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Export of internal Abseil changes -- 341670bce317dd6af8d3c066970230591a47e80c by Martijn Vels <mvels@google.com>: Change GetStack() and GetParentStack() to return absl::Span PiperOrigin-RevId: 368765721 -- 6aaab9536d6957303c7aba100c3afaa6fb0ea2c8 by Martijn Vels <mvels@google.com>: Remove locking from parent stack. This change removes the need to lock all access to `parent_stack' by making the 'copy constructor' logic specify the 'copied from' CordzInfo (where available) to the TrackCord function, after which parent_stack is immutable. PiperOrigin-RevId: 368760630 -- b19e2059cada35a8ede994833018edac94de6ddc by Martijn Vels <mvels@google.com>: Add cordz instrumentation to Cord PiperOrigin-RevId: 368746225 -- 67b8bbf980f0f4e1db79aa32968e9a715a09b51a by Martijn Vels <mvels@google.com>: Create ABSL_INTERNAL_CORDZ_ENABLED define controlling when Cordz code is enabled There are specific builds and condtions under which we don't support cordz sampling, which is per this change represented by ABSL_INTERNAL_CORDZ_ENABLED being defined. PiperOrigin-RevId: 368731603 -- 8cbfe0e3169637a620f4b66ad2bc2ce340879cb0 by Martijn Vels <mvels@google.com>: Add a `rep` property to CordzInfo to be managed by Cord logic. This change adds a `rep` property to CordzInfo, which is intended to be used by collection logic. Mini design: Cord invokes TrackCord() providing the active 'root' cordrep of the newly sampled Cord, returning a CordzInfo with a weak (uncounted) reference to this root. Cord invokes `SetCordRep()` each time the root cordrep of the sampled Cord is updated while holding `mutex()`. Cord must also obtain `mutex()` _before_ removing a reference on the old root. i.e.: Cord must guarantee that the (weak) reference held in CordzInfo is at all times valid. CordzInfo collection code can then safely obtain a (reference counted) rep pointer by adding a reference to `rep_` while holding `mutex()`. This requires only a very brief critical section inside CordzInfo logic, minimizing contention with concurrent Cord updates. Cord code should typically obtain and hold `mutex()` for the entirety of each mutating Cord operation on a sampled cord. As Cord is thread compatible, it never competes on the lock with any other thread. The only possible concurrent access is from Cordz collection code, which should be a relatively rare event. PiperOrigin-RevId: 368673758 -- 1255120dce2bdd6b4205a34a0e555e0b74b6152f by Martijn Vels <mvels@google.com>: Remove 'depth' from active recorded metrics. Going forward we do not 'live' record depth (and size), but will observe these at collection time only. PiperOrigin-RevId: 368636572 -- 83e5146e35f221736b49e9f0a8805f8c159a51db by Martijn Vels <mvels@google.com>: Make cordz targets visible in OSS PiperOrigin-RevId: 368615010 -- dcb16a4f1239151f0a8c70a8cfeb29dabbd113b8 by Martijn Vels <mvels@google.com>: Internal cleanup PiperOrigin-RevId: 368514666 GitOrigin-RevId: 341670bce317dd6af8d3c066970230591a47e80c Change-Id: I94cecfbbd441eb386f99fc5186c468a7a5538862
4 years ago
// 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/strings/internal/cordz_functions.h"
#include <atomic>
#include <cmath>
#include <limits>
#include <random>
#include "absl/base/attributes.h"
#include "absl/base/config.h"
#include "absl/base/internal/exponential_biased.h"
#include "absl/base/internal/raw_logging.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace cord_internal {
namespace {
// The average interval until the next sample. A value of 0 disables profiling
// while a value of 1 will profile all Cords.
std::atomic<int> g_cordz_mean_interval(50000);
} // namespace
#ifdef ABSL_INTERNAL_CORDZ_ENABLED
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
// Special negative 'not initialized' per thread value for cordz_next_sample.
