public void Execute(CancellationToken cancellationToken)
{
using (var connection = _storage.GetConnection())
using (var fetchedJob = connection.FetchNextJob(_context.Queues, cancellationToken))
{
try
{
var stateMachine = _stateMachineFactory.Create(connection);
using (var timeoutCts = new CancellationTokenSource(JobInitializationWaitTimeout))
using (var linkedCts = CancellationTokenSource.CreateLinkedTokenSource(
cancellationToken,
timeoutCts.Token))
{
var processingState = new ProcessingState(_context.ServerId, _context.WorkerNumber);
if (!stateMachine.ChangeState(
fetchedJob.JobId,
processingState,
new[] { EnqueuedState.StateName, ProcessingState.StateName },
linkedCts.Token))
{
// We should re-queue a job identifier only when graceful shutdown
// initiated.
cancellationToken.ThrowIfCancellationRequested();
// We should forget a job in a wrong state, or when timeout exceeded.
fetchedJob.RemoveFromQueue();
return;
}
}
// Checkpoint #3. Job is in the Processing state. However, there are
// no guarantees that it was performed. We need to re-queue it even
// it was performed to guarantee that it was performed AT LEAST once.
// It will be re-queued after the JobTimeout was expired.
var context = new ServerJobExecutionContext(
fetchedJob.JobId, connection, _context, cancellationToken);
var state = PerformJob(fetchedJob.JobId, connection, context);
if (state != null)
{
// Ignore return value, because we should not do anything when current state is not Processing.
stateMachine.ChangeState(fetchedJob.JobId, state, new[] { ProcessingState.StateName });
}
// Checkpoint #4. The job was performed, and it is in the one
// of the explicit states (Succeeded, Scheduled and so on).
// It should not be re-queued, but we still need to remove its
// processing information.
fetchedJob.RemoveFromQueue();
// Success point. No things must be done after previous command
// was succeeded.
}
catch (JobAbortedException)
{
fetchedJob.RemoveFromQueue();
}
catch (Exception ex)
{
Logger.DebugException("An exception occurred while processing a job. It will be re-queued.", ex);
fetchedJob.Requeue();
throw;
}
}
}
public void Execute(CancellationToken cancellationToken)
{
using (var connection = _storage.GetConnection())
using (var fetchedJob = connection.FetchNextJob(_context.Queues, cancellationToken))
{
try
{
var stateMachine = _stateMachineFactory.Create(connection);
using (var timeoutCts = new CancellationTokenSource(JobInitializationWaitTimeout))
using (var linkedCts = CancellationTokenSource.CreateLinkedTokenSource(
cancellationToken,
timeoutCts.Token))
{
var processingState = new ProcessingState(_context.ServerId, _context.WorkerNumber);
if (!stateMachine.ChangeState(
fetchedJob.JobId,
processingState,
new[] { EnqueuedState.StateName, ProcessingState.StateName },
linkedCts.Token))
{
// We should re-queue a job identifier only when graceful shutdown
// initiated.
cancellationToken.ThrowIfCancellationRequested();
// We should forget a job in a wrong state, or when timeout exceeded.
fetchedJob.RemoveFromQueue();
return;
}
}
// Checkpoint #3. Job is in the Processing state. However, there are
// no guarantees that it was performed. We need to re-queue it even
// it was performed to guarantee that it was performed AT LEAST once.
// It will be re-queued after the JobTimeout was expired.
var context = new ServerJobExecutionContext(
fetchedJob.JobId, connection, _context, cancellationToken);
var state = PerformJob(fetchedJob.JobId, connection, context);
if (state != null)
{
// Ignore return value, because we should not do anything when current state is not Processing.
stateMachine.ChangeState(fetchedJob.JobId, state, new[] { ProcessingState.StateName });
}
// Checkpoint #4. The job was performed, and it is in the one
// of the explicit states (Succeeded, Scheduled and so on).
// It should not be re-queued, but we still need to remove its
// processing information.
fetchedJob.RemoveFromQueue();
// Success point. No things must be done after previous command
// was succeeded.
}
catch (JobAbortedException)
{
fetchedJob.RemoveFromQueue();
}
catch (Exception ex)
{
Logger.DebugException("An exception occurred while processing a job. It will be re-queued.", ex);
fetchedJob.Requeue();
throw;
}
}
}