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-rw-r--r--lib/dialyzer/test/behaviour_SUITE_data/results/gen_server_incorrect_args2
-rw-r--r--lib/stdlib/doc/src/gen_server.xml52
-rw-r--r--lib/stdlib/src/gen_server.erl31
-rw-r--r--lib/stdlib/test/erl_internal_SUITE.erl4
-rw-r--r--lib/stdlib/test/gen_server_SUITE.erl111
-rw-r--r--lib/stdlib/test/gen_server_SUITE_data/oc_server.erl12
6 files changed, 185 insertions, 27 deletions
diff --git a/lib/dialyzer/test/behaviour_SUITE_data/results/gen_server_incorrect_args b/lib/dialyzer/test/behaviour_SUITE_data/results/gen_server_incorrect_args
index 1eb8cd455b..1be0ce0d8c 100644
--- a/lib/dialyzer/test/behaviour_SUITE_data/results/gen_server_incorrect_args
+++ b/lib/dialyzer/test/behaviour_SUITE_data/results/gen_server_incorrect_args
@@ -1,5 +1,5 @@
gen_server_incorrect_args.erl:3: Undefined callback function handle_cast/2 (behaviour gen_server)
gen_server_incorrect_args.erl:3: Undefined callback function init/1 (behaviour gen_server)
-gen_server_incorrect_args.erl:7: The inferred return type of handle_call/3 ({'no'} | {'ok'}) has nothing in common with {'noreply',_} | {'noreply',_,'hibernate' | 'infinity' | non_neg_integer()} | {'reply',_,_} | {'stop',_,_} | {'reply',_,_,'hibernate' | 'infinity' | non_neg_integer()} | {'stop',_,_,_}, which is the expected return type for the callback of the gen_server behaviour
+gen_server_incorrect_args.erl:7: The inferred return type of handle_call/3 ({'no'} | {'ok'}) has nothing in common with {'noreply',_} | {'noreply',_,'hibernate' | 'infinity' | non_neg_integer() | {'continue',_}} | {'reply',_,_} | {'stop',_,_} | {'reply',_,_,'hibernate' | 'infinity' | non_neg_integer() | {'continue',_}} | {'stop',_,_,_}, which is the expected return type for the callback of the gen_server behaviour
gen_server_incorrect_args.erl:7: The inferred type for the 2nd argument of handle_call/3 ('boo' | 'foo') is not a supertype of {pid(),_}, which is expected type for this argument in the callback of the gen_server behaviour
diff --git a/lib/stdlib/doc/src/gen_server.xml b/lib/stdlib/doc/src/gen_server.xml
index 7d137fc772..da74e793e6 100644
--- a/lib/stdlib/doc/src/gen_server.xml
+++ b/lib/stdlib/doc/src/gen_server.xml
@@ -60,6 +60,8 @@ gen_server:abcast -----> Module:handle_cast/2
- -----> Module:handle_info/2
+- -----> Module:handle_continue/2
+
- -----> Module:terminate/2
- -----> Module:code_change/3</pre>
@@ -88,6 +90,13 @@ gen_server:abcast -----> Module:handle_cast/2
implies at least two garbage collections (when hibernating and
shortly after waking up) and is not something you want to do
between each call to a busy server.</p>
+
+ <p>If the <c>gen_server</c> process needs to perform an action
+ immediately after initialization or to break the execution of a
+ callback into multiple steps, it can return <c>{continue,Continue}</c>
+ in place of the time-out or hibernation value, which will immediately
+ invoke the <c>handle_continue/2</c> callback.</p>
+
</description>
<funcs>
@@ -610,12 +619,15 @@ gen_server:abcast -----> Module:handle_cast/2
<v>State = term()</v>
<v>Result = {reply,Reply,NewState} | {reply,Reply,NewState,Timeout}</v>
<v>&nbsp;&nbsp;| {reply,Reply,NewState,hibernate}</v>
+ <v>&nbsp;&nbsp;| {reply,Reply,NewState,{continue,Continue}}</v>
<v>&nbsp;&nbsp;| {noreply,NewState} | {noreply,NewState,Timeout}</v>
<v>&nbsp;&nbsp;| {noreply,NewState,hibernate}</v>
+ <v>&nbsp;&nbsp;| {noreply,NewState,{continue,Continue}}</v>
<v>&nbsp;&nbsp;| {stop,Reason,Reply,NewState} | {stop,Reason,NewState}</v>
