osmo_fsm_inst_state_chg(): set T also for zero timeout

Before this patch, if timeout_secs == 0 was passed to
osmo_fsm_inst_state_chg(), the previous T value remained set in the
osmo_fsm_inst->T.

For example:

  osmo_fsm_inst_state_chg(fi, ST_X, 23, 42);
  // timer == 23 seconds; fi->T == 42
  osmo_fsm_inst_state_chg(fi, ST_Y, 0, 0);
  // no timer; fi->T == 42!

Instead, always set to the T value passed to osmo_fsm_inst_state_chg().

Adjust osmo_fsm_inst_state_chg() API doc; need to rephrase to accurately
describe the otherwise unchanged behaviour independently from T.

Verify in fsm_test.c.

Rationale: it is confusing to have a T number remaining from some past state,
especially since the user explicitly passed a T number to
osmo_fsm_inst_state_chg(). (Usually we are passing timeout_secs=0, T=0).

I first thought this behavior was introduced with
osmo_fsm_inst_state_chg_keep_timer(), but in fact osmo_fsm_inst_state_chg()
behaved this way from the start.

This shows up in the C test for the upcoming tdef API, where the test result
printout was showing some past T value sticking around after FSM state
transitions. After this patch, there will be no such confusion.

Change-Id: I65c7c262674a1bc5f37faeca6aa0320ab0174f3c
This commit is contained in:
Neels Hofmeyr 2019-01-28 15:38:09 +01:00 committed by Harald Welte
parent 4ff41d94ce
commit bd5a1dc84f
4 changed files with 71 additions and 7 deletions

View File

@ -458,9 +458,10 @@ static int state_chg(struct osmo_fsm_inst *fi, uint32_t new_state,
fi->state = new_state;
st = &fsm->states[new_state];
if (!keep_timer && timeout_secs) {
if (!keep_timer) {
fi->T = T;
osmo_timer_schedule(&fi->timer, timeout_secs, 0);
if (timeout_secs)
osmo_timer_schedule(&fi->timer, timeout_secs, 0);
}
/* Call 'onenter' last, user might terminate FSM from there */
@ -480,11 +481,17 @@ static int state_chg(struct osmo_fsm_inst *fi, uint32_t new_state,
* function. It verifies that the existing state actually permits a
* transition to new_state.
*
* timeout_secs and T are optional parameters, and only have any effect
* if timeout_secs is not 0. If the timeout function is used, then the
* new_state is entered, and the FSM instances timer is set to expire
* in timeout_secs functions. At that time, the FSM's timer_cb
* function will be called for handling of the timeout by the user.
* If timeout_secs is 0, stay in the new state indefinitely, without a timeout
* (stop the FSM instance's timer if it was runnning).
*
* If timeout_secs > 0, start or reset the FSM instance's timer with this
* timeout. On expiry, invoke the FSM instance's timer_cb -- if no timer_cb is
* set, an expired timer immediately terminates the FSM instance with
* OSMO_FSM_TERM_TIMEOUT.
*
* The value of T is stored in fi->T and is then available for query in
* timer_cb. If passing timeout_secs == 0, it is recommended to also pass T ==
* 0, so that fi->T is reset to 0 when no timeout is invoked.
*
* \param[in] fi FSM instance whose state is to change
* \param[in] new_state The new state into which we should change

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@ -349,6 +349,43 @@ static void test_state_chg_keep_timer()
fprintf(stderr, "--- %s() done\n", __func__);
}
static void test_state_chg_T()
{
struct osmo_fsm_inst *fi;
fprintf(stderr, "\n--- %s()\n", __func__);
fsm.timer_cb = NULL;
/* Test setting to timeout_secs = 0, T = 0 */
fi = osmo_fsm_inst_alloc(&fsm, g_ctx, NULL, LOGL_DEBUG, NULL);
OSMO_ASSERT(fi);
osmo_fsm_inst_state_chg(fi, ST_ONE, 23, 42);
printf("T = %d\n", fi->T);
OSMO_ASSERT(fi->T == 42);
osmo_fsm_inst_state_chg(fi, ST_TWO, 0, 0);
printf("T = %d\n", fi->T);
OSMO_ASSERT(fi->T == 0);
osmo_fsm_inst_term(fi, OSMO_FSM_TERM_REQUEST, NULL);
/* Test setting to timeout_secs = 0, T != 0 */
fi = osmo_fsm_inst_alloc(&fsm, g_ctx, NULL, LOGL_DEBUG, NULL);
OSMO_ASSERT(fi);
osmo_fsm_inst_state_chg(fi, ST_ONE, 23, 42);
printf("T = %d\n", fi->T);
OSMO_ASSERT(fi->T == 42);
osmo_fsm_inst_state_chg(fi, ST_TWO, 0, 11);
printf("T = %d\n", fi->T);
OSMO_ASSERT(fi->T == 11);
osmo_fsm_inst_term(fi, OSMO_FSM_TERM_REQUEST, NULL);
fprintf(stderr, "--- %s() done\n", __func__);
}
static const struct log_info_cat default_categories[] = {
[DMAIN] = {
.name = "DMAIN",
@ -390,6 +427,7 @@ int main(int argc, char **argv)
test_id_api();
test_state_chg_keep_timer();
test_state_chg_T();
osmo_fsm_unregister(&fsm);
exit(0);

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@ -101,3 +101,18 @@ Test_FSM{TWO}: Timeout of T10
Test_FSM{TWO}: Freeing instance
Test_FSM{TWO}: Deallocated
--- test_state_chg_keep_timer() done
--- test_state_chg_T()
Test_FSM{NULL}: Allocated
Test_FSM{NULL}: state_chg to ONE
Test_FSM{ONE}: state_chg to TWO
Test_FSM{TWO}: Terminating (cause = OSMO_FSM_TERM_REQUEST)
Test_FSM{TWO}: Freeing instance
Test_FSM{TWO}: Deallocated
Test_FSM{NULL}: Allocated
Test_FSM{NULL}: state_chg to ONE
Test_FSM{ONE}: state_chg to TWO
Test_FSM{TWO}: Terminating (cause = OSMO_FSM_TERM_REQUEST)
Test_FSM{TWO}: Freeing instance
Test_FSM{TWO}: Deallocated
--- test_state_chg_T() done

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@ -0,0 +1,4 @@
T = 42
T = 0
T = 42
T = 11