rocksdb/thrift/lib/cpp/protocol/TCompactProtocol.h

/*
 * 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_H_
#define THRIFT_PROTOCOL_TCOMPACTPROTOCOL_H_ 1

#include "thrift/lib/cpp/protocol/TVirtualProtocol.h"

#include <stack>
#include <boost/shared_ptr.hpp>

namespace apache { namespace thrift { namespace protocol {

/**
 * C++ Implementation of the Compact Protocol as described in THRIFT-110
 */
template <class Transport_>
class TCompactProtocolT
  : public TVirtualProtocol< TCompactProtocolT<Transport_> > {
 public:
  static const int8_t  VERSION_N = 2;
  static const int8_t  VERSION_LOW = 1;
  static const int8_t  VERSION_DOUBLE_BE = 2;
  static const int8_t  PROTOCOL_ID = static_cast<int8_t>(0x82);
  static const int8_t  VERSION_MASK = 0x1f; // 0001 1111

 protected:
  // Normally we can define static const data members of integral
  // type here.  However there appears to be a gcc issue when the
  // high bit is set (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49896)
  // unless we cast to a value that fits in an int8_t (0x82 and 0xE0 are
  // uint8_t)

  static const int8_t  TYPE_MASK = static_cast<int8_t>(0xE0);
  static const int32_t TYPE_SHIFT_AMOUNT = 5;

  Transport_* trans_;

  /**
   * (Writing) If we encounter a boolean field begin, save the TField here
   * so it can have the value incorporated.
   */
  struct {
    const char* name;
    TType fieldType;
    int16_t fieldId;
  } booleanField_;

  /**
   * (Reading) If we read a field header, and it's a boolean field, save
   * the boolean value here so that readBool can use it.
   */
  struct {
    bool hasBoolValue;
    bool boolValue;
  } boolValue_;

  /**
   * Used to keep track of the last field for the current and previous structs,
   * so we can do the delta stuff.
   */

  std::stack<int16_t> lastField_;
  int16_t lastFieldId_;
  int8_t version_;

 public:
  explicit TCompactProtocolT(boost::shared_ptr<Transport_> trans) :
      TVirtualProtocol< TCompactProtocolT<Transport_> >(trans),
      trans_(trans.get()),
      lastFieldId_(0),
      version_(VERSION_N),
      string_limit_(0),
      string_buf_(NULL),
      string_buf_size_(0),
      container_limit_(0) {
    booleanField_.name = NULL;
    boolValue_.hasBoolValue = false;
  }

  TCompactProtocolT(boost::shared_ptr<Transport_> trans,
                    int32_t string_limit,
                    int32_t container_limit) :
    TVirtualProtocol< TCompactProtocolT<Transport_> >(trans),
    trans_(trans.get()),
    lastFieldId_(0),
    version_(VERSION_N),
    string_limit_(string_limit),
    string_buf_(NULL),
    string_buf_size_(0),
    container_limit_(container_limit) {
    booleanField_.name = NULL;
    boolValue_.hasBoolValue = false;
  }

  virtual ~TCompactProtocolT() {
    if (string_buf_) {
      free(string_buf_);
    }
  }

  /** Set this if you need backwards compatibility with an old version */
  void setVersion(const int8_t version) {
    version_ = version;
  }

  /**
   * Writing functions
   */

  virtual uint32_t writeMessageBegin(const std::string& name,
                                     const TMessageType messageType,
                                     const int32_t seqid);

  uint32_t writeStructBegin(const char* name);

  uint32_t writeStructEnd();

  uint32_t writeFieldBegin(const char* name,
                           const TType fieldType,
                           const int16_t fieldId);

  uint32_t writeFieldStop();

  uint32_t writeListBegin(const TType elemType,
                          const uint32_t size);

  uint32_t writeSetBegin(const TType elemType,
                         const uint32_t size);

  virtual uint32_t writeMapBegin(const TType keyType,
                                 const TType valType,
                                 const uint32_t size);

  uint32_t writeBool(const bool value);

  uint32_t writeByte(const int8_t byte);

  uint32_t writeI16(const int16_t i16);

  uint32_t writeI32(const int32_t i32);

  uint32_t writeI64(const int64_t i64);

  uint32_t writeDouble(const double dub);

  uint32_t writeString(const char* str);

  template <class String_>
  uint32_t writeString(const String_& str);

  template <class String_>
  uint32_t writeBinary(const String_& str);

