Export of internal Abseil changes

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3a871e2cd854a46770a9416189953b2b38980bcf by Andy Getzendanner <durandal@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 280660534

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f5a155fb056dcf68b089c21aebb5bf5159dc0eb3 by Tom Manshreck <shreck@google.com>:

Nit: fix format of algorithm.h comments

PiperOrigin-RevId: 280474139

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08b117a18353c0daf51b33b45100e5a007e5ab0c by Abseil Team <absl-team@google.com>:

Allow absl::Notification::HasBeenNotified to be inlined.

PiperOrigin-RevId: 280453271

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26d33dd2bad72945f1987f7b2669dbec3a6247e6 by Derek Mauro <dmauro@google.com>:

Fix unused variable warnings on Windows

PiperOrigin-RevId: 280324417

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907e9b23029be683af3b443bafd6a577a595922f by Abseil Team <absl-team@google.com>:

PeriodicSampler implementation (for internal-use only)

PiperOrigin-RevId: 280257168
GitOrigin-RevId: 3a871e2cd854a46770a9416189953b2b38980bcf
Change-Id: I6e2978cae22a6adc41c0577e5c21355e9db7c8f5

1 files changed, 175 insertions, 0 deletions

diff --git a/absl/base/internal/periodic_sampler_test.cc b/absl/base/internal/periodic_sampler_test.cc
new file mode 100644
index 000000000000..1ba61377a0f4
--- /dev/null
+++ b/absl/base/internal/periodic_sampler_test.cc
@@ -0,0 +1,175 @@
+// Copyright 2019 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.
+
+#include "absl/base/internal/periodic_sampler.h"
+
+#include <thread>  // NOLINT(build/c++11)
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "absl/base/attributes.h"
+#include "absl/base/macros.h"
+
+namespace absl {
+namespace base_internal {
+namespace {
+
+using testing::Eq;
+using testing::Return;
+using testing::StrictMock;
+
+class MockPeriodicSampler : public PeriodicSamplerBase {
+ public:
+  virtual ~MockPeriodicSampler() = default;
+
+  MOCK_METHOD(int, period, (), (const, noexcept));
+  MOCK_METHOD(int64_t, GetExponentialBiased, (int), (noexcept));
+};
+
+TEST(PeriodicSamplerBaseTest, Sample) {
+  StrictMock<MockPeriodicSampler> sampler;
+
+  EXPECT_CALL(sampler, period()).Times(3).WillRepeatedly(Return(16));
+  EXPECT_CALL(sampler, GetExponentialBiased(16))
+      .WillOnce(Return(1))
+      .WillOnce(Return(2))
+      .WillOnce(Return(3));
+
+  EXPECT_FALSE(sampler.Sample());
+  EXPECT_TRUE(sampler.Sample());
+
+  EXPECT_FALSE(sampler.Sample());
+  EXPECT_FALSE(sampler.Sample());
+  EXPECT_TRUE(sampler.Sample());
+
+  EXPECT_FALSE(sampler.Sample());
+  EXPECT_FALSE(sampler.Sample());
+  EXPECT_FALSE(sampler.Sample());
+}
+
+TEST(PeriodicSamplerBaseTest, ImmediatelySample) {
+  StrictMock<MockPeriodicSampler> sampler;
+
+  EXPECT_CALL(sampler, period()).Times(2).WillRepeatedly(Return(16));
+  EXPECT_CALL(sampler, GetExponentialBiased(16))
