CSpace Mutex

A CSpace is protected by a mutex.

The following functions on a CSpace allow for locking and unlocking it:

$adt+ CSpace
{
    void Lock(ECSpaceLockMode mode);
    void Unlock();
    LockInfo BeginUnlock();
    void EndUnlock(LockInfo info);
};

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void Lock(ECSpaceLockMode mode)

Blocks the calling thread until it successfully gains a lock of the given ECSpaceLockMode on the CSpace. Locking multiple CSpaces must be done in a specific order.

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void Unlock()

Release the lock on the CSpace. Must be called by the thread that locked the CSpace by calling Lock()

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LockInfo BeginUnlock()

Used in the implementation of CSpaceRelinquishLock to relinquish the lock. The returned LockInfo allows for subsequently calling EndUnlock() to reinstate the lock.

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void EndUnlock(LockInfo info)

Reinstates the lock that was previously relinquished by calling BeginUnlock.

CSpaceLock and CSpaceTxn

The RAII classes CSpaceLock and CSpaceTxn allow for locking a CSpace in a given scope.

CSpaceRelinquishLock

The RAII class CSpaceRelinquishLock allows for relinquishing a lock in a given scope.

Exceptions while locking a CSpace

Uncaught exceptions which are thrown while locking a CSpace mutex are regarded as a programming error, and the safest thing to do is to immediately terminate the process - rather than risk persisting objects in an invalid state to a database perhaps causing permanent data coruption or loss.