Open.Threading.ReadWrite

Useful set of extensions and classes for simplifying and optimizing read-write synchronization with ReaderWriterLockSlim.

Purpose

There are very common but tedious patterns to follow when utilizing a ReaderWriterLockSlim. Some of the more complex but useful patterns involve reading (with or without a read lock) and then if a condition is met, acquiring a write lock before proceeding.

This extension library removes the tediousness of properly acquiring and releasing various locks and provides easy access to timeout values if needed.

Basics

---

Read

rwLockSlim.Read(() =>
{
    /* do work inside a read lock */
});

using(rwLockSlim.ReadLock())
{
    /* do work inside a read lock */
}

int result = rwLockSlim.Read(() =>
{
    int i;
    /* produce a result inside read lock */
    return i;
});

---

Write

rwLockSlim.Write(() =>
{
    /* do work inside a read lock */
});

using(rwLockSlim.WriteLock())
{
    /* do work inside a write lock */
}

int result = rwLockSlim.Write(() =>
{
    int i;
    /* produce a result inside write lock */
    return i;
});

---

Upgradable Read

using(rwLockSlim.UpgradableReadLock())
{
    /* do work inside an upgradable read lock */
    if(condition)
    {
        using(rwLockSlim.WriteLock())
        {
            /* upgraded to a write lock */
        }
    }
}

With Timeouts

These throw a TimeoutException if a lock cannot be acquired within the time specified.

---

Read

rwLockSlim.Read(1000 /* ms */, () =>
{
    /* do work inside a read lock */
});

or

using(rwLockSlim.ReadLock(1000)) // ms
{
    /* do work inside a read lock */
}

---

Write

rwLockSlim.Write(1000 /* ms */, () =>
{
    /* do work inside a write lock */
});

or

using(rwLockSlim.WriteLock(1000)) // ms
{
    /* do work inside a write lock */
}

Advanced Examples

---

WriteConditional

This example demonstrates how to properly query a value before writing with a 1 second timeout.

var actionWasInvoked = rwLockSlim.WriteConditional(1000 /* ms */,
() => /* condition that is queried inside an upgradable read lock */,
() => /* do work inside a write lock */);

ReadWriteConditional

This more advanced example optimizes the process of reading and then writing by first testing the condition within a read lock before attempting with an upgradable read lock.

int result = 0;
bool actionWasInvoked = rwLockSlim.ReadWriteConditional(ref result,
isUpgraded => /* condition that is first queried inside a read lock */,
() =>
{
    int i;
    /* do work inside a write lock */
    return i;
});