ENH: for LCLS-I att, give proper error for uninterruptable move

docs/source/upcoming_release_notes/1183-fix_att_move_err.rst

@@ -0,0 +1,33 @@
+1183 fix_att_move_err
+#####################
+
+API Breaks
+----------
+- N/A
+
+Features
+--------
+- Added `PVPositionerNoInterrupt`, a pv positioner base class whose moves
+  cannot be interrupted (and will loudly complain about any such attempts).
+
+Device Updates
+--------------
+- N/A
+
+New Devices
+-----------
+- N/A
+
+Bugfixes
+--------
+- LCLSI attenuator classes (generated from the `Attenuator` factory function)
+  will now raise a much clearer error for when they cannot interrupt a
+  previous move, without trying (and failing) to interrupt the previous move.
+
+Maintenance
+-----------
+- N/A
+
+Contributors
+------------
+- zllentz

pcdsdevices/attenuator.py

@@ -14,7 +14,7 @@
 from ophyd.device import Device
 from ophyd.device import DynamicDeviceComponent as DDC
 from ophyd.device import FormattedComponent as FCpt
-from ophyd.pv_positioner import PVPositioner, PVPositionerPC
+from ophyd.pv_positioner import PVPositionerPC
 from ophyd.signal import EpicsSignal, EpicsSignalRO, Signal, SignalRO
 
 from . import utils
@@ -26,6 +26,7 @@
 from .interface import (BaseInterface, FltMvInterface, LightpathInOutCptMixin,
                         LightpathMixin)
 from .pmps import TwinCATStatePMPS
+from .pv_positioner import PVPositionerNoInterrupt
 from .signal import InternalSignal, MultiDerivedSignal, MultiDerivedSignalRO
 from .type_hints import OphydDataType, SignalToValue
 from .utils import get_status_float, get_status_value
@@ -134,9 +135,9 @@ def _status_update(self, *args, value, **kwargs):
             self.status.put(BladeStateEnum.Unknown, force=True)
 
 
-class AttBase(FltMvInterface, PVPositioner):
+class AttBase(FltMvInterface, PVPositionerNoInterrupt):
     """
-    Base class for attenuators with fundamental frequency.
+    Base class for pre-L2SI beam power attenuators.
 
     This is a device that puts an array of filters in or out to achieve a
     desired transmission ratio.

pcdsdevices/pv_positioner.py

@@ -1,4 +1,6 @@
-from typing import Optional
+from __future__ import annotations
+
+from typing import Callable, Optional
 
