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am 3069270d: am c2bba24d: Merge "Give the timer_create SIGEV_THREAD helper threads sensible names."

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* commit '3069270d8641c7bb57aa308d8f90b4d2dcbf66fc':
  Give the timer_create SIGEV_THREAD helper threads sensible names.
This commit is contained in:
Elliott Hughes 2012-06-06 11:37:25 -07:00 committed by Android Git Automerger
commit 158ad015c2
2 changed files with 217 additions and 249 deletions
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1
libc/Android.mk
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@ -458,6 +458,7 @@ libc_common_cflags := \
-DUSE_DL_PREFIX \ -DUSE_DL_PREFIX \
-DPOSIX_MISTAKE \ -DPOSIX_MISTAKE \
-DLOG_ON_HEAP_ERROR \ -DLOG_ON_HEAP_ERROR \
-std=gnu99
# these macro definitions are required to implement the # these macro definitions are required to implement the
# 'timezone' and 'daylight' global variables, as well as # 'timezone' and 'daylight' global variables, as well as

257
libc/bionic/pthread-timers.c
View File

@ -25,42 +25,43 @@
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE. * SUCH DAMAGE.
*/ */
#include "pthread_internal.h" #include "pthread_internal.h"
#include <linux/time.h>
#include <string.h>
#include <errno.h> #include <errno.h>
#include <linux/time.h>
#include <stdio.h>
#include <string.h>
/* This file implements the support required to implement SIGEV_THREAD posix // Normal (i.e. non-SIGEV_THREAD) timers are created directly by the kernel
* timers. See the following pages for additionnal details: // and are passed as is to/from the caller.
* //
* www.opengroup.org/onlinepubs/000095399/functions/timer_create.html // This file also implements the support required for SIGEV_THREAD ("POSIX interval")
* www.opengroup.org/onlinepubs/000095399/functions/timer_settime.html // timers. See the following pages for additional details:
* www.opengroup.org/onlinepubs/000095399/functions/xsh_chap02_04.html#tag_02_04_01 //
* // www.opengroup.org/onlinepubs/000095399/functions/timer_create.html
* The Linux kernel doesn't support these, so we need to implement them in the // www.opengroup.org/onlinepubs/000095399/functions/timer_settime.html
* C library. We use a very basic scheme where each timer is associated to a // www.opengroup.org/onlinepubs/000095399/functions/xsh_chap02_04.html#tag_02_04_01
* thread that will loop, waiting for timeouts or messages from the program //
* corresponding to calls to timer_settime() and timer_delete(). // The Linux kernel doesn't support these, so we need to implement them in the
* // C library. We use a very basic scheme where each timer is associated to a
* Note also an important thing: Posix mandates that in the case of fork(), // thread that will loop, waiting for timeouts or messages from the program
* the timers of the child process should be disarmed, but not deleted. // corresponding to calls to timer_settime() and timer_delete().
* this is implemented by providing a fork() wrapper (see bionic/fork.c) which //
* stops all timers before the fork, and only re-start them in case of error // Note also an important thing: Posix mandates that in the case of fork(),
* or in the parent process. // the timers of the child process should be disarmed, but not deleted.
* // this is implemented by providing a fork() wrapper (see bionic/fork.c) which
* the stop/start is implemented by the __timer_table_start_stop() function // stops all timers before the fork, and only re-start them in case of error
* below. // or in the parent process.
*/ //
// This stop/start is implemented by the __timer_table_start_stop() function
/* normal (i.e. non-SIGEV_THREAD) timer ids are created directly by the kernel // below.
* and are passed as is to/from the caller. //
* // A SIGEV_THREAD timer ID will always have its TIMER_ID_WRAP_BIT
* on the other hand, a SIGEV_THREAD timer ID will have its TIMER_ID_WRAP_BIT // set to 1. In this implementation, this is always bit 31, which is
* always set to 1. In this implementation, this is always bit 31, which is // guaranteed to never be used by kernel-provided timer ids
* guaranteed to never be used by kernel-provided timer ids //
* // (See code in <kernel>/lib/idr.c, used to manage IDs, to see why.)
