This might have been solved in this week, but in case it wasn't:
You're tackling a general database problem, not a specific task queue or
web2py problem. So you need to solve it with the database: set up another
table to refer to you the task table, such as:
db.define_table('tasks_that_were_set_up',
Field('name', 'string', unique=true),
Field('scheduler', db.scheduler_task, notnull=True, required=True,
unique=True, ondelete='CASCADE'),
)
Make your insert code insert a task to this table as well:
try:
rid = db.scheduler_task.insert(name='task7',....)
db.tasks_that_were_set_up.insert(name='task7', scheduler=rid)
print 'Task was just added to db'
except db.integrity_error_class():
print 'Tasks were already in db.... */
Now, if the task gets removed from the scheduler_task table, because of the
cascading on_delete (which is the default - I just put it there for
emphasis), the record in tasks_that_were_set_up will be removed as well.
And otherwise, because of the unique constraint, the insert to
tasks_that_were_set_up can only succeed once -- and thanks to the
transaction nature -- therefore so does scheduler_task.insert.
