public LockAttemptResult TryLock([NotNull] string lockId, [NotNull] string threadId)
{
var lockMetadata = baseOperationsPerformer.TryGetLockMetadata(lockId) ?? new LockMetadata(lockId, lockId, 0, null, null, 0L);
var newThreshold = NewThreshold(lockMetadata.PreviousThreshold ?? (Timestamp.Now - TimeSpan.FromHours(1)).Ticks);
LockAttemptResult result;
var probableOwnerThreadId = lockMetadata.ProbableOwnerThreadId;
if (!string.IsNullOrEmpty(probableOwnerThreadId) && baseOperationsPerformer.ThreadAlive(lockMetadata.LockRowId, lockMetadata.PreviousThreshold, probableOwnerThreadId))
{
if (probableOwnerThreadId == threadId)
{
throw new InvalidOperationException($"TryLock(lockId = {lockId}, threadId = {threadId}): probableOwnerThreadId == threadId, though it seemed to be impossible!");
}
result = LockAttemptResult.AnotherOwner(probableOwnerThreadId);
}
else
{
result = RunBattle(lockMetadata, threadId, newThreshold);
}
if (result.Status == LockAttemptStatus.Success)
{
lockMetadata = baseOperationsPerformer.TryGetLockMetadata(lockId) ?? new LockMetadata(lockId, lockId, 0, null, null, 0L);
if (lockMetadata.LockCount <= changeLockRowThreshold)
{
var newLockMetadata = new NewLockMetadata(lockId, lockMetadata.LockRowId, lockMetadata.LockCount + 1, newThreshold, threadId);
baseOperationsPerformer.WriteLockMetadata(newLockMetadata, lockMetadata.Timestamp);
}
else
{
var newLockMetadata = new NewLockMetadata(lockId, Guid.NewGuid().ToString(), 1, newThreshold, threadId);
baseOperationsPerformer.WriteThread(newLockMetadata.MainRowKey(), newThreshold, threadId, LockTtl);
baseOperationsPerformer.WriteLockMetadata(newLockMetadata, lockMetadata.Timestamp);
baseOperationsPerformer.WriteThread(lockMetadata.MainRowKey(), newThreshold, threadId, LockTtl.Multiply(10));
}
}
return(result);
}
private LockAttemptResult RunBattle([NotNull] LockMetadata lockMetadata, [NotNull] string threadId, long newThreshold)
{
var items = baseOperationsPerformer.SearchThreads(lockMetadata.MainRowKey(), lockMetadata.PreviousThreshold);
if (items.Length == 1)
{
return(items[0] == threadId?LockAttemptResult.Success() : LockAttemptResult.AnotherOwner(items[0]));
}
if (items.Length > 1)
{
if (items.Any(s => s == threadId))
{
throw new Exception("Lock unknown exception");
}
return(LockAttemptResult.AnotherOwner(items[0]));
}
var beforeOurWriteShades = baseOperationsPerformer.SearchThreads(lockMetadata.ShadowRowKey(), lockMetadata.PreviousThreshold);
if (beforeOurWriteShades.Length > 0)
{
return(LockAttemptResult.ConcurrentAttempt());
}
baseOperationsPerformer.WriteThread(lockMetadata.ShadowRowKey(), newThreshold, threadId, LockTtl);
var shades = baseOperationsPerformer.SearchThreads(lockMetadata.ShadowRowKey(), lockMetadata.PreviousThreshold);
if (shades.Length == 1)
{
items = baseOperationsPerformer.SearchThreads(lockMetadata.MainRowKey(), lockMetadata.PreviousThreshold);
if (items.Length == 0)
{
baseOperationsPerformer.WriteThread(lockMetadata.MainRowKey(), newThreshold, threadId, LockTtl);
baseOperationsPerformer.DeleteThread(lockMetadata.ShadowRowKey(), newThreshold, threadId);
return(LockAttemptResult.Success());
}
}
baseOperationsPerformer.DeleteThread(lockMetadata.ShadowRowKey(), newThreshold, threadId);
return(LockAttemptResult.ConcurrentAttempt());
}