/// <summary>
/// Check the thread with the current turn for the lock and grant a secondary lock if applicable.
/// </summary>
/// <param name="candidateLock">An unexpired lock request on the current thread, or null to just check the turn thread.</param>
/// <returns>The Thread with the current turn for the lock, or null if there are none holding or waiting.</returns>
internal Thread CheckCurrentTurnThread(InterprocessLock candidateLock)
{
if (candidateLock != null && candidateLock.OwningThread != Thread.CurrentThread)
{
throw new InvalidOperationException("A lock request may only be waited on by the thread which created it.");
}
lock (m_QueueLock)
{
if (m_CurrentLockTurn != null)
{
Thread currentOwningThread = m_CurrentLockTurn.OwningThread;
if (candidateLock != null && Thread.CurrentThread == currentOwningThread)
{
candidateLock.GrantTheLock(m_CurrentLockTurn); // Set it as a secondary lock on that holder (same thread).
if (candidateLock.ActualLock == m_CurrentLockTurn) // Sanity-check that it was successful.
{
candidateLock.OurLockProxy = this; // So its dispose-on-close setting pass-through can function.
}
}
return(currentOwningThread); // Whether it's a match or some other thread.
}
return(null); // No thread owns the lock.
}
}
/// <summary>
/// Wait for our turn to have the lock (and wait for the lock) up to our time limit
/// </summary>
/// <param name="lockRequest"></param>
/// <returns></returns>
internal bool AwaitOurTurnOrTimeout(InterprocessLock lockRequest)
{
if (lockRequest.IsExpired)
{
throw new InvalidOperationException("Can't wait on an expired lock request.");
}
if (string.Equals(lockRequest.FullName, m_LockFullFileNamePath, StringComparison.OrdinalIgnoreCase) == false)
{
throw new InvalidOperationException("A lock request may not be queued to a proxy for a different full name.");
}
if (lockRequest.OwningThread != Thread.CurrentThread)
{
throw new InvalidOperationException("A lock request may only be waited on by the thread which created it.");
}
lockRequest.OurLockProxy = this; // Mark the request as pending with us.
// Do NOT clear out current lock owner, this will allow DequeueNextRequest to find one already there, if any.
bool ourTurn = StartNextTurn(lockRequest); // Gets its own queue lock.
if (ourTurn == false)
{
// It's not our turn yet, we need to wait our turn. Are we willing to wait?
if (lockRequest.WaitForLock && lockRequest.WaitTimeout > DateTimeOffset.Now)
{
ourTurn = lockRequest.AwaitTurnOrTimeout();
}
// Still not our turn?
if (ourTurn == false)
{
if (!CommonCentralLogic.SilentMode)
{
// Who actually has the lock right now?
if (m_CurrentLockTurn != null)
{
Thread currentOwningThread = m_CurrentLockTurn.OwningThread;
int currentOwningThreadId = -1;
string currentOwningThreadName = "null";
if (currentOwningThread != null) // To make sure we can't get a null-ref exception from logging this...
{
currentOwningThreadId = currentOwningThread.ManagedThreadId;
currentOwningThreadName = currentOwningThread.Name ?? string.Empty;
}
m_Logger.LogDebug("{0}\r\nA lock request gave up because it is still being held by another thread.\r\n" +
"Lock file: {1}\r\nCurrent holding thread: {2} ({3})",
lockRequest.WaitForLock ? "Lock request timed out" : "Lock request couldn't wait",
m_LockFullFileNamePath, currentOwningThreadId, currentOwningThreadName);
}
else
{
m_Logger.LogError("Lock request turn error\r\nA lock request failed to get its turn but the current lock turn is null. " +
"This probably should not happen.\r\nLock file: {0}\r\n", m_LockFullFileNamePath);
}
}
lockRequest.Dispose(); // Expire the request.
return(false); // Failed to get the lock. Time to give up.
}
}
// Yay, now it's our turn! Do we already hold the lock?
bool validLock;
if (m_FileLock != null)
{
validLock = true; // It's our request's turn and this proxy already holds the lock!
}
else
{
validLock = TryGetLock(lockRequest); // Can we get the lock?
}
// Do we actually have the lock now?
if (validLock)
{
lockRequest.GrantTheLock(lockRequest); // It owns the actual lock itself now.
}
else
{
if (!CommonCentralLogic.SilentMode)
{
m_Logger.LogTrace("{0}\r\nA lock request gave up because it could not obtain the file lock. " +
"It is most likely still held by another process.\r\nLock file: {1}",
lockRequest.WaitForLock ? "Lock request timed out" : "Lock request couldn't wait",
m_LockFullFileNamePath);
}
lockRequest.Dispose(); // Failed to get the lock. Expire the request and give up.
}
return(validLock);
}
