fixeria has uploaded this change for review.
erab_fsm: make erab_release_{cmd,ind}/1 non-blocking
There's no practical benefit(s) in blocking the caller while waiting
for the PFCP Session Deletion Response from the UPF. The response
does not contain any useful information for the caller.
Make the release related API non-blocking by using gen_statem:cast/2
instead of gen_statem:call/2. Adjust state functions to not reply.
Change-Id: If519334359c3ef331720cb87bdba2d969601816e
Related: SYS#7318
---
M src/erab_fsm.erl
M test/erab_fsm_test.erl
2 files changed, 15 insertions(+), 27 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/erlang/osmo-s1gw refs/changes/23/39523/1
diff --git a/src/erab_fsm.erl b/src/erab_fsm.erl
index 9ee9abe..bbb6dad 100644
--- a/src/erab_fsm.erl
+++ b/src/erab_fsm.erl
@@ -136,7 +136,7 @@
-spec erab_release_cmd(pid()) -> ok.
erab_release_cmd(Pid) ->
- gen_statem:call(Pid, ?FUNCTION_NAME).
+ gen_statem:cast(Pid, ?FUNCTION_NAME).
-spec erab_release_rsp(pid()) -> ok.
@@ -146,7 +146,7 @@
-spec erab_release_ind(pid()) -> ok.
erab_release_ind(Pid) ->
- gen_statem:call(Pid, ?FUNCTION_NAME).
+ gen_statem:cast(Pid, ?FUNCTION_NAME).
-spec fetch_info(pid()) -> proplists:proplist().
@@ -305,21 +305,17 @@
?LOG_DEBUG("State change: ~p -> ~p", [OldState, ?FUNCTION_NAME]),
{keep_state, S};
-erab_setup({call, From},
- erab_release_cmd,
+erab_setup(cast, erab_release_cmd,
#erab_state{} = S) ->
?LOG_DEBUG("Rx E-RAB RELEASE Cmd"),
{next_state, session_delete,
- S#erab_state{from = From,
- rel_kind = cmd}};
+ S#erab_state{rel_kind = cmd}};
-erab_setup({call, From},
- erab_release_ind,
+erab_setup(cast, erab_release_ind,
#erab_state{} = S) ->
?LOG_DEBUG("Rx E-RAB RELEASE Ind"),
{next_state, session_delete,
- S#erab_state{from = From,
- rel_kind = ind}};
+ S#erab_state{rel_kind = ind}};
erab_setup(Event, EventData, S) ->
handle_event(?FUNCTION_NAME, Event, EventData, S).
@@ -335,36 +331,27 @@
S#erab_state{seid_rem = undefined},
[{state_timeout, ?ERAB_T_SESSION_DELETE, ?FUNCTION_NAME}]};
-session_delete(state_timeout, _Timeout,
- #erab_state{from = From}) ->
+session_delete(state_timeout, _Timeout, _S) ->
?LOG_ERROR("PFCP session deletion timeout"),
- {stop_and_reply,
- {shutdown, timeout},
- {reply, From, {error, {timeout, ?FUNCTION_NAME}}}};
+ {stop, {shutdown, timeout}};
session_delete(info, #pfcp{} = PDU,
- #erab_state{from = From,
- seid_loc = SEID_Rsp,
+ #erab_state{seid_loc = SEID_Rsp,
rel_kind = RelKind} = S) ->
case PDU of
#pfcp{type = session_deletion_response,
seid = SEID_Rsp, %% matches F-SEID we sent in the ESTABLISH Req
ie = #{pfcp_cause := 'Request accepted'}} ->
?LOG_DEBUG("PFCP session deleted"),
- Reply = {reply, From, ok},
case RelKind of
cmd -> %% E-RAB RELEASE CMD => wait for the RSP
- {next_state, erab_wait_release_rsp,
- S#erab_state{from = undefined},
- [Reply]};
+ {next_state, erab_wait_release_rsp, S};
ind -> %% E-RAB RELEASE IND => terminate immediately
- {stop_and_reply, normal, [Reply]}
+ {stop, normal}
end;
_ ->
?LOG_ERROR("Rx unexpected PFCP PDU: ~p", [PDU]),
- {stop_and_reply,
- {shutdown, unexp_pdu},
- {reply, From, {error, {unexp_pdu, ?FUNCTION_NAME}}}}
+ {stop, {shutdown, unexp_pdu}}
end;
session_delete(Event, EventData, S) ->
diff --git a/test/erab_fsm_test.erl b/test/erab_fsm_test.erl
index e406e88..ec40e2e 100644
--- a/test/erab_fsm_test.erl
+++ b/test/erab_fsm_test.erl
@@ -125,10 +125,11 @@
PDU = pfcp_mock:pdu_rsp_reject(session_deletion_response, ?SEID_Loc),
pfcp_mock:mock_req(session_delete_req, PDU),
unlink(Pid), %% we expect the FSM to terminate abnormally
- Error = {unexp_pdu, session_delete},
[?_assertEqual({ok, ?A2U}, erab_fsm:erab_setup_req(Pid, ?U2C)),
?_assertEqual({ok, ?C2U}, erab_fsm:erab_setup_rsp(Pid, ?U2A)),
- ?_assertEqual({error, Error}, erab_fsm:erab_release_cmd(Pid)),
+ %% erab_fsm:erab_release_cmd/1 is non-blocking,
+ %% so we get ok before the error happens
+ ?_assertEqual(ok, erab_fsm:erab_release_cmd(Pid)),
?_assertNot(erlang:is_process_alive(Pid))].
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