From a22dd242713636fad33ee5965fe0900a425ce50d Mon Sep 17 00:00:00 2001
From: lichao <lichao@aiotlink.com>
Date: 星期四, 25 三月 2021 11:19:15 +0800
Subject: [PATCH] test msg ref count, refactor.
---
src/msg.h | 45 +++++++++++++++++++++++++++++++++++++++++----
1 files changed, 41 insertions(+), 4 deletions(-)
diff --git a/src/msg.h b/src/msg.h
index 8fbb0c5..214bb72 100644
--- a/src/msg.h
+++ b/src/msg.h
@@ -19,13 +19,12 @@
#define MSG_5BILLZET
#include <stdint.h>
+#include "shm.h"
#include <boost/interprocess/offset_ptr.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,
@@ -48,7 +47,45 @@
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_ = 0;
+};
+
+class Msg {
+private:
+ offset_ptr<void> ptr_;
+ offset_ptr<RefCount> count_;
+ void swap(Msg &a) { std::swap(ptr_, a.ptr_); std::swap(count_, a.count_); }
+public:
+ class CountGuard : private boost::noncopyable {
+ Msg &msg_;
+ public:
+ CountGuard(Msg &msg) : msg_(msg) { msg_.AddRef(); }
+ ~CountGuard() { msg_.RemoveRef(); }
+ };
+
+ Msg(void *p=0, RefCount *c=0):ptr_(p), count_(c) {}
+
+ // ~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() { return count_ ? count_->Inc() : 0; }
+ int RemoveRef() { return count_ ? count_->Dec() : 0; }
+ int Count() { return count_ ? count_->Get() : 0; }
+};
+
} // namespace bhome_shm
--
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