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  1. /*
  2.  * Copyright (C) 2006 Ondrej Palkovsky
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /**
  30.  * Asynchronous library
  31.  *
  32.  * The aim of this library is facilitating writing programs utilizing
  33.  * the asynchronous nature of Helenos IPC, yet using a normal way
  34.  * of programming.
  35.  *
  36.  * You should be able to write very simple multithreaded programs,
  37.  * the async framework will automatically take care of most synchronization
  38.  * problems.
  39.  *
  40.  * Default semantics:
  41.  * - send() - send asynchronously. If the kernel refuses to send more
  42.  *            messages, [ try to get responses from kernel, if nothing
  43.  *            found, might try synchronous ]
  44.  *
  45.  * Example of use:
  46.  *
  47.  * 1) Multithreaded client application
  48.  *  create_thread(thread1);
  49.  *  create_thread(thread2);
  50.  *  ...
  51.  *  
  52.  *  thread1() {
  53.  *        conn = ipc_connect_me_to();
  54.  *        c1 = send(conn);
  55.  *        c2 = send(conn);
  56.  *        wait_for(c1);
  57.  *        wait_for(c2);
  58.  *  }
  59.  *
  60.  *
  61.  * 2) Multithreaded server application
  62.  * main() {
  63.  *      async_manager();
  64.  * }
  65.  *
  66.  *
  67.  * client_connection(icallid, *icall) {
  68.  *       if (want_refuse) {
  69.  *           ipc_answer_fast(icallid, ELIMIT, 0, 0);
  70.  *           return;
  71.  *       }
  72.  *       ipc_answer_fast(icallid, 0, 0, 0);
  73.  *
  74.  *       callid = async_get_call(&call);
  75.  *       handle(callid, call);
  76.  *       ipc_answer_fast(callid, 1,2,3);
  77.  *
  78.  *       callid = async_get_call(&call);
  79.  *       ....
  80.  * }
  81.  *
  82.  * TODO: Detaching/joining dead psthreads?
  83.  */
  84. #include <futex.h>
  85. #include <async.h>
  86. #include <psthread.h>
  87. #include <stdio.h>
  88. #include <libadt/hash_table.h>
  89. #include <libadt/list.h>
  90. #include <ipc/ipc.h>
  91. #include <assert.h>
  92. #include <errno.h>
  93.  
  94. static atomic_t conn_futex = FUTEX_INITIALIZER;
  95. static hash_table_t conn_hash_table;
  96.  
  97. typedef struct {
  98.     link_t link;
  99.     ipc_callid_t callid;
  100.     ipc_call_t call;
  101. } msg_t;
  102.  
  103. typedef struct {
  104.     link_t link;
  105.     ipcarg_t in_phone_hash;     /**< Incoming phone hash. */
  106.     link_t msg_queue;              /**< Messages that should be delivered to this thread */
  107.     pstid_t ptid;                /**< Thread associated with this connection */
  108.     int active;                     /**< If this thread is currently active */
  109.     /* Structures for connection opening packet */
  110.     ipc_callid_t callid;
  111.     ipc_call_t call;
  112.     void (*cthread)(ipc_callid_t,ipc_call_t *);
  113. } connection_t;
  114.  
  115. __thread connection_t *PS_connection;
  116.  
  117. /* Hash table functions */
  118.  
  119. #define CONN_HASH_TABLE_CHAINS  32
  120.  
  121. static hash_index_t conn_hash(unsigned long *key)
  122. {
  123.     assert(key);
  124.     return ((*key) >> 4) % CONN_HASH_TABLE_CHAINS;
  125. }
  126.  
  127. static int conn_compare(unsigned long key[], hash_count_t keys, link_t *item)
  128. {
  129.     connection_t *hs;
  130.  
  131.     hs = hash_table_get_instance(item, connection_t, link);
  132.    
  133.     return key[0] == hs->in_phone_hash;
  134. }
  135.  
  136. static void conn_remove(link_t *item)
  137. {
  138.     free(hash_table_get_instance(item, connection_t, link));
  139. }
  140.  
  141.  
  142. /** Operations for NS hash table. */
  143. static hash_table_operations_t conn_hash_table_ops = {
  144.     .hash = conn_hash,
  145.     .compare = conn_compare,
  146.     .remove_callback = conn_remove
  147. };
  148.  
