public TaskExecutionInfo ProcessTaskDefinition(SingleTaskDefinition taskDefinition)
{
var lockInfo = LockInfo.Empty(taskDefinition.Identifier);
var taskTypeInfo = _taskManager.GetTaskInfo(taskDefinition.Identifier);
//links this task's cancellation token to the manager's token
var ctSource = CancellationTokenSource.CreateLinkedTokenSource(_listenerCtSource.Token);
try
{
//Inter-process lock. Ignores the task if it doesn't acquire lock
if (taskTypeInfo == null || !_taskManager.LockManager.TryRenewLock(lockInfo, taskTypeInfo.LockCycle, retryLock: true))
{
return(new TaskExecutionInfo(_managedThreadPool.CreateCompletedTask(), ctSource, lockInfo, taskDefinition));
}
var executionInfoLocal = new TaskExecutionInfo(null, ctSource, lockInfo, taskDefinition);
var taskBody = CreateTaskBody(executionInfoLocal, taskTypeInfo);
var task = _managedThreadPool.QueueUserWorkItem((o) => taskBody(), null);
executionInfoLocal.SetTask(task);
return(executionInfoLocal);
}
catch (Exception ex)
{
ex.LogException();
return(new TaskExecutionInfo(_managedThreadPool.CreateCompletedTask(), ctSource, lockInfo, taskDefinition));
}
}
private async Task <LockInfo> WaitForLockImpl(Guid resource, TimeSpan?lockTimeout, CancellationToken cancellationToken)
{
LockInfo acquiredLock = LockInfo.Empty(resource);
while (!cancellationToken.IsCancellationRequested)
{
acquiredLock = await TryLockAsync(resource, lockTimeout);
if (acquiredLock.AsImmutable().HasLock())
{
break;
}
try
{
await Task.Delay(1000, cancellationToken);
}
catch (OperationCanceledException ex)
{
break;
}
}
return(acquiredLock);
}
private async Task <LockInfo> acquireLockAsync(IDbConnectionAsync conn, Guid resource, int lockReference, TimeSpan timeout)
{
var lockInfo = LockInfo.Empty(resource);
var newLockRef = Math.Max(1, lockReference + 1);
//only acquires lock if old lock reference number matches, and not locked yet.
using (var command = await DbAccessHelperAsync.CreateDbCommand(conn, ACQUIRE_lOCK_COMMANDS))
{
command.Parameters.Add(new SqlParameter("newLockRef", newLockRef));
command.Parameters.Add(new SqlParameter("timeout", Convert.ToInt64(timeout.TotalMilliseconds)));
command.Parameters.Add(new SqlParameter("lockedByMachine", _machineName));
command.Parameters.Add(new SqlParameter("lockedByPID", _PID));
command.Parameters.Add(new SqlParameter("resource", resource));
command.Parameters.Add(new SqlParameter("lockReference", lockReference));
try
{
var dbLockedTill = (DateTime?)await command.ExecuteScalarAsync();
if (dbLockedTill != null)
{
var clock = _clockProvider.GetClock();
lockInfo.Update(dbLockedTill, timeout, newLockRef, clock);
}
}
catch (Exception ex)
{
ex.LogException();
}
return(lockInfo);
}
}
public async Task <LockInfo> TryLockAsync(Guid resource, TimeSpan?lockTimeout)
{
EnsureNotDisposed();
lockTimeout = lockTimeout ?? defaultTimeout;
verifyTimeoutLimits(lockTimeout.Value);
using (var tr = new TransactionScope(TransactionScopeOption.Suppress, TransactionScopeAsyncFlowOption.Enabled))
using (var conn = CreateConnection())
{
var lockReference = await GetFreeReferenceOrNewAsync(conn, resource);
//failed to insert record or resource already locked
if (lockReference == null)
{
return(LockInfo.Empty(resource));
}
//tries to acquire lock
return(await acquireLockAsync(conn, resource, lockReference.Value, lockTimeout.Value));
}
}