+      .WillOnce(Return(0))
+      .WillOnce(Return(1))
+      .WillOnce(Return(2));
+
+  EXPECT_TRUE(sampler.Sample());
+
+  EXPECT_FALSE(sampler.Sample());
+  EXPECT_TRUE(sampler.Sample());
+
+  EXPECT_FALSE(sampler.Sample());
+  EXPECT_FALSE(sampler.Sample());
+}
+
+TEST(PeriodicSamplerBaseTest, Disabled) {
+  StrictMock<MockPeriodicSampler> sampler;
+
+  EXPECT_CALL(sampler, period()).Times(3).WillRepeatedly(Return(0));
+
+  EXPECT_FALSE(sampler.Sample());
+  EXPECT_FALSE(sampler.Sample());
+  EXPECT_FALSE(sampler.Sample());
+}
+
+TEST(PeriodicSamplerBaseTest, AlwaysOn) {
+  StrictMock<MockPeriodicSampler> sampler;
+
+  EXPECT_CALL(sampler, period()).Times(3).WillRepeatedly(Return(1));
+
+  EXPECT_TRUE(sampler.Sample());
+  EXPECT_TRUE(sampler.Sample());
+  EXPECT_TRUE(sampler.Sample());
+}
+
+TEST(PeriodicSamplerBaseTest, Disable) {
+  StrictMock<MockPeriodicSampler> sampler;
+
+  EXPECT_CALL(sampler, period()).WillOnce(Return(16));
+  EXPECT_CALL(sampler, GetExponentialBiased(16)).WillOnce(Return(2));
+  EXPECT_FALSE(sampler.Sample());
+  EXPECT_FALSE(sampler.Sample());
+
+  EXPECT_CALL(sampler, period()).Times(2).WillRepeatedly(Return(0));
+
+  EXPECT_FALSE(sampler.Sample());
+  EXPECT_FALSE(sampler.Sample());
+}
+
+TEST(PeriodicSamplerBaseTest, Enable) {
+  StrictMock<MockPeriodicSampler> sampler;
+
+  EXPECT_CALL(sampler, period()).WillOnce(Return(0));
+  EXPECT_FALSE(sampler.Sample());
+
+  EXPECT_CALL(sampler, period()).Times(2).WillRepeatedly(Return(16));
+  EXPECT_CALL(sampler, GetExponentialBiased(16))
+      .Times(2)
+      .WillRepeatedly(Return(2));
+
+  EXPECT_FALSE(sampler.Sample());
+  EXPECT_FALSE(sampler.Sample());
+  EXPECT_TRUE(sampler.Sample());
+
+  EXPECT_FALSE(sampler.Sample());
+  EXPECT_FALSE(sampler.Sample());
+}
+
+TEST(PeriodicSamplerTest, ConstructConstInit) {
+  struct Tag {};
+  ABSL_CONST_INIT static PeriodicSampler<Tag> sampler;
+  (void)sampler;
+}
+
+TEST(PeriodicSamplerTest, DefaultPeriod0) {
+  struct Tag {};
+  PeriodicSampler<Tag> sampler;
+  EXPECT_THAT(sampler.period(), Eq(0));
+}
+
+TEST(PeriodicSamplerTest, DefaultPeriod) {
+  struct Tag {};
+  PeriodicSampler<Tag, 100> sampler;
+  EXPECT_THAT(sampler.period(), Eq(100));
+}
+
+TEST(PeriodicSamplerTest, SetGlobalPeriod) {
+  struct Tag1 {};
+  struct Tag2 {};
+  PeriodicSampler<Tag1, 25> sampler1;
+  PeriodicSampler<Tag2, 50> sampler2;
+
+  EXPECT_THAT(sampler1.period(), Eq(25));
+  EXPECT_THAT(sampler2.period(), Eq(50));
+
+  std::thread thread([] {
+    PeriodicSampler<Tag1, 25> sampler1;
+    PeriodicSampler<Tag2, 50> sampler2;
+    EXPECT_THAT(sampler1.period(), Eq(25));
+    EXPECT_THAT(sampler2.period(), Eq(50));
+    sampler1.SetGlobalPeriod(10);
+    sampler2.SetGlobalPeriod(20);
+  });
+  thread.join();
+
+  EXPECT_THAT(sampler1.period(), Eq(10));
+  EXPECT_THAT(sampler2.period(), Eq(20));
+}
+
+}  // namespace
+}  // namespace base_internal
+}  // namespace absl