//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in C#:
//ORIGINAL LINE: public VALUE acquire(KEY key) throws NoSuchEntryException, ConcurrentAccessException
public virtual VALUE Acquire(KEY key)
{
Entry entry = _repo.get(key);
if (entry == null)
{
throw new NoSuchEntryException(string.Format("Cannot access '{0}', no such entry exists.", key));
}
if (entry.Acquire())
{
return(entry.Value);
}
throw new ConcurrentAccessException(string.Format("Cannot access '{0}', because another client is currently using it.", key));
}
public override void Run()
{
long maxAllowedAge = _clock.millis() - _timeout;
foreach (KEY key in Keys())
{
Entry entry = _repo.get(key);
if ((entry != null) && (entry.LatestActivityTimestamp < maxAllowedAge))
{
if ((entry.LatestActivityTimestamp < maxAllowedAge) && entry.Acquire())
{
End0(key, entry.Value);
}
}
}
}
/// <summary>
/// End the life of a stored entry. If the entry is currently in use, it will be thrown out as soon as the other client
/// is done with it.
/// </summary>
public virtual VALUE End(KEY key)
{
while (true)
{
Entry entry = _repo.get(key);
if (entry == null)
{
return(default(VALUE));
}
// Ending the life of an entry is somewhat complicated, because we promise the callee here that if someone
// else is concurrently using the entry, we will ensure that either we or the other user will end the entry
// life when the other user is done with it.
// First, assume the entry is in use and try and mark it to be ended by the other user
if (entry.MarkForEndingIfInUse())
{
// The entry was indeed in use, and we successfully marked it to be ended. That's all we need to do here,
// the other user will see the ending flag when releasing the entry.
return(entry.Value);
}
// Marking it for ending failed, likely because the entry is currently idle - lets try and just acquire it
// and throw it out ourselves
if (entry.Acquire())
{
// Got it, just throw it away
End0(key, entry.Value);
return(entry.Value);
}
// We didn't manage to mark this for ending, and we didn't manage to acquire it to end it ourselves, which
// means either we're racing with another thread using it (and we just need to retry), or it's already
// marked for ending. In the latter case, we can bail here.
if (entry.MarkedForEnding)
{
// Someone did indeed manage to mark it for ending, which means it will be thrown out (or has already).
return(entry.Value);
}
}
}
