task.c

/*
 * Copyright (c) 2009 Martin Decky
 * Copyright (c) 2009 Jiri Svoboda
 * 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 <ipc/ipc.h>
#include <adt/hash_table.h>
#include <bool.h>
#include <errno.h>
#include <assert.h>
#include <stdio.h>
#include <macros.h>
#include <malloc.h>
#include "task.h"
#include "ns.h"

#define TASK_HASH_TABLE_CHAINS  256
#define P2I_HASH_TABLE_CHAINS   256

/* TODO:
 *
 * As there is currently no convention that each task has to be waited
 * for, the NS can leak memory because of the zombie tasks.
 *
 */

typedef struct {
        link_t link;
        
        task_id_t id;    
        bool finished;   
        bool have_rval;  
        int retval;      
} hashed_task_t;

static hash_index_t task_hash(unsigned long key[])
{
        assert(key);
        return (LOWER32(key[0]) % TASK_HASH_TABLE_CHAINS);
}

static int task_compare(unsigned long key[], hash_count_t keys, link_t *item)
{
        assert(key);
        assert(keys <= 2);
        assert(item);
        
        hashed_task_t *ht = hash_table_get_instance(item, hashed_task_t, link);
        
        if (keys == 2)
                return ((LOWER32(key[1]) == UPPER32(ht->id))
                    && (LOWER32(key[0]) == LOWER32(ht->id)));
        else
                return (LOWER32(key[0]) == LOWER32(ht->id));
}

static void task_remove(link_t *item)
{
        assert(item);
        free(hash_table_get_instance(item, hashed_task_t, link));
}

static hash_table_operations_t task_hash_table_ops = {
        .hash = task_hash,
        .compare = task_compare,
        .remove_callback = task_remove
};

static hash_table_t task_hash_table;

typedef struct {
        link_t link;
        sysarg_t in_phone_hash;  
        task_id_t id;            
} p2i_entry_t;

static hash_index_t p2i_hash(unsigned long key[])
{
        assert(key);
        return (key[0] % TASK_HASH_TABLE_CHAINS);
}

static int p2i_compare(unsigned long key[], hash_count_t keys, link_t *item)
{
        assert(key);
        assert(keys == 1);
        assert(item);
        
        p2i_entry_t *entry = hash_table_get_instance(item, p2i_entry_t, link);
        
        return (key[0] == entry->in_phone_hash);
}

static void p2i_remove(link_t *item)
{
        assert(item);
        free(hash_table_get_instance(item, p2i_entry_t, link));
}

static hash_table_operations_t p2i_ops = {
        .hash = p2i_hash,
        .compare = p2i_compare,
        .remove_callback = p2i_remove
};

static hash_table_t phone_to_id;

typedef struct {
        link_t link;
        task_id_t id;         
        ipc_callid_t callid;  
} pending_wait_t;

static link_t pending_wait;

int task_init(void)
{
        if (!hash_table_create(&task_hash_table, TASK_HASH_TABLE_CHAINS,
            2, &task_hash_table_ops)) {
                printf(NAME ": No memory available for tasks\n");
                return ENOMEM;
        }
        
        if (!hash_table_create(&phone_to_id, P2I_HASH_TABLE_CHAINS,
            1, &p2i_ops)) {
                printf(NAME ": No memory available for tasks\n");
                return ENOMEM;
        }
        
        list_initialize(&pending_wait);
        return EOK;
}

void process_pending_wait(void)
{
        link_t *cur;
        task_exit_t texit;
        
loop:
        for (cur = pending_wait.next; cur != &pending_wait; cur = cur->next) {
                pending_wait_t *pr = list_get_instance(cur, pending_wait_t, link);
                
                unsigned long keys[2] = {
                        LOWER32(pr->id),
                        UPPER32(pr->id)
                };
                
                link_t *link = hash_table_find(&task_hash_table, keys);
                if (!link)
                        continue;
                
                hashed_task_t *ht = hash_table_get_instance(link, hashed_task_t, link);
                if (!ht->finished)
                        continue;
                
                if (!(pr->callid & IPC_CALLID_NOTIFICATION)) {
                        texit = ht->have_rval ? TASK_EXIT_NORMAL :
                            TASK_EXIT_UNEXPECTED;
                        ipc_answer_2(pr->callid, EOK, texit,
                            ht->retval);
                }
                
                hash_table_remove(&task_hash_table, keys, 2);
                list_remove(cur);
                free(pr);
                goto loop;
        }
}

