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/*

 * 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.

 */

/** @addtogroup ns

 * @{

 */

#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 "task.h"

#include "ns.h"

#define TASK_HASH_TABLE_CHAINS  256

#define P2I_HASH_TABLE_CHAINS  256

static int get_id_by_phone(ipcarg_t phone_hash, task_id_t *id);

/* 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.

 *

 */

/** Task hash table item. */

typedef struct {

	link_t link;

	task_id_t id;	/**< Task ID. */

	bool finished;	/**< Task is done. */

	bool have_rval;	/**< Task returned a value. */

	int retval;	/**< The return value. */

} hashed_task_t;

/** Compute hash index into task hash table.

 *

 * @param key Pointer keys. However, only the first key (i.e. truncated task

 *            number) is used to compute the hash index.

 *

 * @return Hash index corresponding to key[0].

 *

 */

static hash_index_t task_hash(unsigned long *key)

{

	assert(key);

	return (LOWER32(*key) % TASK_HASH_TABLE_CHAINS);

}

/** Compare a key with hashed item.

 *

 * @param key  Array of keys.

 * @param keys Must be less than or equal to 2.

 * @param item Pointer to a hash table item.

 *

 * @return Non-zero if the key matches the item, zero otherwise.

 *

 */

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));

}

/** Perform actions after removal of item from the hash table.

 *

 * @param item Item that was removed from the hash table.

 *

 */

static void task_remove(link_t *item)

{

	assert(item);

	free(hash_table_get_instance(item, hashed_task_t, link));

}

/** Operations for task hash table. */

static hash_table_operations_t task_hash_table_ops = {

	.hash = task_hash,

	.compare = task_compare,

	.remove_callback = task_remove

};

/** Task hash table structure. */

static hash_table_t task_hash_table;

typedef struct {

	link_t link;

	ipcarg_t phash;    /**< Task ID. */

	task_id_t id;    /**< Task ID. */

} p2i_entry_t;

/** Compute hash index into task hash table.

 *

 * @param key Array of keys.

 * @return Hash index corresponding to key[0].

 *

 */

static hash_index_t p2i_hash(unsigned long *key)

{

	assert(key);

	return (*key % TASK_HASH_TABLE_CHAINS);

}

/** Compare a key with hashed item.

 *

 * @param key  Array of keys.

 * @param keys Must be less than or equal to 1.

 * @param item Pointer to a hash table item.

 *

 * @return Non-zero if the key matches the item, zero otherwise.

 *

 */

static int p2i_compare(unsigned long key[], hash_count_t keys, link_t *item)

{

	assert(key);

	assert(keys == 1);

	assert(item);

	p2i_entry_t *e = hash_table_get_instance(item, p2i_entry_t, link);

	return (key[0] == e->phash);

}

/** Perform actions after removal of item from the hash table.

 *

 * @param item Item that was removed from the hash table.

 *

 */

static void p2i_remove(link_t *item)

{

	assert(item);

	free(hash_table_get_instance(item, p2i_entry_t, link));

}

/** Operations for task hash table. */

static hash_table_operations_t p2i_ops = {

	.hash = p2i_hash,

	.compare = p2i_compare,

	.remove_callback = p2i_remove

};

/** Map phone hash to task ID */

static hash_table_t phone_to_id;

/** Pending task wait structure. */

typedef struct {

	link_t link;

	task_id_t id;         /**< Task ID. */

	ipc_callid_t callid;  /**< Call ID waiting for the connection */

} 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;

}

/** Process pending wait requests */

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)

{

	ipcarg_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. */

		retval = ENOENT;

		goto out;

	}

	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;

		}

		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)

{

	task_id_t id;

	unsigned long keys[2];

	link_t *link;

	p2i_entry_t *e;

	hashed_task_t *ht;

	id = MERGE_LOUP32(IPC_GET_ARG1(*call), IPC_GET_ARG2(*call));

	keys[0] = call->in_phone_hash;

	link = hash_table_find(&phone_to_id, keys);

	if (link != NULL)

		return EEXISTS;

	e = (p2i_entry_t *) malloc(sizeof(p2i_entry_t));

	if (e == NULL)

		return ENOMEM;

	ht = (hashed_task_t *) malloc(sizeof(hashed_task_t));

	if (ht == NULL)

		return ENOMEM;

	/* Insert to phone-to-id map. */

	link_initialize(&e->link);

	e->phash = call->in_phone_hash;

	e->id = id;

	hash_table_insert(&phone_to_id, keys, &e->link);

	/* Insert to 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;

}

int ns_task_retval(ipc_call_t *call)

{

	task_id_t id;

	unsigned long keys[2];

	int rc;

	rc = get_id_by_phone(call->in_phone_hash, &id);

	if (rc != EOK)

		return rc;

	keys[0] = LOWER32(id);

	keys[1] = 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;

	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;

}

static int get_id_by_phone(ipcarg_t phone_hash, task_id_t *id)

{

	unsigned long keys[1];

	link_t *link;

	p2i_entry_t *e;

	keys[0] = phone_hash;

	link = hash_table_find(&phone_to_id, keys);

	if (link == NULL)

		return ENOENT;

	e = hash_table_get_instance(link, p2i_entry_t, link);

	*id = e->id;

	return EOK;

}

/**

 * @}

 */