implement router plugins

shards/mishards/__init__.py

@@ -28,8 +28,9 @@ def create_app(testing_config=None):
                                                               settings.TracingConfig,
                                                               span_decorator=GrpcSpanDecorator())
 
-    from mishards.routings import RouterFactory
-    router = RouterFactory.new_router(config.ROUTER_CLASS_NAME, connect_mgr)
+    from mishards.router.factory import RouterFactory
+    router = RouterFactory(config.ROUTER_PLUGIN_PATH).create(config.ROUTER_CLASS_NAME,
+                                                             conn_mgr=connect_mgr)
 
     grpc_server.init_app(conn_mgr=connect_mgr,
                          tracer=tracer,

shards/mishards/router/__init__.py

@@ -0,0 +1,22 @@
+from mishards import exceptions
+
+
+class RouterMixin:
+    def __init__(self, conn_mgr):
+        self.conn_mgr = conn_mgr
+
+    def routing(self, table_name, metadata=None, **kwargs):
+        raise NotImplemented()
+
+    def connection(self, metadata=None):
+        conn = self.conn_mgr.conn('WOSERVER', metadata=metadata)
+        if conn:
+            conn.on_connect(metadata=metadata)
+        return conn.conn
+
+    def query_conn(self, name, metadata=None):
+        conn = self.conn_mgr.conn(name, metadata=metadata)
+        if not conn:
+            raise exceptions.ConnectionNotFoundError(name, metadata=metadata)
+        conn.on_connect(metadata=metadata)
+        return conn.conn

shards/mishards/router/factory.py

@@ -0,0 +1,49 @@
+import os
+import logging
+from functools import partial
+# from pluginbase import PluginBase
+# import importlib
+from utils.pluginextension import MiPluginBase
+
+logger = logging.getLogger(__name__)
+
+here = os.path.abspath(os.path.dirname(__file__))
+get_path = partial(os.path.join, here)
+
+PLUGIN_PACKAGE_NAME = 'router.plugins'
+plugin_base = MiPluginBase(package=PLUGIN_PACKAGE_NAME,
+                           searchpath=[get_path('./plugins')])
+
+
+class RouterFactory(object):
+    PLUGIN_TYPE = 'Router'
+
+    def __init__(self, searchpath=None):
+        self.plugin_package_name = PLUGIN_PACKAGE_NAME
+        self.class_map = {}
+        searchpath = searchpath if searchpath else []
+        searchpath = [searchpath] if isinstance(searchpath, str) else searchpath
+        self.source = plugin_base.make_plugin_source(searchpath=searchpath,
+                                                     identifier=self.__class__.__name__)
+
+        for plugin_name in self.source.list_plugins():
+            plugin = self.source.load_plugin(plugin_name)
+            plugin.setup(self)
+
+    def on_plugin_setup(self, plugin_class):
+        name = getattr(plugin_class, 'name', plugin_class.__name__)
+        self.class_map[name.lower()] = plugin_class
+
+    def plugin(self, name):
+        return self.class_map.get(name, None)
+
+    def create(self, class_name, class_config=None, **kwargs):
+        if not class_name:
+            raise RuntimeError('Please specify router class_name first!')
+
+        this_class = self.plugin(class_name.lower())
+        if not this_class:
+            raise RuntimeError('{} Plugin \'{}\' Not Installed!'.format(self.PLUGIN_TYPE, class_name))
+
+        router = this_class.create(class_config, **kwargs)
+        return router

shards/mishards/router/plugins/file_based_hash_ring_router.py

@@ -1,64 +1,19 @@
 import logging
 from sqlalchemy import exc as sqlalchemy_exc
 from sqlalchemy import and_
-
+from mishards.models import Tables
+from mishards.router import RouterMixin
 from mishards import exceptions, db
 from mishards.hash_ring import HashRing
-from mishards.models import Tables
 
 logger = logging.getLogger(__name__)
 
 
-class RouteManager:
-    ROUTER_CLASSES = {}
-
-    @classmethod
-    def register_router_class(cls, target):
-        name = target.__dict__.get('NAME', None)
-        name = name if name else target.__class__.__name__
-        cls.ROUTER_CLASSES[name] = target
-        return target
-
-    @classmethod
-    def get_router_class(cls, name):
-        return cls.ROUTER_CLASSES.get(name, None)
-
-
-class RouterFactory:
-    @classmethod
-    def new_router(cls, name, conn_mgr, **kwargs):
-        router_class = RouteManager.get_router_class(name)
-        assert router_class
-        return router_class(conn_mgr, **kwargs)
-
-
-class RouterMixin:
-    def __init__(self, conn_mgr):
-        self.conn_mgr = conn_mgr
-
-    def routing(self, table_name, metadata=None, **kwargs):
-        raise NotImplemented()
-
-    def connection(self, metadata=None):
-        conn = self.conn_mgr.conn('WOSERVER', metadata=metadata)
-        if conn:
-            conn.on_connect(metadata=metadata)
-        return conn.conn
-
-    def query_conn(self, name, metadata=None):
-        conn = self.conn_mgr.conn(name, metadata=metadata)
-        if not conn:
-            raise exceptions.ConnectionNotFoundError(name, metadata=metadata)
-        conn.on_connect(metadata=metadata)
-        return conn.conn
-
-
-@RouteManager.register_router_class
-class FileBasedHashRingRouter(RouterMixin):
-    NAME = 'FileBasedHashRingRouter'
+class Factory(RouterMixin):
+    name = 'FileBasedHashRingRouter'
 
     def __init__(self, conn_mgr, **kwargs):
-        super(FileBasedHashRingRouter, self).__init__(conn_mgr)
+        super(Factory, self).__init__(conn_mgr)
 
     def routing(self, table_name, metadata=None, **kwargs):
         range_array = kwargs.pop('range_array', None)
@@ -94,3 +49,16 @@ class FileBasedHashRingRouter(RouterMixin):
             routing[target_host]['file_ids'].append(str(f.id))
 
         return routing
+
+    @classmethod
+    def create(cls, config, **kwargs):
+        conn_mgr = kwargs.pop('conn_mgr', None)
+        if not conn_mgr:
+            raise RuntimeError('Cannot find \'conn_mgr\' to initialize \'{}\''.format(self.name))
+        router = cls(conn_mgr, **kwargs)
+        return router
+
+
+def setup(app):
+    logger.info('Plugin \'{}\' Installed In Package: {}'.format(__file__, app.plugin_package_name))
+    app.on_plugin_setup(Factory)

shards/mishards/settings.py

@@ -76,6 +76,7 @@ class DefaultConfig:
     SQL_ECHO = env.bool('SQL_ECHO', False)
     TRACING_PLUGIN_PATH = env.str('TRACING_PLUGIN_PATH', '')
     TRACING_TYPE = env.str('TRACING_TYPE', '')
+    ROUTER_PLUGIN_PATH = env.str('ROUTER_PLUGIN_PATH', '')
     ROUTER_CLASS_NAME = env.str('ROUTER_CLASS_NAME', 'FileBasedHashRingRouter')
 
 

shards/utils/pluginextension.py

@@ -0,0 +1,15 @@
+import importlib
+from pluginbase import PluginBase, PluginSource
+
+
+class MiPluginSource(PluginSource):
+    def load_plugin(self, name):
+        if '.' in name:
+            raise ImportError('Plugin names cannot contain dots.')
+        with self:
+            return importlib.import_module(self.base.package + '.' + name)
+
+
+class MiPluginBase(PluginBase):
+    def make_plugin_source(self, *args, **kwargs):
+        return MiPluginSource(self, *args, **kwargs)