Merged in cbillington/blacs/callback_priorities (pull request labscri…

…pt-suite#49)

Plugin callback priorities

experiment_queue.py

@@ -40,6 +40,8 @@
 from labscript_utils.connections import ConnectionTable
 
 from blacs.tab_base_classes import MODE_MANUAL, MODE_TRANSITION_TO_BUFFERED, MODE_TRANSITION_TO_MANUAL, MODE_BUFFERED  
+import blacs.plugins as plugins
+
 
 FILEPATH_COLUMN = 0
 
@@ -154,8 +156,6 @@ def __init__(self, BLACS, ui):
         self.manager.daemon=True
         self.manager.start()
 
-        self._callbacks = None
-
     def _create_headers(self):
         self._model.setHorizontalHeaderItem(FILEPATH_COLUMN, QStandardItem('Filepath'))
 
@@ -251,26 +251,6 @@ def manager_repeat_mode(self, value):
         elif value == self.REPEAT_LAST:
             button.setIcon(QIcon(self.ICON_REPEAT_LAST))
 
-    @inmain_decorator(True)
-    def get_callbacks(self, name, update_cache=False):
-        if update_cache or self._callbacks is None:
-            self._callbacks = {}
-            try:
-                for plugin in self.BLACS.plugins.values():
-                    callbacks = plugin.get_callbacks()
-                    if isinstance(callbacks, dict):
-                        for callback_name, callback in callbacks.items():
-                            if callback_name not in self._callbacks:
-                                self._callbacks[callback_name] = []
-                            self._callbacks[callback_name].append(callback)
-            except Exception as e:
-                self._logger.exception('A Error occurred during get_callbacks.')
-
-        if name in self._callbacks:
-            return self._callbacks[name]
-        else:
-            return []
-
     def on_add_shots_triggered(self):
         shot_files = QFileDialog.getOpenFileNames(self._ui, 'Select shot files',
                                                   self.last_opened_shots_folder,
@@ -904,7 +884,7 @@ def restart_function(device_name):
 
             # check for analysis Filters in Plugins
             send_to_analysis = True
-            for callback in self.get_callbacks('analysis_cancel_send'):
+            for callback in plugins.get_callbacks('analysis_cancel_send'):
                 try:
                     if callback(path):
                         send_to_analysis = False
@@ -919,20 +899,18 @@ def restart_function(device_name):
             ##########################################################################################################################################
             #                                                        Plugin callbacks                                                                #
             ########################################################################################################################################## 
-            for plugin in self.BLACS.plugins.values():
-                callbacks = plugin.get_callbacks()
-                if isinstance(callbacks, dict) and 'shot_complete' in callbacks:
-                    try:
-                        callbacks['shot_complete'](path)
-                    except Exception:
-                        logger.exception("Plugin callback raised an exception")
+            for callback in plugins.get_callbacks('shot_complete'):
+                try:
+                    callback(path)
+                except Exception:
+                    logger.exception("Plugin callback raised an exception")
 
             ##########################################################################################################################################
             #                                                        Repeat Experiment?                                                              #
             ##########################################################################################################################################
             # check for repeat Filters in Plugins
             repeat_shot = self.manager_repeat
-            for callback in self.get_callbacks('shot_ignore_repeat'):
+            for callback in plugins.get_callbacks('shot_ignore_repeat'):
                 try:
                     if callback(path):
                         repeat_shot = False

plugins/__init__.py

@@ -16,6 +16,8 @@
 import sys
 import logging
 import importlib
+from types import MethodType
+from collections import defaultdict
 from labscript_utils.labconfig import LabConfig
 from blacs import BLACS_DIR
 PLUGINS_DIR = os.path.join(BLACS_DIR, 'plugins')
@@ -24,6 +26,60 @@
 
 logger = logging.getLogger('BLACS.plugins')
 
+DEFAULT_PRIORITY = 10
+
+class Callback(object):
+    """Class wrapping a callable. At present only differs from a regular
+    function in that it has a "priority" attribute - lower numbers means
+    higher priority. If there are multiple callbacks triggered by the same
+    event, they will be returned in order of priority by get_callbacks"""
+    def __init__(self, func, priority=DEFAULT_PRIORITY):
+        self.priority = priority
+        self.func = func
+
+    def __get__(self, instance, class_):
+        """Make sure our callable binds like an instance method. Otherwise
+        __call__ doesn't get the instance argument."""
+        if instance is None:
+            return self
+        else:
+            return MethodType(self, instance)
+
+    def __call__(self, *args, **kwargs):
+        return self.func(*args, **kwargs)
+
+
+class callback(object):
+    """Decorator to turn a function into a Callback object. Presently
+    optional, and only required if the callback needs to have a non-default
+    priority set"""
+    # Instantiate the decorator:
+    def __init__(self, priority=DEFAULT_PRIORITY):
+        self.priority = priority
+    # Call the decorator
+    def __call__(self, func):
+        return Callback(func, self.priority)
+
+
+def get_callbacks(name):
+    """Return all the callbacks for a particular name, in order of priority"""
+    import __main__
+    BLACS = __main__.app
+    callbacks = []
+    for plugin in BLACS.plugins.values():
+        try:
+            plugin_callbacks = plugin.get_callbacks()
+            if plugin_callbacks is not None:
+                if name in plugin_callbacks:
+                    callbacks.append(plugin_callbacks[name])
+        except Exception as e:
+            logger.exception('Error getting callbacks from %s.' % str(plugin))
+
+    # Sort all callbacks by priority:
+    callbacks.sort(key=lambda callback: getattr(callback, 'priority', DEFAULT_PRIORITY))
+    return callbacks
+
+
 exp_config = LabConfig()
 if not exp_config.has_section('BLACS/plugins'):
     exp_config.add_section('BLACS/plugins')