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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 async_futex = FUTEX_INITIALIZER;
  95. static hash_table_t conn_hash_table;
  96.  
  97. typedef struct {
  98.     pstid_t ptid;                /**< Thread waiting for this message */
  99.     int active;                  /**< If this thread is currently active */
  100.     int done;                    /**< If reply was received */
  101.     ipc_call_t *dataptr;         /**< Pointer where the answer data
  102.                       *   should be stored */
  103.     ipcarg_t retval;
  104. } amsg_t;
  105.  
  106. typedef struct {
  107.     link_t link;
  108.     ipc_callid_t callid;
  109.     ipc_call_t call;
  110. } msg_t;
  111.  
  112. typedef struct {
  113.     link_t link;
  114.     ipcarg_t in_phone_hash;     /**< Incoming phone hash. */
  115.     link_t msg_queue;              /**< Messages that should be delivered to this thread */
  116.     pstid_t ptid;                /**< Thread associated with this connection */
  117.     int active;                     /**< If this thread is currently active */
  118.     /* Structures for connection opening packet */
  119.     ipc_callid_t callid;
  120.     ipc_call_t call;
  121.     void (*cthread)(ipc_callid_t,ipc_call_t *);
  122. } connection_t;
  123.  
  124. __thread connection_t *PS_connection;
  125.  
  126. /* Hash table functions */
  127. #define CONN_HASH_TABLE_CHAINS  32
  128.  
  129. static hash_index_t conn_hash(unsigned long *key)
  130. {
  131.     assert(key);
  132.     return ((*key) >> 4) % CONN_HASH_TABLE_CHAINS;
  133. }
  134.  
  135. static int conn_compare(unsigned long key[], hash_count_t keys, link_t *item)
  136. {
  137.     connection_t *hs;
  138.  
  139.     hs = hash_table_get_instance(item, connection_t, link);
  140.    
  141.     return key[0] == hs->in_phone_hash;
  142. }
  143.  
  144. static void conn_remove(link_t *item)
  145. {
  146.     free(hash_table_get_instance(item, connection_t, link));
  147. }
  148.  
  149.  
  150. /** Operations for NS hash table. */
  151. static hash_table_operations_t conn_hash_table_ops = {
  152.     .hash = conn_hash,
  153.     .compare = conn_compare,
  154.     .remove_callback = conn_remove
  155. };
  156.  
  157. /*************************************************/
  158.  
  159. /** Try to route a call to an appropriate connection thread
  160.  *
  161.  */
  162. static int route_call(ipc_callid_t callid, ipc_call_t *call)
  163. {
  164.     connection_t *conn;
  165.     msg_t *msg;
  166.     link_t *hlp;
  167.     unsigned long key;
  168.  
  169.     futex_down(&async_futex);
  170.  
  171.     key = call->in_phone_hash;
  172.     hlp = hash_table_find(&conn_hash_table, &key);
  173.     if (!hlp) {
  174.         futex_up(&async_futex);
  175.         return 0;
  176.     }
  177.     conn = hash_table_get_instance(hlp, connection_t, link);
  178.  
  179.     msg = malloc(sizeof(*msg));
  180.     msg->callid = callid;
  181.     msg->call = *call;
  182.     list_append(&msg->link, &conn->msg_queue);
  183.    
  184.     if (!conn->active) {
  185.         conn->active = 1;
  186.         psthread_add_ready(conn->ptid);
  187.     }
  188.  
  189.     futex_up(&async_futex);
  190.  
  191.     return 1;
  192. }
  193.  
  194. /** Return new incoming message for current(thread-local) connection */
  195. ipc_callid_t async_get_call(ipc_call_t *call)
  196. {
  197.     msg_t *msg;
  198.     ipc_callid_t callid;
  199.     connection_t *conn;
  200.    
  201.     futex_down(&async_futex);
  202.  
  203.     conn = PS_connection;
  204.     /* If nothing in queue, wait until something appears */
  205.     if (list_empty(&conn->msg_queue)) {
  206.         conn->active = 0;
  207.         psthread_schedule_next_adv(PS_TO_MANAGER);
  208.     }
  209.    
  210.     msg = list_get_instance(conn->msg_queue.next, msg_t, link);
  211.     list_remove(&msg->link);
  212.     callid = msg->callid;
  213.     *call = msg->call;
  214.     free(msg);
  215.    
  216.     futex_up(&async_futex);
  217.     return callid;
  218. }
  219.  
