6、caffe之probuff序列化消息使用

caffe.cpp源代码不在累赘，这里提供一下caffe代码中的序列化消息的使用，caffe中的数据结构使用的序列化消息实现数据之间的存储和传送。先举个例子，然后提供一下caffe源代码中的代码案例；
文件名字为msg.proto

package test;
message msg
{required int32 id=1 ;
required string str=2;
optional string sex=3;
}

Required: 表示是一个必须字段，必须相对于发送方，在发送消息之前必须设置该字段的值，对于接收方，必须能够识别该字段的意思。发送之前没有设置required字段或者无法识别required字段都会引发编解码异常，导致消息被丢弃。

Optional：表示是一个可选字段，可选对于发送方，在发送消息时，可以有选择性的设置或者不设置该字段的值。对于接收方，如果能够识别可选字段就进行相应的处理，如果无法识别，则忽略该字段，消息中的其它字段正常处理。—因为optional字段的特性，很多接口在升级版本中都把后来添加的字段都统一的设置为optional字段，这样老的版本无需升级程序也可以正常的与新的软件进行通信，只不过新的字段无法识别而已，因为并不是每个节点都需要新的功能，因此可以做到按需升级和平滑过渡。

Repeated：表示该字段可以包含0~N个元素。其特性和optional一样，但是每一次可以包含多个值。可以看作是在传递一个数组的值。

字段名称的命名与C、C++、Java等语言的变量命名方式几乎是相同的。

protobuf建议字段的命名采用以下划线分割,例如 first_name .

ubuntu@ubuntu:~$ protoc -I=./ --cpp_out=./ ./msg.proto

生成了这两个文件msg.pb.cc和msg.pb.h
文件msg.pb.h

// Generated by the protocol buffer compiler.  DO NOT EDIT!
// source: msg.proto

#ifndef PROTOBUF_msg_2eproto__INCLUDED
#define PROTOBUF_msg_2eproto__INCLUDED

#include <string>

#include <google/protobuf/stubs/common.h>

#if GOOGLE_PROTOBUF_VERSION < 2005000
#error This file was generated by a newer version of protoc which is
#error incompatible with your Protocol Buffer headers.  Please update
#error your headers.
#endif
#if 2005000 < GOOGLE_PROTOBUF_MIN_PROTOC_VERSION
#error This file was generated by an older version of protoc which is
#error incompatible with your Protocol Buffer headers.  Please
#error regenerate this file with a newer version of protoc.
#endif

#include <google/protobuf/generated_message_util.h>
#include <google/protobuf/message.h>
#include <google/protobuf/repeated_field.h>
#include <google/protobuf/extension_set.h>
#include <google/protobuf/unknown_field_set.h>
// @@protoc_insertion_point(includes)

namespace test {

// Internal implementation detail -- do not call these.
void  protobuf_AddDesc_msg_2eproto();
void protobuf_AssignDesc_msg_2eproto();
void protobuf_ShutdownFile_msg_2eproto();

class msg;

// ===================================================================

class msg : public ::google::protobuf::Message {
 public:
  msg();
  virtual ~msg();

  msg(const msg& from);

  inline msg& operator=(const msg& from) {
    CopyFrom(from);
    return *this;
  }

  inline const ::google::protobuf::UnknownFieldSet& unknown_fields() const {
    return _unknown_fields_;
  }

  inline ::google::protobuf::UnknownFieldSet* mutable_unknown_fields() {
    return &_unknown_fields_;
  }

  static const ::google::protobuf::Descriptor* descriptor();
  static const msg& default_instance();

  void Swap(msg* other);

  // implements Message ----------------------------------------------

  msg* New() const;
  void CopyFrom(const ::google::protobuf::Message& from);
  void MergeFrom(const ::google::protobuf::Message& from);
  void CopyFrom(const msg& from);
  void MergeFrom(const msg& from);
  void Clear();
  bool IsInitialized() const;

  int ByteSize() const;
  bool MergePartialFromCodedStream(
      ::google::protobuf::io::CodedInputStream* input);
  void SerializeWithCachedSizes(
      ::google::protobuf::io::CodedOutputStream* output) const;
  ::google::protobuf::uint8* SerializeWithCachedSizesToArray(::google::protobuf::uint8* output) const;
  int GetCachedSize() const { return _cached_size_; }
  private:
  void SharedCtor();
  void SharedDtor();
  void SetCachedSize(int size) const;
  public:

  ::google::protobuf::Metadata GetMetadata() const;

