Sweden-Number/server/select.c

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/*
* Server main select() loop
*
* Copyright (C) 1998 Alexandre Julliard
*/
#include <assert.h>
#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include "object.h"
struct timeout_user
{
struct timeout_user *next; /* next in sorted timeout list */
struct timeout_user *prev; /* prev in sorted timeout list */
struct timeval when; /* timeout expiry (absolute time) */
timeout_callback callback; /* callback function */
void *private; /* callback private data */
};
static struct select_user *users[FD_SETSIZE]; /* users array */
static fd_set read_set, write_set, except_set; /* current select sets */
static int nb_users; /* current number of users */
static int max_fd; /* max fd in use */
static struct timeout_user *timeout_head; /* sorted timeouts list head */
static struct timeout_user *timeout_tail; /* sorted timeouts list tail */
/* register a user */
void register_select_user( struct select_user *user )
{
assert( !users[user->fd] );
users[user->fd] = user;
if (user->fd > max_fd) max_fd = user->fd;
nb_users++;
}
/* remove a user */
void unregister_select_user( struct select_user *user )
{
assert( users[user->fd] == user );
FD_CLR( user->fd, &read_set );
FD_CLR( user->fd, &write_set );
FD_CLR( user->fd, &except_set );
users[user->fd] = NULL;
if (max_fd == user->fd) while (max_fd && !users[max_fd]) max_fd--;
nb_users--;
}
/* set the events that select waits for on this fd */
void set_select_events( struct select_user *user, int events )
{
assert( users[user->fd] == user );
if (events & READ_EVENT) FD_SET( user->fd, &read_set );
else FD_CLR( user->fd, &read_set );
if (events & WRITE_EVENT) FD_SET( user->fd, &write_set );
else FD_CLR( user->fd, &write_set );
if (events & EXCEPT_EVENT) FD_SET( user->fd, &except_set );
else FD_CLR( user->fd, &except_set );
}
/* check if events are pending */
int check_select_events( struct select_user *user, int events )
{
fd_set read_fds, write_fds, except_fds;
struct timeval tv = { 0, 0 };
FD_ZERO( &read_fds );
FD_ZERO( &write_fds );
FD_ZERO( &except_fds );
if (events & READ_EVENT) FD_SET( user->fd, &read_fds );
if (events & WRITE_EVENT) FD_SET( user->fd, &write_fds );
if (events & EXCEPT_EVENT) FD_SET( user->fd, &except_fds );
return select( user->fd + 1, &read_fds, &write_fds, &except_fds, &tv ) > 0;
}
/* add a timeout user */
struct timeout_user *add_timeout_user( struct timeval *when, timeout_callback func, void *private )
{
struct timeout_user *user;
struct timeout_user *pos;
if (!(user = mem_alloc( sizeof(*user) ))) return NULL;
user->when = *when;
user->callback = func;
user->private = private;
/* Now insert it in the linked list */
for (pos = timeout_head; pos; pos = pos->next)
{
if (pos->when.tv_sec > user->when.tv_sec) break;
if ((pos->when.tv_sec == user->when.tv_sec) &&
(pos->when.tv_usec > user->when.tv_usec)) break;
}
if (pos) /* insert it before 'pos' */
{
if ((user->prev = pos->prev)) user->prev->next = user;
else timeout_head = user;
user->next = pos;
pos->prev = user;
}
else /* insert it at the tail */
{
user->next = NULL;
if (timeout_tail) timeout_tail->next = user;
else timeout_head = user;
user->prev = timeout_tail;
timeout_tail = user;
}
return user;
}
/* remove a timeout user */
void remove_timeout_user( struct timeout_user *user )
{
if (user->next) user->next->prev = user->prev;
else timeout_tail = user->prev;
if (user->prev) user->prev->next = user->next;
else timeout_head = user->next;
free( user );
}
/* make an absolute timeout value from a relative timeout in milliseconds */
void make_timeout( struct timeval *when, int timeout )
{
gettimeofday( when, 0 );
if (!timeout) return;
if ((when->tv_usec += (timeout % 1000) * 1000) >= 1000000)
{
when->tv_usec -= 1000000;
when->tv_sec++;
}
when->tv_sec += timeout / 1000;
}
/* handle an expired timeout */
static void handle_timeout( struct timeout_user *user )
{
if (user->next) user->next->prev = user->prev;
else timeout_tail = user->prev;
if (user->prev) user->prev->next = user->next;
else timeout_head = user->next;
user->callback( user->private );
free( user );
}
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#ifdef DEBUG_OBJECTS
static int do_dump_objects;
/* SIGHUP handler */
static void sighup()
{
do_dump_objects = 1;
}
#endif
/* server main loop */
void select_loop(void)
{
int i, ret;
setsid();
signal( SIGPIPE, SIG_IGN );
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#ifdef DEBUG_OBJECTS
signal( SIGHUP, sighup );
#endif
while (nb_users)
{
fd_set read = read_set, write = write_set, except = except_set;
if (timeout_head)
{
struct timeval tv, now;
gettimeofday( &now, NULL );
if ((timeout_head->when.tv_sec < now.tv_sec) ||
((timeout_head->when.tv_sec == now.tv_sec) &&
(timeout_head->when.tv_usec < now.tv_usec)))
{
handle_timeout( timeout_head );
continue;
}
tv.tv_sec = timeout_head->when.tv_sec - now.tv_sec;
if ((tv.tv_usec = timeout_head->when.tv_usec - now.tv_usec) < 0)
{
tv.tv_usec += 1000000;
tv.tv_sec--;
}
#if 0
printf( "select: " );
for (i = 0; i <= max_fd; i++) printf( "%c", FD_ISSET( i, &read_set ) ? 'r' :
(FD_ISSET( i, &write_set ) ? 'w' : '-') );
printf( " timeout %d.%06d\n", tv.tv_sec, tv.tv_usec );
#endif
ret = select( max_fd + 1, &read, &write, &except, &tv );
}
else /* no timeout */
{
#if 0
printf( "select: " );
for (i = 0; i <= max_fd; i++) printf( "%c", FD_ISSET( i, &read_set ) ? 'r' :
(FD_ISSET( i, &write_set ) ? 'w' : '-') );
printf( " no timeout\n" );
#endif
ret = select( max_fd + 1, &read, &write, &except, NULL );
}
if (!ret) continue;
if (ret == -1) {
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if (errno == EINTR)
{
#ifdef DEBUG_OBJECTS
if (do_dump_objects) dump_objects();
do_dump_objects = 0;
#endif
continue;
}
perror("select");
}
for (i = 0; i <= max_fd; i++)
{
int event = 0;
if (FD_ISSET( i, &except )) event |= EXCEPT_EVENT;
if (FD_ISSET( i, &write )) event |= WRITE_EVENT;
if (FD_ISSET( i, &read )) event |= READ_EVENT;
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/* Note: users[i] might be NULL here, because an event routine
called in an earlier pass of this loop might have removed
the current user ... */
if (event && users[i])
users[i]->func( event, users[i]->private );
}
}
}