  220. /** Thread function that gets created on new connection
  221.  *
  222.  * This function is defined as a weak symbol - to be redefined in
  223.  * user code.
  224.  */
  225. void client_connection(ipc_callid_t callid, ipc_call_t *call)
  226. {
  227.     ipc_answer_fast(callid, ENOENT, 0, 0);
  228. }
  229.  
  230. /** Wrapper for client connection thread
  231.  *
  232.  * When new connection arrives, thread with this function is created.
  233.  * It calls client_connection and does final cleanup.
  234.  *
  235.  * @parameter arg Connection structure pointer
  236.  */
  237. static int connection_thread(void  *arg)
  238. {
  239.     unsigned long key;
  240.     msg_t *msg;
  241.     connection_t *conn;
  242.  
  243.     /* Setup thread local connection pointer */
  244.     PS_connection = (connection_t *)arg;
  245.     conn = PS_connection;
  246.     conn->cthread(conn->callid, &conn->call);
  247.  
  248.     /* Remove myself from connection hash table */
  249.     futex_down(&async_futex);
  250.     key = conn->in_phone_hash;
  251.     hash_table_remove(&conn_hash_table, &key, 1);
  252.     futex_up(&async_futex);
  253.     /* Answer all remaining messages with ehangup */
  254.     while (!list_empty(&conn->msg_queue)) {
  255.         msg = list_get_instance(conn->msg_queue.next, msg_t, link);
  256.         list_remove(&msg->link);
  257.         ipc_answer_fast(msg->callid, EHANGUP, 0, 0);
  258.         free(msg);
  259.     }
  260. }
  261.  
  262. /** Create new thread for a new connection
  263.  *
  264.  * Creates new thread for connection, fills in connection
  265.  * structures and inserts it into the hash table, so that
  266.  * later we can easily do routing of messages to particular
  267.  * threads.
  268.  *
  269.  * @param callid Callid of the IPC_M_CONNECT_ME_TO packet
  270.  * @param call Call data of the opening packet
  271.  * @param cthread Thread function that should be called upon
  272.  *                opening the connection
  273.  * @return New thread id
  274.  */
  275. pstid_t async_new_connection(ipc_callid_t callid, ipc_call_t *call,
  276.                  void (*cthread)(ipc_callid_t,ipc_call_t *))
  277. {
  278.     pstid_t ptid;
  279.     connection_t *conn;
  280.     unsigned long key;
  281.  
  282.     conn = malloc(sizeof(*conn));
  283.     if (!conn) {
  284.         ipc_answer_fast(callid, ENOMEM, 0, 0);
  285.         return NULL;
  286.     }
  287.     conn->in_phone_hash = IPC_GET_ARG3(*call);
  288.     list_initialize(&conn->msg_queue);
  289.     conn->ptid = psthread_create(connection_thread, conn);
  290.     conn->callid = callid;
  291.     conn->call = *call;
  292.     conn->active = 1; /* We will activate it asap */
  293.     conn->cthread = cthread;
  294.     list_initialize(&conn->link);
  295.     if (!conn->ptid) {
  296.         free(conn);
  297.         ipc_answer_fast(callid, ENOMEM, 0, 0);
  298.         return NULL;
  299.     }
  300.     key = conn->in_phone_hash;
  301.     futex_down(&async_futex);
  302.     /* Add connection to hash table */
  303.     hash_table_insert(&conn_hash_table, &key, &conn->link);
  304.     futex_up(&async_futex);
  305.  
  306.     psthread_add_ready(conn->ptid);
  307.  
  308.     return conn->ptid;
  309. }
  310.  
  311. /** Handle call that was received */
  312. static void handle_call(ipc_callid_t callid, ipc_call_t *call)
  313. {
  314.     if (route_call(callid, call))
  315.         return;
  316.  
  317.     switch (IPC_GET_METHOD(*call)) {
  318.     case IPC_M_INTERRUPT:
  319.         break;
  320.     case IPC_M_CONNECT_ME_TO:
  321.         /* Open new connection with thread etc. */
  322.         async_new_connection(callid, call, client_connection);
  323.         break;
  324.     default:
  325.         ipc_answer_fast(callid, EHANGUP, 0, 0);
  326.     }
  327. }
  328.  
  329. /** Endless loop dispatching incoming calls and answers */
  330. int async_manager()
  331. {
  332.     ipc_call_t call;
  333.     ipc_callid_t callid;
  334.  