static constexpr int64_t kInitCordzNextSample = -1;
ABSL_CONST_INIT thread_local int64_t cordz_next_sample = kInitCordzNextSample;
Export of internal Abseil changes -- 341670bce317dd6af8d3c066970230591a47e80c by Martijn Vels <mvels@google.com>: Change GetStack() and GetParentStack() to return absl::Span PiperOrigin-RevId: 368765721 -- 6aaab9536d6957303c7aba100c3afaa6fb0ea2c8 by Martijn Vels <mvels@google.com>: Remove locking from parent stack. This change removes the need to lock all access to `parent_stack' by making the 'copy constructor' logic specify the 'copied from' CordzInfo (where available) to the TrackCord function, after which parent_stack is immutable. PiperOrigin-RevId: 368760630 -- b19e2059cada35a8ede994833018edac94de6ddc by Martijn Vels <mvels@google.com>: Add cordz instrumentation to Cord PiperOrigin-RevId: 368746225 -- 67b8bbf980f0f4e1db79aa32968e9a715a09b51a by Martijn Vels <mvels@google.com>: Create ABSL_INTERNAL_CORDZ_ENABLED define controlling when Cordz code is enabled There are specific builds and condtions under which we don't support cordz sampling, which is per this change represented by ABSL_INTERNAL_CORDZ_ENABLED being defined. PiperOrigin-RevId: 368731603 -- 8cbfe0e3169637a620f4b66ad2bc2ce340879cb0 by Martijn Vels <mvels@google.com>: Add a `rep` property to CordzInfo to be managed by Cord logic. This change adds a `rep` property to CordzInfo, which is intended to be used by collection logic. Mini design: Cord invokes TrackCord() providing the active 'root' cordrep of the newly sampled Cord, returning a CordzInfo with a weak (uncounted) reference to this root. Cord invokes `SetCordRep()` each time the root cordrep of the sampled Cord is updated while holding `mutex()`. Cord must also obtain `mutex()` _before_ removing a reference on the old root. i.e.: Cord must guarantee that the (weak) reference held in CordzInfo is at all times valid. CordzInfo collection code can then safely obtain a (reference counted) rep pointer by adding a reference to `rep_` while holding `mutex()`. This requires only a very brief critical section inside CordzInfo logic, minimizing contention with concurrent Cord updates. Cord code should typically obtain and hold `mutex()` for the entirety of each mutating Cord operation on a sampled cord. As Cord is thread compatible, it never competes on the lock with any other thread. The only possible concurrent access is from Cordz collection code, which should be a relatively rare event. PiperOrigin-RevId: 368673758 -- 1255120dce2bdd6b4205a34a0e555e0b74b6152f by Martijn Vels <mvels@google.com>: Remove 'depth' from active recorded metrics. Going forward we do not 'live' record depth (and size), but will observe these at collection time only. PiperOrigin-RevId: 368636572 -- 83e5146e35f221736b49e9f0a8805f8c159a51db by Martijn Vels <mvels@google.com>: Make cordz targets visible in OSS PiperOrigin-RevId: 368615010 -- dcb16a4f1239151f0a8c70a8cfeb29dabbd113b8 by Martijn Vels <mvels@google.com>: Internal cleanup PiperOrigin-RevId: 368514666 GitOrigin-RevId: 341670bce317dd6af8d3c066970230591a47e80c Change-Id: I94cecfbbd441eb386f99fc5186c468a7a5538862
4 years ago
// kIntervalIfDisabled is the number of profile-eligible events need to occur
// before the code will confirm that cordz is still disabled.
constexpr int64_t kIntervalIfDisabled = 1 << 16;
ABSL_ATTRIBUTE_NOINLINE bool cordz_should_profile_slow() {
thread_local absl::base_internal::ExponentialBiased
exponential_biased_generator;
int32_t mean_interval = get_cordz_mean_interval();
// Check if we disabled profiling. If so, set the next sample to a "large"
// number to minimize the overhead of the should_profile codepath.
