// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2018 Davidlohr Bueso.
 *
 * Benchmark the various operations allowed for epoll_ctl(2).
 * The idea is to concurrently stress a single epoll instance
 */
#ifdef HAVE_EVENTFD_SUPPORT
/* For the CLR_() macros */
#include <string.h>
#include <pthread.h>

#include <errno.h>
#include <inttypes.h>
#include <signal.h>
#include <stdlib.h>
#include <unistd.h>
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/epoll.h>
#include <sys/eventfd.h>
#include <perf/cpumap.h>

#include "../util/mutex.h"
#include "../util/stat.h"
#include <subcmd/parse-options.h>
#include "bench.h"

#include <err.h>

#define printinfo(fmt, arg...) \
        do { if (__verbose) printf(fmt, ## arg); } while (0)

static unsigned int nthreads = 0;
static unsigned int nsecs    = 8;
static bool done, __verbose, randomize;

/*
 * epoll related shared variables.
 */

/* Maximum number of nesting allowed inside epoll sets */
#define EPOLL_MAXNESTS 4

enum {
        OP_EPOLL_ADD,
        OP_EPOLL_MOD,
        OP_EPOLL_DEL,
        EPOLL_NR_OPS,
};

static int epollfd;
static int *epollfdp;
static bool noaffinity;
static unsigned int nested = 0;

/* amount of fds to monitor, per thread */
static unsigned int nfds = 64;

static struct mutex thread_lock;
static unsigned int threads_starting;
static struct stats all_stats[EPOLL_NR_OPS];
static struct cond thread_parent, thread_worker;

struct worker {
        int tid;
        pthread_t thread;
        unsigned long ops[EPOLL_NR_OPS];
        int *fdmap;
};

static const struct option options[] = {
        OPT_UINTEGER('t', "threads", &nthreads, "Specify amount of threads"),
        OPT_UINTEGER('r', "runtime", &nsecs,    "Specify runtime (in seconds)"),
        OPT_UINTEGER('f', "nfds", &nfds, "Specify amount of file descriptors to monitor for each thread"),
        OPT_BOOLEAN( 'n', "noaffinity",  &noaffinity,   "Disables CPU affinity"),
        OPT_UINTEGER( 'N', "nested",  &nested,   "Nesting level epoll hierarchy (default is 0, no nesting)"),
        OPT_BOOLEAN( 'R', "randomize", &randomize,   "Perform random operations on random fds"),
        OPT_BOOLEAN( 'v', "verbose",  &__verbose,   "Verbose mode"),
        OPT_END()
};

static const char * const bench_epoll_ctl_usage[] = {
        "perf bench epoll ctl <options>",
        NULL
};

static void toggle_done(int sig __maybe_unused,
                        siginfo_t *info __maybe_unused,
                        void *uc __maybe_unused)
{
        /* inform all threads that we're done for the day */
        done = true;
        gettimeofday(&bench__end, NULL);
        timersub(&bench__end, &bench__start, &bench__runtime);
}

static void nest_epollfd(void)
{
        unsigned int i;
        struct epoll_event ev;

        if (nested > EPOLL_MAXNESTS)
                nested = EPOLL_MAXNESTS;
        printinfo("Nesting level(s): %d\n", nested);

        epollfdp = calloc(nested, sizeof(int));
        if (!epollfdp)
                err(EXIT_FAILURE, "calloc");

        for (i = 0; i < nested; i++) {
                epollfdp[i] = epoll_create(1);
                if (epollfd < 0)
                        err(EXIT_FAILURE, "epoll_create");
        }

        ev.events = EPOLLHUP; /* anything */
        ev.data.u64 = i; /* any number */

        for (i = nested - 1; i; i--) {
                if (epoll_ctl(epollfdp[i - 1], EPOLL_CTL_ADD,
                              epollfdp[i], &ev) < 0)
                        err(EXIT_FAILURE, "epoll_ctl");
        }

        if (epoll_ctl(epollfd, EPOLL_CTL_ADD, *epollfdp, &ev) < 0)
                err(EXIT_FAILURE, "epoll_ctl");
}

static inline void do_epoll_op(struct worker *w, int op, int fd)
{
        int error;
        struct epoll_event ev;

        ev.events = EPOLLIN;
        ev.data.u64 = fd;

        switch (op) {
        case OP_EPOLL_ADD:
                error = epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &ev);
                break;
        case OP_EPOLL_MOD:
                ev.events = EPOLLOUT;
                error = epoll_ctl(epollfd, EPOLL_CTL_MOD, fd, &ev);
                break;
        case OP_EPOLL_DEL:
                error = epoll_ctl(epollfd, EPOLL_CTL_DEL, fd, NULL);
                break;
        default:
                error = 1;
                break;
        }