* (see code in <kernel>/lib/idr.c, used to manage IDs, to see why)
*/
#define TIMER_ID_WRAP_BIT 0x80000000 #define TIMER_ID_WRAP_BIT 0x80000000
#define TIMER_ID_WRAP(id) ((timer_t)((id) | TIMER_ID_WRAP_BIT)) #define TIMER_ID_WRAP(id) ((timer_t)((id) | TIMER_ID_WRAP_BIT))
@ -171,18 +172,16 @@ thr_timer_table_free( thr_timer_table_t* t, thr_timer_t* timer )
} }
static void static void thr_timer_table_start_stop(thr_timer_table_t* t, int stop) {
thr_timer_table_start_stop( thr_timer_table_t* t, int stop ) if (t == NULL) {
{ return;
int nn; }
pthread_mutex_lock(&t->lock); pthread_mutex_lock(&t->lock);
for (int nn = 0; nn < MAX_THREAD_TIMERS; ++nn) {
for (nn = 0; nn < MAX_THREAD_TIMERS; nn++) {
thr_timer_t* timer = &t->timers[nn]; thr_timer_t* timer = &t->timers[nn];
if (TIMER_ID_IS_VALID(timer->id)) { if (TIMER_ID_IS_VALID(timer->id)) {
/* tell the thread to start/stop */ // Tell the thread to start/stop.
pthread_mutex_lock(&timer->mutex); pthread_mutex_lock(&timer->mutex);
timer->stopped = stop; timer->stopped = stop;
pthread_cond_signal( &timer->cond ); pthread_cond_signal( &timer->cond );
@ -237,18 +236,14 @@ thr_timer_table_from_id( thr_timer_table_t* t,
static pthread_once_t __timer_table_once = PTHREAD_ONCE_INIT; static pthread_once_t __timer_table_once = PTHREAD_ONCE_INIT;
static thr_timer_table_t* __timer_table; static thr_timer_table_t* __timer_table;
static void static void __timer_table_init(void) {
__timer_table_init( void )
{
__timer_table = calloc(1, sizeof(*__timer_table)); __timer_table = calloc(1, sizeof(*__timer_table));
if (__timer_table != NULL) {
if (__timer_table != NULL)
thr_timer_table_init(__timer_table); thr_timer_table_init(__timer_table);
} }
}
static thr_timer_table_t* static thr_timer_table_t* __timer_table_get(void) {
__timer_table_get(void)
{
pthread_once(&__timer_table_once, __timer_table_init); pthread_once(&__timer_table_once, __timer_table_init);
return __timer_table; return __timer_table;
} }
@ -260,13 +255,9 @@ __timer_table_get(void)
** requirements: the timers of fork child processes must be ** requirements: the timers of fork child processes must be
** disarmed but not deleted. ** disarmed but not deleted.
**/ **/
__LIBC_HIDDEN__ void __LIBC_HIDDEN__ void __timer_table_start_stop(int stop) {
__timer_table_start_stop( int stop ) // We access __timer_table directly so we don't create it if it doesn't yet exist.
{ thr_timer_table_start_stop(__timer_table, stop);
if (__timer_table != NULL) {
thr_timer_table_t* table = __timer_table_get();
thr_timer_table_start_stop(table, stop);
}
} }
static thr_timer_t* static thr_timer_t*
@ -293,7 +284,6 @@ thr_timer_unlock( thr_timer_t* t )
/** POSIX TIMERS APIs */ /** POSIX TIMERS APIs */
/* first, declare the syscall stubs */
extern int __timer_create(clockid_t, struct sigevent*, timer_t*); extern int __timer_create(clockid_t, struct sigevent*, timer_t*);
extern int __timer_delete(timer_t); extern int __timer_delete(timer_t);
extern int __timer_gettime(timer_t, struct itimerspec*); extern int __timer_gettime(timer_t, struct itimerspec*);
@ -302,56 +292,48 @@ extern int __timer_getoverrun(timer_t);
static void* timer_thread_start(void*); static void* timer_thread_start(void*);
/* then the wrappers themselves */ int timer_create(clockid_t clock_id, struct sigevent* evp, timer_t* timer_id) {
int // If not a SIGEV_THREAD timer, the kernel can handle it without our help.
timer_create( clockid_t clockid, struct sigevent* evp, timer_t *ptimerid) if (__likely(evp == NULL || evp->sigev_notify != SIGEV_THREAD)) {
{ return __timer_create(clock_id, evp, timer_id);
/* if not a SIGEV_THREAD timer, direct creation by the kernel */ }
if (__likely(evp == NULL || evp->sigev_notify != SIGEV_THREAD))
return __timer_create( clockid, evp, ptimerid );
// check arguments // Check arguments.
