source: mainline/uspace/srv/bd/hr/fge.c

/*
 * Copyright (c) 2025 Miroslav Cimerman
 * Copyright (c) 2024 Vojtech Horky
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup hr
 * @{
 */
/**
 * @file
 * @brief Fibril group executor
 *
 * Fibril pool with pre-allocated storage allowing
 * execution of groups consisting of multiple work
 * units.
 */

#include <adt/bitmap.h>
#include <adt/circ_buf.h>
#include <assert.h>
#include <errno.h>
#include <fibril_synch.h>
#include <stdatomic.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <types/common.h>

#include "fge.h"
#include "util.h"

static void *hr_fpool_make_storage(hr_fpool_t *, ssize_t *);
static void hr_fpool_group_epilogue(hr_fpool_t *);
static errno_t fge_fibril(void *);
static errno_t wu_queue_init(wu_queue_t *, size_t);
static void wu_queue_push(wu_queue_t *, fge_fibril_data_t *);
static void wu_queue_pop(wu_queue_t *, fge_fibril_data_t *);
static ssize_t hr_fpool_get_free_slot(hr_fpool_t *);

hr_fpool_t *hr_fpool_create(size_t fibril_cnt, size_t max_wus,
    size_t wu_storage_size)
{
        assert(max_wus > 0 && wu_storage_size > 0);

        void *bitmap_data = NULL;

        hr_fpool_t *result = calloc(1, sizeof(hr_fpool_t));
        if (result == NULL)
                return NULL;

        result->fibrils = malloc(sizeof(fid_t) * fibril_cnt);
        if (result->fibrils == NULL)
                goto bad;

        result->wu_storage = malloc(wu_storage_size * max_wus);
        if (result->wu_storage == NULL)
                goto bad;

        bitmap_data = calloc(1, bitmap_size(max_wus));
        if (bitmap_data == NULL)
                goto bad;
        bitmap_initialize(&result->bitmap, max_wus, bitmap_data);

        if (wu_queue_init(&result->queue, max_wus) != EOK)
                goto bad;

        fibril_mutex_initialize(&result->lock);
        fibril_condvar_initialize(&result->all_wus_done);

        result->max_wus = max_wus;
        result->fibril_cnt = fibril_cnt;
        result->wu_size = wu_storage_size;
        result->wu_storage_free_count = max_wus;
        result->stop = false;
        result->active_groups = 0;

        for (size_t i = 0; i < fibril_cnt; i++) {
                result->fibrils[i] = fibril_create(fge_fibril, result);
                fibril_start(result->fibrils[i]);
                /* fibril_detach(result->fibrils[i]); */
        }

        return result;
bad:
        if (result->queue.fexecs != NULL)
                free(result->queue.fexecs);
        if (bitmap_data != NULL)
                free(bitmap_data);
        if (result->wu_storage != NULL)
                free(result->wu_storage);
        if (result->fibrils != NULL)
                free(result->fibrils);
        free(result);

        return NULL;
}

void hr_fpool_destroy(hr_fpool_t *pool)
{
        fibril_mutex_lock(&pool->lock);
        pool->stop = true;
        while (pool->active_groups > 0)
                fibril_condvar_wait(&pool->all_wus_done, &pool->lock);

        fibril_mutex_unlock(&pool->lock);

        free(pool->bitmap.bits);
        free(pool->queue.fexecs);
        free(pool->wu_storage);
        free(pool->fibrils);
        free(pool);
}

hr_fgroup_t *hr_fgroup_create(hr_fpool_t *parent, size_t wu_cnt)
{
        assert(wu_cnt > 0);

        hr_fgroup_t *result = hr_malloc_waitok(sizeof(hr_fgroup_t));

        result->reserved_cnt = 0;
        result->own_mem = NULL;
        result->memslots = NULL;

        fibril_mutex_lock(&parent->lock);

        parent->active_groups++;

        if (parent->wu_storage_free_count >= wu_cnt) {
                parent->wu_storage_free_count -= wu_cnt;
                result->reserved_cnt = wu_cnt;
        } else {
                /*
                 * Could be more conservative with memory here and
                 * allocate space only for one work unit and execute
                 * work units sequentially like it was first intended with
                 * the fallback storage.
                 */
                size_t taking = parent->wu_storage_free_count;
                result->own_mem =
                    hr_malloc_waitok(parent->wu_size * (wu_cnt - taking));
                result->reserved_cnt = taking;
                parent->wu_storage_free_count = 0;
        }

        if (result->reserved_cnt > 0) {
                result->memslots =
                    hr_malloc_waitok(sizeof(size_t) * result->reserved_cnt);
        }

        fibril_mutex_unlock(&parent->lock);

        result->pool = parent;
        result->wu_cnt = wu_cnt;
        result->submitted = 0;
        result->reserved_avail = result->reserved_cnt;
        result->own_used = 0;
        result->final_errno = EOK;
        result->finished_okay = 0;
        result->finished_fail = 0;

        fibril_mutex_initialize(&result->lock);
        fibril_condvar_initialize(&result->all_done);

        return result;
}

void *hr_fgroup_alloc(hr_fgroup_t *group)
{
        void *storage;

        fibril_mutex_lock(&group->lock);

        assert(group->submitted < group->wu_cnt);

        if (group->reserved_avail > 0) {
                ssize_t memslot;
                storage = hr_fpool_make_storage(group->pool, &memslot);
                assert(storage != NULL);
                group->reserved_avail--;
                group->memslots[group->submitted] = memslot;
        } else {
                assert(group->own_mem != NULL);
                storage =
                    group->own_mem + group->pool->wu_size * group->own_used;
                group->own_used++;
        }

