Merge branch 'stable'

5 files changed, 55 insertions, 10 deletions

diff --git a/docs/rabbitmq.config.example b/docs/rabbitmq.config.example
index dd1a4e6c87..6be9504b8b 100644
--- a/docs/rabbitmq.config.example
+++ b/docs/rabbitmq.config.example
@@ -193,6 +193,10 @@
    %%
    %% {vm_memory_high_watermark, 0.4},
 
+   %% Alternatively, we can set a limit (in megabytes) of RAM used by the node.
+   %%
+   %% {vm_memory_high_watermark, {absolute, 1024}},
+
    %% Fraction of the high watermark limit at which queues start to
    %% page message out to disc in order to free up memory.
    %%
diff --git a/docs/rabbitmqctl.1.xml b/docs/rabbitmqctl.1.xml
index 74ef71108e..43d00418e6 100644
--- a/docs/rabbitmqctl.1.xml
+++ b/docs/rabbitmqctl.1.xml
@@ -1930,6 +1930,21 @@
             </variablelist>
           </listitem>
         </varlistentry>
+        <varlistentry>
+          <term><cmdsynopsis><command>set_vm_memory_high_watermark absolute</command> <arg choice="req"><replaceable>memory_limit_mb</replaceable></arg></cmdsynopsis></term>
+          <listitem>
+            <variablelist>
+              <varlistentry>
+                <term>memory_limit_mb</term>
+                <listitem><para>
+                    The new memory limit at which flow control is
+                    triggered, expressed in MB as an integer number
+                    greater than or equal to 0.
+                </para></listitem>
+              </varlistentry>
+            </variablelist>
+          </listitem>
+        </varlistentry>
       </variablelist>
     </refsect2>
   </refsect1>
diff --git a/src/rabbit_control_main.erl b/src/rabbit_control_main.erl
index fe0563bbc7..59223dc19b 100644
--- a/src/rabbit_control_main.erl
+++ b/src/rabbit_control_main.erl
@@ -410,6 +410,12 @@ action(set_vm_memory_high_watermark, Node, [Arg], _Opts, Inform) ->
     Inform("Setting memory threshold on ~p to ~p", [Node, Frac]),
     rpc_call(Node, vm_memory_monitor, set_vm_memory_high_watermark, [Frac]);
 
+action(set_vm_memory_high_watermark, Node, ["absolute", Arg], _Opts, Inform) ->
+    Limit = list_to_integer(Arg),
+    Inform("Setting memory threshold on ~p to ~pMB", [Node, Limit]),
+    rpc_call(Node, vm_memory_monitor, set_vm_memory_high_watermark,
+	     [{absolute, Limit}]);
+
 action(set_permissions, Node, [Username, CPerm, WPerm, RPerm], Opts, Inform) ->
     VHost = proplists:get_value(?VHOST_OPT, Opts),
     Inform("Setting permissions for user \"~s\" in vhost \"~s\"",
diff --git a/src/vm_memory_monitor.erl b/src/vm_memory_monitor.erl
index bf9a77c174..fe68f50239 100644
--- a/src/vm_memory_monitor.erl
+++ b/src/vm_memory_monitor.erl
@@ -52,7 +52,7 @@
 
 -record(state, {total_memory,
                 memory_limit,
-                memory_fraction,
+                memory_config_limit,
                 timeout,
                 timer,
                 alarmed,
@@ -63,6 +63,7 @@
 
 -ifdef(use_specs).
 
+-type(vm_memory_high_watermark() :: (float() | {'absolute', integer()})).
 -spec(start_link/1 :: (float()) -> rabbit_types:ok_pid_or_error()).
 -spec(start_link/3 :: (float(), fun ((any()) -> 'ok'),
                        fun ((any()) -> 'ok')) -> rabbit_types:ok_pid_or_error()).
@@ -70,8 +71,8 @@
 -spec(get_vm_limit/0 :: () -> non_neg_integer()).
 -spec(get_check_interval/0 :: () -> non_neg_integer()).
 -spec(set_check_interval/1 :: (non_neg_integer()) -> 'ok').
--spec(get_vm_memory_high_watermark/0 :: () -> float()).
--spec(set_vm_memory_high_watermark/1 :: (float()) -> 'ok').
+-spec(get_vm_memory_high_watermark/0 :: () -> vm_memory_high_watermark()).
+-spec(set_vm_memory_high_watermark/1 :: (vm_memory_high_watermark()) -> 'ok').
 -spec(get_memory_limit/0 :: () -> non_neg_integer()).
 
