CAF（C++ actor framework）(序列化之结构体，任意嵌套STL）（一）

User-Defined Data Types in Messages（用户自定义类型）
All user-defined types must be explicitly “announced” so that CAF can (de)serialize them correctly.

之前干活，一开始不知道CAF自带序列化，都用boost库来做序列化，就是变string 类型发送，发现很多STL有些搞搞比较麻烦，发现诶？CAF居然比boost库好使！

那么就来搞一下看看.

先看一个例子（也是usermanual 里唯一的一个例子，呵呵呵～）其他的例子在github官网里https://github.com/actor-framework/actor-framework/tree/master/examples/type_system （就五个收益很大）

没看错就是那么简单的使用，announce函数。第一个参数是一个string那么之后就是他的所有成员。怎么实现我也不是很懂，上图

大致就是TS 就是参数的类型，可以是可变长度，然后检查他们的类型，我第一看到Is_pod 查了一下（pod类型 是plain old data）就是完全兼容C语言的编程的。（涨姿势了～）

还有uniform_type_info是CAF自己的一个关于类型什么的（没深究，只知道与RTTI有关）。还有一个重要的地方就是你必须写明你要发送的结构体的比较函数 ==（下面代码上有）

进入正题。（announce1.cpp）代码有一点点小长但是信息量很大。

// POD struct
struct foo {
  std::vector<int> a;
  int b;
};

// announce requires foo to have the equal operator implemented
bool operator==(const foo& lhs, const foo& rhs) {
  return lhs.a == rhs.a && lhs.b == rhs.b;
}

// a pair of two ints
using foo_pair = std::pair<int, int>;

// another pair of two ints
using foo_pair2 = std::pair<int, int>;

// a struct with member vector<vector<...>>
struct foo2 {
  int a;
  vector<vector<double>> b;
};

bool operator==(const foo2& lhs, const foo2& rhs) {
  return lhs.a == rhs.a && lhs.b == rhs.b;
}

// receives `remaining` messages
void testee(event_based_actor* self, size_t remaining) {
  auto set_next_behavior = [=] {
    if (remaining > 1) testee(self, remaining - 1);
    else self->quit();
  };
  self->become (
    // note: we sent a foo_pair2, but match on foo_pair
    // that's safe because both are aliases for std::pair<int, int>
    [=](const foo_pair& val) {
      cout << "foo_pair("
         << val.first << ", "
         << val.second << ")"
         << endl;
      set_next_behavior();
    },
    [=](const foo& val) {
      cout << "foo({";
      auto i = val.a.begin();
      auto end = val.a.end();
      if (i != end) {
        cout << *i;
        while (++i != end) {
          cout << ", " << *i;
        }
      }
      cout << "}, " << val.b << ")" << endl;
      set_next_behavior();
    }
  );
}

int main(int, char**) {
  // announces foo to the libcaf type system;
  // the function expects member pointers to all elements of foo
  announce<foo>("foo", &foo::a, &foo::b);
  // announce foo2 to the libcaf type system,
  // note that recursive containers are managed automatically by libcaf
  announce<foo2>("foo2", &foo2::a, &foo2::b);
  // serialization can throw if types are not announced properly
  try {
    // init some test data
    foo2 vd;
    vd.a = 5;
    vd.b.resize(1);
    vd.b.back().push_back(42);
    // serialize test data
    vector<char> buf;
    binary_serializer bs(std::back_inserter(buf));
    bs << vd;
    // deserialize written test data from buffer
    binary_deserializer bd(buf.data(), buf.size());
    foo2 vd2;
    uniform_typeid<foo2>()->deserialize(&vd2, &bd);
    // deserialized data must be equal to original input
    assert(vd == vd2);
    // announce std::pair<int, int> to the type system
    announce<foo_pair>("foo_pair", &foo_pair::first, &foo_pair::second);
    // libcaf returns the same uniform_type_info
    // instance for the type aliases foo_pair and foo_pair2
    assert(uniform_typeid<foo_pair>() == uniform_typeid<foo_pair2>());
  }
  catch (std::exception& e) {
    cerr << "error during type (de)serialization: " << e.what() << endl;
    return -1;
  }
  // spawn a testee that receives two messages of user-defined type
  auto t = spawn(testee, size_t{2});
  { // lifetime scope of self
    scoped_actor self;
    // send t a foo
    self->send(t, foo{std::vector<int>{1, 2, 3, 4}, 5});
    // send t a foo_pair2
    self->send(t, foo_pair2{3, 4});
  }
  await_all_actors_done();
  shutdown();
}

一开始看，就是声明了两种结构体。foo 和foo2，foo2里面有vector<vector<double>> b（其实这里就告诉我们，它不但支持STL，还支持嵌套，而且我亲测pair，map都是可以的。其他应该也没问题吧。）

然后testee里定义了接受两种类型的消息一种是<int,int>（不管别名）,一种是结构体foo 是的没看错，都不用序列化了，直接传（// note that recursive containers are managed automatically by libcaf）。

真心方便，然后是main函数里，使用了二进制去序列化类，再使用反序列化，整个过程就像用读文件非常的方便(注意捕获异常)。那么在最后的scoped_actor send也直接把类传过去非常的方便。

为了证明好用，支持remote actor我写了一个很难看的代码。

#include <vector>
#include <iostream>
#include "caf/all.hpp"
#include "caf/io/all.hpp"
using std::cout;
using std::endl;
using std::vector;
using std::map;
using std::pair;
using namespace caf;

struct foo {
  std::vector<vector<map<int,pair<int,int>>>> a;
  int b;
};
bool operator==(const foo& lhs, const foo& rhs) {
  return lhs.a == rhs.a && lhs.b == rhs.b;
}
// receives `remaining` messages
void testee(event_based_actor* self) {
  self->become (
    [=](const foo& val) {
        aout(self)<<"get it"<<endl;
    }
  );
}
int main(int, char**) {
//  announce<foo2>("foo2", &foo2::a, &foo2::b);
  announce<foo>("foo", &foo::a, &foo::b);
  auto actor = spawn(testee);
  caf::io::publish(actor,10000);
  { // lifetime scope of self
    scoped_actor self;
    auto remoter = caf::io::remote_actor("localhost", 10000);
    self->send(remoter, foo{std::vector<vector<map<int,pair<int,int>>>>{},1,});
  }
  await_all_actors_done();
  shutdown();
}

结果为

不得不服还是很方便的！

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