32_t wsize = 0;

  while (true) {
    if ((n & ~0x7F) == 0) {
      buf[wsize++] = static_cast<int8_t>(n);
      break;
    } else {
      buf[wsize++] = static_cast<int8_t>((n & 0x7F) | 0x80);
      n >>= 7;
    }
  }
  trans_->write(buf, wsize);
  return wsize;
}

/**
 * Write an i64 as a varint. Results in 1-10 bytes on the wire.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::writeVarint64(uint64_t n) {
  uint8_t buf[10];
  uint32_t wsize = 0;

  while (true) {
    if ((n & ~0x7FL) == 0) {
      buf[wsize++] = static_cast<int8_t>(n);
      break;
    } else {
      buf[wsize++] = static_cast<int8_t>((n & 0x7F) | 0x80);
      n >>= 7;
    }
  }
  trans_->write(buf, wsize);
  return wsize;
}

/**
 * Convert l into a zigzag long. This allows negative numbers to be
 * represented compactly as a varint.
 */
template <class Transport_>
uint64_t TCompactProtocolT<Transport_>::i64ToZigzag(const int64_t l) {
  return (static_cast<uint64_t>(l) << 1) ^ (l >> 63);
}

/**
 * Convert n into a zigzag int. This allows negative numbers to be
 * represented compactly as a varint.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::i32ToZigzag(const int32_t n) {
  return (static_cast<uint32_t>(n) << 1) ^ (n >> 31);
}

/**
 * Given a TType value, find the appropriate detail::compact::Types value
 */
template <class Transport_>
int8_t TCompactProtocolT<Transport_>::getCompactType(const TType ttype) {
  return detail::compact::TTypeToCType[ttype];
}

//
// Reading Methods
//

/**
 * Read a message header.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::readMessageBegin(
    std::string& name,
    TMessageType& messageType,
    int32_t& seqid) {
  uint32_t rsize = 0;
  int8_t protocolId;
  int8_t versionAndType;
  int8_t version;

  rsize += readByte(protocolId);
  if (protocolId != PROTOCOL_ID) {
    throw TProtocolException(TProtocolException::BAD_VERSION, "Bad protocol identifier");
  }

  rsize += readByte(versionAndType);
  version = static_cast<int8_t>(versionAndType & VERSION_MASK);
  if (version != VERSION_N) {
    throw TProtocolException(TProtocolException::BAD_VERSION, "Bad protocol version");
  }

  messageType = static_cast<TMessageType>((versionAndType >> TYPE_SHIFT_AMOUNT) & TYPE_BITS);
  rsize += readVarint32(seqid);
  rsize += readString(name);

  return rsize;
}

/**
 * Read a struct begin. There's nothing on the wire for this, but it is our
 * opportunity to push a new struct begin marker on the field stack.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::readStructBegin(std::string& name) {
  name.clear();
  lastField_.push(lastFieldId_);
  lastFieldId_ = 0;
  return 0;
}

/**
 * Doesn't actually consume any wire data, just removes the last field for
 * this struct from the field stack.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::readStructEnd() {
  lastFieldId_ = lastField_.top();
  lastField_.pop();
  return 0;
}

/**
 * Read a field header off the wire.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::readFieldBegin(std::string& name,
                                                       TType& fieldType,
                                                       int16_t& fieldId) {
  (void) name;
  uint32_t rsize = 0;
  int8_t byte;
  int8_t type;

  rsize += readByte(byte);
  type = (byte & 0x0f);

  // if it's a stop, then we can return immediately, as the struct is over.
  if (type == T_STOP) {
    fieldType = T_STOP;
    fieldId = 0;
    return rsize;
  }

  // mask off the 4 MSB of the type header. it could contain a field id delta.
  auto modifier = static_cast<int16_t>(static_cast<uint8_t>(byte & 0xf0) >> 4);
  if (modifier == 0) {
    // not a delta, look ahead for the zigzag varint field id.
    rsize += readI16(fieldId);
  } else {
    fieldId = static_cast<int16_t>(lastFieldId_ + modifier);
  }
  fieldType = getTType(type);

  // if this happens to be a boolean field, the value is encoded in the type
  if (type == detail::compact::CT_BOOLEAN_TRUE ||
      type == detail::compact::CT_BOOLEAN_FALSE) {
    // save the boolean value in a special instance variable.
    boolValue_.hasBoolValue = true;
    boolValue_.boolValue =
      (type == detail::compact::CT_BOOLEAN_TRUE ? true : false);
  }

  // push the new field onto the field stack so we can keep the deltas going.
  lastFieldId_ = fieldId;
  return rsize;
}

