[core] Plugins: Introduction of NodePluginManager

meshroom/_plugins/__init__.py

@@ -0,0 +1,8 @@
+""" Plugins.
+"""
+# Plugins
+from .node import NodePluginManager
+from .base import Status, Pluginator
+
+
+__all__ = ["NodePluginManager", "Status", "Pluginator"]

meshroom/_plugins/base.py

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+""" Base functionality for Plugins.
+"""
+# Types
+from typing import List
+
+# STD
+from contextlib import contextmanager
+import enum
+import importlib
+import inspect
+import logging
+import pkgutil
+
+
+class Status(enum.IntEnum):
+    """ Enum describing the state of the plugin.
+    """
+
+    # UNLOADED or NOT Available - Describing that the plugin is not available in the current set of plugins
+    UNLOADED = -1
+
+    # ERRORED describes that the plugin exists but could not be loaded due to errors with the structure
+    ERRORED = 0
+
+    # LOADED describes that the plugin is currently loaded and is fully functional
+    LOADED = 1
+
+
+class Pluginator:
+    """ The common plugin utilities.
+    """
+
+    @staticmethod
+    @contextmanager
+    def add_to_path(_p):
+        """ A Context Manager to add the provided path to Python's sys.path temporarily.
+        """
+        import sys                  # pylint: disable=import-outside-toplevel
+        old_path = sys.path
+        sys.path = sys.path[:]
+        sys.path.insert(0, _p)
+        try:
+            yield
+        finally:
+            sys.path = old_path
+
+    @staticmethod
+    def get(folder, packageName, classType) -> List:
+        """ Returns Array of Plugin, each holding the plugin and the module it belongs to.
+
+        Args:
+            folder (str): Path to the Directory.
+            packageName (str): Name of the package to import.
+            classType (desc.Node | BaseSubmitter): The base type of plugin which is being imported.
+        """
+        pluginTypes = []
+        errors = []
+
+        # temporarily add folder to python path
+        with Pluginator.add_to_path(folder):
+            # import node package
+            package = importlib.import_module(packageName)
+            packageName = package.packageName if hasattr(package, 'packageName') else package.__name__
+            packageVersion = getattr(package, "__version__", None)
+
+            for importer, pluginName, ispkg in pkgutil.iter_modules(package.__path__):
+                pluginModuleName = '.' + pluginName
+
+                try:
+                    pluginMod = importlib.import_module(pluginModuleName, package=package.__name__)
+                    plugins = [plugin for name, plugin in inspect.getmembers(pluginMod, inspect.isclass)
+                            if plugin.__module__ == '{}.{}'.format(package.__name__, pluginName)
+                            and issubclass(plugin, classType)]
+                    if not plugins:
+                        logging.warning("No class defined in plugin: {}".format(pluginModuleName))
+
+                    # Update the package name and version on the plugin
+                    for p in plugins:
+                        p.packageName = packageName
+                        p.packageVersion = packageVersion
+
+                    # Extend all of the plugins
+                    pluginTypes.extend(plugins)
+                except Exception as exc:
+                    errors.append('  * {}: {}'.format(pluginName, str(exc)))
+
+        if errors:
+            logging.warning('== The following "{package}" plugins could not be loaded ==\n'
+                            '{errorMsg}\n'
+                            .format(package=packageName, errorMsg='\n'.join(errors)))
+
+        return pluginTypes