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/*

 * Copyright (c) 2006 Ondrej Palkovsky

 * 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 libc

 * @{

 */

/** @file

 */

/**

 * Asynchronous library

 *

 * The aim of this library is to provide a facility for writing programs which

 * utilize the asynchronous nature of HelenOS IPC, yet using a normal way of

 * programming.

 *

 * You should be able to write very simple multithreaded programs, the async

 * framework will automatically take care of most synchronization problems.

 *

 * Default semantics:

 * - async_send_*(): Send asynchronously. If the kernel refuses to send

 *                   more messages, [ try to get responses from kernel, if

 *                   nothing found, might try synchronous ]

 *

 * Example of use (pseudo C):

 *

 * 1) Multithreaded client application

 *

 *   fibril_create(fibril1, ...);

 *   fibril_create(fibril2, ...);

 *   ...

 *

 *   int fibril1(void *arg)

 *   {

 *     conn = ipc_connect_me_to();

 *     c1 = async_send(conn);

 *     c2 = async_send(conn);

 *     async_wait_for(c1);

 *     async_wait_for(c2);

 *     ...

 *   }

 *

 *

 * 2) Multithreaded server application

 *

 *   main()

 *   {

 *     async_manager();

 *   }

 *

 *   my_client_connection(icallid, *icall)

 *   {

 *     if (want_refuse) {

 *       ipc_answer_0(icallid, ELIMIT);

 *       return;

 *     }

 *     ipc_answer_0(icallid, EOK);

 *

 *     callid = async_get_call(&call);

 *     handle_call(callid, call);

 *     ipc_answer_2(callid, 1, 2, 3);

 *

 *     callid = async_get_call(&call);

 *     ...

 *   }

 *

 */

#include <futex.h>

#include <async.h>

#include <fibril.h>

#include <stdio.h>

#include <adt/hash_table.h>

#include <adt/list.h>

#include <ipc/ipc.h>

#include <assert.h>

#include <errno.h>

#include <sys/time.h>

#include <arch/barrier.h>

#include <bool.h>

atomic_t async_futex = FUTEX_INITIALIZER;

/** Structures of this type represent a waiting fibril. */

typedef struct {

    /** Expiration time. */

    struct timeval expires;

    /** If true, this struct is in the timeout list. */

    bool inlist;

    /** Timeout list link. */

    link_t link;

    /** Identification of and link to the waiting fibril. */

    fid_t fid;

    /** If true, this fibril is currently active. */

    bool active;

    /** If true, we have timed out. */

    bool timedout;

} awaiter_t;

typedef struct {

    awaiter_t wdata;

    /** If reply was received. */

    bool done;

    /** Pointer to where the answer data is stored. */

    ipc_call_t *dataptr;

    ipcarg_t retval;

} amsg_t;

/**

 * Structures of this type are used to group information about a call and a

 * message queue link.

 */

typedef struct {

    link_t link;

    ipc_callid_t callid;

    ipc_call_t call;

} msg_t;

typedef struct {

    awaiter_t wdata;

    /** Hash table link. */

    link_t link;

    /** Incoming phone hash. */

    ipcarg_t in_phone_hash;

    /** Messages that should be delivered to this fibril. */

    link_t msg_queue;

    /** Identification of the opening call. */

    ipc_callid_t callid;

    /** Call data of the opening call. */

    ipc_call_t call;

    /** Identification of the closing call. */

    ipc_callid_t close_callid;

    /** Fibril function that will be used to handle the connection. */

    void (*cfibril)(ipc_callid_t, ipc_call_t *);

} connection_t;

/** Identifier of the incoming connection handled by the current fibril. */

fibril_local connection_t *FIBRIL_connection;

static void default_client_connection(ipc_callid_t callid, ipc_call_t *call);

static void default_interrupt_received(ipc_callid_t callid, ipc_call_t *call);

static void default_pending(void);

/**

 * Pointer to a fibril function that will be used to handle connections.

 */

static async_client_conn_t client_connection = default_client_connection;

/**

 * Pointer to a fibril function that will be used to handle interrupt

 * notifications.

 */

static async_client_conn_t interrupt_received = default_interrupt_received;

/**

 * Pointer to a fibril function that will be used to handle pending

 * operations.

