Task management

The main entry point for an experimental session is the pymanip.asyncsession.AsyncSession.monitor() function which should be awaited from the main function of the program. The typical main structure of a program is then:

async def monitoring_task(sesn):
    some_value = await sesn.some_device.aget()
    sesn.add_entry(some_value=some_value)
    await sesn.sleep(10)

async def main(sesn):
    async with SomeDevice() as sesn.some_device:
        await sesn.monitor(monitoring_task)

with AsyncSession() as sesn:
    asyncio.run(main(sesn))

In this example, we see the use of the context managers, both for the AsyncSession object, and for the instrument object. The main experimental measurement lies in the monitoring_task() function, which should not be an explicit for loop. Indeed, the sesn.monitor() method will implement the for loop, with checks for the interruption signal.

Possible additionnal initialisation of devices can be added to the main() function. Possible additionnal initalisation of session variables can be added in the with AsyncSession() block. Note that all functions take the session object as its first argument. It is therefore possible to write the same code as a subclass of AsyncSession, but this is not strictly necessary, i.e.

class Monitoring(AsyncSession):

    async def monitoring_task(self):
        some_value = await self.some_device.aget()
        self.add_entry(some_value=some_value)
        await self.sleep(10)

    async def main(self):
        async with SomeDevice() as self.some_device:
            await self.monitor(self.monitoring_task)

with Monitoring() as mon:
    asyncio.run(mon.main())

The benefits of the asynchronous structure of the example program is clearer when plotting tasks, and email tasks are added, or when there are several concurrent monitoring tasks. The main() function may then become:

async def main(sesn):
    async with SomeDevice() as sesn.some_device:
        await sesn.monitor(monitoring_task_a,
                           monitoring_task_b,
                           sesn.plot(['var_a', 'var_b', 'var_c']),
                           sesn.send_email(from_addr='toto@titi.org',
                                           to_addrs='tata@titi.org',
                                           delay_hours=2.0),
                           )

The useful pre-defined tasks are pymanip.asyncsession.AsyncSession.send_email(), pymanip.asyncsession.AsyncSession.plot() and pymanip.asyncsession.AsyncSession.sweep().