1 files changed, 107 insertions, 0 deletions
diff --git a/lib/stdlib/test/sys_sp2.erl b/lib/stdlib/test/sys_sp2.erl
new file mode 100644
index 0000000000..56a5e4d071
--- /dev/null
+++ b/lib/stdlib/test/sys_sp2.erl
@@ -0,0 +1,107 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 1996-2013. All Rights Reserved.
+%%
+%% The contents of this file are subject to the Erlang Public License,
+%% Version 1.1, (the "License"); you may not use this file except in
+%% compliance with the License. You should have received a copy of the
+%% Erlang Public License along with this software. If not, it can be
+%% retrieved online at http://www.erlang.org/.
+%%
+%% 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.
+%%
+%% %CopyrightEnd%
+%%
+-module(sys_sp2).
+-export([start_link/1, stop/0]).
+-export([alloc/0, free/1]).
+-export([init/1]).
+-export([system_continue/3, system_terminate/4,
+         write_debug/3]).
+
+%% Implements the ch4 example from the Design Principles doc.  Same as
+%% sys_sp1 except this module does not export system_get_state/1 or
+%% system_replace_state/2
+
+start_link(NumCh) ->
+    proc_lib:start_link(?MODULE, init, [[self(),NumCh]]).
+
+stop() ->
+    ?MODULE ! stop,
+    ok.
+
+alloc() ->
+    ?MODULE ! {self(), alloc},
+    receive
+        {?MODULE, Res} ->
+            Res
+    end.
+
+free(Ch) ->
+    ?MODULE ! {free, Ch},
+    ok.
+
+%% can't use 2-tuple for state here as we do in sys_sp1, since the 2-tuple
+%% is not compatible with the backward compatibility handling for
+%% sys:get_state in sys.erl
+-record(state, {alloc,free}).
+
+init([Parent,NumCh]) ->
+    register(?MODULE, self()),
+    Chs = channels(NumCh),
+    Deb = sys:debug_options([]),
+    proc_lib:init_ack(Parent, {ok, self()}),
+    loop(Chs, Parent, Deb).
+
+loop(Chs, Parent, Deb) ->
+    receive
+        {From, alloc} ->
+            Deb2 = sys:handle_debug(Deb, fun write_debug/3,
+                                    ?MODULE, {in, alloc, From}),
+            {Ch, Chs2} = alloc(Chs),
+            From ! {?MODULE, Ch},
+            Deb3 = sys:handle_debug(Deb2, fun write_debug/3,
+                                    ?MODULE, {out, {?MODULE, Ch}, From}),
+            loop(Chs2, Parent, Deb3);
+        {free, Ch} ->
+            Deb2 = sys:handle_debug(Deb, fun write_debug/3,
+                                    ?MODULE, {in, {free, Ch}}),
+            Chs2 = free(Ch, Chs),
+            loop(Chs2, Parent, Deb2);
+        {system, From, Request} ->
+            sys:handle_system_msg(Request, From, Parent,
+                                  ?MODULE, Deb, Chs);
+        stop ->
+            sys:handle_debug(Deb, fun write_debug/3,
+                             ?MODULE, {in, stop}),
+            ok
+    end.
+
+system_continue(Parent, Deb, Chs) ->
+    loop(Chs, Parent, Deb).
+
+system_terminate(Reason, _Parent, _Deb, _Chs) ->
+    exit(Reason).
+
+write_debug(Dev, Event, Name) ->
+    io:format(Dev, "~p event = ~p~n", [Name, Event]).
+
+channels(NumCh) ->
+    #state{alloc=[], free=lists:seq(1,NumCh)}.
+
+alloc(#state{free=[]}=Channels) ->
+    {{error, "no channels available"}, Channels};
+alloc(#state{alloc=Allocated, free=[H|T]}) ->
+    {H, #state{alloc=[H|Allocated], free=T}}.
+
+free(Ch, #state{alloc=Alloc, free=Free}=Channels) ->
+    case lists:member(Ch, Alloc) of
+        true ->
+            #state{alloc=lists:delete(Ch, Alloc), free=[Ch|Free]};
+        false ->
+            Channels
+    end.