 */

static async_pending_t pending = default_pending;

static hash_table_t conn_hash_table;

static LIST_INITIALIZE(timeout_list);

#define CONN_HASH_TABLE_CHAINS  32

/** Compute hash into the connection hash table based on the source phone hash.

 *

 * @param key Pointer to source phone hash.

 *

 * @return Index into the connection hash table.

 *

 */

static hash_index_t conn_hash(unsigned long *key)

{

    assert(key);

    return (((*key) >> 4) % CONN_HASH_TABLE_CHAINS);

}

/** Compare hash table item with a key.

 *

 * @param key  Array containing the source phone hash as the only item.

 * @param keys Expected 1 but ignored.

 * @param item Connection hash table item.

 *

 * @return True on match, false otherwise.

 *

 */

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

{

    connection_t *hs = hash_table_get_instance(item, connection_t, link);

    return (key[0] == hs->in_phone_hash);

}

/** Connection hash table removal callback function.

 *

 * This function is called whenever a connection is removed from the connection

 * hash table.

 *

 * @param item Connection hash table item being removed.

 *

 */

static void conn_remove(link_t *item)

{

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

}

/** Operations for the connection hash table. */

static hash_table_operations_t conn_hash_table_ops = {

    .hash = conn_hash,

    .compare = conn_compare,

    .remove_callback = conn_remove

};

/** Sort in current fibril's timeout request.

 *

 * @param wd Wait data of the current fibril.

 *

 */

static void insert_timeout(awaiter_t *wd)

{

    wd->timedout = false;

    wd->inlist = true;

    link_t *tmp = timeout_list.next;

    while (tmp != &timeout_list) {

        awaiter_t *cur = list_get_instance(tmp, awaiter_t, link);

        if (tv_gteq(&cur->expires, &wd->expires))

            break;

        tmp = tmp->next;

    }

    list_append(&wd->link, tmp);

}

/** Try to route a call to an appropriate connection fibril.

 *

 * If the proper connection fibril is found, a message with the call is added to

 * its message queue. If the fibril was not active, it is activated and all

 * timeouts are unregistered.

 *

 * @param callid Hash of the incoming call.

 * @param call   Data of the incoming call.

 *

 * @return False if the call doesn't match any connection.

 *         True if the call was passed to the respective connection fibril.

 *

 */

static bool route_call(ipc_callid_t callid, ipc_call_t *call)

{

    futex_down(&async_futex);

    unsigned long key = call->in_phone_hash;

    link_t *hlp = hash_table_find(&conn_hash_table, &key);

    if (!hlp) {

        futex_up(&async_futex);

        return false;

    }

    connection_t *conn = hash_table_get_instance(hlp, connection_t, link);

    msg_t *msg = malloc(sizeof(*msg));

    if (!msg) {

        futex_up(&async_futex);

        return false;

    }

    msg->callid = callid;

    msg->call = *call;

    list_append(&msg->link, &conn->msg_queue);

    if (IPC_GET_METHOD(*call) == IPC_M_PHONE_HUNGUP)

        conn->close_callid = callid;

    /* If the connection fibril is waiting for an event, activate it */

    if (!conn->wdata.active) {

        /* If in timeout list, remove it */

        if (conn->wdata.inlist) {

            conn->wdata.inlist = false;

            list_remove(&conn->wdata.link);

        }

        conn->wdata.active = true;

        fibril_add_ready(conn->wdata.fid);

    }

    futex_up(&async_futex);

    return true;

}

/** Notification fibril.

 *

 * When a notification arrives, a fibril with this implementing function is

 * created. It calls interrupt_received() and does the final cleanup.

 *

 * @param arg Message structure pointer.

 *

 * @return Always zero.

 *

 */

static int notification_fibril(void *arg)

{

    msg_t *msg = (msg_t *) arg;

    interrupt_received(msg->callid, &msg->call);

    free(msg);

    return 0;

}

/** Process interrupt notification.

 *

 * A new fibril is created which would process the notification.

 *

 * @param callid Hash of the incoming call.

 * @param call   Data of the incoming call.

 *

 * @return False if an error occured.

