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+// Copyright 2022 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/log/internal/conditions.h"
+
+#include <atomic>
+#include <cstdint>
+
+#include "absl/base/config.h"
+#include "absl/base/internal/cycleclock.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace log_internal {
+namespace {
+
+// The following code behaves like AtomicStatsCounter::LossyAdd() for
+// speed since it is fine to lose occasional updates.
+// Returns old value of *counter.
+uint32_t LossyIncrement(std::atomic<uint32_t>* counter) {
+ const uint32_t value = counter->load(std::memory_order_relaxed);
+ counter->store(value + 1, std::memory_order_relaxed);
+ return value;
+}
+
+} // namespace
+
+bool LogEveryNState::ShouldLog(int n) {
+ return n > 0 && (LossyIncrement(&counter_) % static_cast<uint32_t>(n)) == 0;
+}
+
+bool LogFirstNState::ShouldLog(int n) {
+ const uint32_t counter_value = counter_.load(std::memory_order_relaxed);
+ if (static_cast<int64_t>(counter_value) < n) {
+ counter_.store(counter_value + 1, std::memory_order_relaxed);
+ return true;
+ }
+ return false;
+}
+
+bool LogEveryPow2State::ShouldLog() {
+ const uint32_t new_value = LossyIncrement(&counter_) + 1;
+ return (new_value & (new_value - 1)) == 0;
+}
+
+bool LogEveryNSecState::ShouldLog(double seconds) {
+ using absl::base_internal::CycleClock;
+ LossyIncrement(&counter_);
+ const int64_t now_cycles = CycleClock::Now();
+ int64_t next_cycles = next_log_time_cycles_.load(std::memory_order_relaxed);
+#if defined(__myriad2__)
+ // myriad2 does not have 8-byte compare and exchange. Use a racy version that
+ // is "good enough" but will over-log in the face of concurrent logging.
+ if (now_cycles > next_cycles) {
+ next_log_time_cycles_.store(now_cycles + seconds * CycleClock::Frequency(),
+ std::memory_order_relaxed);
+ return true;
+ }
+ return false;
+#else
+ do {
+ if (now_cycles <= next_cycles) return false;
+ } while (!next_log_time_cycles_.compare_exchange_weak(
+ next_cycles, now_cycles + seconds * CycleClock::Frequency(),
+ std::memory_order_relaxed, std::memory_order_relaxed));
+ return true;
+#endif
+}
+
+} // namespace log_internal
+ABSL_NAMESPACE_END
+} // namespace absl