diff options
Diffstat (limited to 'abseil-cpp/absl/container/internal/hashtablez_sampler.cc')
-rw-r--r-- | abseil-cpp/absl/container/internal/hashtablez_sampler.cc | 249 |
1 files changed, 132 insertions, 117 deletions
diff --git a/abseil-cpp/absl/container/internal/hashtablez_sampler.cc b/abseil-cpp/absl/container/internal/hashtablez_sampler.cc index e4484fb..79a0973 100644 --- a/abseil-cpp/absl/container/internal/hashtablez_sampler.cc +++ b/abseil-cpp/absl/container/internal/hashtablez_sampler.cc @@ -14,6 +14,7 @@ #include "absl/container/internal/hashtablez_sampler.h" +#include <algorithm> #include <atomic> #include <cassert> #include <cmath> @@ -21,49 +22,57 @@ #include <limits> #include "absl/base/attributes.h" -#include "absl/base/internal/exponential_biased.h" -#include "absl/container/internal/have_sse.h" +#include "absl/base/config.h" +#include "absl/base/internal/raw_logging.h" #include "absl/debugging/stacktrace.h" #include "absl/memory/memory.h" +#include "absl/profiling/internal/exponential_biased.h" +#include "absl/profiling/internal/sample_recorder.h" #include "absl/synchronization/mutex.h" +#include "absl/time/clock.h" +#include "absl/utility/utility.h" namespace absl { ABSL_NAMESPACE_BEGIN namespace container_internal { + +#ifdef ABSL_INTERNAL_NEED_REDUNDANT_CONSTEXPR_DECL constexpr int HashtablezInfo::kMaxStackDepth; +#endif namespace { ABSL_CONST_INIT std::atomic<bool> g_hashtablez_enabled{ false }; ABSL_CONST_INIT std::atomic<int32_t> g_hashtablez_sample_parameter{1 << 10}; -ABSL_CONST_INIT std::atomic<int32_t> g_hashtablez_max_samples{1 << 20}; +std::atomic<HashtablezConfigListener> g_hashtablez_config_listener{nullptr}; #if defined(ABSL_INTERNAL_HASHTABLEZ_SAMPLE) -ABSL_PER_THREAD_TLS_KEYWORD absl::base_internal::ExponentialBiased +ABSL_PER_THREAD_TLS_KEYWORD absl::profiling_internal::ExponentialBiased g_exponential_biased_generator; #endif +void TriggerHashtablezConfigListener() { + auto* listener = g_hashtablez_config_listener.load(std::memory_order_acquire); + if (listener != nullptr) listener(); +} + } // namespace #if defined(ABSL_INTERNAL_HASHTABLEZ_SAMPLE) -ABSL_PER_THREAD_TLS_KEYWORD int64_t global_next_sample = 0; +ABSL_PER_THREAD_TLS_KEYWORD SamplingState global_next_sample = {0, 0}; #endif // defined(ABSL_INTERNAL_HASHTABLEZ_SAMPLE) -HashtablezSampler& HashtablezSampler::Global() { +HashtablezSampler& GlobalHashtablezSampler() { static auto* sampler = new HashtablezSampler(); return *sampler; } -HashtablezSampler::DisposeCallback HashtablezSampler::SetDisposeCallback( - DisposeCallback f) { - return dispose_.exchange(f, std::memory_order_relaxed); -} - -HashtablezInfo::HashtablezInfo() { PrepareForSampling(); } +HashtablezInfo::HashtablezInfo() = default; HashtablezInfo::~HashtablezInfo() = default; -void HashtablezInfo::PrepareForSampling() { +void HashtablezInfo::PrepareForSampling(int64_t stride, + size_t inline_element_size_value) { capacity.store(0, std::memory_order_relaxed); size.store(0, std::memory_order_relaxed); num_erases.store(0, std::memory_order_relaxed); @@ -72,100 +81,17 @@ void HashtablezInfo::PrepareForSampling() { total_probe_length.store(0, std::memory_order_relaxed); hashes_bitwise_or.store(0, std::memory_order_relaxed); hashes_bitwise_and.store(~size_t{}, std::memory_order_relaxed); + hashes_bitwise_xor.store(0, std::memory_order_relaxed); + max_reserve.store(0, std::memory_order_relaxed); create_time = absl::Now(); + weight = stride; // The inliner makes hardcoded skip_count difficult (especially when combined // with LTO). We use the ability to exclude stacks by regex when encoding // instead. depth = absl::GetStackTrace(stack, HashtablezInfo::kMaxStackDepth, /* skip_count= */ 0); - dead = nullptr; -} - -HashtablezSampler::HashtablezSampler() - : dropped_samples_(0), size_estimate_(0), all_(nullptr), dispose_(nullptr) { - absl::MutexLock l(&graveyard_.init_mu); - graveyard_.dead = &graveyard_; -} - -HashtablezSampler::~HashtablezSampler() { - HashtablezInfo* s = all_.load(std::memory_order_acquire); - while (s != nullptr) { - HashtablezInfo* next = s->next; - delete s; - s = next; - } -} - -void HashtablezSampler::PushNew(HashtablezInfo* sample) { - sample->next = all_.load(std::memory_order_relaxed); - while (!all_.compare_exchange_weak(sample->next, sample, - std::memory_order_release, - std::memory_order_relaxed)) { - } -} - -void HashtablezSampler::PushDead(HashtablezInfo* sample) { - if (auto* dispose = dispose_.load(std::memory_order_relaxed)) { - dispose(*sample); - } - - absl::MutexLock graveyard_lock(&graveyard_.init_mu); - absl::MutexLock sample_lock(&sample->init_mu); - sample->dead = graveyard_.dead; - graveyard_.dead = sample; -} - -HashtablezInfo* HashtablezSampler::PopDead() { - absl::MutexLock graveyard_lock(&graveyard_.init_mu); - - // The list is circular, so eventually it collapses down to - // graveyard_.dead == &graveyard_ - // when it is empty. - HashtablezInfo* sample = graveyard_.dead; - if (sample == &graveyard_) return nullptr; - - absl::MutexLock sample_lock(&sample->init_mu); - graveyard_.dead = sample->dead; - sample->PrepareForSampling(); - return sample; -} - -HashtablezInfo* HashtablezSampler::Register() { - int64_t size = size_estimate_.fetch_add(1, std::memory_order_relaxed); - if (size > g_hashtablez_max_samples.load(std::memory_order_relaxed)) { - size_estimate_.fetch_sub(1, std::memory_order_relaxed); - dropped_samples_.fetch_add(1, std::memory_order_relaxed); - return nullptr; - } - - HashtablezInfo* sample = PopDead(); - if (sample == nullptr) { - // Resurrection failed. Hire a new warlock. - sample = new HashtablezInfo(); - PushNew(sample); - } - - return sample; -} - -void HashtablezSampler::Unregister(HashtablezInfo* sample) { - PushDead(sample); - size_estimate_.fetch_sub(1, std::memory_order_relaxed); -} - -int64_t HashtablezSampler::Iterate( - const std::function<void(const HashtablezInfo& stack)>& f) { - HashtablezInfo* s = all_.load(std::memory_order_acquire); - while (s != nullptr) { - absl::MutexLock l(&s->init_mu); - if (s->dead == nullptr) { - f(*s); - } - s = s->next; - } - - return dropped_samples_.load(std::memory_order_relaxed); + inline_element_size = inline_element_size_value; } static bool ShouldForceSampling() { @@ -180,27 +106,40 @@ static bool ShouldForceSampling() { if (ABSL_PREDICT_TRUE(state == kDontForce)) return false; if (state == kUninitialized) { - state = AbslContainerInternalSampleEverything() ? kForce : kDontForce; + state = ABSL_INTERNAL_C_SYMBOL(AbslContainerInternalSampleEverything)() + ? kForce + : kDontForce; global_state.store(state, std::memory_order_relaxed); } return state == kForce; } -HashtablezInfo* SampleSlow(int64_t* next_sample) { +HashtablezInfo* SampleSlow(SamplingState& next_sample, + size_t inline_element_size) { if (ABSL_PREDICT_FALSE(ShouldForceSampling())) { - *next_sample = 1; - return HashtablezSampler::Global().Register(); + next_sample.next_sample = 1; + const int64_t old_stride = exchange(next_sample.sample_stride, 1); + HashtablezInfo* result = + GlobalHashtablezSampler().Register(old_stride, inline_element_size); + return result; } #if !defined(ABSL_INTERNAL_HASHTABLEZ_SAMPLE) - *next_sample = std::numeric_limits<int64_t>::max(); + next_sample = { + std::numeric_limits<int64_t>::max(), + std::numeric_limits<int64_t>::max(), + }; return nullptr; #else - bool first = *next_sample < 0; - *next_sample = g_exponential_biased_generator.GetStride( + bool first = next_sample.next_sample < 0; + + const int64_t next_stride = g_exponential_biased_generator.GetStride( g_hashtablez_sample_parameter.load(std::memory_order_relaxed)); + + next_sample.next_sample = next_stride; + const int64_t old_stride = exchange(next_sample.sample_stride, next_stride); // Small values of interval are equivalent to just sampling next time. - ABSL_ASSERT(*next_sample >= 1); + ABSL_ASSERT(next_stride >= 1); // g_hashtablez_enabled can be dynamically flipped, we need to set a threshold // low enough that we will start sampling in a reasonable time, so we just use @@ -210,16 +149,53 @@ HashtablezInfo* SampleSlow(int64_t* next_sample) { // We will only be negative on our first count, so we should just retry in // that case. if (first) { - if (ABSL_PREDICT_TRUE(--*next_sample > 0)) return nullptr; - return SampleSlow(next_sample); + if (ABSL_PREDICT_TRUE(--next_sample.next_sample > 0)) return nullptr; + return SampleSlow(next_sample, inline_element_size); } - return HashtablezSampler::Global().Register(); + return GlobalHashtablezSampler().Register(old_stride, inline_element_size); #endif } void