Hi, I have a question on how I can write a piece of code such that I can still get the best performance but can also guarantee it's integrity. Below is a simplified example of what I am try to do. I have some data which resides in shared memory, and in order to protect against multiple updates I use a lock, however I also need to protect against a process dying half-way through an update. So I use code similar to the following: Lock(pshared); if (pshared->UpdateInProgress) doRecovery(pshared); pshared->UpdatedInProgress=TRUE; pshared->value1 = localValue1; /* The critical updates */ pshared->value2 = localValue2; pshared->value3 = localValue3; pshared->UpdateInProgress=FALSE; UnLock(pshared); If when a process gets the lock, he sees that UpdateInProgress is TRUE it knows it has some recovery to do. However my problem is how can I protect against the optomizer re-ordering the code. I guess I need to define the UpdateInProgress flag as volatile, but do I also need to declare the value1, value2 and value3 is pshared as volatile too in order to guarantee that they don't get re-ordered with respect to the UpdateInProgress flag? Appologies for the rather long-winded explanation, but I figured it was the best way of explaining what I am try to achieve. Any guidance is much appreciated. Thanks, Trevor
