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/poll.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include "object.h"
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#include "thread.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 object **poll_users; /* users array */
static struct pollfd *pollfd; /* poll fd array */
static int nb_users; /* count of array entries actually in use */
static int active_users; /* current number of active users */
static int allocated_users; /* count of allocated entries in the array */
static struct object **freelist; /* list of free entries in the array */
static struct timeout_user *timeout_head; /* sorted timeouts list head */
static struct timeout_user *timeout_tail; /* sorted timeouts list tail */
/* add a user and return an opaque handle to it, or -1 on failure */
int add_select_user( struct object *obj )
{
int ret;
if (freelist)
{
ret = freelist - poll_users;
freelist = (struct object **)poll_users[ret];
}
else
{
if (nb_users == allocated_users)
{
struct object **newusers;
struct pollfd *newpoll;
int new_count = allocated_users ? (allocated_users + allocated_users / 2) : 16;
if (!(newusers = realloc( poll_users, new_count * sizeof(*poll_users) ))) return -1;
if (!(newpoll = realloc( pollfd, new_count * sizeof(*pollfd) )))
{
free( newusers );
return -1;
}
poll_users = newusers;
pollfd = newpoll;
allocated_users = new_count;
}
ret = nb_users++;
}
pollfd[ret].fd = obj->fd;
pollfd[ret].events = 0;
pollfd[ret].revents = 0;
poll_users[ret] = obj;
obj->select = ret;
active_users++;
return ret;
}
/* remove an object from the select list and close its fd */
void remove_select_user( struct object *obj )
{
int user = obj->select;
assert( poll_users[user] == obj );
pollfd[user].fd = -1;
pollfd[user].events = 0;
pollfd[user].revents = 0;
poll_users[user] = (struct object *)freelist;
freelist = &poll_users[user];
close( obj->fd );
obj->fd = -1;
obj->select = -1;
active_users--;
}
/* change the fd of an object (the old fd is closed) */
void change_select_fd( struct object *obj, int fd )
{
int user = obj->select;
assert( poll_users[user] == obj );
pollfd[user].fd = fd;
close( obj->fd );
obj->fd = fd;
}
/* set the events that select waits for on this fd */
void set_select_events( struct object *obj, int events )
{
int user = obj->select;
assert( poll_users[user] == obj );
if (events == -1) /* stop waiting on this fd completely */
{
pollfd[user].fd = -1;
pollfd[user].events = 0;
pollfd[user].revents = 0;
}
else if (pollfd[user].fd != -1) pollfd[user].events = events;
}
/* check if events are pending */
int check_select_events( int fd, int events )
{
struct pollfd pfd;
pfd.fd = fd;
pfd.events = events;
return poll( &pfd, 1, 0 ) > 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 (!time_before( &pos->when, when )) 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 );
}
/* add a timeout in milliseconds to an absolute time */
void add_timeout( struct timeval *when, int timeout )
{
if (timeout)
{
long sec = timeout / 1000;
if ((when->tv_usec += (timeout - 1000*sec) * 1000) >= 1000000)
{
when->tv_usec -= 1000000;
when->tv_sec++;
}
when->tv_sec += sec;
}
}
/* handle the next expired timeout */
static void handle_timeout(void)
{
struct timeout_user *user = timeout_head;
timeout_head = user->next;
if (user->next) user->next->prev = user->prev;
else timeout_tail = user->prev;
user->callback( user->private );
free( user );
}
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/* SIGHUP handler */
static void sighup_handler()
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{
#ifdef DEBUG_OBJECTS
dump_objects();
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#endif
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}
/* server main loop */
void select_loop(void)
{
int ret;
sigset_t sigset;
struct sigaction action;
/* block the signals we use */
sigemptyset( &sigset );
sigaddset( &sigset, SIGCHLD );
sigaddset( &sigset, SIGHUP );
sigprocmask( SIG_BLOCK, &sigset, NULL );
/* set the handlers */
action.sa_mask = sigset;
action.sa_flags = 0;
action.sa_handler = sigchld_handler;
sigaction( SIGCHLD, &action, NULL );
action.sa_handler = sighup_handler;
sigaction( SIGHUP, &action, NULL );
while (active_users)
{
long diff = -1;
if (timeout_head)
{
struct timeval now;
gettimeofday( &now, NULL );
while (timeout_head)
{
if (!time_before( &now, &timeout_head->when )) handle_timeout();
else
{
diff = (timeout_head->when.tv_sec - now.tv_sec) * 1000
+ (timeout_head->when.tv_usec - now.tv_usec) / 1000;
break;
}
}
}
sigprocmask( SIG_UNBLOCK, &sigset, NULL );
/* Note: we assume that the signal handlers do not manipulate the pollfd array
* or the timeout list, otherwise there is a race here.
*/
ret = poll( pollfd, nb_users, diff );
sigprocmask( SIG_BLOCK, &sigset, NULL );
if (ret > 0)
{
int i;
for (i = 0; i < nb_users; i++)
{
if (pollfd[i].revents)
{
poll_users[i]->ops->poll_event( poll_users[i], pollfd[i].revents );
if (!--ret) break;
}
}
}
}
}