/* Copyright 2016 Google Inc.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License. */

/* This tests nsync_once */

#include "platform.h"
#include "nsync.h"
#include "testing.h"
#include "closure.h"
#include "smprintf.h"

NSYNC_CPP_USING_

/* Data structure for each test of nsync_once */
struct once_test_s {
        nsync_once once;        /* the nsync_once under test */
        int counter;            /* a counter that should be incremented once */
        nsync_counter done;     /* reaches 0 when all threads done */
        testing t;              /* the test handle */
};

/* Per-thread data structure */
struct once_test_thread_s {
        int id;                 /* thread id */
        struct once_test_s *s;  /* the per-test structure */
};

#define N 4  /* number of threads used per test */
static struct once_test_thread_s ott[N];   /* data structure per thread */
static nsync_mu ott_s_mu = NSYNC_MU_INIT;

/* Increment s->counter by a power of two chosen by the thread id.  Called
   via one of the nsync_run_once* calls.  */
static void once_arg_func (void *v) {
        struct once_test_thread_s *lott = (struct once_test_thread_s *) v;
        struct once_test_s *s;
	nsync_mu_lock (&ott_s_mu);
        s = lott->s;
	nsync_mu_unlock (&ott_s_mu);
        if (s->counter != 0) {
                TEST_ERROR (s->t, ("once_arg_func found counter!=0"));
        }
        s->counter += 1 << (2 * lott->id);
}

/* Call once_arg_func() on the first thread structure. */
static void once_func0 (void) {
        once_arg_func (&ott[0]);
}

/* Call once_arg_func() on the second thread structure. */
static void once_func1 (void) {
        once_arg_func (&ott[1]);
}

/* Pause for a short time, then use one of the nsync_run_once* calls on
   ott->s->once, chosen using the thread id.  This is the body of each test
   thread.  */
static void once_thread (struct once_test_thread_s *lott) {
        struct once_test_s *s;
	nsync_mu_lock (&ott_s_mu);
        s = lott->s;
	nsync_mu_unlock (&ott_s_mu);
        nsync_time_sleep (nsync_time_s_ns (0, 1 * 1000 * 1000));
        switch (lott->id & 3) {
        case 0:  nsync_run_once (&s->once, &once_func0); break;
        case 1:  nsync_run_once_spin (&s->once, &once_func1); break;
        case 2:  nsync_run_once_arg (&s->once, &once_arg_func, lott); break;
        case 3:  nsync_run_once_arg_spin (&s->once, &once_arg_func, lott); break;
        }
        nsync_counter_add (s->done, -1);
}

CLOSURE_DECL_BODY1 (once_thread, struct once_test_thread_s *)

/* Test the functionality of nsync_once */
static void test_once_run (testing t) {
        int i;
        int j;
	for (j = 0; j != N; j++) {
		ott[j].id = j;
	}
        for (i = 0; i != 250; i++) {
                struct once_test_s *s =
			(struct once_test_s *) malloc (sizeof (*s));
                memset ((void *) s, 0, sizeof (*s));
                s->counter = 0;
                s->done = nsync_counter_new (N);
                s->t = t;
                for (j = 0; j != N; j++) {
			nsync_mu_lock (&ott_s_mu);
                        ott[j].s = s;
			nsync_mu_unlock (&ott_s_mu);
		}
                for (j = 0; j != N; j++) {
                        closure_fork (closure_once_thread (&once_thread,
                                                           &ott[j]));
                }
                if (nsync_counter_wait (s->done,
                                        nsync_time_no_deadline) != 0) {
                        TEST_ERROR (t, ("s.done not decremented to 0"));
                }
                if (s->counter == 0) {
                        TEST_ERROR (t, ("s.counter wasn't incremented"));
                }
                /* The counter is expected to be a power of two, because each
                   counter is incremented only via a single nsync_once (so at
                   most one increment should occur) and always by a power of
                   two.  */
                if ((s->counter & (s->counter-1)) != 0) {
                        TEST_ERROR (t, ("s.counter incremented repeatedly: %x",
                                        s->counter));
                }
		nsync_counter_free (s->done);
		free (s);
        }
}

/* Do nothing. */
static void no_op (void) {
}

/* Measure the performance of repeated use of nsync_run_once. */
static void benchmark_nsync_once (testing t) {
	static nsync_once o = NSYNC_ONCE_INIT;
	int n = testing_n (t);
	int i;
	for (i = 0; i != n; i++) {
		nsync_run_once (&o, &no_op);
	}
}

/* Measure the performance of repeated use of pthread_once. */
static void benchmark_native_once (testing t) {
	static pthread_once_t o = PTHREAD_ONCE_INIT;
	int n = testing_n (t);
	int i;
	for (i = 0; i != n; i++) {
		pthread_once (&o, &no_op);
	}
}

int main (int argc, char *argv[]) {
        testing_base tb = testing_new (argc, argv, 0);
        TEST_RUN (tb, test_once_run);
	BENCHMARK_RUN (tb, benchmark_nsync_once);
	BENCHMARK_RUN (tb, benchmark_native_once);
        return (testing_base_exit (tb));
}