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+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2004-2010. 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%
+%%
+
+%%% @doc Common Test Framework test execution control module.
+%%%
+%%% <p>This module is a proxy for calling and handling locks in
+%%% common test hooks.</p>
+
+-module(ct_hooks_lock).
+
+-behaviour(gen_server).
+
+%% API
+-export([start/1, stop/1, request/0, release/0]).
+
+%% gen_server callbacks
+-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
+ terminate/2, code_change/3]).
+
+-define(SERVER, ?MODULE).
+
+-record(state, { id, locked = false, requests = [] }).
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+
+%% @doc Starts the server
+start(Id) ->
+ case gen_server:start({local, ?SERVER}, ?MODULE, Id, []) of
+ {error,{already_started, Pid}} ->
+ {ok,Pid};
+ Else ->
+ Else
+ end.
+
+stop(Id) ->
+ try
+ gen_server:call(?SERVER, {stop,Id})
+ catch exit:{noproc,_} ->
+ stopped
+ end.
+
+request() ->
+ try
+ gen_server:call(?SERVER,{request,self()},infinity)
+ catch exit:{noproc,_} ->
+ locked
+ end.
+
+release() ->
+ try
+ gen_server:call(?SERVER,{release,self()})
+ catch exit:{noproc,_} ->
+ unlocked
+ end.
+
+%%%===================================================================
+%%% gen_server callbacks
+%%%===================================================================
+
+%% @doc Initiates the server
+init(Id) ->
+ {ok, #state{ id = Id }}.
+
+%% @doc Handling call messages
+handle_call({stop,Id}, _From, #state{ id = Id, requests = Reqs } = State) ->
+ [gen_server:reply(Req, locker_stopped) || {Req,_ReqId} <- Reqs],
+ {stop, normal, stopped, State};
+handle_call({stop,_Id}, _From, State) ->
+ {reply, stopped, State};
+handle_call({request, Pid}, _From, #state{ locked = false,
+ requests = [] } = State) ->
+ Ref = monitor(process, Pid),
+ {reply, locked, State#state{ locked = {true, Pid, Ref}} };
+handle_call({request, Pid}, From, #state{ requests = Reqs } = State) ->
+ {noreply, State#state{ requests = Reqs ++ [{From,Pid}] }};
+handle_call({release, Pid}, _From, #state{ locked = {true, Pid, Ref},
+ requests = []} = State) ->
+ demonitor(Ref,[flush]),
+ {reply, unlocked, State#state{ locked = false }};
+handle_call({release, Pid}, _From,
+ #state{ locked = {true, Pid, Ref},
+ requests = [{NextFrom,NextPid}|Rest]} = State) ->
+ demonitor(Ref,[flush]),
+ gen_server:reply(NextFrom,locked),
+ NextRef = monitor(process, NextPid),
+ {reply,unlocked,State#state{ locked = {true, NextPid, NextRef},
+ requests = Rest } };
+handle_call({release, _Pid}, _From, State) ->
+ {reply, not_locked, State}.
+
+%% @doc Handling cast messages
+handle_cast(_Msg, State) ->
+ {noreply, State}.
+
+%% @doc Handling all non call/cast messages
+handle_info({'DOWN',Ref,process,Pid,_},
+ #state{ locked = {true, Pid, Ref},
+ requests = [{NextFrom,NextPid}|Rest] } = State) ->
+ gen_server:reply(NextFrom, locked),
+ NextRef = monitor(process, NextPid),
+ {noreply,State#state{ locked = {true, NextPid, NextRef},
+ requests = Rest } }.
+
+%% @doc This function is called by a gen_server when it is about to terminate.
+terminate(_Reason, _State) ->
+ ok.
+
+%% @doc Convert process state when code is changed
+code_change(_OldVsn, State, _Extra) ->
+ {ok, State}.
+
+%% -------------------------------------------------------------------------
+%% Internal Functions
+%% -------------------------------------------------------------------------