5 files changed, 122 insertions, 40 deletions

diff --git a/Mailman/Defaults.py b/Mailman/Defaults.py
index 3c06b709a..7667bc753 100644
--- a/Mailman/Defaults.py
+++ b/Mailman/Defaults.py
@@ -1,5 +1,3 @@
-# -*- python -*-
-
 # Copyright (C) 1998-2007 by the Free Software Foundation, Inc.
 #
 # This program is free software; you can redistribute it and/or
@@ -19,11 +17,6 @@
 
 """Distributed default settings for significant Mailman config variables."""
 
-# NEVER make site configuration changes to this file.  ALWAYS make them in
-# mm_cfg.py instead, in the designated area.  See the comments in that file
-# for details.
-
-
 import os
 
 from munepy import Enum
@@ -110,11 +103,6 @@ DEFAULT_VAR_DIRECTORY = '/var/mailman'
 # Database options
 #####
 
-# Initialization function for creating the IListManager, IUserManager, and
-# IMessageManager objects, as a Python dotted name.  This function must take
-# zero arguments.
-MANAGERS_INIT_FUNCTION = 'Mailman.database.initialize'
-
 # Use this to set the SQLAlchemy database engine URL.  You generally have one
 # primary database connection for all of Mailman.  List data and most rosters
 # will store their data in this database, although external rosters may access
diff --git a/Mailman/database/__init__.py b/Mailman/database/__init__.py
index 6c6312d0a..d50c33973 100644
--- a/Mailman/database/__init__.py
+++ b/Mailman/database/__init__.py
@@ -20,30 +20,45 @@ from __future__ import with_statement
 import os
 
 from elixir import objectstore
+from zope.interface import implements
 
+from Mailman.interfaces import IDatabase
 from Mailman.database.listmanager import ListManager
 from Mailman.database.usermanager import UserManager
 
+__metaclass__ = type
 __all__ = [
-    'initialize',
-    'flush',
+    'StockDatabase',
+    'flush', # for test convenience
     ]
 
+flush = None
+
 
 
-def initialize():
-    from Mailman.LockFile import LockFile
-    from Mailman.configuration import config
-    from Mailman.database import model
-    # Serialize this so we don't get multiple processes trying to create the
-    # database at the same time.
-    lockfile = os.path.join(config.LOCK_DIR, '<dbcreatelock>')
-    with LockFile(lockfile):
-        model.initialize()
-    config.list_manager = ListManager()
-    config.user_manager = UserManager()
-    flush()
+class StockDatabase:
+    implements(IDatabase)
+
+    def __init__(self):
+        # Expose the flush() method for test case convenience using the stock
+        # database.
+        global flush
+        flush = self.flush
+        self.list_manager = None
+        self.user_manager = None
 
+    def initialize(self):
+        from Mailman.LockFile import LockFile
+        from Mailman.configuration import config
+        from Mailman.database import model
+        # Serialize this so we don't get multiple processes trying to create the
+        # database at the same time.
+        lockfile = os.path.join(config.LOCK_DIR, '<dbcreatelock>')
+        with LockFile(lockfile):
+            model.initialize()
+        self.list_manager = ListManager()
+        self.user_manager = UserManager()
+        self.flush()
 
-def flush():
-    objectstore.flush()
+    def flush(self):
+        objectstore.flush()
diff --git a/Mailman/initialize.py b/Mailman/initialize.py
index 9dee94cbe..03c861066 100644
--- a/Mailman/initialize.py
+++ b/Mailman/initialize.py
@@ -26,12 +26,16 @@ by the command line arguments.
 
 import os
 import sys
+import pkg_resources
+
+from zope.interface.verify import verifyObject
 
 import Mailman.configuration
-import Mailman.database
 import Mailman.ext
 import Mailman.loginit
 
+from Mailman.interfaces import IDatabase, IListManager, IUserManager
+
 DOT = '.'
 
