generic-library/bionic
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Implement pthread_condattr_{get,set}clock.

Browse Source 
We only support CLOCK_REALTIME and CLOCK_MONOTONIC for now,
so we us a single bit from pthread_cond_t->value to denote
the clock type. Note that this reduces the width of the counter
to 30 bits, but this should be large enough for all practical
purposes.

bug: 13232338

Change-Id: I857e7da64b3ecbb23eeac7c9f3fbd460f60231bd
This commit is contained in:
Narayan Kamath 2014-03-03 15:38:51 +00:00
parent 2c7c79e6e5
commit 51e6cb33e3
3 changed files with 116 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

87
libc/bionic/pthread_cond.cpp
View File

@ -32,6 +32,7 @@
#include <limits.h>
#include <sys/atomics.h>
#include <sys/mman.h>
#include <time.h>
#include <unistd.h>
#include "pthread_internal.h"
@ -42,30 +43,55 @@
#include "private/bionic_tls.h"
#include "private/thread_private.h"
// We use one bit in pthread_condattr_t (long) values as the 'shared' flag
// and one bit for the clock type (CLOCK_REALTIME is ((clockid_t) 1), and
// CLOCK_MONOTONIC is ((clockid_t) 0).). The rest of the bits are a counter.
//
// The 'value' field pthread_cond_t has the same layout.
#define COND_SHARED_MASK 0x0001
#define COND_CLOCK_MASK 0x0002
#define COND_COUNTER_STEP 0x0004
#define COND_FLAGS_MASK (COND_SHARED_MASK | COND_CLOCK_MASK)
#define COND_COUNTER_MASK (~COND_FLAGS_MASK)
#define COND_IS_SHARED(c) (((c) & COND_SHARED_MASK) != 0)
#define COND_GET_CLOCK(c) (((c) & COND_CLOCK_MASK) >> 1)
#define COND_SET_CLOCK(attr, c) ((attr) | (c << 1))
int pthread_condattr_init(pthread_condattr_t* attr) {
if (attr == NULL) {
return EINVAL;
}
*attr = PTHREAD_PROCESS_PRIVATE;
*attr = 0;
*attr |= PTHREAD_PROCESS_PRIVATE;
*attr |= (CLOCK_REALTIME << 1);
return 0;
}
int pthread_condattr_getpshared(const pthread_condattr_t* attr, int* pshared) {
if (attr == NULL || pshared == NULL) {
return EINVAL;
}
*pshared = *attr;
*pshared = static_cast<int>(COND_IS_SHARED(*attr));
return 0;
}
int pthread_condattr_setpshared(pthread_condattr_t* attr, int pshared) {
if (attr == NULL) {
return EINVAL;
}
if (pshared != PTHREAD_PROCESS_SHARED && pshared != PTHREAD_PROCESS_PRIVATE) {
return EINVAL;
}
*attr = pshared;
*attr |= pshared;
return 0;
}
int pthread_condattr_getclock(const pthread_condattr_t* attr, clockid_t* clock) {
*clock = COND_GET_CLOCK(*attr);
return 0;
}
int pthread_condattr_setclock(pthread_condattr_t* attr, clockid_t clock) {
if (clock != CLOCK_MONOTONIC && clock != CLOCK_REALTIME) {
return EINVAL;
}
*attr = COND_SET_CLOCK(*attr, clock);
return 0;
}
@ -77,13 +103,6 @@ int pthread_condattr_destroy(pthread_condattr_t* attr) {
return 0;
}
// We use one bit in condition variable values as the 'shared' flag
// The rest is a counter.
#define COND_SHARED_MASK 0x0001
#define COND_COUNTER_INCREMENT 0x0002
#define COND_COUNTER_MASK (~COND_SHARED_MASK)
#define COND_IS_SHARED(c) (((c)->value & COND_SHARED_MASK) != 0)
// XXX *technically* there is a race condition that could allow
// XXX a signal to be missed. If thread A is preempted in _wait()
