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 Action CreateTaskBody(TaskExecutionInfo executionInfoLocal, TaskTypeInfo taskTypeInfo)
{
return(() =>
{
try
{
executionInfoLocal.SendAliveSignal();
executionInfoLocal.SetTaskThread(Thread.CurrentThread);
if (executionInfoLocal.CancellationTokenSource.IsCancellationRequested)
{
return;
}
if (!SetRunningStatus(executionInfoLocal, taskTypeInfo))
{
return;
}
executionInfoLocal.SendAliveSignal();
//Flags executionInfoLocal right before invoking the task implementation
executionInfoLocal.RealTaskInvokedFlag = true;
taskTypeInfo.Invoke(executionInfoLocal.TaskDefinition.JsonParameters, executionInfoLocal);
SetCompletedOrCancelledStatus(executionInfoLocal);
}
catch (ThreadAbortException ex)
{
//Tries to save information about the task status.
//Reverts ThreadAbort
Thread.ResetAbort();
SetAbortedStatus(executionInfoLocal);
}
catch (Exception ex)
{
ex.LogException();
SetCompletedOrCancelledStatus(executionInfoLocal);
}
finally
{
try
{
//See comment below
executionInfoLocal.LockWillBeReleasedFlag = true;
_taskManager.LockManager.Release(executionInfoLocal.LockInfo);
//**** LockWillBeReleasedFlag avoids having the task being aborted right here when it's about to end, because we just released the lock
// and the lifetime manager could try to cancel it forcefully.
}
catch (Exception ex)
{
ex.LogException();
}
}
});
}
internal void Invoke(string jsonParameter, TaskExecutionInfo executionInfo)
{
object parameter = null;
if (jsonParameter != null)
{
parameter = JsonConvert.DeserializeObject(jsonParameter, this.ParamType);
}
var instance = Activator.CreateInstance(this.TaskType);
TaskTypeInfo.TypedInvoke((dynamic)instance, (dynamic)parameter, executionInfo);
}
private bool SetRunningStatus(TaskExecutionInfo executionInfoLocal, TaskTypeInfo taskTypeInfo)
{
var lockInfo = executionInfoLocal.LockInfo;
var taskDefinition = executionInfoLocal.TaskDefinition;
//It may be that the task scheduler took too long to start the thread.
//Renews the lock. Ignores the task if it doesn't acquire lock
if (!_taskManager.LockManager.TryRenewLock(lockInfo, taskTypeInfo.LockCycle, retryLock: true))
{
return(false);
}
using (var tr = new TransactionScope(TransactionScopeOption.Suppress, TransactionScopeAsyncFlowOption.Enabled))
using (var conn = _taskManager.CreateConnection())
using (var command = DbAccessHelper.CreateDbCommand(conn, SET_RUNNING_STATUS_SQL))
{
//milisecond precision
var lastRunAt = _taskManager.GetUtcNow().SetFractionalSecondPrecision(3);
var lockState = lockInfo.AsImmutable();
command.Parameters.Add(new SqlParameter("Id", taskDefinition.Id));
command.Parameters.Add(new SqlParameter("LastRunAt", System.Data.SqlDbType.DateTime2)
{
Value = lastRunAt
});
command.Parameters.Add(new SqlParameter("LockedUntil", System.Data.SqlDbType.DateTime2)
{
Value = lockState.LockedUntil
});
//Has the task been deleted or already handled?
if (command.ExecuteNonQuery() != 1)
{
return(false);
}
executionInfoLocal.LastRunAt = lastRunAt;
return(true);
}
}
private void SetCompletedOrCancelledStatus(TaskExecutionInfo executionInfoLocal)
{
executionInfoLocal.SendAliveSignal();
var lockInfo = executionInfoLocal.LockInfo;
var taskDefinition = executionInfoLocal.TaskDefinition;
/* We should not renew lock here because the task has already completed */
//If the task didn't run, don't do anything.
if (executionInfoLocal.LastRunAt == null)
{
return;
}
try
{
using (var tr = new TransactionScope(TransactionScopeOption.Suppress, TransactionScopeAsyncFlowOption.Enabled))
using (var conn = _taskManager.CreateConnection())
using (var command = DbAccessHelper.CreateDbCommand(conn, SET_COMPLETED_STATUS_FOR_RUNNING))
{
var newStatus = executionInfoLocal.IsCancellationRequested ? Distributed.SingleTaskStatus.CompletedCancelled : Distributed.SingleTaskStatus.Completed;
command.Parameters.Add(new SqlParameter("Id", taskDefinition.Id));
command.Parameters.Add(new SqlParameter("LastRunAt", System.Data.SqlDbType.DateTime2)
{
Value = executionInfoLocal.LastRunAt
});
command.Parameters.Add(new SqlParameter("NewStatus", (int)newStatus));
command.ExecuteNonQuery();
}
}
catch (Exception ex)
{
ex.LogException();
}
}
private void RenewTaskLock(TaskExecutionInfo taskInfo)
{
//renews lock
if (_taskManager.LockManager.TryRenewLock(taskInfo.LockInfo))
{
try
{
using (var tr = new TransactionScope(TransactionScopeOption.Suppress, TransactionScopeAsyncFlowOption.Enabled))
using (var conn = _taskManager.CreateConnection())
using (var command = DbAccessHelper.CreateDbCommand(conn, SET_LOCKEDUNTIL_SQL))
{
var lockedUntil = taskInfo.LockInfo.AsImmutable().LockedUntil;
if (lockedUntil == null)
{
return;
}
command.Parameters.Add(new SqlParameter("Id", taskInfo.TaskDefinition.Id));
command.Parameters.Add(new SqlParameter("LastRunAt", System.Data.SqlDbType.DateTime2)
{
Value = taskInfo.LastRunAt
});
command.Parameters.Add(new SqlParameter("LockedUntil", System.Data.SqlDbType.DateTime2)
{
Value = lockedUntil
});
command.ExecuteNonQuery();
}
}
catch (Exception ex)
{
ex.LogException();
}
}
}
internal static void TypedInvoke <P>(IDistributedTask <P> instance, P parameter, TaskExecutionInfo executionInfo)
{
instance.Run(parameter, executionInfo);
}