 
@@ -55,17 +59,44 @@ def initialize_1(config, propagate_logs):
     Mailman.loginit.initialize(propagate_logs)
     # Set up site extensions directory
     Mailman.ext.__path__.append(Mailman.configuration.config.EXT_DIR)
-    # Initialize the IListManager, IMemberManager, and IMessageManager
-    modparts = Mailman.configuration.config.MANAGERS_INIT_FUNCTION.split(DOT)
-    funcname = modparts.pop()
-    modname  = DOT.join(modparts)
-    __import__(modname)
-    initfunc = getattr(sys.modules[modname], funcname)
-    initfunc()
 
 
 def initialize_2():
-    Mailman.database.initialize()
+    # Find all declared entry points in the mailman.database group.  There
+    # must be exactly one or two such entry points defined.  If there are two,
+    # then we remove the one called 'stock' since that's the one that we
+    # distribute and it's obviously being overridden.  If we're still left
+    # with more than one after we filter out the stock one, it is an error.
+    entrypoints = list(pkg_resources.iter_entry_points('mailman.database'))
+    if len(entrypoints) == 0:
+        raise RuntimeError('No database entry points found')
+    elif len(entrypoints) == 1:
+        # Okay, this is the one to use.
+        entrypoint = entrypoints[0]
+    elif len(database) == 2:
+        # Find the one /not/ named 'stock'.
+        entrypoints = [ep for ep in entrypoints if ep.name <> 'stock']
+        if len(entrypoints) == 0:
+            raise RuntimeError('No database entry points found')
+        elif len(entrypoints) == 2:
+            raise RuntimeError('Too many database entry points defined')
+        else:
+            assert len(entrypoints) == 1, 'Insanity'
+            entrypoint = entrypoint[0]
+    else:
+        raise RuntimeError('Too many database entry points defined')
+    # Instantiate the database entry point, ensure that it's of the right
+    # type, and initialize it.  Then stash the object on our configuration
+    # object.
+    ep_object = entrypoint.load()
+    db = ep_object()
+    verifyObject(IDatabase, db)
+    db.initialize()
+    Mailman.configuration.config.db = db
+    verifyObject(IListManager, db.list_manager)
+    Mailman.configuration.config.list_manager = db.list_manager
+    verifyObject(IUserManager, db.user_manager)
+    Mailman.configuration.config.user_manager = db.user_manager
 
 
 def initialize(config=None, propagate_logs=False):
diff --git a/Mailman/interfaces/database.py b/Mailman/interfaces/database.py
new file mode 100644
index 000000000..8c57ae6b3
--- /dev/null
+++ b/Mailman/interfaces/database.py
@@ -0,0 +1,48 @@
+# Copyright (C) 2007 by the Free Software Foundation, Inc.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
+# USA.
+
+"""Interfaces for database interaction.
+
+By providing an object with this interface and declaring it in a package
+setup.py file as an entry point in the 'mailman.database' group with the name
+'initializer', you can distribute entirely different database layers for
+Mailman's back end.
+"""
+
+from zope.interface import Interface, Attribute
+
+
+
+class IDatabase(Interface):
+    """Database layer interface."""
+
+    def initialize():
+        """Initialize the database layer, using whatever means necessary."""
+
+    def flush():
+        """Flush current database changes."""
+
+    # XXX Eventually we probably need to support a transaction manager
+    # interface, e.g. begin(), commit(), abort().  We will probably also need
+    # to support a shutdown() method for cleanly disconnecting from the
+    # database.sy
+
+    list_manager = Attribute(
+        """The IListManager instance provided by the database layer.""")
+
+    user_manager = Attribute(
+        """The IUserManager instance provided by the database layer.""")
diff --git a/setup.py b/setup.py
index 45167dadc..5db399924 100644
--- a/setup.py
+++ b/setup.py
@@ -82,9 +82,9 @@ Any other spelling is incorrect.""",
     include_package_data = True,
     entry_points    = {
         'console_scripts': list(scripts),
-        'setuptools.file_finders': [
-            'bzr = setuptoolsbzr:find_files_for_bzr',
-            ],
+        'setuptools.file_finders': 'bzr = setuptoolsbzr:find_files_for_bzr',
+        # Entry point for plugging in different database backends.
+        'mailman.database': 'stock = Mailman.database:StockDatabase',
         },
     # Third-party requirements.
     install_requires = [