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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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#include "absl/strings/internal/cordz_functions.h"
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#include <atomic>
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#include <cmath>
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#include <limits>
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#include <random>
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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/internal/exponential_biased.h"
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#include "absl/base/internal/raw_logging.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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namespace {
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// The average interval until the next sample. A value of 0 disables profiling
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// while a value of 1 will profile all Cords.
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std::atomic<int> g_cordz_mean_interval(50000);
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} // namespace
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#ifdef ABSL_INTERNAL_CORDZ_ENABLED
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Export of internal Abseil changes
--
9fc37c11b9e46287acef00ee06ed9adcba54dd13 by Greg Falcon <gfalcon@google.com>:
Rename absl::hash_internal::HashState to absl::hash_internal::MixingHashState.
Before this change, we had two classes named HashState: absl::HashState, the public API used for type erasure, and absl::hash_internal::HashState, the internal concrete implementation ordinarily used.
The internal class used to be named `CityHashState`, but we renamed it to `HashState` it when we changed underlying hash implementation to wyhash. This inadvertent naming conflict made the code much harder to read, and this change intends to undo that.
PiperOrigin-RevId: 373481959
--
4aec55ffddebd085c239352a2e20721091f719a1 by Greg Falcon <gfalcon@google.com>:
Introduce absl::HashOf(), a convenience wrapper around absl::Hash that calculates hashes from the values of its arguments.
PiperOrigin-RevId: 373461406
--
86b5fd8db50bbc8bd0aa9258523527381fe0445d by Abseil Team <absl-team@google.com>:
Improve speed of BlockingCounter by making its most common path lock free.
With the new implementation, the fast path of BlockingCounter::DecrementCount()
is only a fetch_sub operation. This is most times much more efficient than the
previous implementation (full mutex lock/unlock). As a matter of fact, in most
actual usecases in practice, the waiter thread is already waiting on the
Wait() call when DecrementCount() is called, which makes Mutex::Unlock() take
the slow path as there's a waiter thread that it might need to wake up.
PiperOrigin-RevId: 373394164
--
65c876be5eac0cd32583ff8535ede4109d39cf3f by Martijn Vels <mvels@google.com>:
Move the 'sample copied cord' logic into MaybeTrackCord(),
This changes move the logic for selecting if a cord should remain being sampled from Cord to CordzInfo::MaybeTrackCord, and updates the documentation for the latter method.
PiperOrigin-RevId: 373363168
--
e84410bd0aada293a81dfb82656c952e209e21fb by Martijn Vels <mvels@google.com>:
Add check for the first call to cordz_should_profile() for each thread.
This prevents the first cord of a newly created thread to be always sampled, which is a 'bad' kind of determinism for sampling.
PiperOrigin-RevId: 373229768
--
bf09c589dc099ac8f4af780bf7e609c53c27574c by Samuel Benzaquen <sbenza@google.com>:
Refactor the Flags structure into an enum.
This gives us more control over the representation and allows for easier
merging during parsing.
PiperOrigin-RevId: 373163038
--
b947b0c51083b7b6508284b5d31819596c91729e by Derek Mauro <dmauro@google.com>:
Fixes warnings about shadowed variables
Fixes #956
PiperOrigin-RevId: 373158133
GitOrigin-RevId: 9fc37c11b9e46287acef00ee06ed9adcba54dd13
Change-Id: I91f35699f9bf439d1a870c6493946a310afe088c
4 years ago
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// Special negative 'not initialized' per thread value for cordz_next_sample.
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static constexpr int64_t kInitCordzNextSample = -1;
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ABSL_CONST_INIT thread_local int64_t cordz_next_sample = kInitCordzNextSample;
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// kIntervalIfDisabled is the number of profile-eligible events need to occur
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// before the code will confirm that cordz is still disabled.
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constexpr int64_t kIntervalIfDisabled = 1 << 16;
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ABSL_ATTRIBUTE_NOINLINE bool cordz_should_profile_slow() {
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thread_local absl::base_internal::ExponentialBiased
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exponential_biased_generator;
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int32_t mean_interval = get_cordz_mean_interval();
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// Check if we disabled profiling. If so, set the next sample to a "large"
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// number to minimize the overhead of the should_profile codepath.
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if (mean_interval <= 0) {
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cordz_next_sample = kIntervalIfDisabled;
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return false;
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}
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// Check if we're always sampling.
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if (mean_interval == 1) {
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cordz_next_sample = 1;
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return true;
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}
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if (cordz_next_sample <= 0) {
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Export of internal Abseil changes
--
9fc37c11b9e46287acef00ee06ed9adcba54dd13 by Greg Falcon <gfalcon@google.com>:
Rename absl::hash_internal::HashState to absl::hash_internal::MixingHashState.
Before this change, we had two classes named HashState: absl::HashState, the public API used for type erasure, and absl::hash_internal::HashState, the internal concrete implementation ordinarily used.
The internal class used to be named `CityHashState`, but we renamed it to `HashState` it when we changed underlying hash implementation to wyhash. This inadvertent naming conflict made the code much harder to read, and this change intends to undo that.
PiperOrigin-RevId: 373481959
--
4aec55ffddebd085c239352a2e20721091f719a1 by Greg Falcon <gfalcon@google.com>:
Introduce absl::HashOf(), a convenience wrapper around absl::Hash that calculates hashes from the values of its arguments.
PiperOrigin-RevId: 373461406
--
86b5fd8db50bbc8bd0aa9258523527381fe0445d by Abseil Team <absl-team@google.com>:
Improve speed of BlockingCounter by making its most common path lock free.