  // nested types ----------------------------------------------------

  // accessors -------------------------------------------------------

  // required int32 id = 1;
  inline bool has_id() const;
  inline void clear_id();
  static const int kIdFieldNumber = 1;
  inline ::google::protobuf::int32 id() const;
  inline void set_id(::google::protobuf::int32 value);

  // required string str = 2;
  inline bool has_str() const;
  inline void clear_str();
  static const int kStrFieldNumber = 2;
  inline const ::std::string& str() const;
  inline void set_str(const ::std::string& value);
  inline void set_str(const char* value);
  inline void set_str(const char* value, size_t size);
  inline ::std::string* mutable_str();
  inline ::std::string* release_str();
  inline void set_allocated_str(::std::string* str);

  // optional string sex = 3;
  inline bool has_sex() const;
  inline void clear_sex();
  static const int kSexFieldNumber = 3;
  inline const ::std::string& sex() const;
  inline void set_sex(const ::std::string& value);
  inline void set_sex(const char* value);
  inline void set_sex(const char* value, size_t size);
  inline ::std::string* mutable_sex();
  inline ::std::string* release_sex();
  inline void set_allocated_sex(::std::string* sex);

  // @@protoc_insertion_point(class_scope:test.msg)
 private:
  inline void set_has_id();
  inline void clear_has_id();
  inline void set_has_str();
  inline void clear_has_str();
  inline void set_has_sex();
  inline void clear_has_sex();

  ::google::protobuf::UnknownFieldSet _unknown_fields_;

  ::std::string* str_;
  ::std::string* sex_;
  ::google::protobuf::int32 id_;

  mutable int _cached_size_;
  ::google::protobuf::uint32 _has_bits_[(3 + 31) / 32];

  friend void  protobuf_AddDesc_msg_2eproto();
  friend void protobuf_AssignDesc_msg_2eproto();
  friend void protobuf_ShutdownFile_msg_2eproto();

  void InitAsDefaultInstance();
  static msg* default_instance_;
};
// ===================================================================


// ===================================================================

// msg

// required int32 id = 1;
inline bool msg::has_id() const {
  return (_has_bits_[0] & 0x00000001u) != 0;
}
inline void msg::set_has_id() {
  _has_bits_[0] |= 0x00000001u;
}
inline void msg::clear_has_id() {
  _has_bits_[0] &= ~0x00000001u;
}
inline void msg::clear_id() {
  id_ = 0;
  clear_has_id();
}
inline ::google::protobuf::int32 msg::id() const {
  return id_;
}
inline void msg::set_id(::google::protobuf::int32 value) {
  set_has_id();
  id_ = value;
}

// required string str = 2;
inline bool msg::has_str() const {
  return (_has_bits_[0] & 0x00000002u) != 0;
}
inline void msg::set_has_str() {
  _has_bits_[0] |= 0x00000002u;
}
inline void msg::clear_has_str() {
  _has_bits_[0] &= ~0x00000002u;
}
inline void msg::clear_str() {
  if (str_ != &::google::protobuf::internal::kEmptyString) {
    str_->clear();
  }
  clear_has_str();
}
inline const ::std::string& msg::str() const {
  return *str_;
}
inline void msg::set_str(const ::std::string& value) {
  set_has_str();
  if (str_ == &::google::protobuf::internal::kEmptyString) {
    str_ = new ::std::string;
  }
  str_->assign(value);
}
inline void msg::set_str(const char* value) {
  set_has_str();
  if (str_ == &::google::protobuf::internal::kEmptyString) {
    str_ = new ::std::string;
  }
  str_->assign(value);
}
inline void msg::set_str(const char* value, size_t size) {
  set_has_str();
  if (str_ == &::google::protobuf::internal::kEmptyString) {
    str_ = new ::std::string;
  }
  str_->assign(reinterpret_cast<const char*>(value), size);
}
inline ::std::string* msg::mutable_str() {
  set_has_str();
  if (str_ == &::google::protobuf::internal::kEmptyString) {
    str_ = new ::std::string;
  }
  return str_;
}
inline ::std::string* msg::release_str() {
  clear_has_str();
  if (str_ == &::google::protobuf::internal::kEmptyString) {
    return NULL;
  } else {
    ::std::string* temp = str_;
    str_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
    return temp;
  }
}
inline void msg::set_allocated_str(::std::string* str) {
  if (str_ != &::google::protobuf::internal::kEmptyString) {
    delete str_;
  }
  if (str) {
    set_has_str();
    str_ = str;
  } else {
    clear_has_str();
    str_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
  }
}

