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

Merge "Implement pthread barrier."

Browse Source
This commit is contained in:
Yabin Cui 2015-11-17 00:22:54 +00:00 committed by Gerrit Code Review
commit b804b9d67b
11 changed files with 373 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
libc/Android.mk
View File

@ -564,6 +564,7 @@ libc_upstream_openbsd_ndk_src_files := \
libc_pthread_src_files := \
bionic/pthread_atfork.cpp \
bionic/pthread_attr.cpp \
bionic/pthread_barrier.cpp \
bionic/pthread_cond.cpp \
bionic/pthread_create.cpp \
bionic/pthread_detach.cpp \

183
libc/bionic/pthread_barrier.cpp Normal file
View File

@ -0,0 +1,183 @@
/*
* Copyright (C) 2015 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <pthread.h>
#include <stdatomic.h>
#include <stdint.h>
#include "private/bionic_futex.h"
int pthread_barrierattr_init(pthread_barrierattr_t* attr) {
*attr = 0;
return 0;
}
int pthread_barrierattr_destroy(pthread_barrierattr_t* attr) {
*attr = 0;
return 0;
}
int pthread_barrierattr_getpshared(pthread_barrierattr_t* attr, int* pshared) {
*pshared = (*attr & 1) ? PTHREAD_PROCESS_SHARED : PTHREAD_PROCESS_PRIVATE;
return 0;
}
int pthread_barrierattr_setpshared(pthread_barrierattr_t* attr, int pshared) {
if (pshared == PTHREAD_PROCESS_SHARED) {
*attr |= 1;
} else {
*attr &= ~1;
}
return 0;
}
enum BarrierState {
WAIT,
RELEASE,
};
struct pthread_barrier_internal_t {
// One barrier can be used for unlimited number of cycles. In each cycle, [init_count]
// threads must call pthread_barrier_wait() before any of them successfully return from
// the call. It is undefined behavior if there are more than [init_count] threads call
// pthread_barrier_wait() in one cycle.
uint32_t init_count;
// Barrier state. It is WAIT if waiting for more threads to enter the barrier in this cycle,
// otherwise threads are leaving the barrier.
_Atomic(BarrierState) state;
// Number of threads having entered but not left the barrier in this cycle.
atomic_uint wait_count;
// Whether the barrier is shared across processes.
bool pshared;
uint32_t __reserved[4];
};
static_assert(sizeof(pthread_barrier_t) == sizeof(pthread_barrier_internal_t),
"pthread_barrier_t should actually be pthread_barrier_internal_t in implementation."
);
static_assert(alignof(pthread_barrier_t) >= 4,
"pthread_barrier_t should fulfill the alignment of pthread_barrier_internal_t.");
static inline pthread_barrier_internal_t* __get_internal_barrier(pthread_barrier_t* barrier) {
return reinterpret_cast<pthread_barrier_internal_t*>(barrier);
}
int pthread_barrier_init(pthread_barrier_t* barrier_interface, const pthread_barrierattr_t* attr,
unsigned count) {
pthread_barrier_internal_t* barrier = __get_internal_barrier(barrier_interface);
if (count == 0) {
return EINVAL;
}
barrier->init_count = count;
atomic_init(&barrier->state, WAIT);
atomic_init(&barrier->wait_count, 0);
barrier->pshared = false;
if (attr != nullptr && (*attr & 1)) {
barrier->pshared = true;
}
return 0;
}
// According to POSIX standard, pthread_barrier_wait() synchronizes memory between participating
// threads. It means all memory operations made by participating threads before calling
// pthread_barrier_wait() can be seen by all participating threads after the function call.
// We establish this by making a happens-before relation between all threads entering the barrier
// with the last thread entering the barrier, and a happens-before relation between the last
// thread entering the barrier with all threads leaving the barrier.
int pthread_barrier_wait(pthread_barrier_t* barrier_interface) {
pthread_barrier_internal_t* barrier = __get_internal_barrier(barrier_interface);
// Wait until all threads for the previous cycle have left the barrier. This is needed
// as a participating thread can call pthread_barrier_wait() again before other
// threads have left the barrier. Use acquire operation here to synchronize with
// the last thread leaving the previous cycle, so we can read correct wait_count below.
while(atomic_load_explicit(&barrier->state, memory_order_acquire) == RELEASE) {
__futex_wait_ex(&barrier->state, barrier->pshared, RELEASE, nullptr);
}
uint32_t prev_wait_count = atomic_load_explicit(&barrier->wait_count, memory_order_relaxed);
while (true) {
// It happens when there are more than [init_count] threads trying to enter the barrier
// at one cycle. We read the POSIX standard as disallowing this, since additional arriving
// threads are not synchronized with respect to the barrier reset. We also don't know of
// any reasonable cases in which this would be intentional.
if (prev_wait_count >= barrier->init_count) {
return EINVAL;
}
// Use memory_order_acq_rel operation here to synchronize between all threads entering
// the barrier with the last thread entering the barrier.
if (atomic_compare_exchange_weak_explicit(&barrier->wait_count, &prev_wait_count,
prev_wait_count + 1u, memory_order_acq_rel,
memory_order_relaxed)) {
break;
}
}
int result = 0;
if (prev_wait_count + 1 == barrier->init_count) {
result = PTHREAD_BARRIER_SERIAL_THREAD;
if (prev_wait_count != 0) {
// Use release operation here to synchronize between the last thread entering the
// barrier with all threads leaving the barrier.
atomic_store_explicit(&barrier->state, RELEASE, memory_order_release);
__futex_wake_ex(&barrier->state, barrier->pshared, prev_wait_count);
}
} else {
// Use acquire operation here to synchronize between the last thread entering the
// barrier with all threads leaving the barrier.
while (atomic_load_explicit(&barrier->state, memory_order_acquire) == WAIT) {
__futex_wait_ex(&barrier->state, barrier->pshared, WAIT, nullptr);
}
}
// Use release operation here to make it not reordered with previous operations.
if (atomic_fetch_sub_explicit(&barrier->wait_count, 1, memory_order_release) == 1) {
// Use release operation here to synchronize with threads entering the barrier for
// the next cycle, or the thread calling pthread_barrier_destroy().
atomic_store_explicit(&barrier->state, WAIT, memory_order_release);
__futex_wake_ex(&barrier->state, barrier->pshared, barrier->init_count);
}
return result;
}
int pthread_barrier_destroy(pthread_barrier_t* barrier_interface) {
pthread_barrier_internal_t* barrier = __get_internal_barrier(barrier_interface);
if (barrier->init_count == 0) {
return EINVAL;
}
// Use acquire operation here to synchronize with the last thread leaving the barrier.
// So we can read correct wait_count below.
while (atomic_load_explicit(&barrier->state, memory_order_acquire) == RELEASE) {
__futex_wait_ex(&barrier->state, barrier->pshared, RELEASE, nullptr);
}
if (atomic_load_explicit(&barrier->wait_count, memory_order_relaxed) != 0) {
return EBUSY;
}
barrier->init_count = 0;
return 0;
}

