Xtrigger function arg validation.

cylc/flow/config.py

@@ -57,6 +57,7 @@
 from cylc.flow.id import Tokens
 from cylc.flow.cycling.integer import IntegerInterval
 from cylc.flow.cycling.iso8601 import ingest_time, ISO8601Interval
+
 from cylc.flow.exceptions import (
     CylcError,
     InputError,
@@ -82,6 +83,7 @@
 from cylc.flow.print_tree import print_tree
 from cylc.flow.simulation import configure_sim_modes
 from cylc.flow.subprocctx import SubFuncContext
+from cylc.flow.subprocpool import get_func
 from cylc.flow.task_events_mgr import (
     EventData,
     get_event_handler_data
@@ -1711,10 +1713,8 @@ def generate_triggers(self, lexpression, left_nodes, right, seq,
                 if label != 'wall_clock':
                     raise WorkflowConfigError(f"xtrigger not defined: {label}")
                 else:
-                    # Allow "@wall_clock" in the graph as an undeclared
-                    # zero-offset clock xtrigger.
-                    xtrig = SubFuncContext(
-                        'wall_clock', 'wall_clock', [], {})
+                    # Allow "@wall_clock" in graph as implicit zero-offset.
+                    xtrig = SubFuncContext('wall_clock', 'wall_clock', [], {})
 
             if xtrig.func_name == 'wall_clock':
                 if self.cycling_type == INTEGER_CYCLING_TYPE:
@@ -1729,10 +1729,20 @@ def generate_triggers(self, lexpression, left_nodes, right, seq,
                         with suppress(IndexError):
                             xtrig.func_kwargs["offset"] = xtrig.func_args[0]
 
+            # Call the xtrigger's validate_config function if it has one.
+            with suppress(AttributeError, ImportError):
+                get_func(xtrig.func_name, "validate_config", self.fdir)(
+                    xtrig.func_args,
+                    xtrig.func_kwargs,
+                    xtrig.get_signature()
+                )
+
             if self.xtrigger_mgr is None:
+                # Validation only.
                 XtriggerManager.validate_xtrigger(label, xtrig, self.fdir)
             else:
                 self.xtrigger_mgr.add_trig(label, xtrig, self.fdir)
+
             self.taskdefs[right].add_xtrig_label(label, seq)
 
     def get_actual_first_point(self, start_point):

cylc/flow/subprocpool.py

@@ -66,8 +66,10 @@ def _killpg(proc, signal):
     return True
 
 
-def get_func(func_name, src_dir):
-    """Find and return an xtrigger function from a module of the same name.
+def get_func(mod_name, func_name, src_dir):
+    """Find and return a named function from a named module.
+
+    Can be in <src_dir>/lib/python, cylc.flow.xtriggers, or in Python path.
 
     These locations are checked in this order:
     - <src_dir>/lib/python/
@@ -78,13 +80,17 @@ def get_func(func_name, src_dir):
     Workflow source directory passed in as this is executed in an independent
     process in the command pool and therefore doesn't know about the workflow.
 
+    Raises:
+        ImportError, if the module is not found
+        AttributeError, if the function is not found in the module
+
     """
-    if func_name in _XTRIG_FUNCS:
-        return _XTRIG_FUNCS[func_name]
+    if (mod_name, func_name) in _XTRIG_FUNCS:
+        # Found and cached already.
+        return _XTRIG_FUNCS[(mod_name, func_name)]
 
     # First look in <src-dir>/lib/python.
     sys.path.insert(0, os.path.join(src_dir, 'lib', 'python'))
-    mod_name = func_name
     try:
         mod_by_name = __import__(mod_name, fromlist=[mod_name])
     except ImportError:
@@ -101,18 +107,20 @@ def get_func(func_name, src_dir):
         raise
 
     try:
-        _XTRIG_FUNCS[func_name] = getattr(mod_by_name, func_name)
+        _XTRIG_FUNCS[(mod_name, func_name)] = getattr(mod_by_name, func_name)
     except AttributeError:
         # Module func_name has no function func_name, nor an entry_point entry.
         raise
-    return _XTRIG_FUNCS[func_name]
+    return _XTRIG_FUNCS[(mod_name, func_name)]
 
 
 def run_function(func_name, json_args, json_kwargs, src_dir):
     """Run a Python function in the process pool.
 
     func_name(*func_args, **func_kwargs)
 