 -endif.
@@ -128,11 +129,12 @@ init([MemFraction, AlarmFuns]) ->
                      alarm_funs = AlarmFuns },
     {ok, set_mem_limits(State, MemFraction)}.
 
-handle_call(get_vm_memory_high_watermark, _From, State) ->
-    {reply, State#state.memory_fraction, State};
+handle_call(get_vm_memory_high_watermark, _From,
+	    #state{memory_config_limit = MemLimit} = State) ->
+    {reply, MemLimit, State};
 
-handle_call({set_vm_memory_high_watermark, MemFraction}, _From, State) ->
-    {reply, ok, set_mem_limits(State, MemFraction)};
+handle_call({set_vm_memory_high_watermark, MemLimit}, _From, State) ->
+    {reply, ok, set_mem_limits(State, MemLimit)};
 
 handle_call(get_check_interval, _From, State) ->
     {reply, State#state.timeout, State};
@@ -166,7 +168,7 @@ code_change(_OldVsn, State, _Extra) ->
 %% Server Internals
 %%----------------------------------------------------------------------------
 
-set_mem_limits(State, MemFraction) ->
+set_mem_limits(State, MemLimit) ->
     case erlang:system_info(wordsize) of
         4 ->
             error_logger:warning_msg(
@@ -206,12 +208,18 @@ set_mem_limits(State, MemFraction) ->
             _ ->
                 TotalMemory
         end,
-    MemLim = trunc(MemFraction * UsableMemory),
+    MemLim = interpret_limit(MemLimit, UsableMemory),
     error_logger:info_msg("Memory limit set to ~pMB of ~pMB total.~n",
                           [trunc(MemLim/?ONE_MB), trunc(TotalMemory/?ONE_MB)]),
     internal_update(State #state { total_memory    = TotalMemory,
                                    memory_limit    = MemLim,
-                                   memory_fraction = MemFraction}).
+                                   memory_config_limit = MemLimit}).
+
+interpret_limit({'absolute', MemLim}, UsableMemory) ->
+    %% Absolute memory is provided in MB
+    min(MemLim * ?ONE_MB, UsableMemory);
+interpret_limit(MemFraction, UsableMemory) ->
+    trunc(MemFraction * UsableMemory).
 
 internal_update(State = #state { memory_limit = MemLimit,
                                  alarmed      = Alarmed,
diff --git a/test/src/rabbit_tests.erl b/test/src/rabbit_tests.erl
index e7df47a3d8..44bf3da5f2 100644
--- a/test/src/rabbit_tests.erl
+++ b/test/src/rabbit_tests.erl
@@ -91,6 +91,7 @@ all_tests0() ->
     passed = test_configurable_server_properties(),
     passed = vm_memory_monitor_tests:all_tests(),
     passed = credit_flow_test:test_credit_flow_settings(),
+    passed = test_memory_high_watermark(),
     passed = on_disk_store_tunable_parameter_validation_test:test_msg_store_parameter_validation(),
     passed = password_hashing_tests:test_password_hashing(),
     passed = credit_flow_test:test_credit_flow_settings(),
@@ -3218,3 +3219,14 @@ test_configurable_server_properties() ->
 
 nop(_) -> ok.
 nop(_, _) -> ok.
+
+test_memory_high_watermark() ->
+    %% set vm memory high watermark
+    HWM = vm_memory_monitor:get_vm_memory_high_watermark(),
+    %% this will trigger an alarm (memory unit is MB)
+    ok = control_action(set_vm_memory_high_watermark, ["absolute", "2"]),
+    [{{resource_limit,memory,_},[]}] = rabbit_alarm:get_alarms(),
+    %% reset
+    ok = control_action(set_vm_memory_high_watermark, [float_to_list(HWM)]),
+
+    passed.