UnsampleSlow(HashtablezInfo* info) { - HashtablezSampler::Global().Unregister(info); + GlobalHashtablezSampler().Unregister(info); +} + +void RecordRehashSlow(HashtablezInfo* info, size_t total_probe_length) { +#ifdef ABSL_INTERNAL_HAVE_SSE2 + total_probe_length /= 16; +#else + total_probe_length /= 8; +#endif + info->total_probe_length.store(total_probe_length, std::memory_order_relaxed); + info->num_erases.store(0, std::memory_order_relaxed); + // There is only one concurrent writer, so `load` then `store` is sufficient + // instead of using `fetch_add`. + info->num_rehashes.store( + 1 + info->num_rehashes.load(std::memory_order_relaxed), + std::memory_order_relaxed); +} + +void RecordReservationSlow(HashtablezInfo* info, size_t target_capacity) { + info->max_reserve.store( + (std::max)(info->max_reserve.load(std::memory_order_relaxed), + target_capacity), + std::memory_order_relaxed); +} + +void RecordClearedReservationSlow(HashtablezInfo* info) { + info->max_reserve.store(0, std::memory_order_relaxed); +} + +void RecordStorageChangedSlow(HashtablezInfo* info, size_t size, + size_t capacity) { + info->size.store(size, std::memory_order_relaxed); + info->capacity.store(capacity, std::memory_order_relaxed); + if (size == 0) { + // This is a clear, reset the total/num_erases too. + info->total_probe_length.store(0, std::memory_order_relaxed); + info->num_erases.store(0, std::memory_order_relaxed); + } } void RecordInsertSlow(HashtablezInfo* info, size_t hash, @@ -227,7 +203,7 @@ void RecordInsertSlow(HashtablezInfo* info, size_t hash, // SwissTables probe in groups of 16, so scale this to count items probes and // not offset from desired. size_t probe_length = distance_from_desired; -#if ABSL_INTERNAL_RAW_HASH_SET_HAVE_SSE2 +#ifdef ABSL_INTERNAL_HAVE_SSE2 probe_length /= 16; #else probe_length /= 8; @@ -235,6 +211,7 @@ void RecordInsertSlow(HashtablezInfo* info, size_t hash, info->hashes_bitwise_and.fetch_and(hash, std::memory_order_relaxed); info->hashes_bitwise_or.fetch_or(hash, std::memory_order_relaxed); + info->hashes_bitwise_xor.fetch_xor(hash, std::memory_order_relaxed); info->max_probe_length.store( std::max(info->max_probe_length.load(std::memory_order_relaxed), probe_length), @@ -243,11 +220,41 @@ void RecordInsertSlow(HashtablezInfo* info, size_t hash, info->size.fetch_add(1, std::memory_order_relaxed); } +void RecordEraseSlow(HashtablezInfo* info) { + info->size.fetch_sub(1, std::memory_order_relaxed); + // There is only one concurrent writer, so `load` then `store` is sufficient + // instead of using `fetch_add`. + info->num_erases.store(1 + info->num_erases.load(std::memory_order_relaxed), + std::memory_order_relaxed); +} + +void SetHashtablezConfigListener(HashtablezConfigListener l) { + g_hashtablez_config_listener.store(l, std::memory_order_release); +} + +bool IsHashtablezEnabled() { + return g_hashtablez_enabled.load(std::memory_order_acquire); +} + void SetHashtablezEnabled(bool enabled) { + SetHashtablezEnabledInternal(enabled); + TriggerHashtablezConfigListener(); +} + +void SetHashtablezEnabledInternal(bool enabled) { g_hashtablez_enabled.store(enabled, std::memory_order_release); } +int32_t GetHashtablezSampleParameter() { + return g_hashtablez_sample_parameter.load(std::memory_order_acquire); +} + void SetHashtablezSampleParameter(int32_t rate) { + SetHashtablezSampleParameterInternal(rate); + TriggerHashtablezConfigListener(); +} + +void SetHashtablezSampleParameterInternal(int32_t rate) { if (rate > 0) { g_hashtablez_sample_parameter.store(rate, std::memory_order_release); } else { @@ -256,12 +263,20 @@ void SetHashtablezSampleParameter(int32_t rate) { } } -void SetHashtablezMaxSamples(int32_t max) { +size_t GetHashtablezMaxSamples() { + return GlobalHashtablezSampler().GetMaxSamples(); +} + +void SetHashtablezMaxSamples(size_t max) { + SetHashtablezMaxSamplesInternal(max); + TriggerHashtablezConfigListener(); +} + +void SetHashtablezMaxSamplesInternal(size_t max) { if (max > 0) { - g_hashtablez_max_samples.store(max, std::memory_order_release); + GlobalHashtablezSampler().SetMaxSamples(max); } else { - ABSL_RAW_LOG(ERROR, "Invalid hashtablez max samples: %lld", - static_cast<long long>(max)); // NOLINT(runtime/int) + ABSL_RAW_LOG(ERROR, "Invalid hashtablez max samples: 0"); } } |