<v>&nbsp;Reply = term()</v>
<v>&nbsp;NewState = term()</v>
<v>&nbsp;Timeout = int()>=0 | infinity</v>
+ <v>&nbsp;Continue = term()</v>
<v>&nbsp;Reason = term()</v>
</type>
<desc>
@@ -673,9 +685,11 @@ gen_server:abcast -----> Module:handle_cast/2
<v>State = term()</v>
<v>Result = {noreply,NewState} | {noreply,NewState,Timeout}</v>
<v>&nbsp;&nbsp;| {noreply,NewState,hibernate}</v>
+ <v>&nbsp;&nbsp;| {noreply,NewState,{continue,Continue}}</v>
<v>&nbsp;&nbsp;| {stop,Reason,NewState}</v>
<v>&nbsp;NewState = term()</v>
<v>&nbsp;Timeout = int()>=0 | infinity</v>
+ <v>&nbsp;Continue = term()</v>
<v>&nbsp;Reason = term()</v>
</type>
<desc>
@@ -690,6 +704,41 @@ gen_server:abcast -----> Module:handle_cast/2
</func>
<func>
+ <name>Module:handle_continue(Continue, State) -> Result</name>
+ <fsummary>Handle a continue instruction.</fsummary>
+ <type>
+ <v>Continue = term()</v>
+ <v>State = term()</v>
+ <v>Result = {noreply,NewState} | {noreply,NewState,Timeout}</v>
+ <v>&nbsp;&nbsp;| {noreply,NewState,hibernate}</v>
+ <v>&nbsp;&nbsp;| {noreply,NewState,{continue,Continue}}</v>
+ <v>&nbsp;&nbsp;| {stop,Reason,NewState}</v>
+ <v>&nbsp;NewState = term()</v>
+ <v>&nbsp;Timeout = int()>=0 | infinity</v>
+ <v>&nbsp;Continue = term()</v>
+ <v>&nbsp;Reason = normal | term()</v>
+ </type>
+ <desc>
+ <note>
+ <p>This callback is optional, so callback modules need to
+ export it only if they return <c>{continue,Continue}</c>
+ from another callback. If continue is used and the callback
+ is not implemented, the process will exit with <c>undef</c>
+ error.</p>
+ </note>
+ <p>This function is called by a <c>gen_server</c> process whenever
+ a previous callback returns <c>{continue, Continue}</c>.
+ <c>handle_continue/2</c> is invoked immediately after the previous
+ callback, which makes it useful for performing work after
+ initialization or for splitting the work in a callback in
+ multiple steps, updating the process state along the way.</p>
+ <p>For a description of the other arguments and possible return values,
+ see <seealso marker="#Module:handle_call/3">
+ <c>Module:handle_call/3</c></seealso>.</p>
+ </desc>
+ </func>
+
+ <func>
<name>Module:handle_info(Info, State) -> Result</name>
<fsummary>Handle an incoming message.</fsummary>
<type>
@@ -697,6 +746,7 @@ gen_server:abcast -----> Module:handle_cast/2
<v>State = term()</v>
<v>Result = {noreply,NewState} | {noreply,NewState,Timeout}</v>
<v>&nbsp;&nbsp;| {noreply,NewState,hibernate}</v>
+ <v>&nbsp;&nbsp;| {noreply,NewState,{continue,Continue}}</v>
<v>&nbsp;&nbsp;| {stop,Reason,NewState}</v>
<v>&nbsp;NewState = term()</v>
<v>&nbsp;Timeout = int()>=0 | infinity</v>
@@ -726,7 +776,7 @@ gen_server:abcast -----> Module:handle_cast/2
<type>
<v>Args = term()</v>
<v>Result = {ok,State} | {ok,State,Timeout} | {ok,State,hibernate}</v>
- <v>&nbsp;| {stop,Reason} | ignore</v>
+ <v>&nbsp;| {ok,State,{continue,Continue}} | {stop,Reason} | ignore</v>
<v>&nbsp;State = term()</v>
<v>&nbsp;Timeout = int()>=0 | infinity</v>
<v>&nbsp;Reason = term()</v>
diff --git a/lib/stdlib/src/gen_server.erl b/lib/stdlib/src/gen_server.erl
index a3d53efd0d..48ef1c987a 100644
--- a/lib/stdlib/src/gen_server.erl
+++ b/lib/stdlib/src/gen_server.erl
@@ -116,23 +116,27 @@
%%%=========================================================================
-callback init(Args :: term()) ->
- {ok, State :: term()} | {ok, State :: term(), timeout() | hibernate} |
+ {ok, State :: term()} | {ok, State :: term(), timeout() | hibernate | {continue, term()}} |
{stop, Reason :: term()} | ignore.
