public Task <IEnumerable <BackgroundTask> > LockNextAvailableAsync(int readAhead)
{
var all = _tasks.SelectMany(t => t.Value);
// None locked, failed or succeeded, must be due, ordered by due time then priority
var now = GetTaskTimestamp();
var query = all
.Where(t => !t.FailedAt.HasValue && !t.SucceededAt.HasValue && !t.LockedAt.HasValue)
.Where(t => t.RunAt <= now)
.OrderBy(t => t.RunAt)
.ThenBy(t => t.Priority)
.AsList();
var tasks = (query.Count > readAhead ? query.Take(readAhead) : query).AsList();
// Lock tasks:
if (tasks.Any())
{
foreach (var scheduledTask in tasks)
{
scheduledTask.LockedAt = now;
scheduledTask.LockedBy = LockedIdentity.Get();
}
}
return(Task.FromResult(tasks.AsEnumerable()));
}
private async Task LockTasksAsync(IReadOnlyCollection <BackgroundTask> tasks, IDbConnection db, IDbTransaction t)
{
var sql = $@"
UPDATE {TaskTable}
SET
LockedAt = :Now,
LockedBy = :User
WHERE Id IN
:Ids
";
var now = GetTaskTimestamp();
var user = LockedIdentity.Get();
await db.ExecuteAsync(sql, new { Now = now, Ids = tasks.Select(task => task.Id), User = user }, t);
foreach (var task in tasks)
{
task.LockedAt = now;
task.LockedBy = user;
}
}
public async Task <IEnumerable <BackgroundTask> > LockNextAvailableAsync(int readAhead)
{
var now = GetTaskTimestamp();
var tasks = (await _repository.RetrieveAsync(x =>
x.LockedAt == null &&
x.FailedAt == null &&
x.SucceededAt == null &&
x.RunAt <= now)).ToList();
foreach (var task in tasks)
{
task.LockedAt = now;
task.LockedBy = LockedIdentity.Get();
await _repository.UpdateAsync(task.Id, task);
}
return(tasks
.OrderBy(x => x.RunAt)
.ThenBy(x => x.Priority)
.Select(x => (BackgroundTask)x));
}
private void LockTasks(IEnumerable <BackgroundTask> tasks, IDbConnection db, IDbTransaction t)
{
var now = GetTaskTimestamp();
var user = LockedIdentity.Get();
var matches = tasks.AsList();
var ids = GetTaskIds(matches).AsList();
if (_options.CurrentValue.Store.FilterCorrelatedTasks)
{
FilterCorrelatedTasks(db, t, now, ids, matches);
}
var lockTasks = $@"
UPDATE {TaskTable}
SET
LockedAt = @Now,
LockedBy = @User
WHERE Id IN
@Ids;
";
_logger.Debug(() => "Locking {TaskCount} tasks", matches.Count);
var updated = db.Execute(lockTasks, new { Now = now, Ids = ids, User = user }, t);
if (updated != matches.Count)
{
_logger.Warn(() => "Did not lock the expected number of tasks");
}
foreach (var task in matches)
{
task.LockedAt = now;
task.LockedBy = user;
}
}
