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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.
*/
/**
* Asynchronous library
*
* The aim of this library is facilitating writing programs utilizing
* 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:
* - 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:
*
* 1) Multithreaded client application
* create_thread(thread1);
* create_thread(thread2);
* ...
*
* thread1() {
* conn = ipc_connect_me_to();
* c1 = send(conn);
* c2 = send(conn);
* wait_for(c1);
* wait_for(c2);
* }
*
*
* 2) Multithreaded server application
* main() {
* async_manager();
* }
*
*
* client_connection(icallid, *icall) {
* if (want_refuse) {
* ipc_answer_fast(icallid, ELIMIT, 0, 0);
* return;
* }
* ipc_answer_fast(icallid, 0, 0, 0);
*
* callid = async_get_call(&call);
* handle(callid, call);
* ipc_answer_fast(callid, 1,2,3);
*
* callid = async_get_call(&call);
* ....
* }
*
* TODO: Detaching/joining dead psthreads?
*/
#include <futex.h>
#include <async.h>
#include <psthread.h>
#include <stdio.h>
#include <libadt/hash_table.h>
#include <libadt/list.h>
#include <ipc/ipc.h>
#include <assert.h>
#include <errno.h>
static atomic_t conn_futex = FUTEX_INITIALIZER;
static hash_table_t conn_hash_table;
typedef struct {
link_t link;
ipc_callid_t callid;
ipc_call_t call;
} msg_t;
typedef struct {
link_t link;
ipcarg_t in_phone_hash; /**< Incoming phone hash. */
link_t msg_queue; /**< Messages that should be delivered to this thread */
pstid_t ptid; /**< Thread associated with this connection */
int active; /**< If this thread is currently active */
/* Structures for connection opening packet */
ipc_callid_t callid;
ipc_call_t call;
void (*cthread)(ipc_callid_t,ipc_call_t *);
} connection_t;
__thread connection_t *PS_connection;
/* Hash table functions */
#define CONN_HASH_TABLE_CHAINS 32
static hash_index_t conn_hash(unsigned long *key)
{
assert(key);
return ((*key) >> 4) % CONN_HASH_TABLE_CHAINS;
}
static int conn_compare(unsigned long key[], hash_count_t keys, link_t *item)
{
connection_t *hs;
hs = hash_table_get_instance(item, connection_t, link);
return key[0] == hs->in_phone_hash;
}
static void conn_remove(link_t *item)
{
free(hash_table_get_instance(item, connection_t, link));
}
/** Operations for NS hash table. */
static hash_table_operations_t conn_hash_table_ops = {
.hash = conn_hash,
.compare = conn_compare,
.remove_callback = conn_remove
};
/** Try to route a call to an appropriate connection thread
*
*/
static int route_call(ipc_callid_t callid, ipc_call_t *call)
{
connection_t *conn;
msg_t *msg;
link_t *hlp;
unsigned long key;
futex_down(&conn_futex);
key = call->in_phone_hash;
hlp = hash_table_find(&conn_hash_table, &key);
if (!hlp) {
futex_up(&conn_futex);
return 0;
}
conn = hash_table_get_instance(hlp, connection_t, link);
msg = malloc(sizeof(*msg));
msg->callid = callid;
msg->call = *call;
list_append(&msg->link, &conn->msg_queue);
if (!conn->active) {
conn->active = 1;
psthread_add_ready(conn->ptid);
}
futex_up(&conn_futex);
return 1;
}
/** Return new incoming message for current(thread-local) connection */
ipc_callid_t async_get_call(ipc_call_t *call)
{
msg_t *msg;
ipc_callid_t callid;
connection_t *conn;
futex_down(&conn_futex);
conn = PS_connection;
/* If nothing in queue, wait until something appears */
if (list_empty(&conn->msg_queue)) {
conn->active = 0;
psthread_schedule_next_adv(PS_TO_MANAGER);
}
msg = list_get_instance(conn->msg_queue.next, msg_t, link);
list_remove(&msg->link);
callid = msg->callid;
*call = msg->call;
free(msg);
futex_up(&conn_futex);
return callid;
}
/** Thread function that gets created on new connection
*
* This function is defined as a weak symbol - to be redefined in
* user code.
