Add diameter_reg:wait/1

Mostly to use it in the watchdog test suite that's been broken by
sequence masks. Do a bit of cleanup while we're at it.

1 files changed, 142 insertions, 113 deletions

diff --git a/lib/diameter/src/base/diameter_reg.erl b/lib/diameter/src/base/diameter_reg.erl
index 882b9da238..619b12ecad 100644
--- a/lib/diameter/src/base/diameter_reg.erl
+++ b/lib/diameter/src/base/diameter_reg.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 2010-2011. All Rights Reserved.
+%% Copyright Ericsson AB 2010-2012. 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
@@ -30,7 +30,8 @@
          add_new/1,
          del/1,
          repl/2,
-         match/1]).
+         match/1,
+         wait/1]).
 
 -export([start_link/0]).
 
@@ -65,27 +66,22 @@
 %% Table entry containing the Term -> Pid mapping.
 -define(MAPPING(Term, Pid), {Term, Pid}).
 
--record(state, {id = now()}).
-
-%%% ----------------------------------------------------------
-%%% # add(T)
-%%%
-%%% Input:  Term = term()
-%%%
-%%% Output: true
-%%%
-%%% Description: Associate the specified term with self(). The list of pids
-%%%              having this or other assocations can be retrieved using
-%%%              match/1.
-%%%
-%%%              An association is removed when the calling process dies
-%%%              or as a result of calling del/1. Adding the same term
-%%%              more than once is equivalent to adding it exactly once.
-%%%
-%%%              Note that since match/1 takes a pattern as argument,
-%%%              specifying a term that contains match variables is
-%%%              probably not a good idea
-%%% ----------------------------------------------------------
+-record(state, {id = now(),
+                q = []}). %% [{From, Pat}]
+
+%% ===========================================================================
+%% # add(T)
+%%
+%% Associate the specified term with self(). The list of pids having
+%% this or other assocations can be retrieved using match/1.
+%%
+%% An association is removed when the calling process dies or as a
+%% result of calling del/1. Adding the same term more than once is
+%% equivalent to adding it exactly once.
+%%
+%% Note that since match/1 takes a pattern as argument, specifying a
+%% term that contains match variables is probably not a good idea
+%% ===========================================================================
 
 -spec add(any())
    -> true.
@@ -93,17 +89,12 @@
 add(T) ->
     call({add, fun ets:insert/2, T, self()}).
 
-%%% ----------------------------------------------------------
-%%% # add_new(T)
-%%%
-%%% Input:  T = term()
-%%%
-%%% Output: true | false
-%%%
-%%% Description: Like add/1 but only one process is allowed to have the
-%%%              the association, false being returned if an association
-%%%              already exists.
-%%% ----------------------------------------------------------
+%% ===========================================================================
+%% # add_new(T)
+%%
+%% Like add/1 but only one process is allowed to have the the
+%% association, false being returned if an association already exists.
+%% ===========================================================================
 
 -spec add_new(any())
    -> boolean().
@@ -111,16 +102,12 @@ add(T) ->
 add_new(T) ->
     call({add, fun insert_new/2, T, self()}).
 
-%%% ----------------------------------------------------------
-%%% # repl(T, NewT)
-%%%
-%%% Input:  T, NewT = term()
-%%%
-%%% Output: true | false
-%%%
-%%% Description: Like add/1 but only replace an existing association on T,
-%%%              false being returned if it doesn't exist.
-%%% ----------------------------------------------------------
+%% ===========================================================================
+%% # repl(T, NewT)
+%%
+%% Like add/1 but only replace an existing association on T, false
+%% being returned if it doesn't exist.
+%% ===========================================================================
 
 -spec repl(any(), any())
    -> boolean().
@@ -128,15 +115,11 @@ add_new(T) ->
 repl(T, U) ->
     call({repl, T, U, self()}).
 
-%%% ----------------------------------------------------------
-%%% # del(Term)
-%%%
-%%% Input:  Term = term()
-%%%
-%%% Output: true
-%%%
-%%% Description: Remove any existing association of Term with self().
-%%% ----------------------------------------------------------
+%% ===========================================================================
+%% # del(Term)
+%%
+%% Remove any existing association of Term with self().
+%% ===========================================================================
 
 -spec del(any())
    -> true.
@@ -144,20 +127,16 @@ repl(T, U) ->
 del(T) ->
     call({del, T, self()}).
 
