mirror of
git://sourceware.org/git/glibc.git
synced 2024-12-03 04:01:43 +08:00
593 lines
16 KiB
C
593 lines
16 KiB
C
/* Helper code for POSIX timer implementation on NPTL.
|
|
Copyright (C) 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
Contributed by Kaz Kylheku <kaz@ashi.footprints.net>.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Lesser General Public License as
|
|
published by the Free Software Foundation; either version 2.1 of the
|
|
License, or (at your option) any later version.
|
|
|
|
The GNU C Library is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
License along with the GNU C Library; see the file COPYING.LIB. If not,
|
|
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
|
|
Boston, MA 02111-1307, USA. */
|
|
|
|
#include <assert.h>
|
|
#include <errno.h>
|
|
#include <pthread.h>
|
|
#include <stddef.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <sysdep.h>
|
|
#include <time.h>
|
|
#include <unistd.h>
|
|
#include <sys/syscall.h>
|
|
|
|
#include "posix-timer.h"
|
|
#include <pthreadP.h>
|
|
|
|
|
|
/* Number of threads used. */
|
|
#define THREAD_MAXNODES 16
|
|
|
|
/* Array containing the descriptors for the used threads. */
|
|
static struct thread_node thread_array[THREAD_MAXNODES];
|
|
|
|
/* Static array with the structures for all the timers. */
|
|
struct timer_node __timer_array[TIMER_MAX];
|
|
|
|
/* Global lock to protect operation on the lists. */
|
|
pthread_mutex_t __timer_mutex = PTHREAD_MUTEX_INITIALIZER;
|
|
|
|
/* Variable to protext initialization. */
|
|
pthread_once_t __timer_init_once_control = PTHREAD_ONCE_INIT;
|
|
|
|
/* Nonzero if initialization of timer implementation failed. */
|
|
int __timer_init_failed;
|
|
|
|
/* Node for the thread used to deliver signals. */
|
|
struct thread_node __timer_signal_thread_rclk;
|
|
#ifdef _POSIX_CPUTIME
|
|
struct thread_node __timer_signal_thread_pclk;
|
|
#endif
|
|
#ifdef _POSIX_THREAD_CPUTIME
|
|
struct thread_node __timer_signal_thread_tclk;
|
|
#endif
|
|
|
|
/* Lists to keep free and used timers and threads. */
|
|
struct list_links timer_free_list;
|
|
struct list_links thread_free_list;
|
|
struct list_links thread_active_list;
|
|
|
|
|
|
#ifdef __NR_rt_sigqueueinfo
|
|
extern int __syscall_rt_sigqueueinfo (int, int, siginfo_t *);
|
|
#endif
|
|
|
|
|
|
/* List handling functions. */
|
|
static inline void
|
|
list_init (struct list_links *list)
|
|
{
|
|
list->next = list->prev = list;
|
|
}
|
|
|
|
static inline void
|
|
list_append (struct list_links *list, struct list_links *newp)
|
|
{
|
|
newp->prev = list->prev;
|
|
newp->next = list;
|
|
list->prev->next = newp;
|
|
list->prev = newp;
|
|
}
|
|
|
|
static inline void
|
|
list_insbefore (struct list_links *list, struct list_links *newp)
|
|
{
|
|
list_append (list, newp);
|
|
}
|
|
|
|
/*
|
|
* Like list_unlink_ip, except that calling it on a node that
|
|
* is already unlinked is disastrous rather than a noop.
