def trigger_and_read(devices, name='primary', group=None):
"""
Trigger and read a list of detectors and bundle readings into one Event.
Parameters
----------
devices : iterable
devices to trigger (if they have a trigger method) and then read
name : string, optional
event stream name, a convenient human-friendly identifier; default
name is 'primary'
group : string (or any hashable object), optional
identifier used by 'trigger' and 'wait'
Yields
------
msg : Msg
messages to 'trigger', 'wait' and 'read'
"""
# If devices is empty, don't emit 'create'/'save' messages.
if not devices:
yield from bps.null()
devices = bps.separate_devices(devices) # remove redundant entries
rewindable = bps.all_safe_rewind(devices) # if devices can be re-triggered
def inner_trigger_and_read():
nonlocal group
if group is None:
group = short_uid('trigger')
no_wait = True
for obj in devices:
if hasattr(obj, 'trigger'):
no_wait = False
yield from bps.trigger(obj, group=group)
# Skip 'wait' if none of the devices implemented a trigger method.
if not no_wait:
yield from bps.wait(group=group)
yield from bps.create(name)
ret = {} # collect and return readings to give plan access to them
for obj in devices:
reading = (yield from bps.read(obj))
if reading is not None:
ret.update(reading)
yield from bps.save()
return ret
from bluesky.preprocessors import rewindable_wrapper
return (yield from rewindable_wrapper(inner_trigger_and_read(),
rewindable))
def test_nonrewindable_finalizer(RE, hw, start_state, msg_seq):
class FakeSig:
def get(self):
return False
det = hw.det
det.rewindable = FakeSig()
RE.rewindable = start_state
m_col = MsgCollector()
RE.msg_hook = m_col
def evil_plan():
assert RE.rewindable is False
yield Msg('aardvark')
with pytest.raises(KeyError):
RE(rewindable_wrapper(evil_plan(), False))
assert RE.rewindable is start_state
assert [m.command for m in m_col.msgs] == msg_seq
def test_nonrewindable_finalizer(RE, hw, start_state, msg_seq):
class FakeSig:
def get(self):
return False
det = hw.det
det.rewindable = FakeSig()
RE.rewindable = start_state
m_col = MsgCollector()
RE.msg_hook = m_col
def evil_plan():
assert RE.rewindable is False
yield Msg('aardvark')
with pytest.raises(KeyError):
RE(rewindable_wrapper(evil_plan(), False))
assert RE.rewindable is start_state
assert [m.command for m in m_col.msgs] == msg_seq
def shuttergenerator(shutter, value):
return (yield from bpp.rewindable_wrapper(bps.mv(shutter, value), False))