Implement locking for dbapi backends

gramps/gen/db/generic.py

@@ -45,7 +45,8 @@ from . import (DbReadBase, DbWriteBase, DbUndo, DBLOGNAME, DBUNDOFN,
                KEY_TO_CLASS_MAP, REFERENCE_KEY, PERSON_KEY, FAMILY_KEY,
                CITATION_KEY, SOURCE_KEY, EVENT_KEY, MEDIA_KEY, PLACE_KEY,
                REPOSITORY_KEY, NOTE_KEY, TAG_KEY, TXNADD, TXNUPD, TXNDEL,
-               KEY_TO_NAME_MAP)
+               KEY_TO_NAME_MAP, DBMODE_R, DBMODE_W)
+from .utils import write_lock_file, clear_lock_file
 from ..errors import HandleError
 from ..utils.callback import Callback
 from ..updatecallback import UpdateCallback
@@ -581,7 +582,25 @@ class DbGeneric(DbWriteBase, DbReadBase, UpdateCallback, Callback):
         """
         raise NotImplementedError
 
-    def load(self, directory, callback=None, mode=None,
+    def __check_readonly(self, name):
+        """
+        Return True if we don't have read/write access to the database,
+        otherwise return False (that is, we DO have read/write access)
+        """
+
+        # See if we write to the target directory at all?
+        if not os.access(name, os.W_OK):
+            return True
+
+        # See if we lack write access to the database file
+        path = os.path.join(name, 'sqlite.db')
+        if os.path.isfile(path) and not os.access(path, os.W_OK):
+            return True
+
+        # All tests passed.  Inform caller that we are NOT read only
+        return False
+
+    def load(self, directory, callback=None, mode=DBMODE_W,
              force_schema_upgrade=False,
              force_bsddb_upgrade=False,
              force_bsddb_downgrade=False,
@@ -592,6 +611,14 @@ class DbGeneric(DbWriteBase, DbReadBase, UpdateCallback, Callback):
         """
         If update is False: then don't update any files
         """
+        if self.__check_readonly(directory):
+            mode = DBMODE_R
+
+        self.readonly = mode == DBMODE_R
+
+        if not self.readonly:
+            write_lock_file(directory)
+
         # run backend-specific code:
         self._initialize(directory, username, password)
 
@@ -735,6 +762,12 @@ class DbGeneric(DbWriteBase, DbReadBase, UpdateCallback, Callback):
                 self._set_metadata('nmap_index', self.nmap_index)
 
             self._close()
+
+        try:
+            clear_lock_file(self.get_save_path())
+        except IOError:
+            pass
+
         self.db_is_open = False
         self._directory = None
 

gramps/gen/db/utils.py

@@ -39,8 +39,9 @@ import logging
 #------------------------------------------------------------------------
 from ..plug import BasePluginManager
 from ..const import PLUGINS_DIR, USER_PLUGINS
+from ..constfunc import win, get_env_var
 from ..config import config
-from .dbconst import DBLOGNAME
+from .dbconst import DBLOGNAME, DBLOCKFN
 
 #-------------------------------------------------------------------------
 #
@@ -179,3 +180,35 @@ def __index_surname(surn_list):
     else:
         surn = ""
     return surn
+
+def clear_lock_file(name):
+    try:
+        os.unlink(os.path.join(name, DBLOCKFN))
+    except OSError:
+        return
+
+def write_lock_file(name):
+    if not os.path.isdir(name):
+        os.mkdir(name)
+    with open(os.path.join(name, DBLOCKFN), "w", encoding='utf8') as f:
+        if win():
+            user = get_env_var('USERNAME')
+            host = get_env_var('USERDOMAIN')
+            if host is None:
+                host = ""
+        else:
+            host = os.uname()[1]
+            # An ugly workaround for os.getlogin() issue with Konsole
+            try:
+                user = os.getlogin()
+            except:
+                # not win, so don't need get_env_var.
+                # under cron getlogin() throws and there is no USER.
+                user = os.environ.get('USER', 'noUSER')
+        if host:
+            text = "%s@%s" % (user, host)
+        else:
+            text = user
+        # Save only the username and host, so the massage can be
+        # printed with correct locale in DbManager.py when a lock is found
+        f.write(text)

gramps/plugins/db/bsddb/write.py

@@ -72,11 +72,11 @@ from . import (DbBsddbRead, DbWriteBase, BSDDBTxn,
 
 from gramps.gen.db import exceptions
 from gramps.gen.db.dbconst import *
+from gramps.gen.db.utils import write_lock_file, clear_lock_file
 from gramps.gen.utils.callback import Callback
 from gramps.gen.utils.id import create_id
 from gramps.gen.updatecallback import UpdateCallback
 from gramps.gen.errors import DbError, HandleError
-from gramps.gen.constfunc import win, get_env_var
 from gramps.gen.const import HOME_DIR, GRAMPS_LOCALE as glocale
 _ = glocale.translation.gettext
 
@@ -2308,38 +2308,6 @@ class DbBsddb(DbBsddbRead, DbWriteBase, UpdateCallback):
 def _mkname(path, name):
     return os.path.join(path, name + DBEXT)
 
-def clear_lock_file(name):
-    try:
-        os.unlink(os.path.join(name, DBLOCKFN))
-    except OSError:
-        return
-
-def write_lock_file(name):
-    if not os.path.isdir(name):
-        os.mkdir(name)
-    with open(os.path.join(name, DBLOCKFN), "w", encoding='utf8') as f:
-        if win():
-            user = get_env_var('USERNAME')
-            host = get_env_var('USERDOMAIN')
-            if host is None:
-                host = ""
-        else:
-            host = os.uname()[1]
-            # An ugly workaround for os.getlogin() issue with Konsole
-            try:
-                user = os.getlogin()
-            except:
-                # not win, so don't need get_env_var.
-                # under cron getlogin() throws and there is no USER.
-                user = os.environ.get('USER', 'noUSER')
-        if host:
-            text = "%s@%s" % (user, host)
-        else:
-            text = user
-        # Save only the username and host, so the massage can be
-        # printed with correct locale in DbManager.py when a lock is found
-        f.write(text)
-
 def upgrade_researcher(owner_data):
     """
     Upgrade researcher data to include a locality field in the address.