Downgrading ReaderWriterLockSlim UpgradeableReadLock to simple ReadLock

[HosamAly]

The documentation of ReaderWriterLockSlim.EnterUpgradeableReadLock says: "A thread in upgradeable mode can downgrade to read mode or upgrade to write mode." How do I downgrade the lock to a read lock? The documentation does't tell...

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[N a v a n e e t h]

To upgrade to write mode call EnterWriteLock and to downgrade, call ExitWriteLock

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[HosamAly]

Thanks, but I meant to downgrade from UpgradeableReadLock to simple ReadLock. I don't need WriteLock. The rationale is that since only one thread can acquire UpgradeableReadMode, I want to downgrade it when I know it's not needed so that another thread can acquire it.

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[N a v a n e e t h]

Well, the below code will answer it

class Program
{
static ReaderWriterLockSlim rwSlim = new ReaderWriterLockSlim(LockRecursionPolicy.SupportsRecursion);
static void Main(string[] args) {
// entering upgradable read lock
rwSlim.EnterUpgradeableReadLock();
Console.WriteLine(rwSlim.IsUpgradeableReadLockHeld);

        // downgrading to readlock. Now you are in read lock
        rwSlim.EnterReadLock();
        Console.WriteLine(rwSlim.IsReadLockHeld);

        // exiting from upgradable lock
        rwSlim.ExitUpgradeableReadLock();
        Console.WriteLine(rwSlim.IsUpgradeableReadLockHeld);

        // exiting read lock
        rwSlim.ExitReadLock();
        Console.WriteLine(rwSlim.IsReadLockHeld);
    }

}

You need to supply LockRecursionPolicy.SupportsRecursion to indicate that you need recursive locks.

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