25
libc/include/pthread.h
View File

@ -96,6 +96,18 @@ typedef int pthread_once_t;
#define PTHREAD_ONCE_INIT 0
typedef struct {
#if defined(__LP64__)
int64_t __private[4];
#else
int32_t __private[8];
#endif
} pthread_barrier_t;
typedef int pthread_barrierattr_t;
#define PTHREAD_BARRIER_SERIAL_THREAD -1
#if defined(__LP64__)
#define PTHREAD_STACK_MIN (4 * PAGE_SIZE)
#else
@ -130,7 +142,7 @@ 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*, size_t stack_size) __nonnull((1));
int pthread_attr_setstacksize(pthread_attr_t*, size_t) __nonnull((1));
int pthread_condattr_destroy(pthread_condattr_t*) __nonnull((1));
int pthread_condattr_getclock(const pthread_condattr_t*, clockid_t*) __nonnull((1, 2));
@ -205,9 +217,18 @@ int pthread_rwlock_timedrdlock(pthread_rwlock_t*, const struct timespec*) __nonn
int pthread_rwlock_timedwrlock(pthread_rwlock_t*, const struct timespec*) __nonnull((1, 2));
int pthread_rwlock_tryrdlock(pthread_rwlock_t*) __nonnull((1));
int pthread_rwlock_trywrlock(pthread_rwlock_t*) __nonnull((1));
int pthread_rwlock_unlock(pthread_rwlock_t *rwlock) __nonnull((1));
int pthread_rwlock_unlock(pthread_rwlock_t *) __nonnull((1));
int pthread_rwlock_wrlock(pthread_rwlock_t*) __nonnull((1));
int pthread_barrierattr_init(pthread_barrierattr_t* attr) __nonnull((1));
int pthread_barrierattr_destroy(pthread_barrierattr_t* attr) __nonnull((1));
int pthread_barrierattr_getpshared(pthread_barrierattr_t* attr, int* pshared) __nonnull((1, 2));
int pthread_barrierattr_setpshared(pthread_barrierattr_t* attr, int pshared) __nonnull((1));
int pthread_barrier_init(pthread_barrier_t*, const pthread_barrierattr_t*, unsigned) __nonnull((1));
int pthread_barrier_destroy(pthread_barrier_t*) __nonnull((1));
int pthread_barrier_wait(pthread_barrier_t*) __nonnull((1));
pthread_t pthread_self(void) __pure2;
int pthread_setname_np(pthread_t, const char*) __nonnull((2));