if (evp->sigev_notify_function == NULL) { if (evp->sigev_notify_function == NULL) {
errno = EINVAL; errno = EINVAL;
return -1; return -1;
} }
{ // Check that the clock id is supported by the kernel.
struct timespec dummy; struct timespec dummy;
if (clock_gettime(clock_id, &dummy) < 0 && errno == EINVAL) {
/* check that the clock id is supported by the kernel */
if (clock_gettime( clockid, &dummy ) < 0 && errno == EINVAL )
return -1; return -1;
} }
/* create a new timer and its thread */ // Create a new timer and its thread.
{ // TODO: use a single global thread for all timers.
thr_timer_table_t* table = __timer_table_get(); thr_timer_table_t* table = __timer_table_get();
thr_timer_t* timer = thr_timer_table_alloc(table); thr_timer_t* timer = thr_timer_table_alloc(table);
struct sigevent evp0;
if (timer == NULL) { if (timer == NULL) {
errno = ENOMEM; errno = ENOMEM;
return -1; return -1;
} }
/* copy the thread attributes */ // Copy the thread attributes.
if (evp->sigev_notify_attributes == NULL) { if (evp->sigev_notify_attributes == NULL) {
pthread_attr_init(&timer->attributes); pthread_attr_init(&timer->attributes);
} } else {
else {
timer->attributes = ((pthread_attr_t*) evp->sigev_notify_attributes)[0]; timer->attributes = ((pthread_attr_t*) evp->sigev_notify_attributes)[0];
} }
/* Posix says that the default is PTHREAD_CREATE_DETACHED and // Posix says that the default is PTHREAD_CREATE_DETACHED and
* that PTHREAD_CREATE_JOINABLE has undefined behaviour. // that PTHREAD_CREATE_JOINABLE has undefined behavior.
* So simply always use DETACHED :-) // So simply always use DETACHED :-)
*/
pthread_attr_setdetachstate(&timer->attributes, PTHREAD_CREATE_DETACHED); pthread_attr_setdetachstate(&timer->attributes, PTHREAD_CREATE_DETACHED);
timer->callback = evp->sigev_notify_function; timer->callback = evp->sigev_notify_function;
timer->value = evp->sigev_value; timer->value = evp->sigev_value;
timer->clock = clockid; timer->clock = clock_id;
pthread_mutex_init(&timer->mutex, NULL); pthread_mutex_init(&timer->mutex, NULL);
pthread_cond_init(&timer->cond, NULL); pthread_cond_init(&timer->cond, NULL);
@ -362,17 +344,17 @@ timer_create( clockid_t clockid, struct sigevent* evp, timer_t *ptimerid)
timer->period.tv_sec = timer->period.tv_nsec = 0; timer->period.tv_sec = timer->period.tv_nsec = 0;
timer->overruns = 0; timer->overruns = 0;
/* create the thread */ // Create the thread.
if (pthread_create( &timer->thread, &timer->attributes, timer_thread_start, timer ) < 0) { int rc = pthread_create(&timer->thread, &timer->attributes, timer_thread_start, timer);
thr_timer_table_free( __timer_table, timer ); if (rc != 0) {
errno = ENOMEM; thr_timer_table_free(table, timer);
errno = rc;
return -1; return -1;
} }
*ptimerid = timer->id; *timer_id = timer->id;
return 0; return 0;
} }
}
int int
@ -532,78 +514,68 @@ timer_getoverrun(timer_t id)
} }
static void* static void* timer_thread_start(void* arg) {
timer_thread_start( void* _arg ) thr_timer_t* timer = arg;
{
thr_timer_t* timer = _arg;
thr_timer_lock(timer); thr_timer_lock(timer);
/* we loop until timer->done is set in timer_delete() */ // Give this thread a meaningful name.
while (!timer->done) char name[32];
{ snprintf(name, sizeof(name), "POSIX interval timer 0x%08x", timer->id);
pthread_setname_np(pthread_self(), name);
// We loop until timer->done is set in timer_delete().
while (!timer->done) {
struct timespec expires = timer->expires; struct timespec expires = timer->expires;
struct timespec period = timer->period; struct timespec period = timer->period;
struct timespec now;
/* if the timer is stopped or disarmed, wait indefinitely // If the timer is stopped or disarmed, wait indefinitely
* for a state change from timer_settime/_delete/_start_stop // for a state change from timer_settime/_delete/_start_stop.
