Interlocked family of functions for simple Synchronizations.

Jijo Raj — Mon, 24 Mar 2008 19:00:44 +0000

In multithreaded environment we usually use Mutex to synchronize access to resources. But sometimes our resources may be a single integer member variable which holds some count or like that. For such light weight resource, using mutex is not preferred.

For that you can Interlocked family of functions. Please see some of the functions below.

InterlockedIncrement()
InterlockedDecrement()
InterlockedExchange()
InterlockedCompareExchange()
InterlockedExchangePointer()
…

For example if you need to increment a member variable threadsafely, you can use InterlockedIncrement(). That function will ensure the thread synchronization without any additional kernel objects such as mutex etc… Please see the code block below.

long m_lCount = 0;
...
// Increment the value.
InterlockedIncrement( &m_lCount );

InterlockedExchangePointer()

Visual C++ Tips » InterlockedDecrement

Interlocked family of functions for simple Synchronizations.