public void Locksmith_WhenReadLockIsUpgradedWithOnlyOneReader_PreventsNewReadersFromEntering()
{
const int failureValue = 25;
const int expectedValue = 10;
int result = expectedValue;
Locksmith.EnterReadLock(ref lockState, readLockTestObject);
Locksmith.Upgrade(ref lockState, writeLockTestObject);
{
StartNewThreadThatRuns(SetReadResultToFailureValue);
Thread.Sleep(1000);
Assert.That(result, Is.EqualTo(expectedValue));
}
Locksmith.ExitWriteLock(ref lockState, readLockTestObject, writeLockTestObject);
return;
void SetReadResultToFailureValue()
{
Locksmith.EnterReadLock(ref lockState, readLockTestObject);
result = failureValue;
Locksmith.ExitReadLock(ref lockState, readLockTestObject, writeLockTestObject);
}
}
public void Locksmith_WhenReadLockIsUpgraded_ThrowsIfExitReadLockIsCalled()
{
Locksmith.EnterReadLock(ref lockState, readLockTestObject);
Locksmith.Upgrade(ref lockState, writeLockTestObject);
Assert.Throws <SynchronizationLockException>(TryToCallExitReadLock);
Locksmith.ExitWriteLock(ref lockState, readLockTestObject, writeLockTestObject);
return;
void TryToCallExitReadLock() =>
Locksmith.ExitReadLock(ref lockState, readLockTestObject, writeLockTestObject);
}
public void Locksmith_WhenReadLockIsUpgradedWhileOtherReadersAreActive_WaitsUntilAllOtherReadersExitToConvertLock()
{
const int numberOfOtherReaders = 10;
int numberOfReads = 0;
int numberOfExits = 0;
CountdownEvent readEvent = new CountdownEvent(numberOfOtherReaders);
CountdownEvent exitEvent = new CountdownEvent(numberOfOtherReaders);
ManualResetEvent upgradeEvent = new ManualResetEvent(false);
Locksmith.EnterReadLock(ref lockState, readLockTestObject);
for (int i = 0; i < numberOfOtherReaders; i++)
{
StartNewThreadThatRuns(IncrementNumReadsInsideReadLock);
}
readEvent.Wait();
Assert.That(numberOfReads, Is.EqualTo(numberOfOtherReaders));
upgradeEvent.Set();
Locksmith.Upgrade(ref lockState, writeLockTestObject);
{
Assert.That(lockState.IsReadLocked() == false, $"{lockState}");
exitEvent.Wait();
Assert.That(numberOfExits, Is.EqualTo(numberOfOtherReaders));
}
Locksmith.ExitWriteLock(ref lockState, readLockTestObject, writeLockTestObject);
return;
void IncrementNumReadsInsideReadLock()
{
Locksmith.EnterReadLock(ref lockState, readLockTestObject);
{
Interlocked.Increment(ref numberOfReads);
readEvent.Signal();
upgradeEvent.WaitOne();
Thread.Sleep(1000);
Assert.That(ReservedForUpgrade && IsReadLocked);
}
Locksmith.ExitReadLock(ref lockState, readLockTestObject, writeLockTestObject);
Interlocked.Increment(ref numberOfExits);
exitEvent.Signal();
}
}
public bool IfValueEqualsFirstSetToSecond(T valueToTestFor, T valueToSetTo)
{
Locksmith.EnterReadLock(ref lockState, readLockobject);
{
if (lockedValue.Equals(valueToTestFor))
{
Locksmith.Upgrade(ref lockState, this);
{
lockedValue = valueToSetTo;
}
Locksmith.ExitWriteLock(ref lockState, readLockobject, this);
return(true);
}
}
Locksmith.ExitReadLock(ref lockState, readLockobject, this);
return(false);
}
public void Locksmith_WhenReadLockIsUpgradedWhileOtherReadersAreActive_PreventsNewReadersFromEntering()
{
const int numberOfOtherReaders = 10;
int numberOfReadersEntered = 0;
int numberOfExits = 0;
CountdownEvent readEvent = new CountdownEvent(numberOfOtherReaders);
CountdownEvent exitEvent = new CountdownEvent(numberOfOtherReaders);
ManualResetEvent outerUpgradeEvent = new ManualResetEvent(false);
ManualResetEvent innerUpgradeEvent = new ManualResetEvent(false);
for (int i = 0; i < numberOfOtherReaders; i++)
{
StartNewThreadThatRuns(IncrementNumReadsInsideReadLock_FirstSet);
}
readEvent.Wait();
Assert.That(numberOfReadersEntered, Is.EqualTo(numberOfOtherReaders));
StartNewThreadThatRuns(EnterReadLockAndUpgrade);
exitEvent.Wait();
Assert.That(numberOfExits, Is.EqualTo(numberOfOtherReaders));
for (int i = 0; i < numberOfOtherReaders; i++)
{
StartNewThreadThatRuns(IncrementNumReadsInsideReadLock_SecondSet);
}
Thread.Sleep(1000);
Assert.That(numberOfReadersEntered, Is.EqualTo(numberOfOtherReaders));
innerUpgradeEvent.Set();
return;
void EnterReadLockAndUpgrade()
{
Locksmith.EnterReadLock(ref lockState, readLockTestObject);
outerUpgradeEvent.Set();
Locksmith.Upgrade(ref lockState, writeLockTestObject);
{
innerUpgradeEvent.WaitOne();
Assert.That(numberOfExits, Is.EqualTo(numberOfOtherReaders));
}
Locksmith.ExitWriteLock(ref lockState, readLockTestObject, writeLockTestObject);
}
void IncrementNumReadsInsideReadLock_FirstSet()
{
Locksmith.EnterReadLock(ref lockState, readLockTestObject);
{
Interlocked.Increment(ref numberOfReadersEntered);
readEvent.Signal();
outerUpgradeEvent.WaitOne();
Thread.Sleep(1000);
}
Locksmith.ExitReadLock(ref lockState, readLockTestObject, writeLockTestObject);
Interlocked.Increment(ref numberOfExits);
exitEvent.Signal();
}
void IncrementNumReadsInsideReadLock_SecondSet()
{
Locksmith.EnterReadLock(ref lockState, readLockTestObject);
{
Interlocked.Increment(ref numberOfReadersEntered);
}
Locksmith.ExitReadLock(ref lockState, readLockTestObject, writeLockTestObject);
Interlocked.Increment(ref numberOfExits);
}
}