With the new implementation, the fast path of BlockingCounter::DecrementCount()
is only a fetch_sub operation. This is most times much more efficient than the
previous implementation (full mutex lock/unlock). As a matter of fact, in most
actual usecases in practice, the waiter thread is already waiting on the
Wait() call when DecrementCount() is called, which makes Mutex::Unlock() take
the slow path as there's a waiter thread that it might need to wake up.
PiperOrigin-RevId: 373394164
--
65c876be5eac0cd32583ff8535ede4109d39cf3f by Martijn Vels <mvels@google.com>:
Move the 'sample copied cord' logic into MaybeTrackCord(),
This changes move the logic for selecting if a cord should remain being sampled from Cord to CordzInfo::MaybeTrackCord, and updates the documentation for the latter method.
PiperOrigin-RevId: 373363168
--
e84410bd0aada293a81dfb82656c952e209e21fb by Martijn Vels <mvels@google.com>:
Add check for the first call to cordz_should_profile() for each thread.
This prevents the first cord of a newly created thread to be always sampled, which is a 'bad' kind of determinism for sampling.
PiperOrigin-RevId: 373229768
--
bf09c589dc099ac8f4af780bf7e609c53c27574c by Samuel Benzaquen <sbenza@google.com>:
Refactor the Flags structure into an enum.
This gives us more control over the representation and allows for easier
merging during parsing.
PiperOrigin-RevId: 373163038
--
b947b0c51083b7b6508284b5d31819596c91729e by Derek Mauro <dmauro@google.com>:
Fixes warnings about shadowed variables
Fixes #956
PiperOrigin-RevId: 373158133
GitOrigin-RevId: 9fc37c11b9e46287acef00ee06ed9adcba54dd13
Change-Id: I91f35699f9bf439d1a870c6493946a310afe088c
4 years ago
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// If first check on current thread, check cordz_should_profile()
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// again using the created (initial) stride in cordz_next_sample.
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const bool initialized = cordz_next_sample != kInitCordzNextSample;
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cordz_next_sample = exponential_biased_generator.GetStride(mean_interval);
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Export of internal Abseil changes
--
9fc37c11b9e46287acef00ee06ed9adcba54dd13 by Greg Falcon <gfalcon@google.com>:
Rename absl::hash_internal::HashState to absl::hash_internal::MixingHashState.
Before this change, we had two classes named HashState: absl::HashState, the public API used for type erasure, and absl::hash_internal::HashState, the internal concrete implementation ordinarily used.
The internal class used to be named `CityHashState`, but we renamed it to `HashState` it when we changed underlying hash implementation to wyhash. This inadvertent naming conflict made the code much harder to read, and this change intends to undo that.
PiperOrigin-RevId: 373481959
--
4aec55ffddebd085c239352a2e20721091f719a1 by Greg Falcon <gfalcon@google.com>:
Introduce absl::HashOf(), a convenience wrapper around absl::Hash that calculates hashes from the values of its arguments.
PiperOrigin-RevId: 373461406
--
86b5fd8db50bbc8bd0aa9258523527381fe0445d by Abseil Team <absl-team@google.com>:
Improve speed of BlockingCounter by making its most common path lock free.
With the new implementation, the fast path of BlockingCounter::DecrementCount()
is only a fetch_sub operation. This is most times much more efficient than the
previous implementation (full mutex lock/unlock). As a matter of fact, in most
actual usecases in practice, the waiter thread is already waiting on the
Wait() call when DecrementCount() is called, which makes Mutex::Unlock() take
the slow path as there's a waiter thread that it might need to wake up.
PiperOrigin-RevId: 373394164
--
65c876be5eac0cd32583ff8535ede4109d39cf3f by Martijn Vels <mvels@google.com>:
Move the 'sample copied cord' logic into MaybeTrackCord(),
This changes move the logic for selecting if a cord should remain being sampled from Cord to CordzInfo::MaybeTrackCord, and updates the documentation for the latter method.
PiperOrigin-RevId: 373363168
--
e84410bd0aada293a81dfb82656c952e209e21fb by Martijn Vels <mvels@google.com>:
Add check for the first call to cordz_should_profile() for each thread.
This prevents the first cord of a newly created thread to be always sampled, which is a 'bad' kind of determinism for sampling.
PiperOrigin-RevId: 373229768
--
bf09c589dc099ac8f4af780bf7e609c53c27574c by Samuel Benzaquen <sbenza@google.com>:
Refactor the Flags structure into an enum.
This gives us more control over the representation and allows for easier
merging during parsing.
PiperOrigin-RevId: 373163038
--
b947b0c51083b7b6508284b5d31819596c91729e by Derek Mauro <dmauro@google.com>:
Fixes warnings about shadowed variables
Fixes #956
PiperOrigin-RevId: 373158133
GitOrigin-RevId: 9fc37c11b9e46287acef00ee06ed9adcba54dd13
Change-Id: I91f35699f9bf439d1a870c6493946a310afe088c
4 years ago
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return initialized || cordz_should_profile();
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}
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--cordz_next_sample;
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return false;
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}
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void cordz_set_next_sample_for_testing(int64_t next_sample) {
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cordz_next_sample = next_sample;
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}
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#endif // ABSL_INTERNAL_CORDZ_ENABLED
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int32_t get_cordz_mean_interval() {
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return g_cordz_mean_interval.load(std::memory_order_acquire);
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}
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void set_cordz_mean_interval(int32_t mean_interval) {
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g_cordz_mean_interval.store(mean_interval, std::memory_order_release);
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}
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} // namespace cord_internal
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ABSL_NAMESPACE_END
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} // namespace absl
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