-callback handle_call(Request :: term(), From :: {pid(), Tag :: term()},
State :: term()) ->
{reply, Reply :: term(), NewState :: term()} |
- {reply, Reply :: term(), NewState :: term(), timeout() | hibernate} |
+ {reply, Reply :: term(), NewState :: term(), timeout() | hibernate | {continue, term()}} |
{noreply, NewState :: term()} |
- {noreply, NewState :: term(), timeout() | hibernate} |
+ {noreply, NewState :: term(), timeout() | hibernate | {continue, term()}} |
{stop, Reason :: term(), Reply :: term(), NewState :: term()} |
{stop, Reason :: term(), NewState :: term()}.
-callback handle_cast(Request :: term(), State :: term()) ->
{noreply, NewState :: term()} |
- {noreply, NewState :: term(), timeout() | hibernate} |
+ {noreply, NewState :: term(), timeout() | hibernate | {continue, term()}} |
{stop, Reason :: term(), NewState :: term()}.
-callback handle_info(Info :: timeout | term(), State :: term()) ->
{noreply, NewState :: term()} |
- {noreply, NewState :: term(), timeout() | hibernate} |
+ {noreply, NewState :: term(), timeout() | hibernate | {continue, term()}} |
+ {stop, Reason :: term(), NewState :: term()}.
+-callback handle_continue(Info :: term(), State :: term()) ->
+ {noreply, NewState :: term()} |
+ {noreply, NewState :: term(), timeout() | hibernate | {continue, term()}} |
{stop, Reason :: term(), NewState :: term()}.
-callback terminate(Reason :: (normal | shutdown | {shutdown, term()} |
term()),
@@ -149,7 +153,7 @@
Status :: term().
-optional_callbacks(
- [handle_info/2, terminate/2, code_change/3, format_status/2]).
+ [handle_info/2, handle_continue/2, terminate/2, code_change/3, format_status/2]).
%%% -----------------------------------------------------------------
%%% Starts a generic server.
@@ -309,7 +313,7 @@ enter_loop(Mod, Options, State, ServerName, Timeout) ->
Name = gen:get_proc_name(ServerName),
Parent = gen:get_parent(),
Debug = gen:debug_options(Name, Options),
- HibernateAfterTimeout = gen:hibernate_after(Options),
+ HibernateAfterTimeout = gen:hibernate_after(Options),
loop(Parent, Name, State, Mod, Timeout, HibernateAfterTimeout, Debug).
%%%========================================================================
@@ -374,6 +378,19 @@ init_it(Mod, Args) ->
%%% ---------------------------------------------------
%%% The MAIN loop.