/**
 * 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.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::readMapBegin(TType& keyType,
                                                     TType& valType,
                                                     uint32_t& size) {
  uint32_t rsize = 0;
  int8_t kvType = 0;
  int32_t msize = 0;

  rsize += readVarint32(msize);
  if (msize != 0)
    rsize += readByte(kvType);

  if (msize < 0) {
    throw TProtocolException(TProtocolException::NEGATIVE_SIZE);
  } else if (container_limit_ && msize > container_limit_) {
    throw TProtocolException(TProtocolException::SIZE_LIMIT);
  }

  keyType = getTType(static_cast<int8_t>(static_cast<uint8_t>(kvType) >> 4));
  valType = getTType(static_cast<int8_t>(static_cast<uint8_t>(kvType) & 0xf));
  size = static_cast<uint32_t>(msize);

  TMap map(keyType, valType, size);
  checkReadBytesAvailable(map);

  return rsize;
}

/**
 * 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.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::readListBegin(TType& elemType,
                                                      uint32_t& size) {
  int8_t size_and_type;
  uint32_t rsize = 0;
  int32_t lsize;

  rsize += readByte(size_and_type);

  lsize = (static_cast<uint8_t>(size_and_type) >> 4) & 0x0f;
  if (lsize == 15) {
    rsize += readVarint32(lsize);
  }

  if (lsize < 0) {
    throw TProtocolException(TProtocolException::NEGATIVE_SIZE);
  } else if (container_limit_ && lsize > container_limit_) {
    throw TProtocolException(TProtocolException::SIZE_LIMIT);
  }

  elemType = getTType(static_cast<int8_t>(size_and_type & 0x0f));
  size = static_cast<uint32_t>(lsize);

  TList list(elemType, size);
  checkReadBytesAvailable(list);

  return rsize;
}

/**
 * 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.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::readSetBegin(TType& elemType,
                                                     uint32_t& size) {
  return readListBegin(elemType, size);
}

/**
 * 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.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::readBool(bool& value) {
  if (boolValue_.hasBoolValue == true) {
    value = boolValue_.boolValue;
    boolValue_.hasBoolValue = false;
    return 0;
  } else {
    int8_t val;
    readByte(val);
    value = (val == detail::compact::CT_BOOLEAN_TRUE);
    return 1;
  }
}

/**
 * Read a single byte off the wire. Nothing interesting here.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::readByte(int8_t& byte) {
  uint8_t b[1];
  trans_->readAll(b, 1);
  byte = static_cast<int8_t>(b[0]);
  return 1;
}

/**
 * Read an i16 from the wire as a zigzag varint.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::readI16(int16_t& i16) {
  int32_t value;
  uint32_t rsize = readVarint32(value);
  i16 = static_cast<int16_t>(zigzagToI32(value));
  return rsize;
}

/**
 * Read an i32 from the wire as a zigzag varint.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::readI32(int32_t& i32) {
  int32_t value;
  uint32_t rsize = readVarint32(value);
  i32 = zigzagToI32(value);
  return rsize;
}

/**
 * Read an i64 from the wire as a zigzag varint.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::readI64(int64_t& i64) {
  int64_t value;
  uint32_t rsize = readVarint64(value);
  i64 = zigzagToI64(value);
  return rsize;
}

/**
 * No magic here - just read a double off the wire.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::readDouble(double& dub) {
  static_assert(sizeof(double) == sizeof(uint64_t), "sizeof(double) == sizeof(uint64_t)");
  static_assert(std::numeric_limits<double>::is_iec559, "std::numeric_limits<double>::is_iec559");

  union {
    uint64_t bits;
    uint8_t b[8];
  } u;
  trans_->readAll(u.b, 8);
  u.bits = THRIFT_letohll(u.bits);
  dub = bitwise_cast<double>(u.bits);
  return 8;
}

template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::readString(std::string& str) {
  return readBinary(str);
}

/**
 * Read a byte[] from the wire.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::readBinary(std::string& str) {
  int32_t rsize = 0;
  int32_t size;

  rsize += readVarint32(size);
  // Catch empty string case
  if (size == 0) {
    str.clear();
    return rsize;
  }

  // Catch error cases
  if (size < 0) {
    throw TProtocolException(TProtocolException::NEGATIVE_SIZE);
  }
  if (string_limit_ > 0 && size > string_limit_) {
    throw TProtocolException(TProtocolException::SIZE_LIMIT);
  }

  // Check against MaxMessageSize before alloc
  trans_->checkReadBytesAvailable(static_cast<uint32_t>(size));

  // Use the heap here to prevent stack overflow for v. large strings
  if (size > string_buf_size_ || string_buf_ == nullptr) {
    void* new_string_buf = std::realloc(string_buf_, static_cast<uint32_t>(size));
    if (new_string_buf == nullptr) {
      throw std::bad_alloc();
    }
    string_buf_ = static_cast<uint8_t*>(new_string_buf);
    string_buf_size_ = size;
  }
  trans_->readAll(string_buf_, size);
  str.assign(reinterpret_cast<char*>(string_buf_), size);

  return rsize + static_cast<uint32_t>(size);
}


/**
 * Read a TUuid from the wire.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::readUUID(TUuid& uuid) {
  return trans_->readAll(uuid.begin(), uuid.size());
}

