sysprof: allow calling sysprof.report before stop

It is not allowed to call a function `sysprof.report()` without
stopping the profiler. However, sometimes it may be useful to
analyze numbers provided by the report without stopping the
profiler. The patch removes the appropriate condition and allows
reporting without stopping.

Resolves tarantool/tarantool#11229

Reviewed-by: Sergey Kaplun <[email protected]>
Signed-off-by: Sergey Kaplun <[email protected]>
(cherry picked from commit c619bda)

Author: ligurio

src/lj_sysprof.c

@@ -532,8 +532,6 @@ int lj_sysprof_stop(lua_State *L)
 int lj_sysprof_report(struct luam_Sysprof_Counters *counters)
 {
   const struct sysprof *sp = &sysprof;
-  if (sp->state != SPS_IDLE)
-    return PROFILE_ERRUSE;
   memcpy(counters, &sp->counters, sizeof(sp->counters));
   return PROFILE_SUCCESS;
 }

test/tarantool-tests/profilers/misclib-sysprof-lapi.test.lua

@@ -10,7 +10,7 @@ local test = tap.test("misclib-sysprof-lapi"):skipcond({
   ["Disabled due to #10803"] = os.getenv("LUAJIT_TEST_USE_VALGRIND"),
 })
 
-test:plan(44)
+test:plan(45)
 
 jit.off()
 -- XXX: Run JIT tuning functions in a safe frame to avoid errors
@@ -166,13 +166,28 @@ test:is(err, nil, "no error with good interval 1")
 test:is(errno, nil, "no errno with good interval 1")
 misc.sysprof.stop()
 
+-- Intermediate sysprof.report().
+assert(misc.sysprof.start({
+    mode = "D",
+    interval = 1,
+    path = "/dev/null",
+}))
+
+payload()
+
+local report = misc.sysprof.report()
+-- Check the profile is not empty.
+test:ok(report.samples > 0,
+        "number of samples is greater than 0 for the default payload")
+assert(misc.sysprof.stop())
+
 -- DEFAULT MODE
 
 if not pcall(generate_output, { mode = "D", interval = 100 }) then
   test:fail('`default` mode with interval 100')
 end
 
-local report = misc.sysprof.report()
+report = misc.sysprof.report()
 
 -- Check the profile is not empty.
 test:ok(report.samples > 0,