|
|
*/
|
|
|
|
static inline void
|
|
list_unlink (struct list_links *list)
|
|
{
|
|
struct list_links *lnext = list->next, *lprev = list->prev;
|
|
|
|
lnext->prev = lprev;
|
|
lprev->next = lnext;
|
|
}
|
|
|
|
static inline struct list_links *
|
|
list_first (struct list_links *list)
|
|
{
|
|
return list->next;
|
|
}
|
|
|
|
static inline struct list_links *
|
|
list_null (struct list_links *list)
|
|
{
|
|
return list;
|
|
}
|
|
|
|
static inline struct list_links *
|
|
list_next (struct list_links *list)
|
|
{
|
|
return list->next;
|
|
}
|
|
|
|
static inline int
|
|
list_isempty (struct list_links *list)
|
|
{
|
|
return list->next == list;
|
|
}
|
|
|
|
|
|
/* Functions build on top of the list functions. */
|
|
static inline struct thread_node *
|
|
thread_links2ptr (struct list_links *list)
|
|
{
|
|
return (struct thread_node *) ((char *) list
|
|
- offsetof (struct thread_node, links));
|
|
}
|
|
|
|
static inline struct timer_node *
|
|
timer_links2ptr (struct list_links *list)
|
|
{
|
|
return (struct timer_node *) ((char *) list
|
|
- offsetof (struct timer_node, links));
|
|
}
|
|
|
|
|
|
/* Initialize a newly allocated thread structure. */
|
|
static void
|
|
thread_init (struct thread_node *thread, const pthread_attr_t *attr, clockid_t clock_id)
|
|
{
|
|
if (attr != NULL)
|
|
thread->attr = *attr;
|
|
else
|
|
{
|
|
pthread_attr_init (&thread->attr);
|
|
pthread_attr_setdetachstate (&thread->attr, PTHREAD_CREATE_DETACHED);
|
|
}
|
|
|
|
thread->exists = 0;
|
|
list_init (&thread->timer_queue);
|
|
pthread_cond_init (&thread->cond, 0);
|
|
thread->current_timer = 0;
|
|
thread->captured = pthread_self ();
|
|
thread->clock_id = clock_id;
|
|
}
|
|
|
|
|
|
/* Initialize the global lists, and acquire global resources. Error
|
|
reporting is done by storing a non-zero value to the global variable
|
|
timer_init_failed. */
|
|
static void
|
|
init_module (void)
|
|
{
|
|
int i;
|
|
|
|
list_init (&timer_free_list);
|
|
list_init (&thread_free_list);
|
|
list_init (&thread_active_list);
|
|
|
|
for (i = 0; i < TIMER_MAX; ++i)
|
|
{
|
|
list_append (&timer_free_list, &__timer_array[i].links);
|
|
__timer_array[i].inuse = TIMER_FREE;
|
|
}
|
|
|
|
for (i = 0; i < THREAD_MAXNODES; ++i)
|
|
list_append (&thread_free_list, &thread_array[i].links);
|
|
|
|
thread_init (&__timer_signal_thread_rclk, 0, CLOCK_REALTIME);
|
|
#ifdef _POSIX_CPUTIME
|
|
thread_init (&__timer_signal_thread_pclk, 0, CLOCK_PROCESS_CPUTIME_ID);
|
|
#endif
|
|
#ifdef _POSIX_THREAD_CPUTIME
|
|
thread_init (&__timer_signal_thread_tclk, 0, CLOCK_THREAD_CPUTIME_ID);
|
|
#endif
|
|
}
|
|
|
|
|
|
/* This is a handler executed in a child process after a fork()
|
|
occurs. It reinitializes the module, resetting all of the data
|
|
structures to their initial state. The mutex is initialized in
|
|
case it was locked in the parent process. */
|
|
static void
|
|
reinit_after_fork (void)
|
|
{
|
|
init_module ();
|
|
pthread_mutex_init (&__timer_mutex, 0);
|
|
}
|
|
|
|
|
|
/* Called once form pthread_once in timer_init. This initializes the
|
|
module and ensures that reinit_after_fork will be executed in any
|
|
child process. */
|
|
void
|
|
__timer_init_once (void)
|
|
{
|
|
init_module ();
|
|
pthread_atfork (0, 0, reinit_after_fork);
|
|
}
|
|
|
|
|
|
/* Deinitialize a thread that is about to be deallocated. */
|
|
static void
|
|
