python: ovsdb-idl: Add custom transaction operations.

It can be useful to be able to send raw transaction operations
through the Idl's connection. For example, to clean up MAC_Binding
entries for floating IPs without having to monitor the MAC_Binding
table which can be quite large.

Signed-off-by: Terry Wilson <twilson@redhat.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

python/ovs/db/idl.py

@@ -1708,6 +1708,8 @@ class Transaction(object):
 
         self._inserted_rows = {}  # Map from UUID to _InsertedRow
 
+        self._operations = []
+
     def add_comment(self, comment):
         """Appends 'comment' to the comments that will be passed to the OVSDB
         server when this transaction is committed.  (The comment will be
@@ -1843,7 +1845,7 @@ class Transaction(object):
                                    "rows": [rows]})
 
         # Add updates.
-        any_updates = False
+        any_updates = bool(self._operations)
         for row in self._txn_rows.values():
             if row._changes is None:
                 if row._table.is_root:
@@ -1978,6 +1980,8 @@ class Transaction(object):
             operations.append({"op": "comment",
                                "comment": "\n".join(self._comments)})
 
+        operations += self._operations
+
         # Dry run?
         if self.dry_run:
             operations.append({"op": "abort"})
@@ -1996,6 +2000,21 @@ class Transaction(object):
         self.__disassemble()
         return self._status
 
+    def add_op(self, op):
+        """Add a raw OVSDB operation to the transaction
+
+        This can be useful for re-using the existing Idl connection to take
+        actions that are difficult or expensive to do with the Idl itself, e.g.
+        bulk deleting rows from the server without downloading them into a
+        local cache.
+
+        All ops are applied after any other operations in the transaction.
+
+        :param op: An "op" for an OVSDB "transact" request (rfc 7047 Sec 5.2)
+        :type op:  dict
+        """
+        self._operations.append(op)
+
     def commit_block(self):
         """Attempts to commit this transaction, blocking until the commit
         either succeeds or fails.  Returns the final commit status, which may