Add some additional calculation strategy options

Author: lukebakken

src/vm_memory_monitor.erl

@@ -130,30 +130,33 @@ get_memory_use(ratio) ->
 %% be equal to the total size of all pages mapped to the emulator,
 %% according to http://erlang.org/doc/man/erlang.html#memory-0
 %% erlang:memory(total) under-reports memory usage by around 20%
+%%
+%% Win32 Note: 3.6.12 shipped with code that used wmic.exe to get the
+%% WorkingSetSize value for the running erl.exe process. Unfortunately
+%% even with a moderate invocation rate of 1 ops/second that uses more
+%% CPU resources than some Windows users are willing to tolerate.
+%% See rabbitmq/rabbitmq-server#1343 and rabbitmq/rabbitmq-common#224
+%% for details.
 -spec get_process_memory() -> Bytes :: integer().
 get_process_memory() ->
-    case get_memory_calculation_strategy() of
-        rss ->
-            case get_system_process_resident_memory() of
-                {ok, MemInBytes} ->
-                    MemInBytes;
-                {error, Reason}  ->
-                    rabbit_log:debug("Unable to get system memory used. Reason: ~p."
-                                     " Falling back to erlang memory reporting",
-                                     [Reason]),
-                    erlang:memory(total)
-            end;
-        erlang ->
-            erlang:memory(total)
-    end.
+    get_process_memory_using_strategy(get_memory_calculation_strategy()).
+
+get_process_memory_using_strategy(allocated) ->
+    recon_alloc:memory(allocated);
+get_process_memory_using_strategy(erlang) ->
+    erlang:memory(total);
+get_process_memory_using_strategy(legacy) ->
+    erlang:memory(total);
+get_process_memory_using_strategy(rss) ->
+    recon_alloc:memory(allocated).
 
 -spec get_memory_calculation_strategy() -> rss | erlang.
 get_memory_calculation_strategy() ->
     case rabbit_misc:get_env(rabbit, vm_memory_calculation_strategy, rss) of
-        erlang ->
-            erlang;
-        rss ->
-            rss;
+        allocated -> allocated;
+        erlang -> erlang;
+        legacy -> legacy;
+        rss -> rss;
         UnsupportedValue ->
             rabbit_log:warning(
               "Unsupported value '~p' for vm_memory_calculation_strategy. "
@@ -164,20 +167,6 @@ get_memory_calculation_strategy() ->
             rss
     end.
 
-%% Win32 Note: 3.6.12 shipped with code that used wmic.exe to get the
-%% WorkingSetSize value for the running erl.exe process. Unfortunately
-%% even with a moderate invocation rate of 1 ops/second that uses more
-%% CPU resources than some Windows users are willing to tolerate.
-%% See rabbitmq/rabbitmq-server#1343 and rabbitmq/rabbitmq-common#224
-%% for details.
--spec get_system_process_resident_memory() -> {ok, Bytes :: integer()} | {error, term()}.
-get_system_process_resident_memory() ->
-    try
-        {ok, recon_alloc:memory(allocated)}
-    catch _:Error ->
-            {error, {"Failed to get process resident memory", Error}}
-    end.
-
 %%----------------------------------------------------------------------------
 %% gen_server callbacks
 %%----------------------------------------------------------------------------
@@ -390,18 +379,18 @@ cmd(Command) ->
 %% Windows and Freebsd code based on: memsup:get_memory_usage/1
 %% Original code was part of OTP and released under "Erlang Public License".
 
-get_total_memory({unix,darwin}) ->
+get_total_memory({unix, darwin}) ->
     sysctl("hw.memsize");
 
-get_total_memory({unix,freebsd}) ->
+get_total_memory({unix, freebsd}) ->
     PageSize  = sysctl("vm.stats.vm.v_page_size"),
     PageCount = sysctl("vm.stats.vm.v_page_count"),
     PageCount * PageSize;
 
-get_total_memory({unix,openbsd}) ->
+get_total_memory({unix, openbsd}) ->
     sysctl("hw.usermem");
 
-get_total_memory({win32,_OSname}) ->
+get_total_memory({win32, _OSname}) ->
     [Result|_] = os_mon_sysinfo:get_mem_info(),
     {ok, [_MemLoad, TotPhys, _AvailPhys, _TotPage, _AvailPage, _TotV, _AvailV],
      _RestStr} =