7
libc/libc.arm.map
View File

@ -1316,6 +1316,13 @@ LIBC_N {
preadv;
preadv64;
prlimit; # arm mips x86
pthread_barrierattr_destroy;
pthread_barrierattr_getpshared;
pthread_barrierattr_init;
pthread_barrierattr_setpshared;
pthread_barrier_destroy;
pthread_barrier_init;
pthread_barrier_wait;
pwritev;
pwritev64;
scandirat;

7
libc/libc.arm64.map
View File

@ -1161,6 +1161,13 @@ LIBC_N {
getgrnam_r;
preadv;
preadv64;
pthread_barrierattr_destroy;
pthread_barrierattr_getpshared;
pthread_barrierattr_init;
pthread_barrierattr_setpshared;
pthread_barrier_destroy;
pthread_barrier_init;
pthread_barrier_wait;
pwritev;
pwritev64;
scandirat;

7
libc/libc.map.txt
View File

@ -1343,6 +1343,13 @@ LIBC_N {
preadv;
preadv64;
prlimit; # arm mips x86
pthread_barrierattr_destroy;
pthread_barrierattr_getpshared;
pthread_barrierattr_init;
pthread_barrierattr_setpshared;
pthread_barrier_destroy;
pthread_barrier_init;
pthread_barrier_wait;
pwritev;
pwritev64;
scandirat;

7
libc/libc.mips.map
View File

@ -1279,6 +1279,13 @@ LIBC_N {
preadv;
preadv64;
prlimit; # arm mips x86
pthread_barrierattr_destroy;
pthread_barrierattr_getpshared;
pthread_barrierattr_init;
pthread_barrierattr_setpshared;
pthread_barrier_destroy;
pthread_barrier_init;
pthread_barrier_wait;
pwritev;
pwritev64;
scandirat;

7
libc/libc.mips64.map
View File

@ -1161,6 +1161,13 @@ LIBC_N {
getgrnam_r;
preadv;
preadv64;
pthread_barrierattr_destroy;
pthread_barrierattr_getpshared;
pthread_barrierattr_init;
pthread_barrierattr_setpshared;
pthread_barrier_destroy;
pthread_barrier_init;
pthread_barrier_wait;
pwritev;
pwritev64;
scandirat;

7
libc/libc.x86.map
View File

@ -1277,6 +1277,13 @@ LIBC_N {
preadv;
preadv64;
prlimit; # arm mips x86
pthread_barrierattr_destroy;
pthread_barrierattr_getpshared;
pthread_barrierattr_init;
pthread_barrierattr_setpshared;
pthread_barrier_destroy;
pthread_barrier_init;
pthread_barrier_wait;
pwritev;
pwritev64;
scandirat;

7
libc/libc.x86_64.map
View File

@ -1161,6 +1161,13 @@ LIBC_N {
getgrnam_r;
preadv;
preadv64;
pthread_barrierattr_destroy;
pthread_barrierattr_getpshared;
pthread_barrierattr_init;
pthread_barrierattr_setpshared;
pthread_barrier_destroy;
pthread_barrier_init;
pthread_barrier_wait;
pwritev;
pwritev64;
scandirat;