        if (!error)
                w->ops[op]++;
}

static inline void do_random_epoll_op(struct worker *w)
{
        unsigned long rnd1 = random(), rnd2 = random();
        int op, fd;

        fd = w->fdmap[rnd1 % nfds];
        op = rnd2 % EPOLL_NR_OPS;

        do_epoll_op(w, op, fd);
}

static void *workerfn(void *arg)
{
        unsigned int i;
        struct worker *w = (struct worker *) arg;
        struct timespec ts = { .tv_sec = 0,
                               .tv_nsec = 250 };

        mutex_lock(&thread_lock);
        threads_starting--;
        if (!threads_starting)
                cond_signal(&thread_parent);
        cond_wait(&thread_worker, &thread_lock);
        mutex_unlock(&thread_lock);

        /* Let 'em loose */
        do {
                /* random */
                if (randomize) {
                        do_random_epoll_op(w);
                } else {
                        for (i = 0; i < nfds; i++) {
                                do_epoll_op(w, OP_EPOLL_ADD, w->fdmap[i]);
                                do_epoll_op(w, OP_EPOLL_MOD, w->fdmap[i]);
                                do_epoll_op(w, OP_EPOLL_DEL, w->fdmap[i]);
                        }
                }

                nanosleep(&ts, NULL);
        }  while (!done);

        return NULL;
}

static void init_fdmaps(struct worker *w, int pct)
{
        unsigned int i;
        int inc;
        struct epoll_event ev;

        if (!pct)
                return;

        inc = 100/pct;
        for (i = 0; i < nfds; i+=inc) {
                ev.data.fd = w->fdmap[i];
                ev.events = EPOLLIN;

                if (epoll_ctl(epollfd, EPOLL_CTL_ADD, w->fdmap[i], &ev) < 0)
                        err(EXIT_FAILURE, "epoll_ct");
        }
}

static int do_threads(struct worker *worker, struct perf_cpu_map *cpu)
{
        pthread_attr_t thread_attr, *attrp = NULL;
        cpu_set_t *cpuset;
        unsigned int i, j;
        int ret = 0;
        int nrcpus;
        size_t size;

        if (!noaffinity)
                pthread_attr_init(&thread_attr);

        nrcpus = cpu__max_cpu().cpu;
        cpuset = CPU_ALLOC(nrcpus);
        BUG_ON(!cpuset);
        size = CPU_ALLOC_SIZE(nrcpus);

        for (i = 0; i < nthreads; i++) {
                struct worker *w = &worker[i];

                w->tid = i;
                w->fdmap = calloc(nfds, sizeof(int));
                if (!w->fdmap)
                        return 1;

                for (j = 0; j < nfds; j++) {
                        w->fdmap[j] = eventfd(0, EFD_NONBLOCK);
                        if (w->fdmap[j] < 0)
                                err(EXIT_FAILURE, "eventfd");
                }

                /*
                 * Lets add 50% of the fdmap to the epoll instance, and
                 * do it before any threads are started; otherwise there is
                 * an initial bias of the call failing  (mod and del ops).
                 */
                if (randomize)
                        init_fdmaps(w, 50);

                if (!noaffinity) {
                        CPU_ZERO_S(size, cpuset);
                        CPU_SET_S(perf_cpu_map__cpu(cpu, i % perf_cpu_map__nr(cpu)).cpu,
                                        size, cpuset);

                        ret = pthread_attr_setaffinity_np(&thread_attr, size, cpuset);
                        if (ret) {
                                CPU_FREE(cpuset);
                                err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
                        }

                        attrp = &thread_attr;
                }

                ret = pthread_create(&w->thread, attrp, workerfn,
                                     (void *)(struct worker *) w);
                if (ret) {
                        CPU_FREE(cpuset);
                        err(EXIT_FAILURE, "pthread_create");
                }
        }

        CPU_FREE(cpuset);
        if (!noaffinity)
                pthread_attr_destroy(&thread_attr);

        return ret;
}

static void print_summary(void)
{
        int i;
        unsigned long avg[EPOLL_NR_OPS];
        double stddev[EPOLL_NR_OPS];

        for (i = 0; i < EPOLL_NR_OPS; i++) {
                avg[i] = avg_stats(&all_stats[i]);
                stddev[i] = stddev_stats(&all_stats[i]);
        }

