From d3e7f93e69cb24c766292d8780e745caf24d42a8 Mon Sep 17 00:00:00 2001
From: lichao <lichao@aiotlink.com>
Date: 星期四, 25 三月 2021 18:30:51 +0800
Subject: [PATCH] add ref count.
---
src/msg.h | 50 ++++++++++++++++++++++++++++++++++++++++++++------
1 files changed, 44 insertions(+), 6 deletions(-)
diff --git a/src/msg.h b/src/msg.h
index 8fbb0c5..44c961f 100644
--- a/src/msg.h
+++ b/src/msg.h
@@ -19,19 +19,21 @@
#define MSG_5BILLZET
#include <stdint.h>
+#include "shm.h"
#include <boost/interprocess/offset_ptr.hpp>
+#include <boost/uuid/uuid_generators.hpp>
namespace bhome_shm {
-using namespace boost::interprocess;
-
-// safe to be stored in shared memory.
+// msg is safe to be stored in shared memory, so POD data or offset_ptr is required.
// message format: header(meta) + body(data).
enum MsgType {
kMsgTypeNull = 0,
kMsgTypeNormal = 1,
kMsgTypeMaxValue
};
+
+typedef boost::uuids::uuid MQId;
const uint32_t kMsgMetaTag = 0xf1e2d3c4;
@@ -40,15 +42,51 @@
uint16_t type_ = kMsgTypeNormal; // msg type.
uint32_t tag_ = kMsgMetaTag;
uint32_t data_size_ = 0;
- unsigned char src_id_[16] = {0};
+ MQId src_id_;
// more fields add at end, must not change
- MsgMetaV1(){}
+ MsgMetaV1():src_id_(boost::uuids::nil_uuid()){}
bool Parse(const void *p);
void Pack(void *p);
};
-typedef offset_ptr<void> Msg;
+// store ref count, msgs shareing the same data should also hold a pointer of the same RefCount object.
+class RefCount : private boost::noncopyable
+{
+public:
+ int Inc() { Guard lk(mutex_); return ++num_; }
+ int Dec() { Guard lk(mutex_); return --num_; }
+ int Get() { Guard lk(mutex_); return num_; }
+private:
+ Mutex mutex_;
+ int num_ = 1;
+};
+
+class Msg {
+private:
+ offset_ptr<void> ptr_;
+ offset_ptr<RefCount> count_;
+public:
+ Msg(void *p=0, RefCount *c=0):ptr_(p), count_(c) {}
+ void swap(Msg &a) { std::swap(ptr_, a.ptr_); std::swap(count_, a.count_); }
+
+ // ~Msg() { RemoveRef(); }
+ // Msg(const Msg &a):ptr_(a.ptr_), count_(a.count_) { AddRef(); }
+ // Msg(Msg &&a):ptr_(a.ptr_), count_(a.count_) { a.ptr_ = 0; a.count_ = 0; }
+ // Msg & operator = (const Msg &a) { Msg(a).swap(*this); }
+ // Msg & operator = (Msg &&a) { Msg(std::move(a)).swap(*this); }
+
+ template <class T = void> T *get() { return static_cast<T*>(ptr_.get()); }
+ int AddRef() const { return IsCounted() ? count_->Inc() : 1; }
+ int RemoveRef() const{ return IsCounted() ? count_->Dec() : 0; }
+ int Count() const{ return IsCounted() ? count_->Get() : 1; }
+ bool IsCounted() const { return static_cast<bool>(count_); }
+ bool Build(SharedMemory &shm, const MQId &src_id, const void *p, const size_t size, const bool refcount);
+ void FreeFrom(SharedMemory &shm);
+};
+
+inline void swap(Msg &m1, Msg &m2) { m1.swap(m2); }
+
} // namespace bhome_shm
--
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