examples/performance-thread/common/lthread_tls.c

/* SPDX-License-Identifier: BSD-3-Clause
 * Copyright(c) 2015 Intel Corporation
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <limits.h>
#include <inttypes.h>
#include <unistd.h>
#include <pthread.h>
#include <fcntl.h>
#include <sys/time.h>
#include <sys/mman.h>
#include <sched.h>

#include <rte_malloc.h>
#include <rte_log.h>
#include <rte_ring.h>
#include <rte_atomic_64.h>

#include "lthread_tls.h"
#include "lthread_queue.h"
#include "lthread_objcache.h"
#include "lthread_sched.h"

static struct rte_ring *key_pool;
static uint64_t key_pool_init;

/* needed to cause section start and end to be defined */
RTE_DEFINE_PER_LTHREAD(void *, dummy);

static struct lthread_key key_table[LTHREAD_MAX_KEYS];

RTE_INIT(thread_tls_ctor)
{
    key_pool = NULL;
    key_pool_init = 0;
}

/*
 * Initialize a pool of keys
 * These are unique tokens that can be obtained by threads
 * calling lthread_key_create()
 */
void _lthread_key_pool_init(void)
{
    static struct rte_ring *pool;
    struct lthread_key *new_key;
    char name[MAX_LTHREAD_NAME_SIZE];

    bzero(key_table, sizeof(key_table));

    /* only one lcore should do this */
    if (rte_atomic64_cmpset(&key_pool_init, 0, 1)) {

        snprintf(name,
            MAX_LTHREAD_NAME_SIZE,
            "lthread_key_pool_%d",
            getpid());

        pool = rte_ring_create(name,
                    LTHREAD_MAX_KEYS, 0, 0);
        RTE_ASSERT(pool);

        int i;

        for (i = 1; i < LTHREAD_MAX_KEYS; i++) {
            new_key = &key_table[i];
            rte_ring_mp_enqueue((struct rte_ring *)pool,
                        (void *)new_key);
        }
        key_pool = pool;
    }
    /* other lcores wait here till done */
    while (key_pool == NULL) {
        rte_compiler_barrier();
        sched_yield();
    };
}

/*
 * Create a key
 * this means getting a key from the pool
 */
int lthread_key_create(unsigned int *key, tls_destructor_func destructor)
{
    if (key == NULL)
        return POSIX_ERRNO(EINVAL);

    struct lthread_key *new_key;

    if (rte_ring_mc_dequeue((struct rte_ring *)key_pool, (void **)&new_key)
        == 0) {
        new_key->destructor = destructor;
        *key = (new_key - key_table);

        return 0;
    }
    return POSIX_ERRNO(EAGAIN);
}


/*
 * Delete a key
 */
int lthread_key_delete(unsigned int k)
{
    struct lthread_key *key;

    key = (struct lthread_key *) &key_table[k];

    if (k > LTHREAD_MAX_KEYS)
        return POSIX_ERRNO(EINVAL);

    key->destructor = NULL;
    rte_ring_mp_enqueue((struct rte_ring *)key_pool,
                    (void *)key);
    return 0;
}



/*
 * Break association for all keys in use by this thread
 * invoke the destructor if available.
 * Since a destructor can create keys we could enter an infinite loop
 * therefore we give up after LTHREAD_DESTRUCTOR_ITERATIONS
 * the behavior is modelled on pthread
 */
void _lthread_tls_destroy(struct lthread *lt)
{
    int i, k;
    int nb_keys;
    void *data;

    for (i = 0; i < LTHREAD_DESTRUCTOR_ITERATIONS; i++) {

        for (k = 1; k < LTHREAD_MAX_KEYS; k++) {

            /* no keys in use ? */
            nb_keys = lt->tls->nb_keys_inuse;
            if (nb_keys == 0)
                return;

            /* this key not in use ? */
            if (lt->tls->data[k] == NULL)
                continue;

            /* remove this key */
            data = lt->tls->data[k];
            lt->tls->data[k] = NULL;
            lt->tls->nb_keys_inuse = nb_keys-1;

            /* invoke destructor */
            if (key_table[k].destructor != NULL)
                key_table[k].destructor(data);
        }
    }
}

/*
 * Return the pointer associated with a key
 * If the key is no longer valid return NULL
 */
void
*lthread_getspecific(unsigned int k)
{
    void *res = NULL;

    if (k < LTHREAD_MAX_KEYS)
        res = THIS_LTHREAD->tls->data[k];

    return res;
}

/*
 * Set a value against a key
 * If the key is no longer valid return an error
 * when storing value
 */
int lthread_setspecific(unsigned int k, const void *data)
{
    if (k >= LTHREAD_MAX_KEYS)
        return POSIX_ERRNO(EINVAL);

    int n = THIS_LTHREAD->tls->nb_keys_inuse;

    /* discard const qualifier */
    char *p = (char *) (uintptr_t) data;


    if (data != NULL) {
        if (THIS_LTHREAD->tls->data[k] == NULL)
            THIS_LTHREAD->tls->nb_keys_inuse = n+1;
    }

    THIS_LTHREAD->tls->data[k] = (void *) p;
    return 0;
}

/*
 * Allocate data for TLS cache
*/
void _lthread_tls_alloc(struct lthread *lt)
{
    struct lthread_tls *tls;

    tls = _lthread_objcache_alloc((THIS_SCHED)->tls_cache);

    RTE_ASSERT(tls != NULL);

    tls->root_sched = (THIS_SCHED);
    lt->tls = tls;

    /* allocate data for TLS varaiables using RTE_PER_LTHREAD macros */
    if (sizeof(void *) < (uint64_t)RTE_PER_LTHREAD_SECTION_SIZE) {
        lt->per_lthread_data =
            _lthread_objcache_alloc((THIS_SCHED)->per_lthread_cache);
    }
}