+    The function is presumed to be in a module of the same name.
+
     Redirect any function stdout to stderr (and workflow log in debug mode).
     Return value printed to stdout as a JSON string - allows use of the
     existing process pool machinery as-is. src_dir is for local modules.
@@ -121,7 +129,7 @@ def run_function(func_name, json_args, json_kwargs, src_dir):
     func_args = json.loads(json_args)
     func_kwargs = json.loads(json_kwargs)
     # Find and import then function.
-    func = get_func(func_name, src_dir)
+    func = get_func(func_name, func_name, src_dir)
     # Redirect stdout to stderr.
     orig_stdout = sys.stdout
     sys.stdout = sys.stderr

cylc/flow/xtrigger_mgr.py

@@ -262,8 +262,9 @@ def validate_xtrigger(
 
         """
         fname: str = fctx.func_name
+
         try:
-            func = get_func(fname, fdir)
+            func = get_func(fname, fname, fdir)
         except ImportError:
             raise XtriggerConfigError(
                 label,

cylc/flow/xtriggers/wall_clock.py

@@ -17,6 +17,8 @@
 """xtrigger function to trigger off of a wall clock time."""
 
 from time import time
+from cylc.flow.cycling.iso8601 import interval_parse
+from cylc.flow.exceptions import WorkflowConfigError
 
 
 def wall_clock(trigger_time=None):
@@ -27,3 +29,32 @@ def wall_clock(trigger_time=None):
             Trigger time as seconds since Unix epoch.
     """
     return time() > trigger_time
+
+
+def validate_config(f_args, f_kwargs, f_signature):
+    """Validate and manipulate args parsed from the workflow config.
+
+    wall_clock()  # zero offset
+    wall_clock(PT1H)
+    wall_clock(offset=PT1H)
+
+    The offset must be a valid ISO 8601 interval.
+
+    If f_args used, convert to f_kwargs for clarity.
+
+    """
+    n_args = len(f_args)
+    n_kwargs = len(f_kwargs)
+
+    if n_args + n_kwargs > 1:
+        raise WorkflowConfigError(f"xtrigger: too many args: {f_signature}")
+
+    if n_args:
+        f_kwargs["offset"] = f_args[0]
+    elif not n_kwargs:
+        f_kwargs["offset"] = "P0Y"
+
+    try:
+        interval_parse(f_kwargs["offset"])
+    except ValueError:
+        raise WorkflowConfigError(f"xtrigger: invalid offset: {f_signature}")

tests/unit/test_subprocpool.py

@@ -155,7 +155,8 @@ def test_xfunction(self):
             with the_answer_file.open(mode="w") as f:
                 f.write("""the_answer = lambda: 42""")
                 f.flush()
-            fn = get_func("the_answer", temp_dir)
+                f_name = "the_answer"
+            fn = get_func(f_name, f_name, temp_dir)
             result = fn()
             self.assertEqual(42, result)
 
@@ -166,19 +167,18 @@ def test_xfunction_cache(self):
             python_dir.mkdir(parents=True)
             amandita_file = python_dir / "amandita.py"
             with amandita_file.open(mode="w") as f:
-                f.write("""amandita = lambda: 'chocolate'""")
+                f.write("""choco = lambda: 'chocolate'""")
                 f.flush()
-            fn = get_func("amandita", temp_dir)
+            m_name = "amandita"  # module
+            f_name =  "choco"  # function
+            fn = get_func(m_name, f_name, temp_dir)
             result = fn()
             self.assertEqual('chocolate', result)
 
             # is in the cache
-            self.assertTrue('amandita' in _XTRIG_FUNCS)
+            self.assertTrue((m_name, f_name) in _XTRIG_FUNCS)
             # returned from cache
-            self.assertEqual(fn, get_func("amandita", temp_dir))
-            del _XTRIG_FUNCS['amandita']
-            # is not in the cache
-            self.assertFalse('amandita' in _XTRIG_FUNCS)
+            self.assertEqual(fn, get_func(m_name, f_name, temp_dir))
 
     def test_xfunction_import_error(self):
         """Test for error on importing a xtrigger function.
@@ -189,7 +189,7 @@ def test_xfunction_import_error(self):
         """
         with TemporaryDirectory() as temp_dir:
             with self.assertRaises(ModuleNotFoundError):
-                get_func("invalid-module-name", temp_dir)
+                get_func("invalid-module-name", "func-name", temp_dir)
 
     def test_xfunction_attribute_error(self):
         """Test for error on looking for an attribute in a xtrigger script."""
@@ -200,8 +200,9 @@ def test_xfunction_attribute_error(self):
             with the_answer_file.open(mode="w") as f:
                 f.write("""the_droid = lambda: 'excalibur'""")
                 f.flush()
+            f_name = "the_sword"
             with self.assertRaises(AttributeError):
-                get_func("the_sword", temp_dir)
+                get_func(f_name, f_name, temp_dir)
 
 
 @pytest.fixture