// optional string sex = 3;
inline bool msg::has_sex() const {
  return (_has_bits_[0] & 0x00000004u) != 0;
}
inline void msg::set_has_sex() {
  _has_bits_[0] |= 0x00000004u;
}
inline void msg::clear_has_sex() {
  _has_bits_[0] &= ~0x00000004u;
}
inline void msg::clear_sex() {
  if (sex_ != &::google::protobuf::internal::kEmptyString) {
    sex_->clear();
  }
  clear_has_sex();
}
inline const ::std::string& msg::sex() const {
  return *sex_;
}
inline void msg::set_sex(const ::std::string& value) {
  set_has_sex();
  if (sex_ == &::google::protobuf::internal::kEmptyString) {
    sex_ = new ::std::string;
  }
  sex_->assign(value);
}
inline void msg::set_sex(const char* value) {
  set_has_sex();
  if (sex_ == &::google::protobuf::internal::kEmptyString) {
    sex_ = new ::std::string;
  }
  sex_->assign(value);
}
inline void msg::set_sex(const char* value, size_t size) {
  set_has_sex();
  if (sex_ == &::google::protobuf::internal::kEmptyString) {
    sex_ = new ::std::string;
  }
  sex_->assign(reinterpret_cast<const char*>(value), size);
}
inline ::std::string* msg::mutable_sex() {
  set_has_sex();
  if (sex_ == &::google::protobuf::internal::kEmptyString) {
    sex_ = new ::std::string;
  }
  return sex_;
}
inline ::std::string* msg::release_sex() {
  clear_has_sex();
  if (sex_ == &::google::protobuf::internal::kEmptyString) {
    return NULL;
  } else {
    ::std::string* temp = sex_;
    sex_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
    return temp;
  }
}
inline void msg::set_allocated_sex(::std::string* sex) {
  if (sex_ != &::google::protobuf::internal::kEmptyString) {
    delete sex_;
  }
  if (sex) {
    set_has_sex();
    sex_ = sex;
  } else {
    clear_has_sex();
    sex_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
  }
}


// @@protoc_insertion_point(namespace_scope)

}  // namespace test

#ifndef SWIG
namespace google {
namespace protobuf {


}  // namespace google
}  // namespace protobuf
#endif  // SWIG

// @@protoc_insertion_point(global_scope)

#endif  // PROTOBUF_msg_2eproto__INCLUDED

​​文件msg.pb.cc​​

// Generated by the protocol buffer compiler.  DO NOT EDIT!
// source: msg.proto

#define INTERNAL_SUPPRESS_PROTOBUF_FIELD_DEPRECATION
#include "msg.pb.h"

#include <algorithm>

#include <google/protobuf/stubs/common.h>
#include <google/protobuf/stubs/once.h>
#include <google/protobuf/io/coded_stream.h>
#include <google/protobuf/wire_format_lite_inl.h>
#include <google/protobuf/descriptor.h>
#include <google/protobuf/generated_message_reflection.h>
#include <google/protobuf/reflection_ops.h>
#include <google/protobuf/wire_format.h>
// @@protoc_insertion_point(includes)

namespace test {

namespace {

const ::google::protobuf::Descriptor* msg_descriptor_ = NULL;
const ::google::protobuf::internal::GeneratedMessageReflection*
  msg_reflection_ = NULL;

}  // namespace


void protobuf_AssignDesc_msg_2eproto() {
  protobuf_AddDesc_msg_2eproto();
  const ::google::protobuf::FileDescriptor* file =
    ::google::protobuf::DescriptorPool::generated_pool()->FindFileByName(
      "msg.proto");
  GOOGLE_CHECK(file != NULL);
  msg_descriptor_ = file->message_type(0);
  static const int msg_offsets_[3] = {
    GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(msg, id_),
    GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(msg, str_),
    GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(msg, sex_),
  };
  msg_reflection_ =
    new ::google::protobuf::internal::GeneratedMessageReflection(
      msg_descriptor_,
      msg::default_instance_,
      msg_offsets_,
      GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(msg, _has_bits_[0]),
      GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(msg, _unknown_fields_),
      -1,
      ::google::protobuf::DescriptorPool::generated_pool(),
      ::google::protobuf::MessageFactory::generated_factory(),
      sizeof(msg));
}

namespace {

GOOGLE_PROTOBUF_DECLARE_ONCE(protobuf_AssignDescriptors_once_);
inline void protobuf_AssignDescriptorsOnce() {
  ::google::protobuf::GoogleOnceInit(&protobuf_AssignDescriptors_once_,
                 &protobuf_AssignDesc_msg_2eproto);
}

void protobuf_RegisterTypes(const ::std::string&) {
  protobuf_AssignDescriptorsOnce();
  ::google::protobuf::MessageFactory::InternalRegisterGeneratedMessage(
    msg_descriptor_, &msg::default_instance());
}