  149. /** Try to route a call to an appropriate connection thread
  150.  *
  151.  */
  152. static int route_call(ipc_callid_t callid, ipc_call_t *call)
  153. {
  154.     connection_t *conn;
  155.     msg_t *msg;
  156.     link_t *hlp;
  157.     unsigned long key;
  158.  
  159.     futex_down(&conn_futex);
  160.  
  161.     key = call->in_phone_hash;
  162.     hlp = hash_table_find(&conn_hash_table, &key);
  163.     if (!hlp) {
  164.         futex_up(&conn_futex);
  165.         return 0;
  166.     }
  167.     conn = hash_table_get_instance(hlp, connection_t, link);
  168.  
  169.     msg = malloc(sizeof(*msg));
  170.     msg->callid = callid;
  171.     msg->call = *call;
  172.     list_append(&msg->link, &conn->msg_queue);
  173.    
  174.     if (!conn->active) {
  175.         conn->active = 1;
  176.         psthread_add_ready(conn->ptid);
  177.     }
  178.  
  179.     futex_up(&conn_futex);
  180.  
  181.     return 1;
  182. }
  183.  
  184. /** Return new incoming message for current(thread-local) connection */
  185. ipc_callid_t async_get_call(ipc_call_t *call)
  186. {
  187.     msg_t *msg;
  188.     ipc_callid_t callid;
  189.     connection_t *conn;
  190.    
  191.     futex_down(&conn_futex);
  192.  
  193.     conn = PS_connection;
  194.     /* If nothing in queue, wait until something appears */
  195.     if (list_empty(&conn->msg_queue)) {
  196.         conn->active = 0;
  197.         psthread_schedule_next_adv(PS_TO_MANAGER);
  198.     }
  199.    
  200.     msg = list_get_instance(conn->msg_queue.next, msg_t, link);
  201.     list_remove(&msg->link);
  202.     callid = msg->callid;
  203.     *call = msg->call;
  204.     free(msg);
  205.    
  206.     futex_up(&conn_futex);
  207.     return callid;
  208. }
  209.  
  210. /** Thread function that gets created on new connection
  211.  *
  212.  * This function is defined as a weak symbol - to be redefined in
  213.  * user code.
  214.  */
  215. void client_connection(ipc_callid_t callid, ipc_call_t *call)
  216. {
  217.     ipc_answer_fast(callid, ENOENT, 0, 0);
  218. }
  219.  
  220. /** Wrapper for client connection thread
  221.  *
  222.  * When new connection arrives, thread with this function is created.
  223.  * It calls client_connection and does final cleanup.
  224.  *
  225.  * @parameter arg Connection structure pointer
  226.  */
  227. static int connection_thread(void  *arg)
  228. {
  229.     unsigned long key;
  230.     msg_t *msg;
  231.     connection_t *conn;
  232.  
  233.     /* Setup thread local connection pointer */
  234.     PS_connection = (connection_t *)arg;
  235.     conn = PS_connection;
  236.     conn->cthread(conn->callid, &conn->call);
  237.  
  238.     /* Remove myself from connection hash table */
  239.     futex_down(&conn_futex);
  240.     key = conn->in_phone_hash;
  241.     hash_table_remove(&conn_hash_table, &key, 1);
  242.     futex_up(&conn_futex);
  243.     /* Answer all remaining messages with ehangup */
  244.     while (!list_empty(&conn->msg_queue)) {
  245.         msg = list_get_instance(conn->msg_queue.next, msg_t, link);
  246.         list_remove(&msg->link);
  247.         ipc_answer_fast(msg->callid, EHANGUP, 0, 0);
  248.         free(msg);
  249.     }
  250. }
  251.  
  252. /** Create new thread for a new connection
  253.  *
  254.  * Creates new thread for connection, fills in connection
  255.  * structures and inserts it into the hash table, so that
  256.  * later we can easily do routing of messages to particular
  257.  * threads.
