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authorGravatar Abseil Team <absl-team@google.com>2018-12-04 11:01:12 -0800
committerGravatar CJ Johnson <johnsoncj@google.com>2018-12-04 16:27:57 -0500
commit44b0fafc62d9b8f192e8180cbe9c4b806b339d57 (patch)
tree4ada26427deee54333ac271a26c5fe363ba33cc7 /absl/base
parent926bfeb9fff223429c12224b7514243886323e8d (diff)
Export of internal Abseil changes.
-- cd076f55c1fa600131f6dda392533dfe61679fc0 by Abseil Team <absl-team@google.com>: Internal change PiperOrigin-RevId: 224008762 -- e05f62b01286d51044ff86ec6ef565749b9faf82 by Abseil Team <absl-team@google.com>: Create a pow10() test helper function to compute guaranteed-precise double values of 10^x. Not all standard libraries ship bit-accurate pow() functions, causing tests to fail that rely on expected values generated by it. PiperOrigin-RevId: 223883762 -- fd88e5e3f7ab80f7f5df9fd1488cd58b4573be69 by Abseil Team <absl-team@google.com>: Remove some absl:: qualifications to work around inline namespace bugs on MSVC 2015. PiperOrigin-RevId: 223869642 -- 6276cfff969d596edd36a2bbaba65ee045808903 by Abseil Team <absl-team@google.com>: Update absl/memory/CMakeLists.txt to use new functions i.e. absl_cc_(library|test) PiperOrigin-RevId: 223854224 -- 359de9afc7a34c975fd3e0cbc52afd96637d97bd by Chris Kennelly <ckennelly@google.com>: Mark spinlock_benchmark_common as alwayslink = 1. PiperOrigin-RevId: 223844536 -- 450cd8cbe2789a6d54ed1eb87170259bb334f8b9 by Abseil Team <absl-team@google.com>: Support .* (pointer-to-member dereference) expressions in demangle.cc. PiperOrigin-RevId: 223826797 -- 772ca92179c3634f3e31a80bbc272ed8022e3572 by Abseil Team <absl-team@google.com>: Fix misspellings in absl::variant comments and replace a ' with a `. PiperOrigin-RevId: 223807911 -- 35dcdc2fbf299d195658aac101887f6dcad1de2f by Abseil Team <absl-team@google.com>: Bug fix in CMakeLists.txt file (SRCS --> HDRS). The compressed_tuple header-only library is being defined with the SRCS parameter instead of the HDRS parameter and this has been observed to cause some builds on some platforms to attempt to create a static library from it which fails since there are no .cc sources. PiperOrigin-RevId: 223805367 -- 4a57a3d2045bb137c0c97958e45ce425190b8d3e by Chris Kennelly <ckennelly@google.com>: Add test that absl::make_unique value initializes memory. PiperOrigin-RevId: 223801819 -- dfe8289d7f4dcc6bb568a26aaf192a89e896bdfd by Chris Kennelly <ckennelly@google.com>: SpinLock: Use exchange to avoid missing wakeups. The default fast path for SpinLock::Unlock does not use an atomic. If the SpinLock becomes contended while we are unlocking between lockword_.load and lockword_.store, we will fail to wake up the new waiter. This can cause unexpected latency spikes. PiperOrigin-RevId: 223800369 -- 9b9d35df786482f0016f77dd31691eff81503d23 by Abseil Team <absl-team@google.com>: Update absl/hash/CMakeLists.txt to use new functions i.e. absl_cc_(library|test) PiperOrigin-RevId: 223755819 -- c2014e2704b87e7cdce2d2a0287c7e2397752296 by Abseil Team <absl-team@google.com>: Update absl/debugging/CMakeLists.txt to use new functions i.e. absl_cc_(library|test) PiperOrigin-RevId: 223751986 -- d83a4e09126400e3fd80645cb03ee558f532271e by Derek Mauro <dmauro@google.com>: Cleanup synchronization benchmarks. PiperOrigin-RevId: 223589416 -- fad140b473586531b5b12843f942ec27dfcf5e93 by CJ Johnson <johnsoncj@google.com>: Makes unifies the order of forward_iterator and input_iterator overloads PiperOrigin-RevId: 223580660 -- 6cd7c96faa7cc5f79f574e35a1b13837ef187d05 by Abseil Team <absl-team@google.com>: Internal Change. PiperOrigin-RevId: 223561629 -- bd2e545356b0f548af0e3c14bb2f7f0e712e49d0 by Shaindel Schwartz <shaindel@google.com>: Remove misleading comments. try_emplace() does not exist for the hash_set containers. PiperOrigin-RevId: 223543089 -- 0cd380a53b587eb7aacc4003a4a3bbb6c78d7c10 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 