 import numpy as np
 from ophyd.device import Component as Cpt
@@ -160,3 +162,112 @@ def _setup_move(self, position):
     def _toggle_done(self):
         self.done.put(0, force=True)
         self.done.put(1, force=True)
+
+
+class PVPositionerNoInterrupt(PVPositioner):
+    """
+    A PV positioner whose moves cannot be interrupted.
+
+    If we try to start a new move before the previous move completes,
+    instead we will get a clear error advising us to wait.
+
+    Parameters
+    ----------
+    prefix : str, optional
+        The device prefix used for all sub-positioners. This is optional as it
+        may be desirable to specify full PV names for PVPositioners.
+    limits : 2-element sequence, optional
+        (low_limit, high_limit)
+    name : str
+        The device name
+    egu : str, optional
+        The engineering units (EGU) for the position
+    settle_time : float, optional
+        The amount of time to wait after moves to report status completion
+    timeout : float, optional
+        The default timeout to use for motion requests, in seconds.
+
+    Attributes
+    ----------
+    setpoint : Signal
+        The setpoint (request) signal
+    readback : Signal or None
+        The readback PV (e.g., encoder position PV)
+    actuate : Signal or None
+        The actuation PV to set when movement is requested
+    actuate_value : any, optional
+        The actuation value, sent to the actuate signal when motion is
+        requested
+    stop_signal : Signal or None
+        The stop PV to set when motion should be stopped
+    stop_value : any, optional
+        The value sent to stop_signal when a stop is requested
+    done : Signal
+        A readback value indicating whether motion is finished
+    done_value : any, optional
+        The value that the done pv should be when motion has completed
+    put_complete : bool, optional
+        If set, the specified PV should allow for asynchronous put completion
+        to indicate motion has finished.  If ``actuate`` is specified, it will be
+        used for put completion.  Otherwise, the ``setpoint`` will be used.  See
+        the `-c` option from ``caput`` for more information.
+    """
+    def __init__(self, *args, **kwargs):
+        if self.__class__ is PVPositionerNoInterrupt:
+            raise TypeError(
+                "PVPositionerNoInterrupt must be subclassed with the correct "
+                "signals set in the class definition."
+            )
+        super().__init__(*args, **kwargs)
+
+    def move(
+        self,
+        position: float,
+        wait: bool = True,
+        timeout: float | None = None,
+        moved_cb: Callable[[PVPositionerNoInterrupt], None] | None = None,
+    ):
+        """
+        Move to a specified position, optionally waiting for motion to
+        complete. Unlike the standard move, this will fail with a clear
+        error message when a move is already in progress.
+
+        Parameters
+        ----------
+        position : float
+            Position to move to
+        moved_cb : callable
+            Call this callback when movement has finished. This callback must
+            accept one keyword argument: 'obj' which will be set to this
+            positioner instance.
+        timeout : float, optional
+            Maximum time to wait for the motion. If None, the default timeout
+            for this positioner is used.
+
+        Returns
+        -------
+        status : MoveStatus
+
+        Raises
+        ------
+        TimeoutError
+            When motion takes longer than ``timeout``
+        ValueError
+            On invalid positions
+        RuntimeError
+            If motion fails other than timing out, including when a move is
+            attempted while another move is already in progress.
+        """
+        if self.moving:
+            try:
+                progress = f"Position = {self.position}, goal = {self.setpoint.get()}."
+            except Exception:
+                progress = ""
+            raise RuntimeError(
+                f"The {self.name} device cannot start a new move because the "
+                "previous move has not completed. This is not an "
+                "interruptable positioner. Try waiting after the previous "
+                f"move or for the move's status to complete. {progress}"
+            )
+        else:
+            return super().move(position, wait=wait, timeout=timeout, moved_cb=moved_cb)

pcdsdevices/tests/test_attenuator.py

@@ -82,6 +82,16 @@ def test_attenuator_motion(fake_att):
     assert att.setpoint.get() == 0
 
 
+@pytest.mark.timeout(5)
+def test_attenuator_no_interrupt(fake_att):
+    logger.debug('test_attenuator_no_interrupt')
+    att = fake_att
+    # Set as already moving
+    att.done.sim_put(1)
+    with pytest.raises(RuntimeError):
+        att.move(0.5)
+
+
 @pytest.mark.timeout(5)
 def test_attenuator_subscriptions(fake_att):
     logger.debug('test_attenuator_subscriptions')

pcdsdevices/tests/test_pv_positioner.py

@@ -0,0 +1,34 @@
+import pytest
+from ophyd.device import Component as Cpt
+from ophyd.signal import Signal
+
+from pcdsdevices.pv_positioner import PVPositionerNoInterrupt
+
+
+class PVPositionerNoInterruptLocal(PVPositionerNoInterrupt):
+    setpoint = Cpt(Signal)
+    done = Cpt(Signal)
+
+
+@pytest.fixture(scope="function")
+def pvpos_no(request):
+    return PVPositionerNoInterruptLocal(name=request.node.name)
+
+
+def test_pvpos_no_motion(pvpos_no):
+    pvpos_no.done.put(1)
+    status = pvpos_no.move(100, wait=False)
+    # This is kind of silly but let's sim the full move
+    pvpos_no.done.put(0)
+    pvpos_no.done.put(1)
+    assert pvpos_no.setpoint.get() == 100
+    status.wait(timeout=1.0)
+    assert status.done
+    assert status.success
+
+
+def test_pvpos_no_interrupt(pvpos_no):
+    # Already moving, can't start a new one
+    pvpos_no.done.put(0)
+    with pytest.raises(RuntimeError):
+        pvpos_no.move(100, wait=False)