source: mainline/uspace/srv/sysman/sysman.c@ e8747bd8

/*
 * Copyright (c) 2015 Michal Koutny
 * 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.
 */

#include <adt/hash_table.h>
#include <adt/list.h>
#include <errno.h>
#include <fibril_synch.h>
#include <stdlib.h>

#include "log.h"
#include "sysman.h"
#include "task.h"
#include "unit.h"


/* Do not expose this generally named type */
typedef struct {
        link_t event_queue;

        event_handler_t handler;
        void *data;
} event_t;

typedef struct {
        link_t callbacks;

        callback_handler_t handler;
        void *data;
} obj_callback_t;

typedef struct {
        ht_link_t ht_link;

        void *object;
        list_t callbacks;
} observed_object_t;

static LIST_INITIALIZE(event_queue);
static fibril_mutex_t event_queue_mtx;
static fibril_condvar_t event_queue_nonempty_cv;
static fibril_condvar_t event_queue_empty_cv;

static hash_table_t observed_objects;
static fibril_mutex_t observed_objects_mtx;
static fibril_condvar_t observed_objects_cv;

/*
 * Hash table functions
 */
static size_t observed_objects_ht_hash(const ht_link_t *item)
{
        observed_object_t *callbacks =
            hash_table_get_inst(item, observed_object_t, ht_link);

        return (size_t) callbacks->object;
}

static size_t observed_objects_ht_key_hash(void *key)
{
        void *object = *(void **) key;
        return (size_t) object;
}

static bool observed_objects_ht_key_equal(void *key, const ht_link_t *item)
{
        void *object = *(void **)key;
        return (
            hash_table_get_inst(item, observed_object_t, ht_link)->object ==
            object);
}

static hash_table_ops_t observed_objects_ht_ops = {
        .hash            = &observed_objects_ht_hash,
        .key_hash        = &observed_objects_ht_key_hash,
        .equal           = NULL,
        .key_equal       = &observed_objects_ht_key_equal,
        .remove_callback = NULL
};

/*
 * Static functions
 */

static observed_object_t *observed_object_create(void *object)
{
        observed_object_t *result = malloc(sizeof(observed_object_t));
        if (result) {
                result->object = object;
                list_initialize(&result->callbacks);
                hash_table_insert(&observed_objects, &result->ht_link);
        }
        return result;
}

static void observed_object_destroy(observed_object_t **ptr_observed_object)
{
        observed_object_t *observed_object = *ptr_observed_object;
        if (observed_object == NULL) {
                return;
        }

        ht_link_t *item = &observed_object->ht_link;
        hash_table_remove_item(&observed_objects, item);
        free(observed_object);
        *ptr_observed_object = NULL;
}

static void notify_observers(void *object)
{
        ht_link_t *item = hash_table_find(&observed_objects, &object);
        if (item == NULL) {
                return;
        }
        observed_object_t *observed_object =
            hash_table_get_inst(item, observed_object_t, ht_link);

        list_foreach_safe(observed_object->callbacks, cur_link, next_link) {
                obj_callback_t *callback =
                    list_get_instance(cur_link, obj_callback_t, callbacks);
                callback->handler(object, callback->data);
                list_remove(cur_link);
                free(callback);
        }

        observed_object_destroy(&observed_object);
}

/*
 * Non-static functions
 */
void sysman_events_init(void)
{
        fibril_mutex_initialize(&event_queue_mtx);
        fibril_condvar_initialize(&event_queue_nonempty_cv);
        fibril_condvar_initialize(&event_queue_empty_cv);

        bool table =
            hash_table_create(&observed_objects, 0, 0, &observed_objects_ht_ops);
        if (!table) {
                sysman_log(LVL_FATAL, "%s: Failed initialization", __func__);
                abort();
        }
        fibril_mutex_initialize(&observed_objects_mtx);
        fibril_condvar_initialize(&observed_objects_cv);
}

int sysman_events_loop(void *unused)
{
        while (1) {
                /* Pop event */
                fibril_mutex_lock(&event_queue_mtx);
                while (list_empty(&event_queue)) {
                        fibril_condvar_signal(&event_queue_empty_cv);
                        fibril_condvar_wait(&event_queue_nonempty_cv,
                            &event_queue_mtx);
                }

                link_t *li_event = list_first(&event_queue);
                list_remove(li_event);
                event_t *event =
                    list_get_instance(li_event, event_t, event_queue);
                fibril_mutex_unlock(&event_queue_mtx);

                /* Process event */
                //sysman_log(LVL_DEBUG2, "process_event(%p, %p)",
                //    event->handler, event->data);
                event->handler(event->data);
                free(event);
        }
}

/** Create and queue job for unit
 *
 * If unit already has the same job assigned callback is moved to it.
 *
 * @param[in]  callback  (optional) callback must explicitly delete reference
 *                       to job, void callback(void *job, void *callback_arg)
 *
 * return EBUSY  unit already has a job assigned of different type
 */
int sysman_run_job(unit_t *unit, unit_state_t target_state,
    callback_handler_t callback, void *callback_arg)
{
        job_t *job = job_create(unit, target_state);
        if (job == NULL) {
                return ENOMEM;
        }

        if (callback != NULL) {
                job_add_ref(job);
                //TODO sysman_object_observer is not fibril-safe CANNOT BE CALLED HERE!
                sysman_object_observer(job, callback, callback_arg);
        }