}  // namespace

void protobuf_ShutdownFile_msg_2eproto() {
  delete msg::default_instance_;
  delete msg_reflection_;
}

void protobuf_AddDesc_msg_2eproto() {
  static bool already_here = false;
  if (already_here) return;
  already_here = true;
  GOOGLE_PROTOBUF_VERIFY_VERSION;

  ::google::protobuf::DescriptorPool::InternalAddGeneratedFile(
    "\n\tmsg.proto\022\004test\"+\n\003msg\022\n\n\002id\030\001 \002(\005\022\013\n\003"
    "str\030\002 \002(\t\022\013\n\003sex\030\003 \001(\t", 62);
  ::google::protobuf::MessageFactory::InternalRegisterGeneratedFile(
    "msg.proto", &protobuf_RegisterTypes);
  msg::default_instance_ = new msg();
  msg::default_instance_->InitAsDefaultInstance();
  ::google::protobuf::internal::OnShutdown(&protobuf_ShutdownFile_msg_2eproto);
}

// Force AddDescriptors() to be called at static initialization time.
struct StaticDescriptorInitializer_msg_2eproto {
  StaticDescriptorInitializer_msg_2eproto() {
    protobuf_AddDesc_msg_2eproto();
  }
} static_descriptor_initializer_msg_2eproto_;

// ===================================================================

#ifndef _MSC_VER
const int msg::kIdFieldNumber;
const int msg::kStrFieldNumber;
const int msg::kSexFieldNumber;
#endif  // !_MSC_VER

msg::msg()
  : ::google::protobuf::Message() {
  SharedCtor();
}

void msg::InitAsDefaultInstance() {
}

msg::msg(const msg& from)
  : ::google::protobuf::Message() {
  SharedCtor();
  MergeFrom(from);
}

void msg::SharedCtor() {
  _cached_size_ = 0;
  id_ = 0;
  str_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
  sex_ = const_cast< ::std::string*>(&::google::protobuf::internal::kEmptyString);
  ::memset(_has_bits_, 0, sizeof(_has_bits_));
}

msg::~msg() {
  SharedDtor();
}

void msg::SharedDtor() {
  if (str_ != &::google::protobuf::internal::kEmptyString) {
    delete str_;
  }
  if (sex_ != &::google::protobuf::internal::kEmptyString) {
    delete sex_;
  }
  if (this != default_instance_) {
  }
}

void msg::SetCachedSize(int size) const {
  GOOGLE_SAFE_CONCURRENT_WRITES_BEGIN();
  _cached_size_ = size;
  GOOGLE_SAFE_CONCURRENT_WRITES_END();
}
const ::google::protobuf::Descriptor* msg::descriptor() {
  protobuf_AssignDescriptorsOnce();
  return msg_descriptor_;
}

const msg& msg::default_instance() {
  if (default_instance_ == NULL) protobuf_AddDesc_msg_2eproto();
  return *default_instance_;
}

msg* msg::default_instance_ = NULL;

msg* msg::New() const {
  return new msg;
}

void msg::Clear() {
  if (_has_bits_[0 / 32] & (0xffu << (0 % 32))) {
    id_ = 0;
    if (has_str()) {
      if (str_ != &::google::protobuf::internal::kEmptyString) {
        str_->clear();
      }
    }
    if (has_sex()) {
      if (sex_ != &::google::protobuf::internal::kEmptyString) {
        sex_->clear();
      }
    }
  }
  ::memset(_has_bits_, 0, sizeof(_has_bits_));
  mutable_unknown_fields()->Clear();
}

bool msg::MergePartialFromCodedStream(
    ::google::protobuf::io::CodedInputStream* input) {
#define DO_(EXPRESSION) if (!(EXPRESSION)) return false
  ::google::protobuf::uint32 tag;
  while ((tag = input->ReadTag()) != 0) {
    switch (::google::protobuf::internal::WireFormatLite::GetTagFieldNumber(tag)) {
      // required int32 id = 1;
      case 1: {
        if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
            ::google::protobuf::internal::WireFormatLite::WIRETYPE_VARINT) {
          DO_((::google::protobuf::internal::WireFormatLite::ReadPrimitive<
                   ::google::protobuf::int32, ::google::protobuf::internal::WireFormatLite::TYPE_INT32>(
                 input, &id_)));
          set_has_id();
        } else {
          goto handle_uninterpreted;
        }
        if (input->ExpectTag(18)) goto parse_str;
        break;
      }