 *         True if the call was passed to the notification fibril.

 *

 */

static bool process_notification(ipc_callid_t callid, ipc_call_t *call)

{

    futex_down(&async_futex);

    msg_t *msg = malloc(sizeof(*msg));

    if (!msg) {

        futex_up(&async_futex);

        return false;

    }

    msg->callid = callid;

    msg->call = *call;

    fid_t fid = fibril_create(notification_fibril, msg);

    fibril_add_ready(fid);

    futex_up(&async_futex);

    return true;

}

/** Pending fibril.

 *

 * After each call the pending operations are executed in a separate

 * fibril. The function pending() is c.

 *

 * @param arg Unused.

 *

 * @return Always zero.

 *

 */

static int pending_fibril(void *arg)

{

    pending();

    return 0;

}

/** Process pending actions.

 *

 * A new fibril is created which would process the pending operations.

 *

 * @return False if an error occured.

 *         True if the execution was passed to the pending fibril.

 *

 */

static bool process_pending(void)

{

    futex_down(&async_futex);

    fid_t fid = fibril_create(pending_fibril, NULL);

    fibril_add_ready(fid);

    futex_up(&async_futex);

    return true;

}

/** Return new incoming message for the current (fibril-local) connection.

 *

 * @param call  Storage where the incoming call data will be stored.

 * @param usecs Timeout in microseconds. Zero denotes no timeout.

 *

 * @return If no timeout was specified, then a hash of the

 *         incoming call is returned. If a timeout is specified,

 *         then a hash of the incoming call is returned unless

 *         the timeout expires prior to receiving a message. In

 *         that case zero is returned.

 *

 */

ipc_callid_t async_get_call_timeout(ipc_call_t *call, suseconds_t usecs)

{

    assert(FIBRIL_connection);

    /* Why doing this?

     * GCC 4.1.0 coughs on FIBRIL_connection-> dereference.

     * GCC 4.1.1 happilly puts the rdhwr instruction in delay slot.

     *           I would never expect to find so many errors in

     *           a compiler.

     */

    connection_t *conn = FIBRIL_connection;

    futex_down(&async_futex);

    if (usecs) {

        gettimeofday(&conn->wdata.expires, NULL);

        tv_add(&conn->wdata.expires, usecs);

    } else

        conn->wdata.inlist = false;

    /* If nothing in queue, wait until something arrives */

    while (list_empty(&conn->msg_queue)) {

        if (usecs)

            insert_timeout(&conn->wdata);

        conn->wdata.active = false;

        /*

         * Note: the current fibril will be rescheduled either due to a

         * timeout or due to an arriving message destined to it. In the

         * former case, handle_expired_timeouts() and, in the latter

         * case, route_call() will perform the wakeup.

         */

        fibril_switch(FIBRIL_TO_MANAGER);

        /*

         * Futex is up after getting back from async_manager.

         * Get it again.

         */

        futex_down(&async_futex);

        if ((usecs) && (conn->wdata.timedout)

            && (list_empty(&conn->msg_queue))) {

            /* If we timed out -> exit */

            futex_up(&async_futex);

            return 0;

        }

    }

    msg_t *msg = list_get_instance(conn->msg_queue.next, msg_t, link);

    list_remove(&msg->link);

    ipc_callid_t callid = msg->callid;

    *call = msg->call;

    free(msg);

    futex_up(&async_futex);

    return callid;

}

/** Default fibril function that gets called to handle new connection.

 *

 * This function is defined as a weak symbol - to be redefined in user code.

 *

 * @param callid Hash of the incoming call.

 * @param call   Data of the incoming call.

 *

 */

static void default_client_connection(ipc_callid_t callid, ipc_call_t *call)

{

    ipc_answer_0(callid, ENOENT);

}

/** Default fibril function that gets called to handle interrupt notifications.

 *

 * This function is defined as a weak symbol - to be redefined in user code.

 *

 * @param callid Hash of the incoming call.

 * @param call   Data of the incoming call.

 *

 */

static void default_interrupt_received(ipc_callid_t callid, ipc_call_t *call)

{

}

/** Default fibril function that gets called to handle pending operations.