*/
void client_connection(ipc_callid_t callid, ipc_call_t *call)
{
ipc_answer_fast(callid, ENOENT, 0, 0);
}
/** Wrapper for client connection thread
*
* When new connection arrives, thread with this function is created.
* It calls client_connection and does final cleanup.
*
* @parameter arg Connection structure pointer
*/
static int connection_thread(void *arg)
{
unsigned long key;
msg_t *msg;
connection_t *conn;
/* Setup thread local connection pointer */
PS_connection = (connection_t *)arg;
conn = PS_connection;
conn->cthread(conn->callid, &conn->call);
/* Remove myself from connection hash table */
futex_down(&conn_futex);
key = conn->in_phone_hash;
hash_table_remove(&conn_hash_table, &key, 1);
futex_up(&conn_futex);
/* Answer all remaining messages with ehangup */
while (!list_empty(&conn->msg_queue)) {
msg = list_get_instance(conn->msg_queue.next, msg_t, link);
list_remove(&msg->link);
ipc_answer_fast(msg->callid, EHANGUP, 0, 0);
free(msg);
}
}
/** Create new thread for a new connection
*
* Creates new thread for connection, fills in connection
* structures and inserts it into the hash table, so that
* later we can easily do routing of messages to particular
* threads.
*
* @param callid Callid of the IPC_M_CONNECT_ME_TO packet
* @param call Call data of the opening packet
* @param cthread Thread function that should be called upon
* opening the connection
* @return New thread id
*/
pstid_t async_new_connection(ipc_callid_t callid, ipc_call_t *call,
void (*cthread)(ipc_callid_t,ipc_call_t *))
{
pstid_t ptid;
connection_t *conn;
unsigned long key;
conn = malloc(sizeof(*conn));
if (!conn) {
ipc_answer_fast(callid, ENOMEM, 0, 0);
return NULL;
}
conn->in_phone_hash = IPC_GET_ARG3(*call);
list_initialize(&conn->msg_queue);
conn->ptid = psthread_create(connection_thread, conn);
conn->callid = callid;
conn->call = *call;
conn->active = 1; /* We will activate it asap */
conn->cthread = cthread;
list_initialize(&conn->link);
if (!conn->ptid) {
free(conn);
ipc_answer_fast(callid, ENOMEM, 0, 0);
return NULL;
}
key = conn->in_phone_hash;
futex_down(&conn_futex);
/* Add connection to hash table */
hash_table_insert(&conn_hash_table, &key, &conn->link);
futex_up(&conn_futex);
psthread_add_ready(conn->ptid);
return conn->ptid;
}
/** Handle call to a task */
static void handle_call(ipc_callid_t callid, ipc_call_t *call)
{
if (route_call(callid, call))
return;
switch (IPC_GET_METHOD(*call)) {
case IPC_M_INTERRUPT:
break;
case IPC_M_CONNECT_ME_TO:
/* Open new connection with thread etc. */
async_new_connection(callid, call, client_connection);
break;
default:
ipc_answer_fast(callid, EHANGUP, 0, 0);
}
}
/** Endless loop dispatching incoming calls and answers */
int async_manager()
{
ipc_call_t call;
ipc_callid_t callid;
while (1) {
if (psthread_schedule_next_adv(PS_FROM_MANAGER)) {
futex_up(&conn_futex); /* conn_futex is always held
* when entering manager thread
*/
continue;
}
callid = ipc_wait_cycle(&call,SYNCH_NO_TIMEOUT,SYNCH_BLOCKING);
if (callid & IPC_CALLID_ANSWERED)
continue;
handle_call(callid, &call);
}
}
/** Function to start async_manager as a standalone thread
*
* When more kernel threads are used, one async manager should
* exist per thread. The particular implementation may change,
* currently one async_manager is started automatically per kernel
* thread except main thread.
*/
static int async_manager_thread(void *arg)
{
futex_up(&conn_futex); /* conn_futex is always locked when entering
* manager */
async_manager();
}
/** Add one manager to manager list */
void async_create_manager(void)
{
pstid_t ptid;
ptid = psthread_create(async_manager_thread, NULL);
psthread_add_manager(ptid);
}
/** Remove one manager from manager list */
void async_destroy_manager(void)
{
psthread_remove_manager();
}
/** Initialize internal structures needed for async manager */
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;
}
}