/**
 * 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.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::readVarint32(int32_t& i32) {
  int64_t val;
  uint32_t rsize = readVarint64(val);
  i32 = static_cast<int32_t>(val);
  return rsize;
}

/**
 * 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.
 */
template <class Transport_>
uint32_t TCompactProtocolT<Transport_>::readVarint64(int64_t& i64) {
  uint32_t rsize = 0;
  uint64_t val = 0;
  int shift = 0;
  uint8_t buf[10];  // 64 bits / (7 bits/byte) = 10 bytes.
  uint32_t buf_size = sizeof(buf);
  const uint8_t* borrowed = trans_->borrow(buf, &buf_size);

  // Fast path.
  if (borrowed != nullptr) {
    while (true) {
      uint8_t byte = borrowed[rsize];
      rsize++;
      val |= static_cast<uint64_t>(byte & 0x7f) << shift;
      shift += 7;
      if (!(byte & 0x80)) {
        i64 = val;
        trans_->consume(rsize);
        return rsize;
      }
      // Have to check for invalid data so we don't crash.
      if (UNLIKELY(rsize == sizeof(buf))) {
        throw TProtocolException(TProtocolException::INVALID_DATA, "Variable-length int over 10 bytes.");
      }
    }
  }

  // Slow path.
  else {
    while (true) {
      uint8_t byte;
      rsize += trans_->readAll(&byte, 1);
      val |= static_cast<uint64_t>(byte & 0x7f) << shift;
      shift += 7;
      if (!(byte & 0x80)) {
        i64 = val;
        return rsize;
      }
      // Might as well check for invalid data on the slow path too.
      if (UNLIKELY(rsize >= sizeof(buf))) {
        throw TProtocolException(TProtocolException::INVALID_DATA, "Variable-length int over 10 bytes.");
      }
    }
  }
}

/**
 * Convert from zigzag int to int.
 */
template <class Transport_>
int32_t TCompactProtocolT<Transport_>::zigzagToI32(uint32_t n) {
  return (n >> 1) ^ static_cast<uint32_t>(-static_cast<int32_t>(n & 1));
}

/**
 * Convert from zigzag long to long.
 */
template <class Transport_>
int64_t TCompactProtocolT<Transport_>::zigzagToI64(uint64_t n) {
  return (n >> 1) ^ static_cast<uint64_t>(-static_cast<int64_t>(n & 1));
}

template <class Transport_>
TType TCompactProtocolT<Transport_>::getTType(int8_t type) {
  switch (type) {
    case T_STOP:
      return T_STOP;
    case detail::compact::CT_BOOLEAN_FALSE:
    case detail::compact::CT_BOOLEAN_TRUE:
      return T_BOOL;
    case detail::compact::CT_BYTE:
      return T_BYTE;
    case detail::compact::CT_I16:
      return T_I16;
    case detail::compact::CT_I32:
      return T_I32;
    case detail::compact::CT_I64:
      return T_I64;
    case detail::compact::CT_DOUBLE:
      return T_DOUBLE;
    case detail::compact::CT_BINARY:
      return T_STRING;
    case detail::compact::CT_LIST:
      return T_LIST;
    case detail::compact::CT_SET:
      return T_SET;
    case detail::compact::CT_MAP:
      return T_MAP;
    case detail::compact::CT_STRUCT:
      return T_STRUCT;
    case detail::compact::CT_UUID:
      return T_UUID;
    default:
      throw TException(std::string("don't know what type: ") + static_cast<char>(type));
  }
}

// Return the minimum number of bytes a type will consume on the wire
template <class Transport_>
int TCompactProtocolT<Transport_>::getMinSerializedSize(TType type)
{
  switch (type)
  {
    case T_STOP:    return 1;  // T_STOP needs to count itself
    case T_VOID:    return 1;  // T_VOID needs to count itself
    case T_BOOL:   return sizeof(int8_t);
    case T_DOUBLE: return 8;  // uses fixedLongToBytes() which always writes 8 bytes
    case T_BYTE: return sizeof(int8_t);
    case T_I16:     return sizeof(int8_t);  // zigzag
    case T_I32:     return sizeof(int8_t);  // zigzag
    case T_I64:     return sizeof(int8_t);  // zigzag
    case T_STRING: return sizeof(int8_t);  // string length
    case T_STRUCT:  return 1;  // empty struct needs at least 1 byte for the T_STOP
    case T_MAP:     return sizeof(int8_t);  // element count
    case T_SET:    return sizeof(int8_t);  // element count
    case T_LIST:    return sizeof(int8_t);  // element count
    case T_UUID:    return 16; // 16 bytes
    default: throw TProtocolException(TProtocolException::UNKNOWN, "unrecognized type code");
  }
}


}}} // apache::thrift::protocol

#endif // _THRIFT_PROTOCOL_TCOMPACTPROTOCOL_TCC_