223512551 -- 7156dfee599cb72e9adddfe0e6ae07a95ddf10bb by Greg Miller <jgm@google.com>: Fixes UB that would result from constructing, multiplying, or dividing a Duration with a double "NaN" value. This CL changes the absl::Duration *implementation* to return an InfiniteDuration value that has the same sign as the given NaN. PiperOrigin-RevId: 223407499 -- 196b7d18609958267951882baf7f9429e49bcafa by CJ Johnson <johnsoncj@google.com>: Addresses NVCC+MSVC compilation bug where `inlined_capacity()` was not considered valid in constexpr PiperOrigin-RevId: 223397718 GitOrigin-RevId: cd076f55c1fa600131f6dda392533dfe61679fc0 Change-Id: I5423ca6470f661a7c6f73aa8fee49990446f157f
Diffstat (limited to 'absl/base')
-rw-r--r--absl/base/BUILD.bazel28
-rw-r--r--absl/base/internal/spinlock.h4
-rw-r--r--absl/base/internal/spinlock_benchmark.cc52
3 files changed, 82 insertions, 2 deletions
diff --git a/absl/base/BUILD.bazel b/absl/base/BUILD.bazel
index 44de05e3..4566c697 100644
--- a/absl/base/BUILD.bazel
+++ b/absl/base/BUILD.bazel
@@ -107,6 +107,7 @@ cc_library(
"internal/identity.h",
"internal/inline_variable.h",
"internal/invoke.h",
+ "internal/scheduling_mode.h",
],
copts = ABSL_DEFAULT_COPTS,
visibility = [
@@ -314,6 +315,33 @@ cc_test(
)
cc_library(
+ name = "spinlock_benchmark_common",
+ testonly = 1,
+ srcs = ["internal/spinlock_benchmark.cc"],
+ copts = ABSL_DEFAULT_COPTS,
+ visibility = [
+ "//absl/base:__pkg__",
+ ],
+ deps = [
+ ":base",
+ ":base_internal",
+ "//absl/synchronization",
+ "@com_github_google_benchmark//:benchmark_main",
+ ],
+ alwayslink = 1,
+)
+
+cc_binary(
+ name = "spinlock_benchmark",
+ testonly = 1,
+ copts = ABSL_DEFAULT_COPTS,
+ visibility = ["//visibility:private"],
+ deps = [
+ ":spinlock_benchmark_common",
+ ],
+)
+
+cc_library(
name = "endian",
hdrs = [
"internal/endian.h",
diff --git a/absl/base/internal/spinlock.h b/absl/base/internal/spinlock.h
index dcce0109..eb3eec9c 100644
--- a/absl/base/internal/spinlock.h
+++ b/absl/base/internal/spinlock.h
@@ -101,8 +101,8 @@ class LOCKABLE SpinLock {
inline void Unlock() UNLOCK_FUNCTION() {
ABSL_TSAN_MUTEX_PRE_UNLOCK(this, 0);
uint32_t lock_value = lockword_.load(std::memory_order_relaxed);
- lockword_.store(lock_value & kSpinLockCooperative,
- std::memory_order_release);
+ lock_value = lockword_.exchange(lock_value & kSpinLockCooperative,
+ std::memory_order_release);
if ((lock_value & kSpinLockDisabledScheduling) != 0) {
base_internal::SchedulingGuard::EnableRescheduling(true);
diff --git a/absl/base/internal/spinlock_benchmark.cc b/absl/base/internal/spinlock_benchmark.cc
new file mode 100644
index 00000000..907d3e27
--- /dev/null
+++ b/absl/base/internal/spinlock_benchmark.cc
@@ -0,0 +1,52 @@
+// 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.
+
+// See also //absl/synchronization:mutex_benchmark for a comparison of SpinLock
+// and Mutex performance under varying levels of contention.
+
+#include "absl/base/internal/raw_logging.h"
+#include "absl/base/internal/scheduling_mode.h"
+#include "absl/base/internal/spinlock.h"
+#include "absl/synchronization/internal/create_thread_identity.h"
+#include "benchmark/benchmark.h"
+
+namespace {
+
+template <absl::base_internal::SchedulingMode scheduling_mode>
+static void BM_SpinLock(benchmark::State& state) {
+ // Ensure a ThreadIdentity is installed.
+ ABSL_INTERNAL_CHECK(
+ absl::synchronization_internal::GetOrCreateCurrentThreadIdentity() !=
+ nullptr,
+ "GetOrCreateCurrentThreadIdentity() failed");
+
+ static auto* spinlock = new absl::base_internal::SpinLock(scheduling_mode);
+ for (auto _ : state) {
+ absl::base_internal::SpinLockHolder holder(spinlock);
+ }
+}
+
+BENCHMARK_TEMPLATE(BM_SpinLock,
+ absl::base_internal::SCHEDULE_KERNEL_ONLY)
+ ->UseRealTime()
+ ->Threads(1)
+ ->ThreadPerCpu();
+
+BENCHMARK_TEMPLATE(BM_SpinLock,
+ absl::base_internal::SCHEDULE_COOPERATIVE_AND_KERNEL)
+ ->UseRealTime()
+ ->Threads(1)
+ ->ThreadPerCpu();
+
+} // namespace