/*
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* =====================================================================================
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*
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* Filename: msg.h
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*
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* Description:
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*
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* Version: 1.0
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* Created: 2021年03月24日 16时49分20秒
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* Revision: none
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* Compiler: gcc
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*
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* Author: Li Chao (),
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* Organization:
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*
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* =====================================================================================
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*/
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#ifndef MSG_5BILLZET
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#define MSG_5BILLZET
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#include <stdint.h>
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#include "shm.h"
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#include <boost/interprocess/offset_ptr.hpp>
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#include <boost/uuid/uuid_generators.hpp>
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namespace bhome_shm {
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// msg is safe to be stored in shared memory, so POD data or offset_ptr is required.
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// message format: header(meta) + body(data).
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enum MsgType {
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kMsgTypeNull = 0,
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kMsgTypeNormal = 1,
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kMsgTypeMaxValue
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};
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typedef boost::uuids::uuid MQId;
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const uint32_t kMsgMetaTag = 0xf1e2d3c4;
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struct MsgMetaV1 {
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uint16_t self_size_ = sizeof(MsgMetaV1); // sizeof(*this)
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uint16_t type_ = kMsgTypeNormal; // msg type.
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uint32_t tag_ = kMsgMetaTag;
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uint32_t data_size_ = 0;
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MQId src_id_;
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// more fields add at end, must not change
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MsgMetaV1():src_id_(boost::uuids::nil_uuid()){}
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bool Parse(const void *p);
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void Pack(void *p);
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};
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// store ref count, msgs shareing the same data should also hold a pointer of the same RefCount object.
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class RefCount : private boost::noncopyable
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{
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public:
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int Inc() { Guard lk(mutex_); return ++num_; }
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int Dec() { Guard lk(mutex_); return --num_; }
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int Get() { Guard lk(mutex_); return num_; }
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private:
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Mutex mutex_;
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int num_ = 1;
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};
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class Msg {
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private:
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offset_ptr<void> ptr_;
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offset_ptr<RefCount> count_;
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public:
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Msg(void *p=0, RefCount *c=0):ptr_(p), count_(c) {}
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void swap(Msg &a) { std::swap(ptr_, a.ptr_); std::swap(count_, a.count_); }
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template <class T = void> T *get() { return static_cast<T*>(ptr_.get()); }
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// AddRef and Release works for both counted and not counted msg.
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int AddRef() const { return IsCounted() ? count_->Inc() : 1; }
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int Release(SharedMemory &shm) const;
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int Count() const{ return IsCounted() ? count_->Get() : 1; }
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bool IsCounted() const { return static_cast<bool>(count_); }
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bool Build(SharedMemory &shm, const MQId &src_id, const void *p, const size_t size, const bool refcount);
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};
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inline void swap(Msg &m1, Msg &m2) { m1.swap(m2); }
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} // namespace bhome_shm
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#endif // end of include guard: MSG_5BILLZET
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