%%% ---------------------------------------------------
+
+loop(Parent, Name, State, Mod, {continue, Continue} = Msg, HibernateAfterTimeout, Debug) ->
+ Reply = try_dispatch(Mod, handle_continue, Continue, State),
+ case Debug of
+ [] ->
+ handle_common_reply(Reply, Parent, Name, undefined, Msg, Mod,
+ HibernateAfterTimeout, State);
+ _ ->
+ Debug1 = sys:handle_debug(Debug, fun print_event/3, Name, Msg),
+ handle_common_reply(Reply, Parent, Name, undefined, Msg, Mod,
+ HibernateAfterTimeout, State, Debug1)
+ end;
+
loop(Parent, Name, State, Mod, hibernate, HibernateAfterTimeout, Debug) ->
proc_lib:hibernate(?MODULE,wake_hib,[Parent, Name, State, Mod, HibernateAfterTimeout, Debug]);
diff --git a/lib/stdlib/test/erl_internal_SUITE.erl b/lib/stdlib/test/erl_internal_SUITE.erl
index 789a9d4363..7d9df1f989 100644
--- a/lib/stdlib/test/erl_internal_SUITE.erl
+++ b/lib/stdlib/test/erl_internal_SUITE.erl
@@ -80,7 +80,7 @@ callbacks(application) ->
callbacks(gen_server) ->
[{init,1}, {handle_call,3}, {handle_cast,2},
{handle_info,2}, {terminate,2}, {code_change,3},
- {format_status,2}];
+ {format_status,2}, {handle_continue, 2}];
callbacks(gen_fsm) ->
[{init,1}, {handle_event,3}, {handle_sync_event,4},
{handle_info,3}, {terminate,3}, {code_change,4},
@@ -101,7 +101,7 @@ callbacks(supervisor) ->
optional_callbacks(application) ->
[];
optional_callbacks(gen_server) ->
- [{handle_info, 2}, {terminate, 2}, {code_change, 3}, {format_status, 2}];
+ [{handle_info, 2}, {handle_continue, 2}, {terminate, 2}, {code_change, 3}, {format_status, 2}];
optional_callbacks(gen_fsm) ->
[{handle_info, 3}, {terminate, 3}, {code_change, 4}, {format_status, 2}];
optional_callbacks(gen_event) ->
diff --git a/lib/stdlib/test/gen_server_SUITE.erl b/lib/stdlib/test/gen_server_SUITE.erl
index 2e9dc4d4fb..2bc220fef2 100644
--- a/lib/stdlib/test/gen_server_SUITE.erl
+++ b/lib/stdlib/test/gen_server_SUITE.erl
@@ -27,7 +27,7 @@
-export([all/0, suite/0,groups/0,init_per_suite/1, end_per_suite/1,
init_per_group/2,end_per_group/2]).
-export([start/1, crash/1, call/1, cast/1, cast_fast/1,
- info/1, abcast/1, multicall/1, multicall_down/1,
+ continue/1, info/1, abcast/1, multicall/1, multicall_down/1,
call_remote1/1, call_remote2/1, call_remote3/1,
call_remote_n1/1, call_remote_n2/1, call_remote_n3/1, spec_init/1,
spec_init_local_registered_parent/1,
@@ -37,7 +37,8 @@
get_state/1, replace_state/1, call_with_huge_message_queue/1,
undef_handle_call/1, undef_handle_cast/1, undef_handle_info/1,
undef_init/1, undef_code_change/1, undef_terminate1/1,
- undef_terminate2/1, undef_in_terminate/1, undef_in_handle_info/1
+ undef_terminate2/1, undef_in_terminate/1, undef_in_handle_info/1,
+ undef_handle_continue/1
]).
-export([stop1/1, stop2/1, stop3/1, stop4/1, stop5/1, stop6/1, stop7/1,
@@ -52,7 +53,7 @@
%% The gen_server behaviour
--export([init/1, handle_call/3, handle_cast/2,
+-export([init/1, handle_call/3, handle_cast/2, handle_continue/2,
handle_info/2, code_change/3, terminate/2, format_status/2]).
suite() ->
@@ -61,7 +62,7 @@ suite() ->
all() ->
[start, {group,stop}, crash, call, cast, cast_fast, info, abcast,
- multicall, multicall_down, call_remote1, call_remote2,
+ continue, multicall, multicall_down, call_remote1, call_remote2,
call_remote3, call_remote_n1, call_remote_n2,
call_remote_n3, spec_init,
spec_init_local_registered_parent,
@@ -76,7 +77,7 @@ groups() ->
[{stop, [],
[stop1, stop2, stop3, stop4, stop5, stop6, stop7, stop8, stop9, stop10]},
{undef_callbacks, [],
- [undef_handle_call, undef_handle_cast, undef_handle_info,
+ [undef_handle_call, undef_handle_cast, undef_handle_info, undef_handle_continue,
undef_init, undef_code_change, undef_terminate1, undef_terminate2]}].
@@ -458,6 +459,47 @@ call(Config) when is_list(Config) ->
ok.
%% --------------------------------------
+%% Test handle_continue.
