From 1d6c040dcb9a01648edc66d8c0006c8c9294a705 Mon Sep 17 00:00:00 2001
From: lichao <lichao@aiotlink.com>
Date: 星期四, 22 四月 2021 18:28:30 +0800
Subject: [PATCH] add mutex timeout limit; use atomic as refcount.
---
src/shm.h | 50 +++++++++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 49 insertions(+), 1 deletions(-)
diff --git a/src/shm.h b/src/shm.h
index 28745dc..5bf8e41 100644
--- a/src/shm.h
+++ b/src/shm.h
@@ -19,12 +19,15 @@
#ifndef SHM_6CHO6D6C
#define SHM_6CHO6D6C
+#include <atomic>
#include <boost/interprocess/managed_shared_memory.hpp>
#include <boost/interprocess/sync/interprocess_condition.hpp>
#include <boost/interprocess/sync/interprocess_mutex.hpp>
#include <boost/interprocess/sync/scoped_lock.hpp>
#include <boost/noncopyable.hpp>
#include <boost/uuid/uuid.hpp>
+#include <chrono>
+#include <thread>
namespace bhome_shm
{
@@ -32,7 +35,52 @@
using namespace boost::interprocess;
typedef managed_shared_memory mshm_t;
-typedef interprocess_mutex Mutex;
+
+class CasMutex
+{
+ std::atomic<bool> flag_;
+ bool cas(bool expected, bool new_val) { return flag_.compare_exchange_strong(expected, new_val); }
+
+public:
+ CasMutex() :
+ flag_(false) {}
+ bool try_lock() { return cas(false, true); }
+ void lock()
+ {
+ while (!try_lock()) { std::this_thread::yield(); }
+ }
+ void unlock() { cas(true, false); }
+};
+
+class MutexWithTimeLimit
+{
+ typedef boost::interprocess::interprocess_mutex MutexT;
+ // typedef CasMutex MutexT;
+ typedef std::chrono::steady_clock Clock;
+ typedef Clock::duration Duration;
+ static Duration Now() { return Clock::now().time_since_epoch(); }
+
+ const Duration limit_;
+ std::atomic<Duration> last_lock_time_;
+ MutexT mutex_;
+
+public:
+ typedef MutexT::internal_mutex_type internal_mutex_type;
+ const internal_mutex_type &internal_mutex() const { return mutex_.internal_mutex(); }
+ internal_mutex_type &internal_mutex() { return mutex_.internal_mutex(); }
+
+ explicit MutexWithTimeLimit(Duration limit) :
+ limit_(limit) {}
+ MutexWithTimeLimit() :
+ MutexWithTimeLimit(std::chrono::seconds(1)) {}
+ ~MutexWithTimeLimit() { static_assert(std::is_pod<Duration>::value); }
+ bool try_lock();
+ void lock();
+ void unlock() { mutex_.unlock(); }
+};
+
+// typedef boost::interprocess::interprocess_mutex Mutex;
+typedef MutexWithTimeLimit Mutex;
typedef scoped_lock<Mutex> Guard;
typedef interprocess_condition Cond;
--
Gitblit v1.8.0