thread_deinit (struct thread_node *thread)
|
|
{
|
|
assert (list_isempty (&thread->timer_queue));
|
|
pthread_cond_destroy (&thread->cond);
|
|
}
|
|
|
|
|
|
/* Allocate a thread structure from the global free list. Global
|
|
mutex lock must be held by caller. The thread is moved to
|
|
the active list. */
|
|
struct thread_node *
|
|
__timer_thread_alloc (const pthread_attr_t *desired_attr, clockid_t clock_id)
|
|
{
|
|
struct list_links *node = list_first (&thread_free_list);
|
|
|
|
if (node != list_null (&thread_free_list))
|
|
{
|
|
struct thread_node *thread = thread_links2ptr (node);
|
|
list_unlink (node);
|
|
thread_init (thread, desired_attr, clock_id);
|
|
list_append (&thread_active_list, node);
|
|
return thread;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
/* Return a thread structure to the global free list. Global lock
|
|
must be held by caller. */
|
|
void
|
|
__timer_thread_dealloc (struct thread_node *thread)
|
|
{
|
|
thread_deinit (thread);
|
|
list_unlink (&thread->links);
|
|
list_append (&thread_free_list, &thread->links);
|
|
}
|
|
|
|
|
|
/* Each of our threads which terminates executes this cleanup
|
|
handler. We never terminate threads ourselves; if a thread gets here
|
|
it means that the evil application has killed it. If the thread has
|
|
timers, these require servicing and so we must hire a replacement
|
|
thread right away. We must also unblock another thread that may
|
|
have been waiting for this thread to finish servicing a timer (see
|
|
timer_delete()). */
|
|
|
|
static void
|
|
thread_cleanup (void *val)
|
|
{
|
|
if (val != NULL)
|
|
{
|
|
struct thread_node *thread = val;
|
|
|
|
/* How did the signal thread get killed? */
|
|
assert (thread != &__timer_signal_thread_rclk);
|
|
#ifdef _POSIX_CPUTIME
|
|
assert (thread != &__timer_signal_thread_pclk);
|
|
#endif
|
|
#ifdef _POSIX_THREAD_CPUTIME
|
|
assert (thread != &__timer_signal_thread_tclk);
|
|
#endif
|
|
|
|
pthread_mutex_lock (&__timer_mutex);
|
|
|
|
thread->exists = 0;
|
|
|
|
/* We are no longer processing a timer event. */
|
|
thread->current_timer = 0;
|
|
|
|
if (list_isempty (&thread->timer_queue))
|
|
__timer_thread_dealloc (thread);
|
|
else
|
|
(void) __timer_thread_start (thread);
|
|
|
|
pthread_mutex_unlock (&__timer_mutex);
|
|
|
|
/* Unblock potentially blocked timer_delete(). */
|
|
pthread_cond_broadcast (&thread->cond);
|
|
}
|
|
}
|
|
|
|
|
|
/* Handle a timer which is supposed to go off now. */
|
|
static void
|
|
thread_expire_timer (struct thread_node *self, struct timer_node *timer)
|
|
{
|
|
self->current_timer = timer; /* Lets timer_delete know timer is running. */
|
|
|
|
pthread_mutex_unlock (&__timer_mutex);
|
|
|
|
switch (__builtin_expect (timer->event.sigev_notify, SIGEV_SIGNAL))
|
|
{
|
|
case SIGEV_NONE:
|
|
assert (! "timer_create should never have created such a timer");
|
|
break;
|
|
|
|
case SIGEV_SIGNAL:
|
|
#ifdef __NR_rt_sigqueueinfo
|
|
{
|
|
siginfo_t info;
|
|
|
|
/* First, clear the siginfo_t structure, so that we don't pass our
|
|
stack content to other tasks. */
|
|
memset (&info, 0, sizeof (siginfo_t));
|
|
/* We must pass the information about the data in a siginfo_t
|
|
value. */
|
|
info.si_signo = timer->event.sigev_signo;
|
|
info.si_code = SI_TIMER;
|
|
info.si_pid = timer->creator_pid;
|
|
info.si_uid = getuid ();
|
|
info.si_value = timer->event.sigev_value;