+%% --------------------------------------
+
+continue(Config) when is_list(Config) ->
+ {ok, Pid} = gen_server:start_link(gen_server_SUITE, {continue, self()}, []),
+ [{Pid, continue}, {Pid, after_continue}] = read_replies(Pid),
+
+ gen_server:call(Pid, {continue_reply, self()}),
+ [{Pid, continue}, {Pid, after_continue}] = read_replies(Pid),
+
+ gen_server:call(Pid, {continue_noreply, self()}),
+ [{Pid, continue}, {Pid, after_continue}] = read_replies(Pid),
+
+ gen_server:cast(Pid, {continue_noreply, self()}),
+ [{Pid, continue}, {Pid, after_continue}] = read_replies(Pid),
+
+ Pid ! {continue_noreply, self()},
+ [{Pid, continue}, {Pid, after_continue}] = read_replies(Pid),
+
+ Pid ! {continue_continue, self()},
+ [{Pid, before_continue}, {Pid, continue}, {Pid, after_continue}] = read_replies(Pid),
+
+ Ref = monitor(process, Pid),
+ Pid ! continue_stop,
+ verify_down_reason(Ref, Pid, normal).
+
+read_replies(Pid) ->
+ receive
+ {Pid, ack} -> read_replies()
+ after
+ 1000 -> ct:fail({continue, ack})
+ end.
+
+read_replies() ->
+ receive
+ Msg -> [Msg | read_replies()]
+ after
+ 0 -> []
+ end.
+
+%% --------------------------------------
%% Test call to nonexisting processes on remote nodes
%% --------------------------------------
@@ -1346,7 +1388,7 @@ echo_loop() ->
%% Test the default implementation of terminate if the callback module
%% does not export it
undef_terminate1(Config) when is_list(Config) ->
- {ok, Server} = gen_server:start(oc_server, [], []),
+ {ok, Server} = oc_server:start(),
MRef = monitor(process, Server),
ok = gen_server:stop(Server),
ok = verify_down_reason(MRef, Server, normal).
@@ -1354,7 +1396,7 @@ undef_terminate1(Config) when is_list(Config) ->
%% Test the default implementation of terminate if the callback module
%% does not export it
undef_terminate2(Config) when is_list(Config) ->
- {ok, Server} = gen_server:start(oc_server, [], []),
+ {ok, Server} = oc_server:start(),
MRef = monitor(process, Server),
ok = gen_server:stop(Server, {error, test}, infinity),
ok = verify_down_reason(MRef, Server, {error, test}).
@@ -1377,7 +1419,7 @@ undef_init(_Config) ->
%% The upgrade should fail if code_change is expected in the callback module
%% but not exported, but the server should continue with the old code
undef_code_change(Config) when is_list(Config) ->
- {ok, Server} = gen_server:start(oc_server, [], []),
+ {ok, Server} = oc_server:start(),
{error, {'EXIT', {undef, [{oc_server, code_change, [_, _, _], _}|_]}}}
= fake_upgrade(Server, ?MODULE),
true = is_process_alive(Server).
@@ -1385,7 +1427,7 @@ undef_code_change(Config) when is_list(Config) ->
%% The server should crash if the handle_call callback is
%% not exported in the callback module
undef_handle_call(_Config) ->
- {ok, Server} = gen_server:start(oc_server, [], []),
+ {ok, Server} = oc_server:start(),
try
gen_server:call(Server, call_msg),
ct:fail(should_crash)
@@ -1397,17 +1439,25 @@ undef_handle_call(_Config) ->
%% The server should crash if the handle_cast callback is
%% not exported in the callback module
undef_handle_cast(_Config) ->
- {ok, Server} = gen_server:start(oc_server, [], []),
+ {ok, Server} = oc_server:start(),
MRef = monitor(process, Server),
gen_server:cast(Server, cast_msg),
verify_undef_down(MRef, Server, oc_server, handle_cast),
ok.
+%% The server should crash if the handle_continue callback is
+%% not exported in the callback module
+undef_handle_continue(_Config) ->
+ {ok, Server} = oc_server:start(continue),
+ MRef = monitor(process, Server),
+ verify_undef_down(MRef, Server, oc_server, handle_continue),
+ ok.