-%%% ----------------------------------------------------------
-%%% # match(Pat)
-%%%
-%%% Input:  Pat = pattern in the sense of ets:match_object/2.
-%%%
-%%% Output: list of {Term, Pid}
-%%%
-%%% Description: Return the list of associations whose Term, as specified
-%%%              to add/1 or add_new/1, matches the specified pattern.
-%%%
-%%%              Note that there's no guarantee that the returned processes
-%%%              are still alive. (Although one that isn't will soon have
-%%%              its associations removed.)
-%%% ----------------------------------------------------------
+%% ===========================================================================
+%% # match(Pat)
+%%
+%% Return the list of associations whose Term, as specified to add/1
+%% or add_new/1, matches the specified pattern.
+%%
+%% Note that there's no guarantee that the returned processes are
+%% still alive. (Although one that isn't will soon have its
+%% associations removed.)
+%% ===========================================================================
 
 -spec match(tuple())
    -> [{term(), pid()}].
@@ -165,9 +144,17 @@ del(T) ->
 match(Pat) ->
     ets:match_object(?TABLE, ?MAPPING(Pat, '_')).
 
-%% ---------------------------------------------------------
-%% EXPORTED INTERNAL FUNCTIONS
-%% ---------------------------------------------------------
+%% ===========================================================================
+%% # wait(Pat)
+%%
+%% Like match/1 but return only when the result is non-empty or fails.
+%% It's up to the caller to ensure that the wait won't be forever.
+%% ===========================================================================
+
+wait(Pat) ->
+    call({wait, Pat}).
+
+%% ===========================================================================
 
 start_link() ->
     ServerName = {local, ?SERVER},
@@ -182,7 +169,7 @@ uptime() ->
 
 %% pids/0
 %%
-%% Output: list of {Pid, [Term, ...]}
+%% Return: list of {Pid, [Term, ...]}
 
 pids() ->
     to_list(fun swap/1).
@@ -202,89 +189,100 @@ id(T) -> T.
 
 %% terms/0
 %%
-%% Output: list of {Term, [Pid, ...]}
+%% Return: list of {Term, [Pid, ...]}
 
 terms() ->
     to_list(fun id/1).
 
 swap({X,Y}) -> {Y,X}.
 
-%%% ----------------------------------------------------------
-%%% # init(Role)
-%%%
-%%% Output: {ok, State}
-%%% ----------------------------------------------------------
+%% ----------------------------------------------------------
+%% # init/1
+%% ----------------------------------------------------------
 
 init(_) ->
     ets:new(?TABLE, [bag, named_table]),
     {ok, #state{}}.
 
-%%% ----------------------------------------------------------
-%%% # handle_call(Request, From, State)
-%%% ----------------------------------------------------------
+%% ----------------------------------------------------------
+%% # handle_call/3
+%% ----------------------------------------------------------
 
-handle_call({add, Fun, Key, Pid}, _, State) ->
+handle_call(Req, From, S)
+  when not is_record(S, state) ->
+    handle_call(Req, From, upgrade(S));
+
+handle_call({add, Fun, Key, Pid}, _, S) ->
     B = Fun(?TABLE, {Key, Pid}),
     monitor(B andalso no_monitor(Pid), Pid),
-    {reply, B, State};
+    {reply, B, pending(B, S)};
 
-handle_call({del, Key, Pid}, _, State) ->
-    {reply, ets:delete_object(?TABLE, ?MAPPING(Key, Pid)), State};
+handle_call({del, Key, Pid}, _, S) ->
+    {reply, ets:delete_object(?TABLE, ?MAPPING(Key, Pid)), S};
 