|
|
|
|
INLINE_SYSCALL (rt_sigqueueinfo, 3, info.si_pid, info.si_signo, &info);
|
|
}
|
|
#else
|
|
if (pthread_kill (self->captured, timer->event.sigev_signo) != 0)
|
|
{
|
|
if (pthread_kill (self->id, timer->event.sigev_signo) != 0)
|
|
abort ();
|
|
}
|
|
#endif
|
|
break;
|
|
|
|
case SIGEV_THREAD:
|
|
timer->event.sigev_notify_function (timer->event.sigev_value);
|
|
break;
|
|
|
|
default:
|
|
assert (! "unknown event");
|
|
break;
|
|
}
|
|
|
|
pthread_mutex_lock (&__timer_mutex);
|
|
|
|
self->current_timer = 0;
|
|
|
|
pthread_cond_broadcast (&self->cond);
|
|
}
|
|
|
|
|
|
/* Thread function; executed by each timer thread. The job of this
|
|
function is to wait on the thread's timer queue and expire the
|
|
timers in chronological order as close to their scheduled time as
|
|
possible. */
|
|
static void
|
|
__attribute__ ((noreturn))
|
|
thread_func (void *arg)
|
|
{
|
|
struct thread_node *self = arg;
|
|
|
|
/* Register cleanup handler, in case rogue application terminates
|
|
this thread. (This cannot happen to __timer_signal_thread, which
|
|
doesn't invoke application callbacks). */
|
|
|
|
pthread_cleanup_push (thread_cleanup, self);
|
|
|
|
pthread_mutex_lock (&__timer_mutex);
|
|
|
|
while (1)
|
|
{
|
|
struct list_links *first;
|
|
struct timer_node *timer = NULL;
|
|
|
|
/* While the timer queue is not empty, inspect the first node. */
|
|
first = list_first (&self->timer_queue);
|
|
if (first != list_null (&self->timer_queue))
|
|
{
|
|
struct timespec now;
|
|
|
|
timer = timer_links2ptr (first);
|
|
|
|
/* This assumes that the elements of the list of one thread
|
|
are all for the same clock. */
|
|
clock_gettime (timer->clock, &now);
|
|
|
|
while (1)
|
|
{
|
|
/* If the timer is due or overdue, remove it from the queue.
|
|
If it's a periodic timer, re-compute its new time and
|
|
requeue it. Either way, perform the timer expiry. */
|
|
if (timespec_compare (&now, &timer->expirytime) < 0)
|
|
break;
|
|
|
|
list_unlink_ip (first);
|
|
|
|
if (__builtin_expect (timer->value.it_interval.tv_sec, 0) != 0
|
|
|| timer->value.it_interval.tv_nsec != 0)
|
|
{
|
|
timer->overrun_count = 0;
|
|
timespec_add (&timer->expirytime, &timer->expirytime,
|
|
&timer->value.it_interval);
|
|
while (timespec_compare (&timer->expirytime, &now) < 0)
|
|
{
|
|
timespec_add (&timer->expirytime, &timer->expirytime,
|
|
&timer->value.it_interval);
|
|
if (timer->overrun_count < DELAYTIMER_MAX)
|
|
++timer->overrun_count;
|
|
}
|
|
__timer_thread_queue_timer (self, timer);
|
|
}
|
|
|
|
thread_expire_timer (self, timer);
|
|
|
|
first = list_first (&self->timer_queue);
|
|
if (first == list_null (&self->timer_queue))
|
|
break;
|
|
|
|
timer = timer_links2ptr (first);
|
|
}
|
|
}
|
|
|
|
/* If the queue is not empty, wait until the expiry time of the
|
|
first node. Otherwise wait indefinitely. Insertions at the
|
|
head of the queue must wake up the thread by broadcasting
|
|
this condition variable. */
|
|
if (timer != NULL)
|
|
pthread_cond_timedwait (&self->cond, &__timer_mutex,
|
|
&timer->expirytime);
|
|
else
|
|
pthread_cond_wait (&self->cond, &__timer_mutex);
|
|
}
|
|
/* This macro will never be executed since the while loop loops
|
|
forever - but we have to add it for proper nesting. */
|
|
pthread_cleanup_pop (1);
|
|
}
|
|
|
|
|
|
/* Enqueue a timer in wakeup order in the thread's timer queue.
