L2SS-1650: Allow Tango threads during read/write

attribute_wrapper/attribute_wrapper.py

@@ -4,8 +4,9 @@
 import logging
 from functools import reduce
 from operator import mul
+from contextlib import nullcontext
 
-from tango import AttrWriteType, AttReqType
+from tango import AttrWriteType, AttReqType, AutoTangoAllowThreads
 from tango.server import attribute
 
 from attribute_wrapper.attribute_io import AttributeIO
@@ -26,6 +27,7 @@ class AttributeWrapper(attribute):
         datatype=None,
         dims=(1,),
         access=AttrWriteType.READ,
+        allow_threads=True,
         **kwargs,
     ):
         """
@@ -41,6 +43,8 @@ class AttributeWrapper(attribute):
         datatype: any numpy datatype
         dims: dimensions of the attribute as a tuple, or (1,) for a scalar.
         init_value: value
+        allow_threads: if True, release Tango device lock during I/O, allowing other Tango
+                       threads to execute.
         """
 
         # ensure the type is a numpy array.
@@ -62,6 +66,8 @@ class AttributeWrapper(attribute):
 
         self.datatype = datatype
 
+        self.io_context = AutoTangoAllowThreads if allow_threads else nullcontext
+
         if dims == (1,):
             # scalar
             # Tango defines a scalar as having dimensions (1,0), see
@@ -109,6 +115,7 @@ class AttributeWrapper(attribute):
                 try:
                     io = self.get_attribute_io(device)
 
+                    with self.io_context(device):
                         return io.cached_write_function(value)
                 except Exception as e:
                     raise e.__class__(
@@ -129,6 +136,7 @@ class AttributeWrapper(attribute):
                 try:
                     io = self.get_attribute_io(device)
 
+                    with self.io_context(device):
                         return io.cached_read_function()
                 except Exception as e:
                     raise e.__class__(
@@ -154,6 +162,7 @@ class AttributeWrapper(attribute):
                 try:
                     io = self.get_attribute_io(device)
 
+                    with AutoTangoAllowThreads(device):
                         return io.read_function()
                 except Exception as e:
                     raise e.__class__(
@@ -182,14 +191,15 @@ class AttributeWrapper(attribute):
             **kwargs,
         )
 
-    def get_attribute_io(self, device):
-        """Returns the attribute I/O functions from device"""
+    def make_attribute_io(self, device: Device) -> AttributeIO:
+        """Creates and returns a new AttributeIO object for a given device"""
 
-        try:
-            return device._attribute_wrapper_io[self]
-        except KeyError:
-            device._attribute_wrapper_io[self] = AttributeIO(device, self)
-            return device._attribute_wrapper_io[self]
+        return AttributeIO(device, self)
+
+    def get_attribute_io(self, device: Device) -> AttributeIO:
+        """Returns the (cached) attribute I/O functions from device"""
+
+        return device._attribute_wrapper_io.setdefault(self, self.make_attribute_io(device))
 
     def set_comm_client(self, device, client):
         """Takes communication client with 'get_mapping' function