4141from cylc .flow .task_proxy import TaskProxy
4242from cylc .flow .wallclock import get_current_time_string
4343
44- _XTRIG_FUNCS : dict = {}
44+ _XTRIG_MOD_CACHE : dict = {}
45+ _XTRIG_FUNC_CACHE : dict = {}
4546
4647
4748def _killpg (proc , signal ):
@@ -66,68 +67,86 @@ def _killpg(proc, signal):
6667 return True
6768
6869
69- def get_func ( func_name , src_dir ):
70- """Find and return an xtrigger function from a module of the same name .
70+ def get_xtrig_mod ( mod_name , src_dir ):
71+ """Find, cache, and return a named xtrigger module .
7172
72- These locations are checked in this order:
73- - <src_dir>/lib/python/
74- - `$CYLC_PYTHONPATH`
75- - defined via a `cylc.xtriggers` entry point for an
76- installed Python package.
73+ Locations checked in this order:
74+ - <src_dir>/lib/python (prepend to sys.path)
75+ - $CYLC_PYTHONPATH (already in sys.path)
76+ - `cylc.xtriggers` entry point
7777
78- Workflow source directory passed in as this is executed in an independent
79- process in the command pool and therefore doesn't know about the workflow.
78+ (Check entry point last so users can override with local implementations).
79+
80+ Workflow source dir passed in - this executes in an independent subprocess.
81+
82+ Raises:
83+ ImportError, if the module is not found
8084
8185 """
82- if func_name in _XTRIG_FUNCS :
83- return _XTRIG_FUNCS [func_name ]
86+ if mod_name in _XTRIG_MOD_CACHE :
87+ # Found and cached already.
88+ return _XTRIG_MOD_CACHE [mod_name ]
8489
8590 # First look in <src-dir>/lib/python.
8691 sys .path .insert (0 , os .path .join (src_dir , 'lib' , 'python' ))
87- mod_name = func_name
8892 try :
89- mod_by_name = __import__ (mod_name , fromlist = [mod_name ])
93+ _XTRIG_MOD_CACHE [ mod_name ] = __import__ (mod_name , fromlist = [mod_name ])
9094 except ImportError :
91- # Look for xtriggers via entry_points for external sources.
92- # Do this after the lib/python and PYTHONPATH approaches to allow
93- # users to override entry_point definitions with local/custom
94- # implementations.
95+ # Then entry point.
9596 for entry_point in iter_entry_points ('cylc.xtriggers' ):
96- if func_name == entry_point .name :
97- _XTRIG_FUNCS [func_name ] = entry_point .load ()
98- return _XTRIG_FUNCS [func_name ]
99-
97+ if mod_name == entry_point .name :
98+ _XTRIG_MOD_CACHE [mod_name ] = entry_point .load ()
99+ return _XTRIG_MOD_CACHE [mod_name ]
100100 # Still unable to find anything so abort
101101 raise
102102
103- try :
104- _XTRIG_FUNCS [func_name ] = getattr (mod_by_name , func_name )
105- except AttributeError :
106- # Module func_name has no function func_name, nor an entry_point entry.
107- raise
108- return _XTRIG_FUNCS [func_name ]
103+ return _XTRIG_MOD_CACHE [mod_name ]
104+
105+
106+ def get_xtrig_func (mod_name , func_name , src_dir ):
107+ """Find, cache, and return a function from an xtrigger module.
108+
109+ Raises:
110+ ImportError, if the module is not found
111+ AttributeError, if the function is not found in the module
112+
113+ """
114+ if (mod_name , func_name ) in _XTRIG_FUNC_CACHE :
115+ return _XTRIG_FUNC_CACHE [(mod_name , func_name )]
116+
117+ mod = get_xtrig_mod (mod_name , src_dir )
118+
119+ _XTRIG_FUNC_CACHE [(mod_name , func_name )] = getattr (mod , func_name )
120+
121+ return _XTRIG_FUNC_CACHE [(mod_name , func_name )]
109122
110123
111124def run_function (func_name , json_args , json_kwargs , src_dir ):
112125 """Run a Python function in the process pool.
113126
114127 func_name(*func_args, **func_kwargs)
115128
129+ The function is presumed to be in a module of the same name.
130+
116131 Redirect any function stdout to stderr (and workflow log in debug mode).
117132 Return value printed to stdout as a JSON string - allows use of the
118133 existing process pool machinery as-is. src_dir is for local modules.
119134
120135 """
121136 func_args = json .loads (json_args )
122137 func_kwargs = json .loads (json_kwargs )
138+
123139 # Find and import then function.
124- func = get_func (func_name , src_dir )
140+ func = get_xtrig_func (func_name , func_name , src_dir )
141+
125142 # Redirect stdout to stderr.
126143 orig_stdout = sys .stdout
127144 sys .stdout = sys .stderr
128145 res = func (* func_args , ** func_kwargs )
146+
129147 # Restore stdout.
130148 sys .stdout = orig_stdout
149+
131150 # Write function return value as JSON to stdout.
132151 sys .stdout .write (json .dumps (res ))
133152
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