-handle_call({repl, T, U, Pid}, _, State) ->
+handle_call({repl, T, U, Pid}, _, S) ->
     MatchSpec = [{?MAPPING('$1', Pid),
                   [{'=:=', '$1', {const, T}}],
                   ['$_']}],
-    {reply, repl(ets:select(?TABLE, MatchSpec), U, Pid), State};
+    {reply, repl(ets:select(?TABLE, MatchSpec), U, Pid), S};
+
+handle_call({wait, Pat}, From, #state{q = Q} = S) ->
+    case find(Pat) of
+        {ok, L} ->
+            {reply, L, S};
+        false ->
+            {noreply, S#state{q = [{From, Pat} | Q]}}
+    end;
 
-handle_call(state, _, State) ->
-    {reply, State, State};
+handle_call(state, _, S) ->
+    {reply, S, S};
 
-handle_call(uptime, _, #state{id = Time} = State) ->
-    {reply, diameter_lib:now_diff(Time), State};
+handle_call(uptime, _, #state{id = Time} = S) ->
+    {reply, diameter_lib:now_diff(Time), S};
 
-handle_call(Req, From, State) ->
+handle_call(Req, From, S) ->
     ?UNEXPECTED([Req, From]),
-    {reply, nok, State}.
+    {reply, nok, S}.
 
-%%% ----------------------------------------------------------
-%%% # handle_cast(Request, State)
-%%% ----------------------------------------------------------
+%% ----------------------------------------------------------
+%% # handle_cast/2
+%% ----------------------------------------------------------
 
-handle_cast(Msg, State)->
+handle_cast(Msg, S)->
     ?UNEXPECTED([Msg]),
-    {noreply, State}.
+    {noreply, S}.
 
-%%% ----------------------------------------------------------
-%%% # handle_info(Request, State)
-%%% ----------------------------------------------------------
+%% ----------------------------------------------------------
+%% # handle_info/2
+%% ----------------------------------------------------------
 
-handle_info({'DOWN', MRef, process, Pid, _}, State) ->
+handle_info({'DOWN', MRef, process, Pid, _}, S) ->
     ets:delete_object(?TABLE, ?MONITOR(Pid, MRef)),
     ets:match_delete(?TABLE, ?MAPPING('_', Pid)),
-    {noreply, State};
+    {noreply, S};
 
-handle_info(Info, State) ->
+handle_info(Info, S) ->
     ?UNEXPECTED([Info]),
-    {noreply, State}.
+    {noreply, S}.
 
-%%% ----------------------------------------------------------
-%%% # terminate(Reason, State)
-%%% ----------------------------------------------------------
+%% ----------------------------------------------------------
+%% # terminate/2
+%% ----------------------------------------------------------
 
 terminate(_Reason, _State)->
     ok.
 
-%%% ----------------------------------------------------------
-%%% # code_change(OldVsn, State, Extra)
-%%% ----------------------------------------------------------
+%% ----------------------------------------------------------
+%% # code_change/3
+%% ----------------------------------------------------------
 
 code_change(_OldVsn, State, _Extra) ->
     {ok, State}.
 
-%% ---------------------------------------------------------
-%% INTERNAL FUNCTIONS
-%% ---------------------------------------------------------
+%% ===========================================================================
+
+upgrade(S) ->
+    #state{} = list_to_tuple(tuple_to_list(S) ++ [[]]).
 
 monitor(true, Pid) ->
     ets:insert(?TABLE, ?MONITOR(Pid, erlang:monitor(process, Pid)));
@@ -321,6 +319,37 @@ repl([?MAPPING(_, Pid) = M], Key, Pid) ->
 repl([], _, _) ->
     false.
 
+%% pending/1
+
+pending(true, #state{q = [_|_] = Q} = S) ->
+    S#state{q = q(lists:reverse(Q), [])}; %% retain reply order
+pending(_, S) ->
+    S.
+
+q([], Q) ->
+    Q;
+q([{From, Pat} = T | Rest], Q) ->
+    case find(Pat) of
+        {ok, L} ->
+            gen_server:reply(From, L),
+            q(Rest, Q);
+        false ->
+            q(Rest, [T|Q])
+    end.
+
+%% find/1
+
+find(Pat) ->
+    try match(Pat) of
+        [] ->
+            false;
+        L ->
+            {ok, L}
+    catch
+        _:_ ->
+            {ok, []}
+    end.
+
 %% call/1
 
 call(Request) ->