Make virtual host record versioned

Add metadata fields to virtual host

Address feedback in #2080

 * Switch to functions for vhost record accessors
 * Restore rabbit_vhost:list/0 behavior, introduce rabbit_vhost:all/0
   to compensate
 * Store tags as an array of atoms, the same way we do for user tags
 * Type spec fixes
 * Other minor interface improvements suggested by @dumbbell

Co-Authored-By: Michael Klishin <mklishin@pivotal.io>

[#166298298]

1 files changed, 181 insertions, 0 deletions

diff --git a/src/vhost.erl b/src/vhost.erl
new file mode 100644
index 0000000000..7bcb6d18e5
--- /dev/null
+++ b/src/vhost.erl
@@ -0,0 +1,181 @@
+%% The contents of this file are subject to the Mozilla Public License
+%% Version 1.1 (the "License"); you may not use this file except in
+%% compliance with the License. You may obtain a copy of the License
+%% at https://www.mozilla.org/MPL/
+%%
+%% Software distributed under the License is distributed on an "AS IS"
+%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+%% the License for the specific language governing rights and
+%% limitations under the License.
+%%
+%% The Original Code is RabbitMQ.
+%%
+%% The Initial Developer of the Original Code is GoPivotal, Inc.
+%% Copyright (c) 2018-2019 Pivotal Software, Inc.  All rights reserved.
+%%
+
+-module(vhost).
+
+-include_lib("rabbit_common/include/rabbit.hrl").
+-include("vhost.hrl").
+
+-export([
+  new/2,
+  new/3,
+  fields/0,
+  fields/1,
+  info_keys/0,
+  record_version_to_use/0,
+  upgrade/1,
+  upgrade_to/2,
+  pattern_match_all/0,
+  get_name/1,
+  get_limits/1,
+  get_metadata/1,
+  get_description/1,
+  get_tags/1,
+  set_limits/2
+]).
+
+-define(record_version, vhost_v2).
+
+-type(name() :: binary()).
+
+-type(metadata_key() :: atom()).
+
+-type(metadata() :: #{description => binary(),
+                      tags => [atom()],
+                      metadata_key() => any()} | undefined).
+
+-type vhost() :: vhost_v1:vhost_v1() | vhost_v2().
+
+-record(vhost, {
+    %% name as a binary
+    virtual_host :: name() | '_',
+    %% proplist of limits configured, if any
+    limits :: list() | '_',
+    metadata :: metadata() | '_'
+}).
+
+-type vhost_v2() :: #vhost{
+                          virtual_host :: name(),
+                          limits :: list(),
+                          metadata :: metadata()
+                         }.
+
+-type vhost_pattern() :: vhost_v1:vhost_v1_pattern() |
+                         vhost_v2_pattern().
+-type vhost_v2_pattern() :: #vhost{
+                                  virtual_host :: name() | '_',
+                                  limits :: '_',
+                                  metadata :: '_'
+                                 }.
+
+-export_type([name/0,
+              metadata_key/0,
+              metadata/0,
+              vhost/0,
+              vhost_v2/0,
+              vhost_pattern/0,
+              vhost_v2_pattern/0]).
+
+-spec new(name(), list()) -> vhost().
+new(Name, Limits) ->
+    case record_version_to_use() of
+        ?record_version ->
+          #vhost{virtual_host = Name, limits = Limits};
+        _ ->
+          vhost_v1:new(Name, Limits)
+    end.
+
+-spec new(rabbit_vhost:name(), list(), map()) -> vhost().
+new(Name, Limits, Metadata) ->
+    case record_version_to_use() of
+        ?record_version ->
+          #vhost{virtual_host = Name, limits = Limits, metadata = Metadata};
+        _ ->
+          vhost_v1:new(Name, Limits)
+    end.
+
+-spec record_version_to_use() -> vhost_v1 | vhost_v2.
+
+record_version_to_use() ->
+    case rabbit_feature_flags:is_enabled(virtual_host_metadata) of
+        true  -> ?record_version;
+        false -> vhost_v1:record_version_to_use()
+    end.
+
+-spec upgrade(vhost()) -> vhost().
+
+upgrade(#vhost{} = VHost) -> VHost;
+upgrade(OldVHost)         -> upgrade_to(record_version_to_use(), OldVHost).
+
+-spec upgrade_to
+(vhost_v2, vhost()) -> vhost_v2();
+(vhost_v1, vhost_v1:vhost_v1()) -> vhost_v1:vhost_v1().
+
+upgrade_to(?record_version, #vhost{} = VHost) ->
+    VHost;
+upgrade_to(?record_version, OldVHost) ->
+    Fields = erlang:tuple_to_list(OldVHost) ++ [#{}],
+    #vhost{} = erlang:list_to_tuple(Fields);
+upgrade_to(Version, OldVHost) ->
+    vhost_v1:upgrade_to(Version, OldVHost).
+
+
+fields() ->
+    case record_version_to_use() of
+        ?record_version -> fields(?record_version);
+        _               -> vhost_v1:fields()
+    end.
+
+fields(?record_version) -> record_info(fields, vhost);
+fields(Version)         -> vhost_v1:fields(Version).
+
+info_keys() ->
+    case record_version_to_use() of
+        %% note: this reports description and tags separately even though
+        %% they are stored in the metadata map. MK.
+        ?record_version -> [name, description, tags, metadata, tracing, cluster_state];
+        _               -> vhost_v1:info_keys()
+    end.
+
+-spec pattern_match_all() -> vhost_pattern().
+
+pattern_match_all() ->
+    case record_version_to_use() of
+        ?record_version -> #vhost{_ = '_'};
+        _               -> vhost_v1:pattern_match_all()
+    end.
+
+-spec get_name(vhost()) -> name().
+get_name(#vhost{virtual_host = Value}) -> Value;
+get_name(VHost) -> vhost_v1:get_name(VHost).
+
+-spec get_limits(vhost()) -> list().
+get_limits(#vhost{limits = Value}) -> Value;
+get_limits(VHost) -> vhost_v1:get_limits(VHost).
+
+-spec get_metadata(vhost()) -> metadata().
+get_metadata(#vhost{metadata = Value}) -> Value;
+get_metadata(VHost) -> vhost_v1:get_limits(VHost).
+
+-spec get_description(vhost()) -> binary().
+get_description(#vhost{} = VHost) ->
+    maps:get(description, get_metadata(VHost), undefined);
+get_description(VHost) ->
+    vhost_v1:get_description(VHost).
+
+-spec get_tags(vhost()) -> [atom()].
+get_tags(#vhost{} = VHost) ->
+    maps:get(tags, get_metadata(VHost), undefined);
+get_tags(VHost) ->
+    vhost_v1:get_tags(VHost).
+
+set_limits(VHost, Value) ->
+    case record_version_to_use() of
+      ?record_version ->
+        VHost#vhost{limits = Value};
+      _ ->
+        vhost_v1:set_limits(VHost, Value)
+    end.