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Diffstat (limited to 'third_party/abseil_cpp/absl/synchronization/internal/futex.h')
| -rw-r--r-- | third_party/abseil_cpp/absl/synchronization/internal/futex.h | 154 |
1 files changed, 0 insertions, 154 deletions
diff --git a/third_party/abseil_cpp/absl/synchronization/internal/futex.h b/third_party/abseil_cpp/absl/synchronization/internal/futex.h deleted file mode 100644 index 06fbd6d072..0000000000 --- a/third_party/abseil_cpp/absl/synchronization/internal/futex.h +++ /dev/null @@ -1,154 +0,0 @@ -// Copyright 2020 The Abseil Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// https://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. -#ifndef ABSL_SYNCHRONIZATION_INTERNAL_FUTEX_H_ -#define ABSL_SYNCHRONIZATION_INTERNAL_FUTEX_H_ - -#include "absl/base/config.h" - -#ifdef _WIN32 -#include <windows.h> -#else -#include <sys/time.h> -#include <unistd.h> -#endif - -#ifdef __linux__ -#include <linux/futex.h> -#include <sys/syscall.h> -#endif - -#include <errno.h> -#include <stdio.h> -#include <time.h> - -#include <atomic> -#include <cstdint> - -#include "absl/base/optimization.h" -#include "absl/synchronization/internal/kernel_timeout.h" - -#ifdef ABSL_INTERNAL_HAVE_FUTEX -#error ABSL_INTERNAL_HAVE_FUTEX may not be set on the command line -#elif defined(__BIONIC__) -// Bionic supports all the futex operations we need even when some of the futex -// definitions are missing. -#define ABSL_INTERNAL_HAVE_FUTEX -#elif defined(__linux__) && defined(FUTEX_CLOCK_REALTIME) -// FUTEX_CLOCK_REALTIME requires Linux >= 2.6.28. -#define ABSL_INTERNAL_HAVE_FUTEX -#endif - -#ifdef ABSL_INTERNAL_HAVE_FUTEX - -namespace absl { -ABSL_NAMESPACE_BEGIN -namespace synchronization_internal { - -// Some Android headers are missing these definitions even though they -// support these futex operations. -#ifdef __BIONIC__ -#ifndef SYS_futex -#define SYS_futex __NR_futex -#endif -#ifndef FUTEX_WAIT_BITSET -#define FUTEX_WAIT_BITSET 9 -#endif -#ifndef FUTEX_PRIVATE_FLAG -#define FUTEX_PRIVATE_FLAG 128 -#endif -#ifndef FUTEX_CLOCK_REALTIME -#define FUTEX_CLOCK_REALTIME 256 -#endif -#ifndef FUTEX_BITSET_MATCH_ANY -#define FUTEX_BITSET_MATCH_ANY 0xFFFFFFFF -#endif -#endif - -#if defined(__NR_futex_time64) && !defined(SYS_futex_time64) -#define SYS_futex_time64 __NR_futex_time64 -#endif - -#if defined(SYS_futex_time64) && !defined(SYS_futex) -#define SYS_futex SYS_futex_time64 -#endif - -class FutexImpl { - public: - static int WaitUntil(std::atomic<int32_t> *v, int32_t val, - KernelTimeout t) { - int err = 0; - if (t.has_timeout()) { - // https://locklessinc.com/articles/futex_cheat_sheet/ - // Unlike FUTEX_WAIT, FUTEX_WAIT_BITSET uses absolute time. - struct timespec abs_timeout = t.MakeAbsTimespec(); - // Atomically check that the futex value is still 0, and if it - // is, sleep until abs_timeout or until woken by FUTEX_WAKE. - err = syscall( - SYS_futex, reinterpret_cast<int32_t *>(v), - FUTEX_WAIT_BITSET | FUTEX_PRIVATE_FLAG | FUTEX_CLOCK_REALTIME, val, - &abs_timeout, nullptr, FUTEX_BITSET_MATCH_ANY); - } else { - // Atomically check that the futex value is still 0, and if it - // is, sleep until woken by FUTEX_WAKE. - err = syscall(SYS_futex, reinterpret_cast<int32_t *>(v), - FUTEX_WAIT | FUTEX_PRIVATE_FLAG, val, nullptr); - } - if (ABSL_PREDICT_FALSE(err != 0)) { - err = -errno; - } - return err; - } - - static int WaitBitsetAbsoluteTimeout(std::atomic<int32_t> *v, int32_t val, - int32_t bits, - const struct timespec *abstime) { - int err = syscall(SYS_futex, reinterpret_cast<int32_t *>(v), - FUTEX_WAIT_BITSET | FUTEX_PRIVATE_FLAG, val, abstime, - nullptr, bits); - if (ABSL_PREDICT_FALSE(err != 0)) { - err = -errno; - } - return err; - } - - static int Wake(std::atomic<int32_t> *v, int32_t count) { - int err = syscall(SYS_futex, reinterpret_cast<int32_t *>(v), - FUTEX_WAKE | FUTEX_PRIVATE_FLAG, count); - if (ABSL_PREDICT_FALSE(err < 0)) { - err = -errno; - } - return err; - } - - // FUTEX_WAKE_BITSET - static int WakeBitset(std::atomic<int32_t> *v, int32_t count, int32_t bits) { - int err = syscall(SYS_futex, reinterpret_cast<int32_t *>(v), - FUTEX_WAKE_BITSET | FUTEX_PRIVATE_FLAG, count, nullptr, - nullptr, bits); - if (ABSL_PREDICT_FALSE(err < 0)) { - err = -errno; - } - return err; - } -}; - -class Futex : public FutexImpl {}; - -} // namespace synchronization_internal -ABSL_NAMESPACE_END -} // namespace absl - -#endif // ABSL_INTERNAL_HAVE_FUTEX - -#endif // ABSL_SYNCHRONIZATION_INTERNAL_FUTEX_H_ |