      // required string str = 2;
      case 2: {
        if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
            ::google::protobuf::internal::WireFormatLite::WIRETYPE_LENGTH_DELIMITED) {
         parse_str:
          DO_(::google::protobuf::internal::WireFormatLite::ReadString(
                input, this->mutable_str()));
          ::google::protobuf::internal::WireFormat::VerifyUTF8String(
            this->str().data(), this->str().length(),
            ::google::protobuf::internal::WireFormat::PARSE);
        } else {
          goto handle_uninterpreted;
        }
        if (input->ExpectTag(26)) goto parse_sex;
        break;
      }

      // optional string sex = 3;
      case 3: {
        if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
            ::google::protobuf::internal::WireFormatLite::WIRETYPE_LENGTH_DELIMITED) {
         parse_sex:
          DO_(::google::protobuf::internal::WireFormatLite::ReadString(
                input, this->mutable_sex()));
          ::google::protobuf::internal::WireFormat::VerifyUTF8String(
            this->sex().data(), this->sex().length(),
            ::google::protobuf::internal::WireFormat::PARSE);
        } else {
          goto handle_uninterpreted;
        }
        if (input->ExpectAtEnd()) return true;
        break;
      }

      default: {
      handle_uninterpreted:
        if (::google::protobuf::internal::WireFormatLite::GetTagWireType(tag) ==
            ::google::protobuf::internal::WireFormatLite::WIRETYPE_END_GROUP) {
          return true;
        }
        DO_(::google::protobuf::internal::WireFormat::SkipField(
              input, tag, mutable_unknown_fields()));
        break;
      }
    }
  }
  return true;
#undef DO_
}

void msg::SerializeWithCachedSizes(
    ::google::protobuf::io::CodedOutputStream* output) const {
  // required int32 id = 1;
  if (has_id()) {
    ::google::protobuf::internal::WireFormatLite::WriteInt32(1, this->id(), output);
  }

  // required string str = 2;
  if (has_str()) {
    ::google::protobuf::internal::WireFormat::VerifyUTF8String(
      this->str().data(), this->str().length(),
      ::google::protobuf::internal::WireFormat::SERIALIZE);
    ::google::protobuf::internal::WireFormatLite::WriteString(
      2, this->str(), output);
  }

  // optional string sex = 3;
  if (has_sex()) {
    ::google::protobuf::internal::WireFormat::VerifyUTF8String(
      this->sex().data(), this->sex().length(),
      ::google::protobuf::internal::WireFormat::SERIALIZE);
    ::google::protobuf::internal::WireFormatLite::WriteString(
      3, this->sex(), output);
  }

  if (!unknown_fields().empty()) {
    ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
        unknown_fields(), output);
  }
}

::google::protobuf::uint8* msg::SerializeWithCachedSizesToArray(
    ::google::protobuf::uint8* target) const {
  // required int32 id = 1;
  if (has_id()) {
    target = ::google::protobuf::internal::WireFormatLite::WriteInt32ToArray(1, this->id(), target);
  }

  // required string str = 2;
  if (has_str()) {
    ::google::protobuf::internal::WireFormat::VerifyUTF8String(
      this->str().data(), this->str().length(),
      ::google::protobuf::internal::WireFormat::SERIALIZE);
    target =
      ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
        2, this->str(), target);
  }

  // optional string sex = 3;
  if (has_sex()) {
    ::google::protobuf::internal::WireFormat::VerifyUTF8String(
      this->sex().data(), this->sex().length(),
      ::google::protobuf::internal::WireFormat::SERIALIZE);
    target =
      ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
        3, this->sex(), target);
  }

  if (!unknown_fields().empty()) {
    target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
        unknown_fields(), target);
  }
  return target;
}

int msg::ByteSize() const {
  int total_size = 0;

  if (_has_bits_[0 / 32] & (0xffu << (0 % 32))) {
    // required int32 id = 1;
    if (has_id()) {
      total_size += 1 +
        ::google::protobuf::internal::WireFormatLite::Int32Size(
          this->id());
    }

    // required string str = 2;
    if (has_str()) {
      total_size += 1 +
        ::google::protobuf::internal::WireFormatLite::StringSize(
          this->str());
    }