@ -97,10 +116,10 @@ int pthread_cond_init(pthread_cond_t* cond, const pthread_condattr_t* attr) {
return EINVAL;
}
cond->value = 0;
if (attr != NULL && *attr == PTHREAD_PROCESS_SHARED) {
cond->value |= COND_SHARED_MASK;
if (attr != NULL) {
cond->value = (*attr & COND_FLAGS_MASK);
} else {
cond->value = 0;
}
return 0;
@ -123,10 +142,10 @@ static int __pthread_cond_pulse(pthread_cond_t* cond, int counter) {
return EINVAL;
}
long flags = (cond->value & ~COND_COUNTER_MASK);
int flags = (cond->value & COND_FLAGS_MASK);
while (true) {
long old_value = cond->value;
long new_value = ((old_value - COND_COUNTER_INCREMENT) & COND_COUNTER_MASK) | flags;
int old_value = cond->value;
int new_value = ((old_value - COND_COUNTER_STEP) & COND_COUNTER_MASK) | flags;
if (__bionic_cmpxchg(old_value, new_value, &cond->value) == 0) {
break;
}
@ -142,7 +161,7 @@ static int __pthread_cond_pulse(pthread_cond_t* cond, int counter) {
// hold the mutex, they're subject to race conditions anyway.
ANDROID_MEMBAR_FULL();
__futex_wake_ex(&cond->value, COND_IS_SHARED(cond), counter);
__futex_wake_ex(&cond->value, COND_IS_SHARED(cond->value), counter);
return 0;
}
@ -151,7 +170,7 @@ int __pthread_cond_timedwait_relative(pthread_cond_t* cond, pthread_mutex_t* mut
int old_value = cond->value;
pthread_mutex_unlock(mutex);
int status = __futex_wait_ex(&cond->value, COND_IS_SHARED(cond), old_value, reltime);
int status = __futex_wait_ex(&cond->value, COND_IS_SHARED(cond->value), old_value, reltime);
pthread_mutex_lock(mutex);
if (status == -ETIMEDOUT) {
@ -186,21 +205,23 @@ int pthread_cond_signal(pthread_cond_t* cond) {
}
int pthread_cond_wait(pthread_cond_t* cond, pthread_mutex_t* mutex) {
return __pthread_cond_timedwait(cond, mutex, NULL, CLOCK_REALTIME);
return __pthread_cond_timedwait(cond, mutex, NULL, COND_GET_CLOCK(cond->value));
}
int pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t * mutex, const timespec *abstime) {
return __pthread_cond_timedwait(cond, mutex, abstime, CLOCK_REALTIME);
return __pthread_cond_timedwait(cond, mutex, abstime, COND_GET_CLOCK(cond->value));
}
// TODO: this exists only for backward binary compatibility.
int pthread_cond_timedwait_monotonic(pthread_cond_t* cond, pthread_mutex_t* mutex, const timespec* abstime) {
#if !defined(__LP64__)
// TODO: this exists only for backward binary compatibility on 32 bit platforms.
extern "C" int pthread_cond_timedwait_monotonic(pthread_cond_t* cond, pthread_mutex_t* mutex, const timespec* abstime) {
return __pthread_cond_timedwait(cond, mutex, abstime, CLOCK_MONOTONIC);
}
int pthread_cond_timedwait_monotonic_np(pthread_cond_t* cond, pthread_mutex_t* mutex, const timespec* abstime) {
extern "C" int pthread_cond_timedwait_monotonic_np(pthread_cond_t* cond, pthread_mutex_t* mutex, const timespec* abstime) {
return __pthread_cond_timedwait(cond, mutex, abstime, CLOCK_MONOTONIC);
}
#endif // !defined(__LP64__)
int pthread_cond_timedwait_relative_np(pthread_cond_t* cond, pthread_mutex_t* mutex, const timespec* reltime) {
return __pthread_cond_timedwait_relative(cond, mutex, reltime);