        fibril_mutex_unlock(&group->lock);

        return storage;
}

void hr_fgroup_submit(hr_fgroup_t *group, hr_wu_t wu, void *arg)
{
        fibril_mutex_lock(&group->lock);
        assert(group->submitted < group->wu_cnt);

        fge_fibril_data_t executor;
        executor.wu = wu;
        executor.arg = arg;
        executor.group = group;

        if (group->submitted < group->reserved_cnt)
                executor.memslot = group->memslots[group->submitted];
        else
                executor.memslot = -1;

        group->submitted++;
        fibril_mutex_unlock(&group->lock);

        wu_queue_push(&group->pool->queue, &executor);
}

errno_t hr_fgroup_wait(hr_fgroup_t *group, size_t *rokay, size_t *rfailed)
{
        fibril_mutex_lock(&group->lock);
        assert(group->submitted <= group->wu_cnt);

        while (true) {
                size_t finished = group->finished_fail + group->finished_okay;
                if (finished == group->submitted)
                        break;

                fibril_condvar_wait(&group->all_done, &group->lock);
        }

        if (rokay)
                *rokay = group->finished_okay;
        if (rfailed)
                *rfailed = group->finished_fail;

        errno_t rc = group->final_errno;

        fibril_mutex_unlock(&group->lock);

        hr_fpool_group_epilogue(group->pool);

        if (group->memslots != NULL)
                free(group->memslots);
        if (group->own_mem != NULL)
                free(group->own_mem);
        free(group);

        return rc;
}

static void *hr_fpool_make_storage(hr_fpool_t *pool, ssize_t *rmemslot)
{
        fibril_mutex_lock(&pool->lock);
        ssize_t memslot = hr_fpool_get_free_slot(pool);
        assert(memslot != -1);

        bitmap_set(&pool->bitmap, memslot, 1);

        fibril_mutex_unlock(&pool->lock);

        if (rmemslot)
                *rmemslot = memslot;

        return pool->wu_storage + pool->wu_size * memslot;
}

static void hr_fpool_group_epilogue(hr_fpool_t *pool)
{
        fibril_mutex_lock(&pool->lock);

        pool->active_groups--;
        if (pool->active_groups == 0)
                fibril_condvar_signal(&pool->all_wus_done);

        fibril_mutex_unlock(&pool->lock);
}

static errno_t fge_fibril(void *arg)
{
        hr_fpool_t *pool = arg;
        while (true) {
                fge_fibril_data_t executor;
                fibril_mutex_lock(&pool->lock);

                while (circ_buf_nused(&pool->queue.cbuf) == 0 && !pool->stop) {
                        fibril_condvar_wait(&pool->queue.not_empty,
                            &pool->lock);
                }

                if (pool->stop && circ_buf_nused(&pool->queue.cbuf) == 0) {
                        fibril_mutex_unlock(&pool->lock);
                        break;
                }

                wu_queue_pop(&pool->queue, &executor);

                fibril_mutex_unlock(&pool->lock);

                hr_fgroup_t *group = executor.group;

                errno_t rc = executor.wu(executor.arg);

                if (rc == EOK) {
                        fibril_mutex_lock(&group->lock);
                        group->finished_okay++;
                        fibril_mutex_unlock(&group->lock);
                } else {
                        fibril_mutex_lock(&group->lock);
                        group->finished_fail++;
                        if (rc == EAGAIN)
                                group->final_errno = EAGAIN;
                        fibril_mutex_unlock(&group->lock);
                }

                fibril_mutex_lock(&pool->lock);
                if (executor.memslot > -1) {
                        bitmap_set(&pool->bitmap, executor.memslot, 0);
                        pool->wu_storage_free_count++;
                }

                fibril_mutex_lock(&group->lock);
                size_t finished = group->finished_fail + group->finished_okay;
                if (finished == group->submitted)
                        fibril_condvar_signal(&group->all_done);
                fibril_mutex_unlock(&group->lock);

                fibril_mutex_unlock(&pool->lock);
        }
        return EOK;
}

static errno_t wu_queue_init(wu_queue_t *queue, size_t nmemb)
{
        queue->fexecs = malloc(sizeof(fge_fibril_data_t) * nmemb);
        if (queue->fexecs == NULL)
                return ENOMEM;

        circ_buf_init(&queue->cbuf, queue->fexecs, nmemb,
            sizeof(fge_fibril_data_t));

        fibril_mutex_initialize(&queue->lock);
        fibril_condvar_initialize(&queue->not_empty);
        fibril_condvar_initialize(&queue->not_full);

        return EOK;
}

static void wu_queue_push(wu_queue_t *queue, fge_fibril_data_t *executor)
{
        fibril_mutex_lock(&queue->lock);

        while (circ_buf_push(&queue->cbuf, executor) == EAGAIN)
                fibril_condvar_wait(&queue->not_full, &queue->lock);

        fibril_condvar_signal(&queue->not_empty);

        fibril_mutex_unlock(&queue->lock);
}

static void wu_queue_pop(wu_queue_t *queue, fge_fibril_data_t *executor)
{
        fibril_mutex_lock(&queue->lock);

        while (circ_buf_pop(&queue->cbuf, executor) == EAGAIN)
                fibril_condvar_wait(&queue->not_empty, &queue->lock);

        fibril_condvar_signal(&queue->not_full);

        fibril_mutex_unlock(&queue->lock);
}

static ssize_t hr_fpool_get_free_slot(hr_fpool_t *pool)
{
        bitmap_t *bitmap = &pool->bitmap;
        for (size_t i = 0; i < pool->max_wus; i++)
                if (!bitmap_get(bitmap, i))
                        return i;
        return -1;
}

/** @}
 */