Keep track of connections, introduce per-vhost limits

docs/rabbitmqctl.1.xml

@@ -1214,6 +1214,55 @@
       </variablelist>
     </refsect2>
 
+    <refsect2>
+      <title>Virtual Host Limits</title>
+      <para>
+        It is possible to enforce certain limits on virtual hosts.
+      </para>
+      <variablelist>
+        <varlistentry>
+          <term><cmdsynopsis><command>set_vhost_limits</command> <arg choice="opt">-p <replaceable>vhostpath</replaceable></arg> <arg choice="req"><replaceable>definition</replaceable></arg></cmdsynopsis></term>
+          <listitem>
+            <para>
+              Sets virtual host limits
+            </para>
+            <variablelist>
+              <varlistentry>
+                <term>definition</term>
+                <listitem><para>
+                    The definition of the limits, as a
+                    JSON term. In most shells you are very likely to
+                    need to quote this.
+
+                    Recognised limits: max-connections (0 means "no limit").
+                </para></listitem>
+              </varlistentry>
+            </variablelist>
+            <para role="example-prefix">For example:</para>
+            <screen role="example">rabbitmqctl set_vhost_limits -p qa_env '{"max-connections": 1024}'</screen>
+            <para role="example">
+              This command limits the max number of concurrent connections in vhost <command>qa_env</command>
+              to 1024.
+            </para>
+          </listitem>
+        </varlistentry>
+
+<varlistentry>
+          <term><cmdsynopsis><command>clear_vhost_limits</command> <arg choice="opt">-p <replaceable>vhostpath</replaceable></arg></cmdsynopsis></term>
+          <listitem>
+            <para>
+              Clears virtual host limits
+            </para>
+            <para role="example-prefix">For example:</para>
+            <screen role="example">rabbitmqctl clear_vhost_limits -p qa_env</screen>
+            <para role="example">
+              This command clears vhost limits in vhost <command>qa_env</command>.
+            </para>
+          </listitem>
+        </varlistentry>
+      </variablelist>
+    </refsect2>
+
     <refsect2>
       <title>Server Status</title>
       <para>
@@ -2036,9 +2085,9 @@
               <varlistentry>
                 <term>fraction</term>
                 <listitem><para>
-                    Limit relative to the total amount available RAM 
-                    as a non-negative floating point number. 
-                    Values lower than 1.0 can be dangerous and 
+                    Limit relative to the total amount available RAM
+                    as a non-negative floating point number.
+                    Values lower than 1.0 can be dangerous and
                     should be used carefully.
                 </para></listitem>
               </varlistentry>

include/rabbit_cli.hrl

@@ -30,7 +30,6 @@
 -define(OFFLINE_OPT, "--offline").
 -define(ONLINE_OPT, "--online").
 
-
 -define(NODE_DEF(Node), {?NODE_OPT, {option, Node}}).
 -define(QUIET_DEF, {?QUIET_OPT, flag}).
 -define(VHOST_DEF, {?VHOST_OPT, {option, "/"}}).

src/rabbit.erl

@@ -178,6 +178,11 @@
                     {mfa,         {rabbit_direct, boot, []}},
                     {requires,    log_relay}]}).
 
+-rabbit_boot_step({connection_tracker,
+                   [{description, "helps track node-local connections"},
+                    {mfa,         {rabbit_connection_tracker, boot, []}},
+                    {requires,    log_relay}]}).
+
 -rabbit_boot_step({networking,
                    [{mfa,         {rabbit_networking, boot, []}},
                     {requires,    log_relay}]}).

src/rabbit_connection_tracker.erl

@@ -0,0 +1,99 @@
+%% 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 http://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) 2007-2016 Pivotal Software, Inc.  All rights reserved.
+%%
+
+-module(rabbit_connection_tracker).
+
+%% Abstracts away how tracked connection records are stored
+%% and queried.
+%%
+%% See also:
+%%
+%%  * rabbit_connection_tracking_handler
+%%  * rabbit_reader
+%%  * rabbit_event
+
+-behaviour(gen_server2).
+
+%% API
+-export([boot/0, start_link/0, reregister/1]).
+
+%% gen_fsm callbacks
+-export([init/1,
+  handle_call/3,
+  handle_cast/2,
+  handle_info/2,
+  terminate/2,
+  code_change/3]).
+
+-define(SERVER, ?MODULE).
+
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+
+boot() ->
+  {ok, _} = start_link(),
+  ok.
+
+start_link() ->
+  gen_server2:start_link({local, ?SERVER}, ?MODULE, [], []).
+
+reregister(Node) ->
+  rabbit_log:info("Telling node ~p to re-register tracked connections", [Node]),
+  gen_server2:cast({?SERVER, Node}, reregister).
+
+%%%===================================================================
+%%% gen_server callbacks
+%%%===================================================================
+
+init([]) ->
+  {ok, {}}.
+
+handle_call(_Req, _From, State) ->
+  {noreply, State}.
+
+handle_cast(reregister, State) ->
+  Cs = rabbit_networking:connections_local(),
+  rabbit_log:info("Connection tracker: asked to re-register ~p client connections", [length(Cs)]),
+  case Cs of
+    [] -> ok;
+    Cs ->
+      [reregister_connection(C) || C <- Cs],
+      ok
+  end,
+  rabbit_log:info("Done re-registering client connections"),
+  {noreply, State}.
+
+handle_info(_Req, State) ->
+  {noreply, State}.
+
+terminate(_Reason, _State) ->
+  ok.
+
+code_change(_OldVsn, State, _Extra) ->
+  {ok, State}.
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+
+reregister_connection(Conn) ->
+  try
+    Conn ! reregister
+  catch _:Error ->
+    rabbit_log:error("Failed to re-register connection ~p after a network split: ~p", [Conn, Error])
+  end.