  258.  *
  259.  * @param callid Callid of the IPC_M_CONNECT_ME_TO packet
  260.  * @param call Call data of the opening packet
  261.  * @param cthread Thread function that should be called upon
  262.  *                opening the connection
  263.  * @return New thread id
  264.  */
  265. pstid_t async_new_connection(ipc_callid_t callid, ipc_call_t *call,
  266.                  void (*cthread)(ipc_callid_t,ipc_call_t *))
  267. {
  268.     pstid_t ptid;
  269.     connection_t *conn;
  270.     unsigned long key;
  271.  
  272.     conn = malloc(sizeof(*conn));
  273.     if (!conn) {
  274.         ipc_answer_fast(callid, ENOMEM, 0, 0);
  275.         return NULL;
  276.     }
  277.     conn->in_phone_hash = IPC_GET_ARG3(*call);
  278.     list_initialize(&conn->msg_queue);
  279.     conn->ptid = psthread_create(connection_thread, conn);
  280.     conn->callid = callid;
  281.     conn->call = *call;
  282.     conn->active = 1; /* We will activate it asap */
  283.     conn->cthread = cthread;
  284.     list_initialize(&conn->link);
  285.     if (!conn->ptid) {
  286.         free(conn);
  287.         ipc_answer_fast(callid, ENOMEM, 0, 0);
  288.         return NULL;
  289.     }
  290.     key = conn->in_phone_hash;
  291.     futex_down(&conn_futex);
  292.     /* Add connection to hash table */
  293.     hash_table_insert(&conn_hash_table, &key, &conn->link);
  294.     futex_up(&conn_futex);
  295.  
  296.     psthread_add_ready(conn->ptid);
  297.  
  298.     return conn->ptid;
  299. }
  300.  
  301. /** Handle call to a task */
  302. static void handle_call(ipc_callid_t callid, ipc_call_t *call)
  303. {
  304.     if (route_call(callid, call))
  305.         return;
  306.  
  307.     switch (IPC_GET_METHOD(*call)) {
  308.     case IPC_M_INTERRUPT:
  309.         break;
  310.     case IPC_M_CONNECT_ME_TO:
  311.         /* Open new connection with thread etc. */
  312.         async_new_connection(callid, call, client_connection);
  313.         break;
  314.     default:
  315.         ipc_answer_fast(callid, EHANGUP, 0, 0);
  316.     }
  317. }
  318.  
  319. /** Endless loop dispatching incoming calls and answers */
  320. int async_manager()
  321. {
  322.     ipc_call_t call;
  323.     ipc_callid_t callid;
  324.  
  325.     while (1) {
  326.         if (psthread_schedule_next_adv(PS_FROM_MANAGER)) {
  327.             futex_up(&conn_futex); /* conn_futex is always held
  328.                         * when entering manager thread
  329.                         */
  330.             continue;
  331.         }
  332.         callid = ipc_wait_cycle(&call,SYNCH_NO_TIMEOUT,SYNCH_BLOCKING);
  333.  
  334.         if (callid & IPC_CALLID_ANSWERED)
  335.             continue;
  336.         handle_call(callid, &call);
  337.     }
  338. }
  339.  
  340. /** Function to start async_manager as a standalone thread
  341.  *
  342.  * When more kernel threads are used, one async manager should
  343.  * exist per thread. The particular implementation may change,
  344.  * currently one async_manager is started automatically per kernel
  345.  * thread except main thread.
  346.  */
  347. static int async_manager_thread(void *arg)
  348. {
  349.     futex_up(&conn_futex); /* conn_futex is always locked when entering
  350.                 * manager */
  351.     async_manager();
  352. }
  353.  
  354. /** Add one manager to manager list */
  355. void async_create_manager(void)
  356. {
  357.     pstid_t ptid;
  358.  
  359.     ptid = psthread_create(async_manager_thread, NULL);
  360.     psthread_add_manager(ptid);
  361. }
  362.  
  363. /** Remove one manager from manager list */
  364. void async_destroy_manager(void)
  365. {
  366.     psthread_remove_manager();
  367. }
  368.  
  369. /** Initialize internal structures needed for async manager */
  370. int _async_init(void)
  371. {
  372.     if (!hash_table_create(&conn_hash_table, CONN_HASH_TABLE_CHAINS, 1, &conn_hash_table_ops)) {
  373.         printf("%s: cannot create hash table\n", "async");
  374.         return ENOMEM;
  375.     }
  376.    
  377. }
  378.