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-rw-r--r--absl/synchronization/internal/futex.h139
-rw-r--r--absl/synchronization/internal/kernel_timeout.h3
-rw-r--r--absl/synchronization/internal/waiter.cc70
3 files changed, 146 insertions, 66 deletions
diff --git a/absl/synchronization/internal/futex.h b/absl/synchronization/internal/futex.h
new file mode 100644
index 00000000..3539f491
--- /dev/null
+++ b/absl/synchronization/internal/futex.h
@@ -0,0 +1,139 @@
+// 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"
+
+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_SYNCHRONIZATION_INTERNAL_FUTEX_H_
diff --git a/absl/synchronization/internal/kernel_timeout.h b/absl/synchronization/internal/kernel_timeout.h
index 1084e1e6..bbd4d2d7 100644
--- a/absl/synchronization/internal/kernel_timeout.h
+++ b/absl/synchronization/internal/kernel_timeout.h
@@ -26,6 +26,7 @@
#define ABSL_SYNCHRONIZATION_INTERNAL_KERNEL_TIMEOUT_H_
#include <time.h>
+
#include <algorithm>
#include <limits>
@@ -142,7 +143,7 @@ inline struct timespec KernelTimeout::MakeAbsTimespec() {
struct timespec abstime;
int64_t seconds = (std::min)(n / kNanosPerSecond,
- int64_t{(std::numeric_limits<time_t>::max)()});
+ int64_t{(std::numeric_limits<time_t>::max)()});
abstime.tv_sec = static_cast<time_t>(seconds);
abstime.tv_nsec = static_cast<decltype(abstime.tv_nsec)>(n % kNanosPerSecond);
return abstime;
diff --git a/absl/synchronization/internal/waiter.cc b/absl/synchronization/internal/waiter.cc
index b6150b9b..c51855b0 100644
--- a/absl/synchronization/internal/waiter.cc
+++ b/absl/synchronization/internal/waiter.cc
@@ -48,6 +48,11 @@
#include "absl/base/optimization.h"
#include "absl/synchronization/internal/kernel_timeout.h"
+#if ABSL_WAITER_MODE == ABSL_WAITER_MODE_FUTEX
+#include "absl/synchronization/internal/futex.h"
+#endif
+
+
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace synchronization_internal {
@@ -66,71 +71,6 @@ static void MaybeBecomeIdle() {
#if ABSL_WAITER_MODE == ABSL_WAITER_MODE_FUTEX
-// 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 Futex {
- 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 (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;
- }
-};
-
Waiter::Waiter() {
futex_.store(0, std::memory_order_relaxed);
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-07-10 15:48:49 +0000