+
%% The server should log but not crash if the handle_info callback is
%% calling an undefined function
undef_handle_info(Config) when is_list(Config) ->
error_logger_forwarder:register(),
- {ok, Server} = gen_server:start(oc_server, [], []),
+ {ok, Server} = oc_server:start(),
Server ! hej,
wait_until_processed(Server, hej, 10),
true = is_process_alive(Server),
@@ -1570,8 +1620,11 @@ init(hibernate) ->
init(sleep) ->
ct:sleep(1000),
{ok, []};
+init({continue, Pid}) ->
+ self() ! {after_continue, Pid},
+ {ok, [], {continue, {message, Pid}}};
init({state,State}) ->
- {ok, State}.
+ {ok,State}.
handle_call(started_p, _From, State) ->
io:format("FROZ"),
@@ -1604,6 +1657,12 @@ handle_call(shutdown_reason, _From, _State) ->
handle_call({call_undef_fun, Mod, Fun}, _From, State) ->
Mod:Fun(),
{reply, ok, State};
+handle_call({continue_reply, Pid}, _From, State) ->
+ self() ! {after_continue, Pid},
+ {reply, ok, State, {continue, {message, Pid}}};
+handle_call({continue_noreply, Pid}, From, State) ->
+ self() ! {after_continue, Pid},
+ {noreply, State, {continue, {message, Pid, From}}};
handle_call(stop_shutdown_reason, _From, State) ->
{stop,{shutdown,stop_reason},State}.
@@ -1620,6 +1679,9 @@ handle_cast(hibernate_later, _State) ->
handle_cast({call_undef_fun, Mod, Fun}, State) ->
Mod:Fun(),
{noreply, State};
+handle_cast({continue_noreply, Pid}, State) ->
+ self() ! {after_continue, Pid},
+ {noreply, State, {continue, {message, Pid}}};
handle_cast({From, stop}, State) ->
io:format("BAZ"),
{stop, {From,stopped}, State}.
@@ -1657,9 +1719,34 @@ handle_info(continue, From) ->
{noreply, []};
handle_info({From, stop}, State) ->
{stop, {From,stopped_info}, State};
+handle_info({after_continue, Pid}, State) ->
+ Pid ! {self(), after_continue},
+ Pid ! {self(), ack},
+ {noreply, State};
+handle_info({continue_noreply, Pid}, State) ->
+ self() ! {after_continue, Pid},
+ {noreply, State, {continue, {message, Pid}}};
+handle_info({continue_continue, Pid}, State) ->
+ {noreply, State, {continue, {continue, Pid}}};
+handle_info(continue_stop, State) ->
+ {noreply, State, {continue, stop}};
handle_info(_Info, State) ->
{noreply, State}.
+handle_continue({continue, Pid}, State) ->
+ Pid ! {self(), before_continue},
+ self() ! {after_continue, Pid},
+ {noreply, State, {continue, {message, Pid}}};
+handle_continue(stop, State) ->
+ {stop, normal, State};
+handle_continue({message, Pid}, State) ->
+ Pid ! {self(), continue},
+ {noreply, State};
+handle_continue({message, Pid, From}, State) ->
+ Pid ! {self(), continue},
+ gen_server:reply(From, ok),
+ {noreply, State}.
+
code_change(_OldVsn,
{new, {undef_in_code_change, {Mod, Fun}}} = State,
_Extra) ->
diff --git a/lib/stdlib/test/gen_server_SUITE_data/oc_server.erl b/lib/stdlib/test/gen_server_SUITE_data/oc_server.erl
index 4ba37987f3..7b92a49bf6 100644
--- a/lib/stdlib/test/gen_server_SUITE_data/oc_server.erl
+++ b/lib/stdlib/test/gen_server_SUITE_data/oc_server.erl
@@ -22,7 +22,7 @@
-behaviour(gen_server).
%% API
--export([start/0]).
+-export([start/0, start/1]).
%% gen_server callbacks
-export([init/1]).
@@ -30,8 +30,12 @@
-record(state, {}).
start() ->
- gen_server:start({local, ?MODULE}, ?MODULE, [], []).
+ gen_server:start(?MODULE, ok, []).
-init([]) ->
- {ok, #state{}}.
+start(continue) ->
+ gen_server:start(?MODULE, continue, []).
+init(ok) ->
+ {ok, #state{}};
+init(continue) ->
+ {ok, #state{}, {continue, continue}}.