if (mean_interval <= 0) {
cordz_next_sample = kIntervalIfDisabled;
return false;
}
// Check if we're always sampling.
if (mean_interval == 1) {
cordz_next_sample = 1;
return true;
}
if (cordz_next_sample <= 0) {
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
// If first check on current thread, check cordz_should_profile()
// again using the created (initial) stride in cordz_next_sample.
const bool initialized = cordz_next_sample != kInitCordzNextSample;
Export of internal Abseil changes -- 341670bce317dd6af8d3c066970230591a47e80c by Martijn Vels <mvels@google.com>: Change GetStack() and GetParentStack() to return absl::Span PiperOrigin-RevId: 368765721 -- 6aaab9536d6957303c7aba100c3afaa6fb0ea2c8 by Martijn Vels <mvels@google.com>: Remove locking from parent stack. This change removes the need to lock all access to `parent_stack' by making the 'copy constructor' logic specify the 'copied from' CordzInfo (where available) to the TrackCord function, after which parent_stack is immutable. PiperOrigin-RevId: 368760630 -- b19e2059cada35a8ede994833018edac94de6ddc by Martijn Vels <mvels@google.com>: Add cordz instrumentation to Cord PiperOrigin-RevId: 368746225 -- 67b8bbf980f0f4e1db79aa32968e9a715a09b51a by Martijn Vels <mvels@google.com>: Create ABSL_INTERNAL_CORDZ_ENABLED define controlling when Cordz code is enabled There are specific builds and condtions under which we don't support cordz sampling, which is per this change represented by ABSL_INTERNAL_CORDZ_ENABLED being defined. PiperOrigin-RevId: 368731603 -- 8cbfe0e3169637a620f4b66ad2bc2ce340879cb0 by Martijn Vels <mvels@google.com>: Add a `rep` property to CordzInfo to be managed by Cord logic. This change adds a `rep` property to CordzInfo, which is intended to be used by collection logic. Mini design: Cord invokes TrackCord() providing the active 'root' cordrep of the newly sampled Cord, returning a CordzInfo with a weak (uncounted) reference to this root. Cord invokes `SetCordRep()` each time the root cordrep of the sampled Cord is updated while holding `mutex()`. Cord must also obtain `mutex()` _before_ removing a reference on the old root. i.e.: Cord must guarantee that the (weak) reference held in CordzInfo is at all times valid. CordzInfo collection code can then safely obtain a (reference counted) rep pointer by adding a reference to `rep_` while holding `mutex()`. This requires only a very brief critical section inside CordzInfo logic, minimizing contention with concurrent Cord updates. Cord code should typically obtain and hold `mutex()` for the entirety of each mutating Cord operation on a sampled cord. As Cord is thread compatible, it never competes on the lock with any other thread. The only possible concurrent access is from Cordz collection code, which should be a relatively rare event. PiperOrigin-RevId: 368673758 -- 1255120dce2bdd6b4205a34a0e555e0b74b6152f by Martijn Vels <mvels@google.com>: Remove 'depth' from active recorded metrics. Going forward we do not 'live' record depth (and size), but will observe these at collection time only. PiperOrigin-RevId: 368636572 -- 83e5146e35f221736b49e9f0a8805f8c159a51db by Martijn Vels <mvels@google.com>: Make cordz targets visible in OSS PiperOrigin-RevId: 368615010 -- dcb16a4f1239151f0a8c70a8cfeb29dabbd113b8 by Martijn Vels <mvels@google.com>: Internal cleanup PiperOrigin-RevId: 368514666 GitOrigin-RevId: 341670bce317dd6af8d3c066970230591a47e80c Change-Id: I94cecfbbd441eb386f99fc5186c468a7a5538862
4 years ago
cordz_next_sample = exponential_biased_generator.GetStride(mean_interval);