 *

 * This function is defined as a weak symbol - to be redefined in user code.

 *

 */

static void default_pending(void)

{

}

/** Wrapper for client connection fibril.

 *

 * When a new connection arrives, a fibril with this implementing function is

 * created. It calls client_connection() and does the final cleanup.

 *

 * @param arg Connection structure pointer.

 *

 * @return Always zero.

 *

 */

static int connection_fibril(void *arg)

{

    /*

     * Setup fibril-local connection pointer and call client_connection().

     *

     */

    FIBRIL_connection = (connection_t *) arg;

    FIBRIL_connection->cfibril(FIBRIL_connection->callid,

        &FIBRIL_connection->call);

    /* Remove myself from the connection hash table */

    futex_down(&async_futex);

    unsigned long key = FIBRIL_connection->in_phone_hash;

    hash_table_remove(&conn_hash_table, &key, 1);

    futex_up(&async_futex);

    /* Answer all remaining messages with EHANGUP */

    while (!list_empty(&FIBRIL_connection->msg_queue)) {

        msg_t *msg;

        msg = list_get_instance(FIBRIL_connection->msg_queue.next,

            msg_t, link);

        list_remove(&msg->link);

        ipc_answer_0(msg->callid, EHANGUP);

        free(msg);

    }

    if (FIBRIL_connection->close_callid)

        ipc_answer_0(FIBRIL_connection->close_callid, EOK);

    return 0;

}

/** Create a new fibril for a new connection.

 *

 * Create new fibril for connection, fill in connection structures and inserts

 * it into the hash table, so that later we can easily do routing of messages to

 * particular fibrils.

 *

 * @param in_phone_hash Identification of the incoming connection.

 * @param callid        Hash of the opening IPC_M_CONNECT_ME_TO call.

 *                      If callid is zero, the connection was opened by

 *                      accepting the IPC_M_CONNECT_TO_ME call and this function

 *                      is called directly by the server.

 * @param call          Call data of the opening call.

 * @param cfibril       Fibril function that should be called upon opening the

 *                      connection.

 *

 * @return New fibril id or NULL on failure.

 *

 */

fid_t async_new_connection(ipcarg_t in_phone_hash, ipc_callid_t callid,

    ipc_call_t *call, void (*cfibril)(ipc_callid_t, ipc_call_t *))

{

    connection_t *conn = malloc(sizeof(*conn));

    if (!conn) {

        if (callid)

            ipc_answer_0(callid, ENOMEM);

        return NULL;

    }

    conn->in_phone_hash = in_phone_hash;

    list_initialize(&conn->msg_queue);

    conn->callid = callid;

    conn->close_callid = false;

    if (call)

        conn->call = *call;

    /* We will activate the fibril ASAP */

    conn->wdata.active = true;

    conn->cfibril = cfibril;

    conn->wdata.fid = fibril_create(connection_fibril, conn);

    if (!conn->wdata.fid) {

        free(conn);

        if (callid)

            ipc_answer_0(callid, ENOMEM);

        return NULL;

    }

    /* Add connection to the connection hash table */

    unsigned long key = conn->in_phone_hash;

    futex_down(&async_futex);

    hash_table_insert(&conn_hash_table, &key, &conn->link);

    futex_up(&async_futex);

    fibril_add_ready(conn->wdata.fid);

    return conn->wdata.fid;

}

/** Handle a call that was received.

 *

 * If the call has the IPC_M_CONNECT_ME_TO method, a new connection is created.

 * Otherwise the call is routed to its connection fibril.

 *

 * @param callid Hash of the incoming call.

 * @param call   Data of the incoming call.