120
tests/pthread_test.cpp
View File

@ -721,11 +721,11 @@ TEST(pthread, pthread_rwlock_smoke) {
ASSERT_EQ(0, pthread_rwlock_destroy(&l));
}
static void WaitUntilThreadSleep(std::atomic<pid_t>& pid) {
while (pid == 0) {
static void WaitUntilThreadSleep(std::atomic<pid_t>& tid) {
while (tid == 0) {
usleep(1000);
}
std::string filename = android::base::StringPrintf("/proc/%d/stat", pid.load());
std::string filename = android::base::StringPrintf("/proc/%d/stat", tid.load());
std::regex regex {R"(\s+S\s+)"};
while (true) {
@ -1665,3 +1665,117 @@ TEST(pthread, big_enough_signal_stack_for_64bit_arch) {
kill(getpid(), SIGUSR1);
ASSERT_TRUE(signal_handler_on_altstack_done);
}
TEST(pthread, pthread_barrierattr_smoke) {
pthread_barrierattr_t attr;
ASSERT_EQ(0, pthread_barrierattr_init(&attr));
int pshared;
ASSERT_EQ(0, pthread_barrierattr_getpshared(&attr, &pshared));
ASSERT_EQ(PTHREAD_PROCESS_PRIVATE, pshared);
ASSERT_EQ(0, pthread_barrierattr_setpshared(&attr, PTHREAD_PROCESS_SHARED));
ASSERT_EQ(0, pthread_barrierattr_getpshared(&attr, &pshared));
ASSERT_EQ(PTHREAD_PROCESS_SHARED, pshared);
ASSERT_EQ(0, pthread_barrierattr_destroy(&attr));
}
struct BarrierTestHelperArg {
std::atomic<pid_t> tid;
pthread_barrier_t* barrier;
size_t iteration_count;
};
static void BarrierTestHelper(BarrierTestHelperArg* arg) {
arg->tid = gettid();
for (size_t i = 0; i < arg->iteration_count; ++i) {
ASSERT_EQ(0, pthread_barrier_wait(arg->barrier));
}
}
TEST(pthread, pthread_barrier_smoke) {
const size_t BARRIER_ITERATION_COUNT = 10;
const size_t BARRIER_THREAD_COUNT = 10;
pthread_barrier_t barrier;
ASSERT_EQ(0, pthread_barrier_init(&barrier, nullptr, BARRIER_THREAD_COUNT + 1));
std::vector<pthread_t> threads(BARRIER_THREAD_COUNT);
std::vector<BarrierTestHelperArg> args(threads.size());
for (size_t i = 0; i < threads.size(); ++i) {
args[i].tid = 0;
args[i].barrier = &barrier;
args[i].iteration_count = BARRIER_ITERATION_COUNT;
ASSERT_EQ(0, pthread_create(&threads[i], nullptr,
reinterpret_cast<void* (*)(void*)>(BarrierTestHelper), &args[i]));
}
for (size_t iteration = 0; iteration < BARRIER_ITERATION_COUNT; ++iteration) {
for (size_t i = 0; i < threads.size(); ++i) {
WaitUntilThreadSleep(args[i].tid);
}
ASSERT_EQ(PTHREAD_BARRIER_SERIAL_THREAD, pthread_barrier_wait(&barrier));
}
for (size_t i = 0; i < threads.size(); ++i) {
ASSERT_EQ(0, pthread_join(threads[i], nullptr));
}
ASSERT_EQ(0, pthread_barrier_destroy(&barrier));
}
TEST(pthread, pthread_barrier_destroy) {
pthread_barrier_t barrier;
ASSERT_EQ(0, pthread_barrier_init(&barrier, nullptr, 2));
pthread_t thread;
BarrierTestHelperArg arg;
arg.tid = 0;
arg.barrier = &barrier;
arg.iteration_count = 1;
ASSERT_EQ(0, pthread_create(&thread, nullptr,
reinterpret_cast<void* (*)(void*)>(BarrierTestHelper), &arg));
WaitUntilThreadSleep(arg.tid);
ASSERT_EQ(EBUSY, pthread_barrier_destroy(&barrier));
ASSERT_EQ(PTHREAD_BARRIER_SERIAL_THREAD, pthread_barrier_wait(&barrier));
// Verify if the barrier can be destroyed directly after pthread_barrier_wait().
ASSERT_EQ(0, pthread_barrier_destroy(&barrier));
ASSERT_EQ(0, pthread_join(thread, nullptr));
#if defined(__BIONIC__)
ASSERT_EQ(EINVAL, pthread_barrier_destroy(&barrier));
#endif
}
struct BarrierOrderingTestHelperArg {
pthread_barrier_t* barrier;
size_t* array;
size_t array_length;
size_t id;
};
void BarrierOrderingTestHelper(BarrierOrderingTestHelperArg* arg) {
const size_t ITERATION_COUNT = 10000;
for (size_t i = 1; i <= ITERATION_COUNT; ++i) {
arg->array[arg->id] = i;
int ret = pthread_barrier_wait(arg->barrier);
ASSERT_TRUE(ret == 0 || ret == PTHREAD_BARRIER_SERIAL_THREAD);
for (size_t j = 0; j < arg->array_length; ++j) {
ASSERT_EQ(i, arg->array[j]);
}
ret = pthread_barrier_wait(arg->barrier);
ASSERT_TRUE(ret == 0 || ret == PTHREAD_BARRIER_SERIAL_THREAD);
}
}
TEST(pthread, pthread_barrier_check_ordering) {
const size_t THREAD_COUNT = 4;
pthread_barrier_t barrier;
ASSERT_EQ(0, pthread_barrier_init(&barrier, nullptr, THREAD_COUNT));
size_t array[THREAD_COUNT];
std::vector<pthread_t> threads(THREAD_COUNT);
std::vector<BarrierOrderingTestHelperArg> args(THREAD_COUNT);
for (size_t i = 0; i < THREAD_COUNT; ++i) {
args[i].barrier = &barrier;
args[i].array = array;
args[i].array_length = THREAD_COUNT;
args[i].id = i;
ASSERT_EQ(0, pthread_create(&threads[i], nullptr,
reinterpret_cast<void* (*)(void*)>(BarrierOrderingTestHelper),
&args[i]));
}
for (size_t i = 0; i < THREAD_COUNT; ++i) {
ASSERT_EQ(0, pthread_join(threads[i], nullptr));
}
}