void wait_for_task(task_id_t id, ipc_call_t *call, ipc_callid_t callid)
{
        sysarg_t retval;
        task_exit_t texit;
        
        unsigned long keys[2] = {
                LOWER32(id),
                UPPER32(id)
        };
        
        link_t *link = hash_table_find(&task_hash_table, keys);
        hashed_task_t *ht = (link != NULL) ?
            hash_table_get_instance(link, hashed_task_t, link) : NULL;
        
        if (ht == NULL) {
                /* No such task exists. */
                ipc_answer_0(callid, ENOENT);
                return;
        }
        
        if (!ht->finished) {
                /* Add to pending list */
                pending_wait_t *pr =
                    (pending_wait_t *) malloc(sizeof(pending_wait_t));
                if (!pr) {
                        retval = ENOMEM;
                        goto out;
                }
                
                link_initialize(&pr->link);
                pr->id = id;
                pr->callid = callid;
                list_append(&pr->link, &pending_wait);
                return;
        }
        
        hash_table_remove(&task_hash_table, keys, 2);
        retval = EOK;
        
out:
        if (!(callid & IPC_CALLID_NOTIFICATION)) {
                texit = ht->have_rval ? TASK_EXIT_NORMAL : TASK_EXIT_UNEXPECTED;
                ipc_answer_2(callid, retval, texit, ht->retval);
        }
}

int ns_task_id_intro(ipc_call_t *call)
{
        unsigned long keys[2];
        
        task_id_t id = MERGE_LOUP32(IPC_GET_ARG1(*call), IPC_GET_ARG2(*call));
        keys[0] = call->in_phone_hash;
        
        link_t *link = hash_table_find(&phone_to_id, keys);
        if (link != NULL)
                return EEXISTS;
        
        p2i_entry_t *entry = (p2i_entry_t *) malloc(sizeof(p2i_entry_t));
        if (entry == NULL)
                return ENOMEM;
        
        hashed_task_t *ht = (hashed_task_t *) malloc(sizeof(hashed_task_t));
        if (ht == NULL)
                return ENOMEM;
        
        /*
         * Insert into the phone-to-id map.
         */
        
        link_initialize(&entry->link);
        entry->in_phone_hash = call->in_phone_hash;
        entry->id = id;
        hash_table_insert(&phone_to_id, keys, &entry->link);
        
        /*
         * Insert into the main table.
         */
        
        keys[0] = LOWER32(id);
        keys[1] = UPPER32(id);
        
        link_initialize(&ht->link);
        ht->id = id;
        ht->finished = false;
        ht->have_rval = false;
        ht->retval = -1;
        hash_table_insert(&task_hash_table, keys, &ht->link);
        
        return EOK;
}

static int get_id_by_phone(sysarg_t phone_hash, task_id_t *id)
{
        unsigned long keys[1] = {phone_hash};
        
        link_t *link = hash_table_find(&phone_to_id, keys);
        if (link == NULL)
                return ENOENT;
        
        p2i_entry_t *entry = hash_table_get_instance(link, p2i_entry_t, link);
        *id = entry->id;
        
        return EOK;
}

int ns_task_retval(ipc_call_t *call)
{
        task_id_t id;
        int rc = get_id_by_phone(call->in_phone_hash, &id);
        if (rc != EOK)
                return rc;
        
        unsigned long keys[2] = {
                LOWER32(id),
                UPPER32(id)
        };
        
        link_t *link = hash_table_find(&task_hash_table, keys);
        hashed_task_t *ht = (link != NULL) ?
            hash_table_get_instance(link, hashed_task_t, link) : NULL;
        
        if ((ht == NULL) || (ht->finished))
                return EINVAL;
        
        ht->finished = true;
        ht->have_rval = true;
        ht->retval = IPC_GET_ARG1(*call);
        
        return EOK;
}

int ns_task_disconnect(ipc_call_t *call)
{
        unsigned long keys[2];
        
        task_id_t id;
        int rc = get_id_by_phone(call->in_phone_hash, &id);
        if (rc != EOK)
                return rc;
        
        /* Delete from phone-to-id map. */
        keys[0] = call->in_phone_hash;
        hash_table_remove(&phone_to_id, keys, 1);
        
        /* Mark task as finished. */
        keys[0] = LOWER32(id);
        keys[1] = UPPER32(id);
        
        link_t *link = hash_table_find(&task_hash_table, keys);
        hashed_task_t *ht =
            hash_table_get_instance(link, hashed_task_t, link);
        if (ht == NULL)
                return EOK;
        
        ht->finished = true;
        
        return EOK;
}

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