 *

 */

static void handle_call(ipc_callid_t callid, ipc_call_t *call)

{

    /* Unrouted call - do some default behaviour */

    if ((callid & IPC_CALLID_NOTIFICATION)) {

        process_notification(callid, call);

        goto out;

    }

    switch (IPC_GET_METHOD(*call)) {

    case IPC_M_CONNECT_ME:

    case IPC_M_CONNECT_ME_TO:

        /* Open new connection with fibril etc. */

        async_new_connection(IPC_GET_ARG5(*call), callid, call,

            client_connection);

        goto out;

    }

    /* Try to route the call through the connection hash table */

    if (route_call(callid, call))

        goto out;

    /* Unknown call from unknown phone - hang it up */

    ipc_answer_0(callid, EHANGUP);

    return;

out:

    process_pending();

}

/** Fire all timeouts that expired. */

static void handle_expired_timeouts(void)

{

    struct timeval tv;

    gettimeofday(&tv, NULL);

    futex_down(&async_futex);

    link_t *cur = timeout_list.next;

    while (cur != &timeout_list) {

        awaiter_t *waiter = list_get_instance(cur, awaiter_t, link);

        if (tv_gt(&waiter->expires, &tv))

            break;

        cur = cur->next;

        list_remove(&waiter->link);

        waiter->inlist = false;

        waiter->timedout = true;

        /*

         * Redundant condition?

         * The fibril should not be active when it gets here.

         */

        if (!waiter->active) {

            waiter->active = true;

            fibril_add_ready(waiter->fid);

        }

    }

    futex_up(&async_futex);

}

/** Endless loop dispatching incoming calls and answers.

 *

 * @return Never returns.

 *

 */

static int async_manager_worker(void)

{

    while (true) {

        if (fibril_switch(FIBRIL_FROM_MANAGER)) {

            futex_up(&async_futex);

            /*

             * async_futex is always held when entering a manager

             * fibril.

             */

            continue;

        }

        futex_down(&async_futex);

        suseconds_t timeout;

        if (!list_empty(&timeout_list)) {

            awaiter_t *waiter = list_get_instance(timeout_list.next,

                awaiter_t, link);

            struct timeval tv;

            gettimeofday(&tv, NULL);

            if (tv_gteq(&tv, &waiter->expires)) {

                futex_up(&async_futex);

                handle_expired_timeouts();

                continue;

            } else

                timeout = tv_sub(&waiter->expires, &tv);

        } else

            timeout = SYNCH_NO_TIMEOUT;

        futex_up(&async_futex);

        ipc_call_t call;

        ipc_callid_t callid = ipc_wait_cycle(&call, timeout,

            SYNCH_FLAGS_NONE);

        if (!callid) {

            handle_expired_timeouts();

            continue;

        }

        if (callid & IPC_CALLID_ANSWERED)

            continue;

        handle_call(callid, &call);

    }

    return 0;

}

/** Function to start async_manager as a standalone fibril.

 *

 * When more kernel threads are used, one async manager should exist per thread.

 *

 * @param arg Unused.

 * @return Never returns.

 *

 */

static int async_manager_fibril(void *arg)

{

    futex_up(&async_futex);

    /*

     * async_futex is always locked when entering manager

     */

    async_manager_worker();

    return 0;

}

/** Add one manager to manager list. */

void async_create_manager(void)

{

    fid_t fid = fibril_create(async_manager_fibril, NULL);

    fibril_add_manager(fid);

}

/** Remove one manager from manager list */

void async_destroy_manager(void)

{

    fibril_remove_manager();

}

/** Initialize the async framework.

 *

 * @return Zero on success or an error code.

 */

int _async_init(void)

{

    if (!hash_table_create(&conn_hash_table, CONN_HASH_TABLE_CHAINS, 1,

        &conn_hash_table_ops)) {

        printf("%s: cannot create hash table\n", "async");

        return ENOMEM;

    }

    return 0;

}

/** Reply received callback.

 *

 * This function is called whenever a reply for an asynchronous message sent out

 * by the asynchronous framework is received.

 *

 * Notify the fibril which is waiting for this message that it has arrived.

 *

 * @param arg    Pointer to the asynchronous message record.

 * @param retval Value returned in the answer.

 * @param data   Call data of the answer.

 */

static void reply_received(void *arg, int retval, ipc_call_t *data)

{

    futex_down(&async_futex);

    amsg_t *msg = (amsg_t *) arg;

    msg->retval = retval;

    /* Copy data after futex_down, just in case the call was detached */

    if ((msg->dataptr) && (data))

        *msg->dataptr = *data;

    write_barrier();

    /* Remove message from timeout list */

    if (msg->wdata.inlist)

        list_remove(&msg->wdata.link);

    msg->done = true;