  /**
  * These methods are called by structs, but don't actually have any wired
  * output or purpose
  */
  virtual uint32_t writeMessageEnd() { return 0; }
  uint32_t writeMapEnd() { return 0; }
  uint32_t writeListEnd() { return 0; }
  uint32_t writeSetEnd() { return 0; }
  uint32_t writeFieldEnd() { return 0; }

 protected:
  int32_t writeFieldBeginInternal(const char* name,
                                  const TType fieldType,
                                  const int16_t fieldId,
                                  int8_t typeOverride);
  uint32_t writeCollectionBegin(int8_t elemType, int32_t size);
  uint32_t writeVarint32(uint32_t n);
  uint32_t writeVarint64(uint64_t n);
  uint64_t i64ToZigzag(const int64_t l);
  uint32_t i32ToZigzag(const int32_t n);
  inline int8_t getCompactType(int8_t ttype);

 public:
  uint32_t readMessageBegin(std::string& name,
                            TMessageType& messageType,
                            int32_t& seqid);

  uint32_t readStructBegin(std::string& name);

  uint32_t readStructEnd();

  uint32_t readFieldBegin(std::string& name,
                          TType& fieldType,
                          int16_t& fieldId);

  uint32_t readMapBegin(TType& keyType,
                        TType& valType,
                        uint32_t& size);

  uint32_t readListBegin(TType& elemType,
                         uint32_t& size);

  uint32_t readSetBegin(TType& elemType,
                        uint32_t& size);

  uint32_t readBool(bool& value);
  // Provide the default readBool() implementation for std::vector<bool>
  using TVirtualProtocol< TCompactProtocolT<Transport_> >::readBool;

  uint32_t readByte(int8_t& byte);

  uint32_t readI16(int16_t& i16);

  uint32_t readI32(int32_t& i32);

  uint32_t readI64(int64_t& i64);

  uint32_t readDouble(double& dub);

  template <class String_>
  uint32_t readString(String_& str);

  template <class String_>
  uint32_t readBinary(String_& str);

  /*
   *These methods are here for the struct to call, but don't have any wire
   * encoding.
   */
  uint32_t readMessageEnd() { return 0; }
  uint32_t readFieldEnd() { return 0; }
  uint32_t readMapEnd() { return 0; }
  uint32_t readListEnd() { return 0; }
  uint32_t readSetEnd() { return 0; }

 protected:
  uint32_t readVarint32(int32_t& i32);
  uint32_t readVarint64(int64_t& i64);
  int32_t zigzagToI32(uint32_t n);
  int64_t zigzagToI64(uint64_t n);
  TType getTType(int8_t type);

  // Buffer for reading strings, save for the lifetime of the protocol to
  // avoid memory churn allocating memory on every string read
  int32_t string_limit_;
  uint8_t* string_buf_;
  int32_t string_buf_size_;
  int32_t container_limit_;
};

typedef TCompactProtocolT<TTransport> TCompactProtocol;

/**
 * Constructs compact protocol handlers
 */
template <class Transport_>
class TCompactProtocolFactoryT : public TProtocolFactory {
 public:
  TCompactProtocolFactoryT() :
    string_limit_(0),
    container_limit_(0) {}

  TCompactProtocolFactoryT(int32_t string_limit, int32_t container_limit) :
    string_limit_(string_limit),
    container_limit_(container_limit) {}

  virtual ~TCompactProtocolFactoryT() {}

  void setStringSizeLimit(int32_t string_limit) {
    string_limit_ = string_limit;
  }

  void setContainerSizeLimit(int32_t container_limit) {
    container_limit_ = container_limit;
  }

  boost::shared_ptr<TProtocol> getProtocol(boost::shared_ptr<TTransport> trans) {
    boost::shared_ptr<Transport_> specific_trans =
      boost::dynamic_pointer_cast<Transport_>(trans);
    TProtocol* prot;
    if (specific_trans) {
      prot = new TCompactProtocolT<Transport_>(specific_trans, string_limit_,
                                               container_limit_);
    } else {
      prot = new TCompactProtocol(trans, string_limit_, container_limit_);
    }

    return boost::shared_ptr<TProtocol>(prot);
  }

 private:
  int32_t string_limit_;
  int32_t container_limit_;

};

typedef TCompactProtocolFactoryT<TTransport> TCompactProtocolFactory;

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

#include "TCompactProtocol.tcc"

#endif