        printf("\nAveraged %ld ADD operations (+- %.2f%%)\n",
               avg[OP_EPOLL_ADD], rel_stddev_stats(stddev[OP_EPOLL_ADD],
                                                   avg[OP_EPOLL_ADD]));
        printf("Averaged %ld MOD operations (+- %.2f%%)\n",
               avg[OP_EPOLL_MOD], rel_stddev_stats(stddev[OP_EPOLL_MOD],
                                                   avg[OP_EPOLL_MOD]));
        printf("Averaged %ld DEL operations (+- %.2f%%)\n",
               avg[OP_EPOLL_DEL], rel_stddev_stats(stddev[OP_EPOLL_DEL],
                                                   avg[OP_EPOLL_DEL]));
}

int bench_epoll_ctl(int argc, const char **argv)
{
        int j, ret = 0;
        struct sigaction act;
        struct worker *worker = NULL;
        struct perf_cpu_map *cpu;
        struct rlimit rl, prevrl;
        unsigned int i;

        argc = parse_options(argc, argv, options, bench_epoll_ctl_usage, 0);
        if (argc) {
                usage_with_options(bench_epoll_ctl_usage, options);
                exit(EXIT_FAILURE);
        }

        memset(&act, 0, sizeof(act));
        sigfillset(&act.sa_mask);
        act.sa_sigaction = toggle_done;
        sigaction(SIGINT, &act, NULL);

        cpu = perf_cpu_map__new_online_cpus();
        if (!cpu)
                goto errmem;

        /* a single, main epoll instance */
        epollfd = epoll_create(1);
        if (epollfd < 0)
                err(EXIT_FAILURE, "epoll_create");

        /*
         * Deal with nested epolls, if any.
         */
        if (nested)
                nest_epollfd();

        /* default to the number of CPUs */
        if (!nthreads)
                nthreads = perf_cpu_map__nr(cpu);

        worker = calloc(nthreads, sizeof(*worker));
        if (!worker)
                goto errmem;

        if (getrlimit(RLIMIT_NOFILE, &prevrl))
            err(EXIT_FAILURE, "getrlimit");
        rl.rlim_cur = rl.rlim_max = nfds * nthreads * 2 + 50;
        printinfo("Setting RLIMIT_NOFILE rlimit from %" PRIu64 " to: %" PRIu64 "\n",
                  (uint64_t)prevrl.rlim_max, (uint64_t)rl.rlim_max);
        if (setrlimit(RLIMIT_NOFILE, &rl) < 0)
                err(EXIT_FAILURE, "setrlimit");

        printf("Run summary [PID %d]: %d threads doing epoll_ctl ops "
               "%d file-descriptors for %d secs.\n\n",
               getpid(), nthreads, nfds, nsecs);

        for (i = 0; i < EPOLL_NR_OPS; i++)
                init_stats(&all_stats[i]);

        mutex_init(&thread_lock);
        cond_init(&thread_parent);
        cond_init(&thread_worker);

        threads_starting = nthreads;

        gettimeofday(&bench__start, NULL);

        do_threads(worker, cpu);

        mutex_lock(&thread_lock);
        while (threads_starting)
                cond_wait(&thread_parent, &thread_lock);
        cond_broadcast(&thread_worker);
        mutex_unlock(&thread_lock);

        sleep(nsecs);
        toggle_done(0, NULL, NULL);
        printinfo("main thread: toggling done\n");

        for (i = 0; i < nthreads; i++) {
                ret = pthread_join(worker[i].thread, NULL);
                if (ret)
                        err(EXIT_FAILURE, "pthread_join");
        }

        /* cleanup & report results */
        cond_destroy(&thread_parent);
        cond_destroy(&thread_worker);
        mutex_destroy(&thread_lock);

        for (i = 0; i < nthreads; i++) {
                unsigned long t[EPOLL_NR_OPS];

                for (j = 0; j < EPOLL_NR_OPS; j++) {
                        t[j] = worker[i].ops[j];
                        update_stats(&all_stats[j], t[j]);
                }

                if (nfds == 1)
                        printf("[thread %2d] fdmap: %p [ add: %04ld; mod: %04ld; del: %04lds ops ]\n",
                               worker[i].tid, &worker[i].fdmap[0],
                               t[OP_EPOLL_ADD], t[OP_EPOLL_MOD], t[OP_EPOLL_DEL]);
                else
                        printf("[thread %2d] fdmap: %p ... %p [ add: %04ld ops; mod: %04ld ops; del: %04ld ops ]\n",
                               worker[i].tid, &worker[i].fdmap[0],
                               &worker[i].fdmap[nfds-1],
                               t[OP_EPOLL_ADD], t[OP_EPOLL_MOD], t[OP_EPOLL_DEL]);
        }

        print_summary();

        close(epollfd);
        perf_cpu_map__put(cpu);
        for (i = 0; i < nthreads; i++)
                free(worker[i].fdmap);

        free(worker);
        return ret;
errmem:
        err(EXIT_FAILURE, "calloc");
}
#endif // HAVE_EVENTFD_SUPPORT