  335.     while (1) {
  336.         if (psthread_schedule_next_adv(PS_FROM_MANAGER)) {
  337.             futex_up(&async_futex); /* async_futex is always held
  338.                         * when entering manager thread
  339.                         */
  340.             continue;
  341.         }
  342.         callid = ipc_wait_cycle(&call,SYNCH_NO_TIMEOUT,SYNCH_BLOCKING);
  343.  
  344.         if (callid & IPC_CALLID_ANSWERED)
  345.             continue;
  346.  
  347.         handle_call(callid, &call);
  348.     }
  349. }
  350.  
  351. /** Function to start async_manager as a standalone thread
  352.  *
  353.  * When more kernel threads are used, one async manager should
  354.  * exist per thread. The particular implementation may change,
  355.  * currently one async_manager is started automatically per kernel
  356.  * thread except main thread.
  357.  */
  358. static int async_manager_thread(void *arg)
  359. {
  360.     futex_up(&async_futex); /* async_futex is always locked when entering
  361.                 * manager */
  362.     async_manager();
  363. }
  364.  
  365. /** Add one manager to manager list */
  366. void async_create_manager(void)
  367. {
  368.     pstid_t ptid;
  369.  
  370.     ptid = psthread_create(async_manager_thread, NULL);
  371.     psthread_add_manager(ptid);
  372. }
  373.  
  374. /** Remove one manager from manager list */
  375. void async_destroy_manager(void)
  376. {
  377.     psthread_remove_manager();
  378. }
  379.  
  380. /** Initialize internal structures needed for async manager */
  381. int _async_init(void)
  382. {
  383.     if (!hash_table_create(&conn_hash_table, CONN_HASH_TABLE_CHAINS, 1, &conn_hash_table_ops)) {
  384.         printf("%s: cannot create hash table\n", "async");
  385.         return ENOMEM;
  386.     }
  387.    
  388. }
  389.  
  390. /** IPC handler for messages in async framework
  391.  *
  392.  * Notify thread that is waiting for this message, that it arrived
  393.  */
  394. static void reply_received(void *private, int retval,
  395.                ipc_call_t *data)
  396. {
  397.     amsg_t *msg = (amsg_t *) private;
  398.  
  399.     msg->retval = retval;
  400.  
  401.     futex_down(&async_futex);
  402.     /* Copy data after futex_down, just in case the
  403.      * call was detached
  404.      */
  405.     if (msg->dataptr)
  406.         *msg->dataptr = *data;
  407.    
  408.     msg->done = 1;
  409.     if (! msg->active) {
  410.         msg->active = 1;
  411.         psthread_add_ready(msg->ptid);
  412.     }
  413.     futex_up(&async_futex);
  414. }
  415.  
  416. /** Send message and return id of the sent message
  417.  *
  418.  * The return value can be used as input for async_wait() to wait
  419.  * for completion.
  420.  */
  421. aid_t async_send_2(int phoneid, ipcarg_t method, ipcarg_t arg1, ipcarg_t arg2,
  422.            ipc_call_t *dataptr)
  423. {
  424.     amsg_t *msg;
  425.  
  426.     msg = malloc(sizeof(*msg));
  427.     msg->active = 1;
  428.     msg->done = 0;
  429.     msg->dataptr = dataptr;
  430.     ipc_call_async_2(phoneid,method,arg1,arg2,msg,reply_received);
  431.  
  432.     return (aid_t) msg;
  433. }
  434.  
  435. /** Wait for a message sent by async framework
  436.  *
  437.  * @param amsgid Message ID to wait for
  438.  * @param retval Pointer to variable where will be stored retval
  439.  *               of the answered message. If NULL, it is ignored.
  440.  *
  441.  */
  442. void async_wait_for(aid_t amsgid, ipcarg_t *retval)
  443. {
  444.     amsg_t *msg = (amsg_t *) amsgid;
  445.     connection_t *conn;
  446.  
  447.     futex_down(&async_futex);
  448.     if (msg->done) {
  449.         futex_up(&async_futex);
  450.         goto done;
  451.     }
  452.  
  453.     msg->ptid = psthread_get_id();
  454.     msg->active = 0;
  455.     /* Leave locked async_futex when entering this function */
  456.     psthread_schedule_next_adv(PS_TO_MANAGER);
  457.     /* futex is up automatically after psthread_schedule_next...*/
  458. done:
  459.     if (retval)
  460.         *retval = msg->retval;
  461.     free(msg);
  462. }
  463.