ossim::RWLock Class Reference

Code was derived from https://gist.github.com/mshockwave. More...

#include <RWLock.h>

Public Member Functions
	RWLock ()
void	lockWrite ()
bool	tryLockWrite ()
void	unlockWrite ()
void	lockRead ()
bool	tryLockRead ()
void	unlockRead ()

Private Attributes
std::mutex	m_waitMutex
std::condition_variable	m_waitConditional
std::atomic_int	m_refCounter
const int	MIN_INT

Detailed Description

Code was derived from https://gist.github.com/mshockwave.

Has a pure c++11 implementation for read/write locks allowing one to choose the locking technique to use.

At the bottom we added typedefs so you do not have to specify the template values.

Example:

ossim::RWLock mutex;
// enter a section that just needs read only access 
{
     ossim::ScopeReadLock  lock(mutex);
}
// enter some section that requires write
{
    ossim::ScopeWriteLock  lock(mutex); 
}

Definition at line 38 of file RWLock.h.

Constructor & Destructor Documentation

RWLock()

ossim::RWLock::RWLock

(

)

Definition at line 3 of file RWLock.cpp.

                    :
        m_refCounter(0),
        MIN_INT(std::numeric_limits<int>::min())
{

}

Member Function Documentation

lockRead()

void ossim::RWLock::lockRead

(

)

Definition at line 46 of file RWLock.cpp.

Referenced by ossim::ScopeReadLock::ScopeReadLock().

{
    if(m_refCounter.fetch_add(1, std::memory_order_acquire) < 0){
        m_refCounter.fetch_sub(1, std::memory_order_release);

        std::unique_lock<std::mutex> lk(m_waitMutex);
        m_waitConditional.wait(lk, [this]{
            return m_refCounter.fetch_add(1, std::memory_order_acquire) >= 0;
        });
        lk.unlock();
    }
}

lockWrite()

void ossim::RWLock::lockWrite

(

)

Definition at line 10 of file RWLock.cpp.

Referenced by ossim::ScopeWriteLock::ScopeWriteLock().

{
    int expected = 0;
    if(!m_refCounter.compare_exchange_strong(expected, MIN_INT,
                                             std::memory_order_acquire,
                                             std::memory_order_relaxed)){
        expected = 0;

        std::unique_lock<std::mutex> lk(m_waitMutex);
        m_waitConditional.wait(lk, [this,&expected] {
            if(!m_refCounter.compare_exchange_strong(expected, MIN_INT,
                                                     std::memory_order_acquire,
                                                     std::memory_order_relaxed)){
                expected = 0;
                return false;
            }
            return true;
        });
        lk.unlock();
    }
}

tryLockRead()

bool ossim::RWLock::tryLockRead

(

)

Definition at line 59 of file RWLock.cpp.

{
    return m_refCounter.fetch_add(1, std::memory_order_acquire) >= 0;
}

tryLockWrite()

bool ossim::RWLock::tryLockWrite

(

)

Definition at line 32 of file RWLock.cpp.

{
    int expected = 0;
    return m_refCounter.compare_exchange_strong(expected, MIN_INT,
                                                std::memory_order_acquire,
                                                std::memory_order_relaxed);
}

unlockRead()

void ossim::RWLock::unlockRead

(

)

Definition at line 64 of file RWLock.cpp.

Referenced by ossim::ScopeReadLock::~ScopeReadLock().

{
    m_refCounter.fetch_sub(1, std::memory_order_release);
    m_waitConditional.notify_one();
}

unlockWrite()

void ossim::RWLock::unlockWrite

(

)

Definition at line 40 of file RWLock.cpp.

Referenced by ossim::ScopeWriteLock::~ScopeWriteLock().

{
    m_refCounter.store(0, std::memory_order_release);
    m_waitConditional.notify_all();
}

Member Data Documentation

m_refCounter

std::atomic_int ossim::RWLock::m_refCounter

private

Definition at line 42 of file RWLock.h.

m_waitConditional

std::condition_variable ossim::RWLock::m_waitConditional

private

Definition at line 41 of file RWLock.h.

m_waitMutex

std::mutex ossim::RWLock::m_waitMutex

private

Definition at line 40 of file RWLock.h.

MIN_INT

const int ossim::RWLock::MIN_INT

private

Definition at line 43 of file RWLock.h.

---

The documentation for this class was generated from the following files:

• RWLock.h
• RWLock.cpp