Abseil Common Libraries (C++) (grcp 依赖)
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86 lines
2.8 KiB
86 lines
2.8 KiB
4 years ago
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// Copyright 2019 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef ABSL_STRINGS_CORDZ_FUNCTIONS_H_
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#define ABSL_STRINGS_CORDZ_FUNCTIONS_H_
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#include <stdint.h>
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#include "absl/base/attributes.h"
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#include "absl/base/config.h"
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#include "absl/base/optimization.h"
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namespace absl {
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ABSL_NAMESPACE_BEGIN
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namespace cord_internal {
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// Returns the current sample rate. This represents the average interval
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// between samples.
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int32_t get_cordz_mean_interval();
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// Sets the sample rate with the average interval between samples.
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void set_cordz_mean_interval(int32_t mean_interval);
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// Enable cordz unless any of the following applies:
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// - no thread local support
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// - MSVC build
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// - Android build
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// - Apple build
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// - DLL build
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// Hashtablez is turned off completely in opensource builds.
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// MSVC's static atomics are dynamically initialized in debug mode, which breaks
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// sampling.
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#if defined(ABSL_HAVE_THREAD_LOCAL) && !defined(_MSC_VER) && \
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!defined(ABSL_BUILD_DLL) && !defined(ABSL_CONSUME_DLL) && \
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!defined(__ANDROID__) && !defined(__APPLE__)
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#define ABSL_INTERNAL_CORDZ_ENABLED 1
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#endif
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#ifdef ABSL_INTERNAL_CORDZ_ENABLED
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// cordz_next_sample is the number of events until the next sample event. If
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// the value is 1 or less, the code will check on the next event if cordz is
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// enabled, and if so, will sample the Cord. cordz is only enabled when we can
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// use thread locals.
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ABSL_CONST_INIT extern thread_local int64_t cordz_next_sample;
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// Determines if the next sample should be profiled. If it is, the value pointed
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// at by next_sample will be set with the interval until the next sample.
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bool cordz_should_profile_slow();
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// Returns true if the next cord should be sampled.
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inline bool cordz_should_profile() {
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if (ABSL_PREDICT_TRUE(cordz_next_sample > 1)) {
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cordz_next_sample--;
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return false;
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}
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return cordz_should_profile_slow();
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}
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// Sets the interval until the next sample (for testing only)
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void cordz_set_next_sample_for_testing(int64_t next_sample);
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#else // ABSL_INTERNAL_CORDZ_ENABLED
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inline bool cordz_should_profile() { return false; }
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inline void cordz_set_next_sample_for_testing(int64_t) {}
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#endif // ABSL_INTERNAL_CORDZ_ENABLED
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} // namespace cord_internal
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ABSL_NAMESPACE_END
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} // namespace absl
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#endif // ABSL_STRINGS_CORDZ_FUNCTIONS_H_
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