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
return initialized || cordz_should_profile();
Export of internal Abseil changes -- 341670bce317dd6af8d3c066970230591a47e80c by Martijn Vels <mvels@google.com>: Change GetStack() and GetParentStack() to return absl::Span PiperOrigin-RevId: 368765721 -- 6aaab9536d6957303c7aba100c3afaa6fb0ea2c8 by Martijn Vels <mvels@google.com>: Remove locking from parent stack. This change removes the need to lock all access to `parent_stack' by making the 'copy constructor' logic specify the 'copied from' CordzInfo (where available) to the TrackCord function, after which parent_stack is immutable. PiperOrigin-RevId: 368760630 -- b19e2059cada35a8ede994833018edac94de6ddc by Martijn Vels <mvels@google.com>: Add cordz instrumentation to Cord PiperOrigin-RevId: 368746225 -- 67b8bbf980f0f4e1db79aa32968e9a715a09b51a by Martijn Vels <mvels@google.com>: Create ABSL_INTERNAL_CORDZ_ENABLED define controlling when Cordz code is enabled There are specific builds and condtions under which we don't support cordz sampling, which is per this change represented by ABSL_INTERNAL_CORDZ_ENABLED being defined. PiperOrigin-RevId: 368731603 -- 8cbfe0e3169637a620f4b66ad2bc2ce340879cb0 by Martijn Vels <mvels@google.com>: Add a `rep` property to CordzInfo to be managed by Cord logic. This change adds a `rep` property to CordzInfo, which is intended to be used by collection logic. Mini design: Cord invokes TrackCord() providing the active 'root' cordrep of the newly sampled Cord, returning a CordzInfo with a weak (uncounted) reference to this root. Cord invokes `SetCordRep()` each time the root cordrep of the sampled Cord is updated while holding `mutex()`. Cord must also obtain `mutex()` _before_ removing a reference on the old root. i.e.: Cord must guarantee that the (weak) reference held in CordzInfo is at all times valid. CordzInfo collection code can then safely obtain a (reference counted) rep pointer by adding a reference to `rep_` while holding `mutex()`. This requires only a very brief critical section inside CordzInfo logic, minimizing contention with concurrent Cord updates. Cord code should typically obtain and hold `mutex()` for the entirety of each mutating Cord operation on a sampled cord. As Cord is thread compatible, it never competes on the lock with any other thread. The only possible concurrent access is from Cordz collection code, which should be a relatively rare event. PiperOrigin-RevId: 368673758 -- 1255120dce2bdd6b4205a34a0e555e0b74b6152f by Martijn Vels <mvels@google.com>: Remove 'depth' from active recorded metrics. Going forward we do not 'live' record depth (and size), but will observe these at collection time only. PiperOrigin-RevId: 368636572 -- 83e5146e35f221736b49e9f0a8805f8c159a51db by Martijn Vels <mvels@google.com>: Make cordz targets visible in OSS PiperOrigin-RevId: 368615010 -- dcb16a4f1239151f0a8c70a8cfeb29dabbd113b8 by Martijn Vels <mvels@google.com>: Internal cleanup PiperOrigin-RevId: 368514666 GitOrigin-RevId: 341670bce317dd6af8d3c066970230591a47e80c Change-Id: I94cecfbbd441eb386f99fc5186c468a7a5538862
4 years ago
}
--cordz_next_sample;
return false;
}
void cordz_set_next_sample_for_testing(int64_t next_sample) {
cordz_next_sample = next_sample;
}
#endif // ABSL_INTERNAL_CORDZ_ENABLED
int32_t get_cordz_mean_interval() {
return g_cordz_mean_interval.load(std::memory_order_acquire);
}
void set_cordz_mean_interval(int32_t mean_interval) {
g_cordz_mean_interval.store(mean_interval, std::memory_order_release);
}
} // namespace cord_internal
ABSL_NAMESPACE_END
} // namespace absl