uthread.c

Go to the documentation of this file.

/* -*- C -*- */
/*
 * Copyright (c) 2012-2020 Seagate Technology LLC and/or its Affiliates
 *
 * 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.
 *
 * For any questions about this software or licensing,
 * please email opensource@seagate.com or cortx-questions@seagate.com.
 *
 */


#include <stdlib.h>      /* getenv */
#include <unistd.h>      /* getpid */
#include <errno.h>       /* program_invocation_name */
#include <stdio.h>       /* snprinf */
#include <linux/limits.h>/* PATH_MAX */

#define M0_TRACE_SUBSYSTEM M0_TRACE_SUBSYS_MEMORY
#include "lib/trace.h"
#include "lib/misc.h"    /* M0_SET0 */
#include "lib/string.h"  /* m0_strdup */
#include "lib/memory.h"
#include "lib/errno.h"
#include "lib/thread.h"
#include "lib/arith.h"
#include "lib/bitmap.h"
#include "lib/assert.h"
#include "module/instance.h"  /* m0_set */
#include "addb2/global.h"     /* m0_addb2_global_thread_enter */

static pthread_attr_t pthread_attr_default;

static __thread struct m0_thread thread = {};
static __thread struct m0_thread_tls *tls = NULL;

static struct m0_thread main_thread = {
        .t_state = TS_RUNNING,
        .t_tls   = {
                .tls_self = &main_thread
        },
        .t_namebuf = "main()"
};

M0_INTERNAL struct m0_thread_tls *m0_thread_tls(void)
{
        if (tls == NULL) {
                thread = (struct m0_thread) {
                        .t_state = TS_RUNNING,
                        .t_tls   = {
                                .tls_m0_instance =
                                        main_thread.t_tls.tls_m0_instance,
                                .tls_self = &thread,
                        },
                        .t_namebuf = "anon"
                };
                tls = &thread.t_tls;
        }
        return tls;
}

static void *uthread_trampoline(void *arg)
{
        struct m0_thread *t = arg;

        tls = &t->t_tls;
        m0_thread_trampoline(arg);
        tls = NULL;
        return NULL;
}

M0_INTERNAL int m0_thread_init_impl(struct m0_thread *q, const char *_)
{
        M0_PRE(q->t_state == TS_RUNNING);

        return -pthread_create(&q->t_h.h_id, &pthread_attr_default,
                               uthread_trampoline, q);
}

int m0_thread_join(struct m0_thread *q)
{
        int result;

        M0_PRE(q->t_state == TS_RUNNING);
        M0_PRE(!pthread_equal(q->t_h.h_id, pthread_self()));

        result = -pthread_join(q->t_h.h_id, NULL);
        if (result == 0)
                q->t_state = TS_PARKED;
        return result;
}

M0_INTERNAL int m0_thread_signal(struct m0_thread *q, int sig)
{
        return -pthread_kill(q->t_h.h_id, sig);
}

M0_INTERNAL int m0_thread_confine(struct m0_thread *q,
                                  const struct m0_bitmap *processors)
{
        size_t    idx;
        size_t    nr_bits = min64u(processors->b_nr, CPU_SETSIZE);
        cpu_set_t cpuset;

        CPU_ZERO(&cpuset);

        for (idx = 0; idx < nr_bits; ++idx) {
                if (m0_bitmap_get(processors, idx))
                        CPU_SET(idx, &cpuset);
        }

        return -pthread_setaffinity_np(q->t_h.h_id, sizeof cpuset, &cpuset);
}

M0_INTERNAL char m0_argv0[PATH_MAX] = {};

M0_INTERNAL char *m0_debugger_args[4] = {
        NULL, /* debugger name */
        NULL, /* our binary name */
        NULL, /* our process id */
        NULL
};

M0_INTERNAL int m0_threads_init(struct m0 *instance)
{
        m0_set(instance);
        return -pthread_attr_init(&pthread_attr_default) ?:
                -pthread_attr_setdetachstate(&pthread_attr_default,
                                             PTHREAD_CREATE_JOINABLE);
}

M0_INTERNAL void m0_threads_fini(void)
{
        (void)pthread_attr_destroy(&pthread_attr_default);
}

M0_INTERNAL int m0_threads_once_init(void)
{
        static char             pidbuf[20];
        char                   *env_ptr;

        if (readlink("/proc/self/exe", m0_argv0, sizeof m0_argv0) == -1)
                return M0_ERR_INFO(errno, "%s", strerror(errno));

        env_ptr = getenv("M0_DEBUGGER");
        if (env_ptr != NULL)
                m0_debugger_args[0] = m0_strdup(env_ptr);
        /*
         * Note: program_invocation_name requires _GNU_SOURCE.
         */
        m0_debugger_args[1] = program_invocation_name;
        m0_debugger_args[2] = pidbuf;
        (void)snprintf(pidbuf, ARRAY_SIZE(pidbuf), "%i", getpid());
        tls = &main_thread.t_tls;
        return 0;
}

M0_INTERNAL void m0_threads_once_fini(void)
{
        m0_free0(&m0_debugger_args[0]);
}

M0_INTERNAL void m0_enter_awkward(void)
{
        struct m0_thread_tls *tls = m0_thread_tls();

        /*
         * m0_enter_awkward() can be called at arbitrary moment. It is possible
         * that TLS is not yet set (or already released) at this time (this
         * happens, for example, when a timer signal) arrives to a thread
         * executing glibc code, creating or destroying a thread.
         */
        if (tls != NULL)
                M0_CNT_INC(tls->tls_arch.tat_awkward);
}

M0_INTERNAL void m0_exit_awkward(void)
{
        struct m0_thread_tls *tls = m0_thread_tls();

        if (tls != NULL)
                M0_CNT_DEC(tls->tls_arch.tat_awkward);
}

M0_INTERNAL bool m0_is_awkward(void)
{
        return m0_thread_tls()->tls_arch.tat_awkward != 0;
}

M0_INTERNAL uint64_t m0_pid(void)
{
        return getpid();
}

M0_INTERNAL uint64_t m0_process(void)
{
        return m0_pid();
}

M0_INTERNAL int m0_thread_arch_adopt(struct m0_thread *thread,
                                     struct m0 *instance, bool full)
{
        M0_PRE(M0_IS0(thread));

        thread->t_tls.tls_self = thread;
        tls = &thread->t_tls;
        m0_set(instance);
        if (full)
                m0_addb2_global_thread_enter();
        return 0;
}

M0_INTERNAL void m0_thread_arch_shun(void)
{
        m0_addb2_global_thread_leave();
        tls = NULL;
}

#undef M0_TRACE_SUBSYSTEM

/*
 *  Local variables:
 *  c-indentation-style: "K&R"
 *  c-basic-offset: 8
 *  tab-width: 8
 *  fill-column: 80
 *  scroll-step: 1
 *  End:
 */