|
|
Returns 1 if the timer was inserted at the head of the queue,
|
|
causing the queue's next wakeup time to change. */
|
|
|
|
int
|
|
__timer_thread_queue_timer (struct thread_node *thread,
|
|
struct timer_node *insert)
|
|
{
|
|
struct list_links *iter;
|
|
int athead = 1;
|
|
|
|
for (iter = list_first (&thread->timer_queue);
|
|
iter != list_null (&thread->timer_queue);
|
|
iter = list_next (iter))
|
|
{
|
|
struct timer_node *timer = timer_links2ptr (iter);
|
|
|
|
if (timespec_compare (&insert->expirytime, &timer->expirytime) < 0)
|
|
break;
|
|
athead = 0;
|
|
}
|
|
|
|
list_insbefore (iter, &insert->links);
|
|
return athead;
|
|
}
|
|
|
|
|
|
/* Start a thread and associate it with the given thread node. Global
|
|
lock must be held by caller. */
|
|
int
|
|
__timer_thread_start (struct thread_node *thread)
|
|
{
|
|
int retval = 1;
|
|
|
|
assert (!thread->exists);
|
|
thread->exists = 1;
|
|
|
|
if (pthread_create (&thread->id, &thread->attr,
|
|
(void *(*) (void *)) thread_func, thread) != 0)
|
|
{
|
|
thread->exists = 0;
|
|
retval = -1;
|
|
}
|
|
|
|
return retval;
|
|
}
|
|
|
|
|
|
void
|
|
__timer_thread_wakeup (struct thread_node *thread)
|
|
{
|
|
pthread_cond_broadcast (&thread->cond);
|
|
}
|
|
|
|
|
|
/* Compare two pthread_attr_t thread attributes for exact equality.
|
|
Returns 1 if they are equal, otherwise zero if they are not equal or
|
|
contain illegal values. This version is LinuxThreads-specific for
|
|
performance reason. One could use the access functions to get the
|
|
values of all the fields of the attribute structure. */
|
|
static int
|
|
thread_attr_compare (const pthread_attr_t *left, const pthread_attr_t *right)
|
|
{
|
|
struct pthread_attr *ileft = (struct pthread_attr *) left;
|
|
struct pthread_attr *iright = (struct pthread_attr *) right;
|
|
|
|
return (ileft->flags == iright->flags
|
|
&& ileft->schedpolicy == iright->schedpolicy
|
|
&& (ileft->schedparam.sched_priority
|
|
== iright->schedparam.sched_priority));
|
|
}
|
|
|
|
|
|
/* Search the list of active threads and find one which has matching
|
|
attributes. Global mutex lock must be held by caller. */
|
|
struct thread_node *
|
|
__timer_thread_find_matching (const pthread_attr_t *desired_attr,
|
|
clockid_t desired_clock_id)
|
|
{
|
|
struct list_links *iter = list_first (&thread_active_list);
|
|
|
|
while (iter != list_null (&thread_active_list))
|
|
{
|
|
struct thread_node *candidate = thread_links2ptr (iter);
|
|
|
|
if (thread_attr_compare (desired_attr, &candidate->attr)
|
|
&& desired_clock_id == candidate->clock_id)
|
|
{
|
|
list_unlink (iter);
|
|
return candidate;
|
|
}
|
|
|
|
iter = list_next (iter);
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
|
|
/* Grab a free timer structure from the global free list. The global
|
|
lock must be held by the caller. */
|
|
struct timer_node *
|
|
__timer_alloc (void)
|
|
{
|
|
struct list_links *node = list_first (&timer_free_list);
|
|
|
|
if (node != list_null (&timer_free_list))
|
|
{
|
|
struct timer_node *timer = timer_links2ptr (node);
|
|
list_unlink_ip (node);
|
|
timer->inuse = TIMER_INUSE;
|
|
timer->refcount = 1;
|
|
return timer;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
|
|
/* Return a timer structure to the global free list. The global lock
|
|
must be held by the caller. */
|
|
void
|
|
__timer_dealloc (struct timer_node *timer)
|
|
{
|
|
assert (timer->refcount == 0);
|
|
timer->thread = NULL; /* Break association between timer and thread. */
|
|
timer->inuse = TIMER_FREE;
|
|
list_append (&timer_free_list, &timer->links);
|
|
}
|
|
|
|
|
|
/* Thread cancellation handler which unlocks a mutex. */
|
|
void
|
|
__timer_mutex_cancel_handler (void *arg)
|
|
{
|
|
pthread_mutex_unlock (arg);
|
|
}
|