    // optional string sex = 3;
    if (has_sex()) {
      total_size += 1 +
        ::google::protobuf::internal::WireFormatLite::StringSize(
          this->sex());
    }

  }
  if (!unknown_fields().empty()) {
    total_size +=
      ::google::protobuf::internal::WireFormat::ComputeUnknownFieldsSize(
        unknown_fields());
  }
  GOOGLE_SAFE_CONCURRENT_WRITES_BEGIN();
  _cached_size_ = total_size;
  GOOGLE_SAFE_CONCURRENT_WRITES_END();
  return total_size;
}

void msg::MergeFrom(const ::google::protobuf::Message& from) {
  GOOGLE_CHECK_NE(&from, this);
  const msg* source =
    ::google::protobuf::internal::dynamic_cast_if_available<const msg*>(
      &from);
  if (source == NULL) {
    ::google::protobuf::internal::ReflectionOps::Merge(from, this);
  } else {
    MergeFrom(*source);
  }
}

void msg::MergeFrom(const msg& from) {
  GOOGLE_CHECK_NE(&from, this);
  if (from._has_bits_[0 / 32] & (0xffu << (0 % 32))) {
    if (from.has_id()) {
      set_id(from.id());
    }
    if (from.has_str()) {
      set_str(from.str());
    }
    if (from.has_sex()) {
      set_sex(from.sex());
    }
  }
  mutable_unknown_fields()->MergeFrom(from.unknown_fields());
}

void msg::CopyFrom(const ::google::protobuf::Message& from) {
  if (&from == this) return;
  Clear();
  MergeFrom(from);
}

void msg::CopyFrom(const msg& from) {
  if (&from == this) return;
  Clear();
  MergeFrom(from);
}

bool msg::IsInitialized() const {
  if ((_has_bits_[0] & 0x00000003) != 0x00000003) return false;

  return true;
}

void msg::Swap(msg* other) {
  if (other != this) {
    std::swap(id_, other->id_);
    std::swap(str_, other->str_);
    std::swap(sex_, other->sex_);
    std::swap(_has_bits_[0], other->_has_bits_[0]);
    _unknown_fields_.Swap(&other->_unknown_fields_);
    std::swap(_cached_size_, other->_cached_size_);
  }
}

::google::protobuf::Metadata msg::GetMetadata() const {
  protobuf_AssignDescriptorsOnce();
  ::google::protobuf::Metadata metadata;
  metadata.descriptor = msg_descriptor_;
  metadata.reflection = msg_reflection_;
  return metadata;
}


// @@protoc_insertion_point(namespace_scope)

}  // namespace test

// @@protoc_insertion_point(global_scope)

文件名字为reader.cpp

#include<iostream>
#include<fstream>
#include"msg.pb.h"
using namespace std;
int main(int argc,char* argv[])
{ test::msg obj;
fstream input("./log",ios::in|ios::binary);
obj.ParseFromIstream(&input);
cout<<obj.id()<<endl;
cout<<obj.str()<<endl;
return 0;}

文件名字为writer.cpp

#include<fstream>
#include<iostream>
#include"msg.pb.h"
using namespace std;
int main(int argc,char* argv[])
{test::msg obj;
obj.set_id(120);
obj.set_str("i am a student");
fstream output("./log",ios::out|ios::binary);
obj.SerializeToOstream(&output);
return 0;}

ubuntu@ubuntu:~$ protoc -I=./ --cpp_out=./ ./msg.proto
ubuntu@ubuntu:~$ g++  msg.pb.cc reader.cpp -o reader  `pkg-config --cflags --libs protobuf` -lpthread
ubuntu@ubuntu:~$ g++  msg.pb.cc writer.cpp -o writer  `pkg-config --cflags --libs protobuf` -lpthread
ubuntu@ubuntu:~$ ./writer 
ubuntu@ubuntu:~$ ./reader 
120
i am a student

完成了数据从write 到read的操作；

在caffe源代码进行编译过程中，首先把/caffe/src/caffe/proto/caffe.proto 编译成caffe/build/src/caffe/proto/caffe.pb.cc和caffe/build/src/caffe/proto/caffe.pb.h序列化文件，然后在caffe.cpp中使用序列化的变量；我们只需读懂/caffe/src/caffe/proto/caffe.proto文件即可，按照阅读代码需要，查阅这个函数的变量即可；列如

caffe::SolverParameter solver_param;//源代码中的定义消息；caffe 表示包名； SolverParameter表示消息名； solver_param 表示定义的变量名；