        /* Pass reference to event */
        sysman_raise_event(&sysman_event_job_process, job);

        return EOK;
}

void sysman_raise_event(event_handler_t handler, void *data)
{
        //sysman_log(LVL_DEBUG2, "%s(%p, %p)", __func__, handler, data);
        event_t *event = malloc(sizeof(event_t));
        if (event == NULL) {
                sysman_log(LVL_FATAL, "%s: cannot allocate event", __func__);
                // TODO think about aborting system critical task
                abort();
        }
        link_initialize(&event->event_queue);
        event->handler = handler;
        event->data = data;

        fibril_mutex_lock(&event_queue_mtx);
        list_append(&event->event_queue, &event_queue);
        /* There's only single event loop, broadcast is unnecessary */
        fibril_condvar_signal(&event_queue_nonempty_cv);
        fibril_mutex_unlock(&event_queue_mtx);
}

/** Empty current content of event queue
 *
 * This is potentially blocking call and as long as fibrils are cooperatively
 * scheduled, queue will be empty upon return from this function.
 */
void sysman_process_queue(void)
{
        fibril_mutex_lock(&event_queue_mtx);
        while (!list_empty(&event_queue)) {
                fibril_condvar_wait(&event_queue_empty_cv, &event_queue_mtx);
        }
        fibril_mutex_unlock(&event_queue_mtx);
}

/** Register single-use object observer callback
 *
 * TODO no one handles return value, it's quite fatal to lack memory for
 *      callbacks...
 *
 * @return EOK on success
 * @return ENOMEM
 */
int sysman_object_observer(void *object, callback_handler_t handler, void *data)
{
        int rc;
        observed_object_t *observed_object = NULL;
        observed_object_t *new_observed_object = NULL;
        ht_link_t *ht_link = hash_table_find(&observed_objects, &object);

        if (ht_link == NULL) {
                new_observed_object = observed_object_create(object);
                if (new_observed_object == NULL) {
                        rc = ENOMEM;
                        goto fail;
                }
                observed_object = new_observed_object;
        } else {
                observed_object =
                    hash_table_get_inst(ht_link, observed_object_t, ht_link);
        }

        obj_callback_t *obj_callback = malloc(sizeof(obj_callback_t));
        if (obj_callback == NULL) {
                rc = ENOMEM;
                goto fail;
        }

        obj_callback->handler = handler;
        obj_callback->data = data;
        list_append(&obj_callback->callbacks, &observed_object->callbacks);
        return EOK;

fail:
        free(new_observed_object);
        return rc;
}

int sysman_move_observers(void *src_object, void *dst_object)
{
        ht_link_t *src_link = hash_table_find(&observed_objects, &src_object);
        if (src_link == NULL) {
                return EOK;
        }

        ht_link_t *dst_link = hash_table_find(&observed_objects, &dst_object);
        observed_object_t *dst_observed_object;
        if (dst_link == NULL) {
                dst_observed_object = observed_object_create(dst_object);
                if (dst_observed_object == NULL) {
                        return ENOMEM;
                }
        } else {
                dst_observed_object =
                    hash_table_get_inst(dst_link, observed_object_t, ht_link);
        }

        observed_object_t *src_observed_object =
            hash_table_get_inst(src_link, observed_object_t, ht_link);

        list_concat(&dst_observed_object->callbacks,
            &src_observed_object->callbacks);
        observed_object_destroy(&src_observed_object);

        return EOK;
}

size_t sysman_observers_count(void *object)
{
        ht_link_t *ht_link = hash_table_find(&observed_objects, &object);

        if (ht_link == NULL) {
                return 0;
        }

        observed_object_t *observed_object =
            hash_table_get_inst(ht_link, observed_object_t, ht_link);

        return list_count(&observed_object->callbacks);
}


/*
 * Event handlers
 */

// NOTE must run in main event loop fibril
void sysman_event_job_process(void *data)
{
        job_t *job = data;
        dyn_array_t job_closure;
        dyn_array_initialize(&job_closure, job_t *);

        int rc = job_create_closure(job, &job_closure);
        if (rc != EOK) {
                sysman_log(LVL_ERROR, "Cannot create closure for job %p (%i)",
                    job, rc);
                goto fail;
        }

        /*
         * If jobs are queued, reference is passed from closure to the queue,
         * otherwise, we still have the reference.
         */
        rc = job_queue_add_closure(&job_closure);
        if (rc != EOK) {
                goto fail;
        }

        /* We don't need job anymore */
        job_del_ref(&job);

        job_queue_process();
        return;

fail:
        job->retval = JOB_FAILED;
        job_finish(job);
        job_del_ref(&job);

        dyn_array_foreach(job_closure, job_t *, closure_job) {
                job_del_ref(&(*closure_job));
        }
        dyn_array_destroy(&job_closure);
}

void sysman_event_job_finished(void *data)
{
        notify_observers(data);
        /* Unreference the event data */
        job_t *job = data;
        job_del_ref(&job);

        /* The finished job, might have been blocking */
        job_queue_process();
}

void sysman_event_unit_exposee_created(void *data)
{
        unit_exposee_created(data);
}

void sysman_event_unit_failed(void *data)
{
        unit_fail(data);
}

void sysman_event_unit_state_changed(void *data)
{
        notify_observers(data);
}