8
libc/include/pthread.h
View File

@ -127,11 +127,13 @@ int pthread_attr_setschedparam(pthread_attr_t*, const struct sched_param*) __non
int pthread_attr_setschedpolicy(pthread_attr_t*, int) __nonnull((1));
int pthread_attr_setscope(pthread_attr_t*, int) __nonnull((1));
int pthread_attr_setstack(pthread_attr_t*, void*, size_t) __nonnull((1));
int pthread_attr_setstacksize(pthread_attr_t * attr, size_t stack_size) __nonnull((1));
int pthread_attr_setstacksize(pthread_attr_t*, size_t stack_size) __nonnull((1));
int pthread_condattr_destroy(pthread_condattr_t*) __nonnull((1));
int pthread_condattr_getclock(const pthread_condattr_t*, clockid_t*) __nonnull((1, 2));
int pthread_condattr_getpshared(const pthread_condattr_t*, int*) __nonnull((1, 2));
int pthread_condattr_init(pthread_condattr_t*) __nonnull((1));
int pthread_condattr_setclock(pthread_condattr_t*, clockid_t) __nonnull((1));
int pthread_condattr_setpshared(pthread_condattr_t*, int) __nonnull((1));
int pthread_cond_broadcast(pthread_cond_t*) __nonnull((1));
@ -236,7 +238,9 @@ extern void __pthread_cleanup_pop(__pthread_cleanup_t*, int);
int pthread_attr_getstackaddr(const pthread_attr_t*, void**) __nonnull((1, 2)); /* deprecated */
int pthread_attr_setstackaddr(pthread_attr_t*, void*) __nonnull((1)); /* deprecated */
/* Bionic additions that are deprecated even in the 32-bit ABI. */
// Bionic additions that are deprecated even in the 32-bit ABI.
//
// TODO: Remove them once chromium_org / NFC have switched over.
int pthread_cond_timedwait_monotonic_np(pthread_cond_t*, pthread_mutex_t*, const struct timespec*);
int pthread_cond_timedwait_monotonic(pthread_cond_t*, pthread_mutex_t*, const struct timespec*);
#define HAVE_PTHREAD_COND_TIMEDWAIT_MONOTONIC 1

56
tests/pthread_test.cpp
View File

@ -22,6 +22,7 @@
#include <pthread.h>
#include <signal.h>
#include <sys/mman.h>
#include <time.h>
#include <unistd.h>
TEST(pthread, pthread_key_create) {
@ -597,3 +598,58 @@ TEST(pthread, pthread_attr_getscope) {
ASSERT_EQ(0, pthread_attr_getscope(&attr, &scope));
ASSERT_EQ(PTHREAD_SCOPE_SYSTEM, scope);
}
TEST(pthread, pthread_condattr_init) {
pthread_condattr_t attr;
pthread_condattr_init(&attr);
clockid_t clock;
ASSERT_EQ(0, pthread_condattr_getclock(&attr, &clock));
ASSERT_EQ(CLOCK_REALTIME, clock);
int pshared;
ASSERT_EQ(0, pthread_condattr_getpshared(&attr, &pshared));
ASSERT_EQ(PTHREAD_PROCESS_PRIVATE, pshared);
}
TEST(pthread, pthread_condattr_setclock) {
pthread_condattr_t attr;
pthread_condattr_init(&attr);
ASSERT_EQ(0, pthread_condattr_setclock(&attr, CLOCK_REALTIME));
clockid_t clock;
ASSERT_EQ(0, pthread_condattr_getclock(&attr, &clock));
ASSERT_EQ(CLOCK_REALTIME, clock);
ASSERT_EQ(0, pthread_condattr_setclock(&attr, CLOCK_MONOTONIC));
ASSERT_EQ(0, pthread_condattr_getclock(&attr, &clock));
ASSERT_EQ(CLOCK_MONOTONIC, clock);
ASSERT_EQ(EINVAL, pthread_condattr_setclock(&attr, CLOCK_PROCESS_CPUTIME_ID));
}
TEST(pthread, pthread_cond_broadcast__preserves_condattr_flags) {
#if defined(__BIONIC__) // This tests a bionic implementation detail.
pthread_condattr_t attr;
pthread_condattr_init(&attr);
ASSERT_EQ(0, pthread_condattr_setclock(&attr, CLOCK_MONOTONIC));
ASSERT_EQ(0, pthread_condattr_setpshared(&attr, PTHREAD_PROCESS_SHARED));
pthread_cond_t cond_var;
ASSERT_EQ(0, pthread_cond_init(&cond_var, &attr));
ASSERT_EQ(0, pthread_cond_signal(&cond_var));
ASSERT_EQ(0, pthread_cond_broadcast(&cond_var));
attr = static_cast<pthread_condattr_t>(cond_var.value);
clockid_t clock;
ASSERT_EQ(0, pthread_condattr_getclock(&attr, &clock));
ASSERT_EQ(CLOCK_MONOTONIC, clock);
int pshared;
ASSERT_EQ(0, pthread_condattr_getpshared(&attr, &pshared));
ASSERT_EQ(PTHREAD_PROCESS_SHARED, pshared);
#else // __BIONIC__
GTEST_LOG_(INFO) << "This test does nothing.\n";
#endif // __BIONIC__
}