*/ if (timer->stopped || timespec_is_zero(&expires)) {
if ( timer->stopped || timespec_is_zero(&expires) )
{
pthread_cond_wait(&timer->cond, &timer->mutex); pthread_cond_wait(&timer->cond, &timer->mutex);
continue; continue;
} }
/* otherwise, we need to do a timed wait until either a // Otherwise, we need to do a timed wait until either a
* state change of the timer expiration time. // state change of the timer expiration time.
*/ struct timespec now;
clock_gettime(timer->clock, &now); clock_gettime(timer->clock, &now);
if (timespec_cmp( &expires, &now ) > 0) if (timespec_cmp(&expires, &now) > 0) {
{ // Cool, there was no overrun, so compute the
/* cool, there was no overrun, so compute the // relative timeout as 'expires - now', then wait.
* relative timeout as 'expires - now', then wait
*/
int ret;
struct timespec diff = expires; struct timespec diff = expires;
timespec_sub(&diff, &now); timespec_sub(&diff, &now);
ret = __pthread_cond_timedwait_relative( int ret = __pthread_cond_timedwait_relative(&timer->cond, &timer->mutex, &diff);
&timer->cond, &timer->mutex, &diff);
/* if we didn't timeout, it means that a state change // If we didn't time out, it means that a state change
* occured, so reloop to take care of it. // occurred, so loop to take care of it.
*/ if (ret != ETIMEDOUT) {
if (ret != ETIMEDOUT)
continue; continue;
} }
else } else {
{ // Overrun was detected before we could wait!
/* overrun was detected before we could wait ! */ if (!timespec_is_zero(&period)) {
if (!timespec_is_zero( &period ) ) // For periodic timers, compute total overrun count.
{
/* for periodic timers, compute total overrun count */
do { do {
timespec_add(&expires, &period); timespec_add(&expires, &period);
if (timer->overruns < DELAYTIMER_MAX) if (timer->overruns < DELAYTIMER_MAX) {
timer->overruns += 1; timer->overruns += 1;
}
} while (timespec_cmp(&expires, &now) < 0); } while (timespec_cmp(&expires, &now) < 0);
/* backtrack the last one, because we're going to // Backtrack the last one, because we're going to
* add the same value just a bit later */ // add the same value just a bit later.
timespec_sub(&expires, &period); timespec_sub(&expires, &period);
} } else {
else // For non-periodic timers, things are simple.
{
/* for non-periodic timer, things are simple */
timer->overruns = 1; timer->overruns = 1;
} }
} }
/* if we get there, a timeout was detected. // If we get here, a timeout was detected.
* first reload/disarm the timer has needed // First reload/disarm the timer as needed.
*/
if (!timespec_is_zero(&period)) { if (!timespec_is_zero(&period)) {
timespec_add(&expires, &period); timespec_add(&expires, &period);
} else { } else {
@ -611,29 +583,24 @@ timer_thread_start( void* _arg )
} }
timer->expires = expires; timer->expires = expires;
/* now call the timer callback function. release the // Now call the timer callback function. Release the
* lock to allow the function to modify the timer setting // lock to allow the function to modify the timer setting
* or call timer_getoverrun(). // or call timer_getoverrun().
* // NOTE: at this point we trust the callback not to be a
* NOTE: at this point we trust the callback not to be a // total moron and pthread_kill() the timer thread
* total moron and pthread_kill() the timer thread
*/
thr_timer_unlock(timer); thr_timer_unlock(timer);
timer->callback(timer->value); timer->callback(timer->value);
thr_timer_lock(timer); thr_timer_lock(timer);
/* now clear the overruns counter. it only makes sense // Now clear the overruns counter. it only makes sense
* within the callback */ // within the callback.
timer->overruns = 0; timer->overruns = 0;
} }
thr_timer_unlock(timer); thr_timer_unlock(timer);
/* free the timer object now. there is no need to call // Free the timer object.
* __timer_table_get() since we're guaranteed that __timer_table thr_timer_table_free(__timer_table_get(), timer);
* is initialized in this thread
*/
thr_timer_table_free(__timer_table, timer);
return NULL; return NULL;
} }