diff options
| -rw-r--r-- | absl/base/BUILD.bazel | 1 | ||||
| -rw-r--r-- | absl/base/internal/spinlock_linux.inc | 72 | ||||
| -rw-r--r-- | absl/base/internal/spinlock_wait.cc | 4 | ||||
| -rw-r--r-- | absl/strings/str_cat_test.cc | 3 | ||||
| -rw-r--r-- | absl/strings/string_view_test.cc | 3 |
5 files changed, 80 insertions, 3 deletions
diff --git a/absl/base/BUILD.bazel b/absl/base/BUILD.bazel index b0f4b680df5e..7063f96a4589 100644 --- a/absl/base/BUILD.bazel +++ b/absl/base/BUILD.bazel @@ -30,6 +30,7 @@ cc_library( name = "spinlock_wait", srcs = [ "internal/spinlock_akaros.inc", + "internal/spinlock_linux.inc", "internal/spinlock_posix.inc", "internal/spinlock_wait.cc", "internal/spinlock_win32.inc", diff --git a/absl/base/internal/spinlock_linux.inc b/absl/base/internal/spinlock_linux.inc new file mode 100644 index 000000000000..94c861dc6ca2 --- /dev/null +++ b/absl/base/internal/spinlock_linux.inc @@ -0,0 +1,72 @@ +// Copyright 2018 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 +// +// http://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. +// +// This file is a Linux-specific part of spinlock_wait.cc + +#include <linux/futex.h> +#include <sys/syscall.h> +#include <unistd.h> + +#include <atomic> +#include <cerrno> +#include <climits> +#include <cstdint> +#include <ctime> + +#include "absl/base/attributes.h" + +// The SpinLock lockword is `std::atomic<uint32_t>`. Here we assert that +// `std::atomic<uint32_t>` is bitwise equivalent of the `int` expected +// by SYS_futex. We also assume that reads/writes done to the lockword +// by SYS_futex have rational semantics with regard to the +// std::atomic<> API. C++ provides no guarantees of these assumptions, +// but they are believed to hold in practice. +static_assert(sizeof(std::atomic<uint32_t>) == sizeof(int), + "SpinLock lockword has the wrong size for a 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_PRIVATE_FLAG +#define FUTEX_PRIVATE_FLAG 128 +#endif +#endif + +extern "C" { + +ABSL_ATTRIBUTE_WEAK void AbslInternalSpinLockDelay( + std::atomic<uint32_t> *w, uint32_t value, int loop, + absl::base_internal::SchedulingMode) { + if (loop != 0) { + int save_errno = errno; + struct timespec tm; + tm.tv_sec = 0; + // Increase the delay; we expect (but do not rely on) explicit wakeups. + // We don't rely on explicit wakeups because we intentionally allow for + // a race on the kSpinLockSleeper bit. + tm.tv_nsec = 16 * absl::base_internal::SpinLockSuggestedDelayNS(loop); + syscall(SYS_futex, w, FUTEX_WAIT | FUTEX_PRIVATE_FLAG, value, &tm); + errno = save_errno; + } +} + +ABSL_ATTRIBUTE_WEAK void AbslInternalSpinLockWake(std::atomic<uint32_t> *w, + bool all) { + syscall(SYS_futex, w, FUTEX_WAKE | FUTEX_PRIVATE_FLAG, all ? INT_MAX : 1, 0); +} + +} // extern "C" diff --git a/absl/base/internal/spinlock_wait.cc b/absl/base/internal/spinlock_wait.cc index 9f6e9911e109..0fde9c04b73b 100644 --- a/absl/base/internal/spinlock_wait.cc +++ b/absl/base/internal/spinlock_wait.cc @@ -13,7 +13,7 @@ // limitations under the License. // The OS-specific header included below must provide two calls: -// base::subtle::SpinLockDelay() and base::subtle::SpinLockWake(). +// AbslInternalSpinLockDelay() and AbslInternalSpinLockWake(). // See spinlock_wait.h for the specs. #include <atomic> @@ -23,6 +23,8 @@ #if defined(_WIN32) #include "absl/base/internal/spinlock_win32.inc" +#elif defined(__linux__) +#include "absl/base/internal/spinlock_linux.inc" #elif defined(__akaros__) #include "absl/base/internal/spinlock_akaros.inc" #else diff --git a/absl/strings/str_cat_test.cc b/absl/strings/str_cat_test.cc index e9d676906382..555d8db3eb85 100644 --- a/absl/strings/str_cat_test.cc +++ b/absl/strings/str_cat_test.cc @@ -28,7 +28,8 @@ #define ABSL_EXPECT_DEBUG_DEATH(statement, regex) \ EXPECT_DEBUG_DEATH(statement, ".*") #else -#define ABSL_EXPECT_DEBUG_DEATH EXPECT_DEBUG_DEATH +#define ABSL_EXPECT_DEBUG_DEATH(statement, regex) \ + EXPECT_DEBUG_DEATH(statement, regex) #endif namespace { diff --git a/absl/strings/string_view_test.cc b/absl/strings/string_view_test.cc index fffa7b99205f..3818fb207a08 100644 --- a/absl/strings/string_view_test.cc +++ b/absl/strings/string_view_test.cc @@ -35,7 +35,8 @@ #define ABSL_EXPECT_DEATH_IF_SUPPORTED(statement, regex) \ EXPECT_DEATH_IF_SUPPORTED(statement, ".*") #else -#define ABSL_EXPECT_DEATH_IF_SUPPORTED EXPECT_DEATH_IF_SUPPORTED +#define ABSL_EXPECT_DEATH_IF_SUPPORTED(statement, regex) \ + EXPECT_DEATH_IF_SUPPORTED(statement, regex) #endif namespace { |