diff options
author | Alberto Lerner <alerner@10gen.com> | 2013-08-19 19:41:24 -0400 |
---|---|---|
committer | Alberto Lerner <alerner@10gen.com> | 2013-08-20 07:09:44 -0400 |
commit | 9fb1245ae1133f76c52105f561dd4d02f531f2de (patch) | |
tree | 1d9c3863d4451f44c9986bc01b17797fcb29c085 /src/mongo/db/wire_version.h | |
parent | 0f99864fcf8f82ff2c7cb685281bc9e5d6bc6616 (diff) | |
download | mongo-9fb1245ae1133f76c52105f561dd4d02f531f2de.tar.gz |
SERVER-10529 Allow isMaster to report the wire version (range) it expects.
Diffstat (limited to 'src/mongo/db/wire_version.h')
-rw-r--r-- | src/mongo/db/wire_version.h | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/src/mongo/db/wire_version.h b/src/mongo/db/wire_version.h new file mode 100644 index 00000000000..9718e24110c --- /dev/null +++ b/src/mongo/db/wire_version.h @@ -0,0 +1,50 @@ +/** +* Copyright (C) 2013 10gen Inc. +* +* This program is free software: you can redistribute it and/or modify +* it under the terms of the GNU Affero General Public License, version 3, +* as published by the Free Software Foundation. +* +* 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 Affero General Public License for more details. +* +* You should have received a copy of the GNU Affero General Public License +* along with this program. If not, see <http://www.gnu.org/licenses/>. +*/ + +namespace mongo { + + /** + * The 'WireVersion' captures all "protocol events" the write protocol went through. A + * protocol event is a change in the syntax of messages on the wire or the semantics of + * existing messages. We may also add "logical" entries for releases, although that's not + * mandatory. + * + * We use the wire version to determine if two agents (a driver, a mongos, or a mongod) can + * interact. Each agent carries two versions, a 'max' and a 'min' one. If the two agents + * are on the same 'max' number, they stricly speak the same wire protocol and it is safe + * to allow them to communicate. If two agents' ranges do not intersect, they should not be + * allowed to communicate. + * + * If two agents have at least one version in common they can communicate, but one of the + * sides has to be ready to compensate for not being on its partner version. + */ + enum WireVersion { + // Everything before we started tracking. + RELEASE_2_4_AND_BEFORE = 0, + + // The aggregation command may now be requested to return cursors. + AGG_RETURNS_CURSORS = 1, + }; + + // Latest version that the server accepts. This should always be at the latest entry in + // WireVersion. + static const int maxWireVersion = AGG_RETURNS_CURSORS; + + // Minimum version that the server accepts. We should bump this whenever we don't want + // to allow communication with too old agents. + static const int minWireVersion = RELEASE_2_4_AND_BEFORE; + +} // namespace mongo |