use maildir for MonthlyArchiver

src/extra_mailman_archivers/monthly_archiver.py

@@ -20,17 +20,20 @@
 # GNU Mailman.  If not, see <http://www.gnu.org/licenses/>.
 
 """
-A simple archiver which copies each message into a folder for the current
-month.
+A simple archiver which copies each message into a maildir folder for the
+current year and month.
 """
 
 from contextlib import suppress
+from datetime import timedelta
 from email.utils import parsedate
-import gzip
 import logging
+from mailbox import Mailbox
 import os
 import time
 
+from flufl.lock import Lock
+from mailbox import Maildir
 from mailman.config import config
 from mailman.interfaces.archiver import IArchiver
 from public import public
@@ -44,7 +47,7 @@ log = logging.getLogger('mailman.archiver')
 @implementer(IArchiver)
 class MonthlyArchiver:
     """
-    A simple archiver which copies each message into a folder for the
+    A simple archiver which copies each message into a maildir for the
     current month. It is adapted from the `Prototype` archiver.
     """
 
@@ -67,8 +70,8 @@ class MonthlyArchiver:
     def archive_message(mlist, message):
         """See `IArchiver`.
 
-        This archiver saves messages into a folder for the current year and
-        month, e.g. '2021-April'.
+        This archiver saves messages into a maildir for the current year and
+        month, e.g. '2021/April'.
 
         :type mlist: mailman.model.listmanager.ListManager
         :type message: mailman.email.message.Message
@@ -81,24 +84,35 @@ class MonthlyArchiver:
             log.warning('Could not extract date from message %s, using '
                         'local time instead' % message_id)
             date = time.localtime()
-        year_and_month = time.strftime('%Y-%B', date)
+        year = time.strftime('%Y')
+        month = time.strftime('%B')
 
         archive_dir = os.path.join(
             config.ARCHIVE_DIR,
             MonthlyArchiver.name,
             mlist.fqdn_listname,
-            year_and_month
+            year,
+            month
         )
         with suppress(FileExistsError):
             os.makedirs(archive_dir, 0o775)
+        for subdir in ['cur', 'new', 'tmp']:
+            with suppress(FileExistsError):
+                os.makedirs(os.path.join(archive_dir, subdir), 0o775)
+        maildir = Maildir(archive_dir, create=True)
+
+        # maildir.add() is not thread-safe
+        lock_file = os.path.join(
+            config.LOCK_DIR, '{0}-maildir.lock'.format(mlist.fqdn_listname))
+        lock = Lock(lock_file)
+        try:
+            lock.lock(timeout=timedelta(seconds=3))
+            filename = maildir.add(message)
+        finally:
+            lock.unlock(unconditionally=True)
+        # If we fail to acquire the lock, let the error propagate up
 
-        # Just use the current timestamp as the file name
-        filename = str(round(time.time(), 3)) + '.mail.gz'
-        dst = os.path.join(archive_dir, filename)
         log.info('MonthlyArchiver archived message %s to %s' %
-                 (message_id, dst))
-        # gzip the file to try to save some disk space
-        with gzip.open(dst, 'wb') as fo:
-            fo.write(message.as_bytes())
+                 (message_id, filename))
 
         return None