summaryrefslogtreecommitdiff
path: root/absl/container/internal
diff options
context:
space:
mode:
Diffstat (limited to 'absl/container/internal')
-rw-r--r--absl/container/internal/hashtablez_sampler.cc104
-rw-r--r--absl/container/internal/hashtablez_sampler.h81
-rw-r--r--absl/container/internal/hashtablez_sampler_test.cc3
-rw-r--r--absl/container/internal/raw_hash_set_test.cc4
4 files changed, 16 insertions, 176 deletions
diff --git a/absl/container/internal/hashtablez_sampler.cc b/absl/container/internal/hashtablez_sampler.cc
index 5a29bed7..ca03d9b6 100644
--- a/absl/container/internal/hashtablez_sampler.cc
+++ b/absl/container/internal/hashtablez_sampler.cc
@@ -25,6 +25,7 @@
#include "absl/container/internal/have_sse.h"
#include "absl/debugging/stacktrace.h"
#include "absl/memory/memory.h"
+#include "absl/profiling/internal/sample_recorder.h"
#include "absl/synchronization/mutex.h"
namespace absl {
@@ -37,7 +38,6 @@ 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};
#if defined(ABSL_INTERNAL_HASHTABLEZ_SAMPLE)
ABSL_PER_THREAD_TLS_KEYWORD absl::base_internal::ExponentialBiased
@@ -50,16 +50,11 @@ ABSL_PER_THREAD_TLS_KEYWORD absl::base_internal::ExponentialBiased
ABSL_PER_THREAD_TLS_KEYWORD int64_t global_next_sample = 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;
@@ -80,93 +75,6 @@ void HashtablezInfo::PrepareForSampling() {
// 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);
}
static bool ShouldForceSampling() {
@@ -192,7 +100,7 @@ static bool ShouldForceSampling() {
HashtablezInfo* SampleSlow(int64_t* next_sample) {
if (ABSL_PREDICT_FALSE(ShouldForceSampling())) {
*next_sample = 1;
- return HashtablezSampler::Global().Register();
+ return GlobalHashtablezSampler().Register();
}
#if !defined(ABSL_INTERNAL_HASHTABLEZ_SAMPLE)
@@ -217,12 +125,12 @@ HashtablezInfo* SampleSlow(int64_t* next_sample) {
return SampleSlow(next_sample);
}
- return HashtablezSampler::Global().Register();
+ return GlobalHashtablezSampler().Register();
#endif
}
void UnsampleSlow(HashtablezInfo* info) {
- HashtablezSampler::Global().Unregister(info);
+ GlobalHashtablezSampler().Unregister(info);
}
void RecordInsertSlow(HashtablezInfo* info, size_t hash,
@@ -262,7 +170,7 @@ void SetHashtablezSampleParameter(int32_t rate) {
void SetHashtablezMaxSamples(int32_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)
diff --git a/absl/container/internal/hashtablez_sampler.h b/absl/container/internal/hashtablez_sampler.h
index 85685f72..d86207f5 100644
--- a/absl/container/internal/hashtablez_sampler.h
+++ b/absl/container/internal/hashtablez_sampler.h
@@ -47,6 +47,7 @@
#include "absl/base/internal/per_thread_tls.h"
#include "absl/base/optimization.h"
#include "absl/container/internal/have_sse.h"
+#include "absl/profiling/internal/sample_recorder.h"
#include "absl/synchronization/mutex.h"
#include "absl/utility/utility.h"
@@ -57,7 +58,7 @@ namespace container_internal {
// Stores information about a sampled hashtable. All mutations to this *must*
// be made through `Record*` functions below. All reads from this *must* only
// occur in the callback to `HashtablezSampler::Iterate`.
-struct HashtablezInfo {
+struct HashtablezInfo : public profiling_internal::Sample<HashtablezInfo> {
// Constructs the object but does not fill in any fields.
HashtablezInfo();
~HashtablezInfo();
@@ -80,14 +81,6 @@ struct HashtablezInfo {
std::atomic<size_t> hashes_bitwise_and;
std::atomic<size_t> hashes_bitwise_xor;
- // `HashtablezSampler` maintains intrusive linked lists for all samples. See
- // comments on `HashtablezSampler::all_` for details on these. `init_mu`
- // guards the ability to restore the sample to a pristine state. This
- // prevents races with sampling and resurrecting an object.
- absl::Mutex init_mu;
- HashtablezInfo* next;
- HashtablezInfo* dead ABSL_GUARDED_BY(init_mu);
-
// All of the fields below are set by `PrepareForSampling`, they must not be
// mutated in `Record*` functions. They are logically `const` in that sense.
// These are guarded by init_mu, but that is not externalized to clients, who
@@ -231,73 +224,11 @@ inline HashtablezInfoHandle Sample() {
#endif // !ABSL_PER_THREAD_TLS
}
-// Holds samples and their associated stack traces with a soft limit of
-// `SetHashtablezMaxSamples()`.
-//
-// Thread safe.
-class HashtablezSampler {
- public:
- // Returns a global Sampler.
- static HashtablezSampler& Global();
-
- HashtablezSampler();
- ~HashtablezSampler();
-
- // Registers for sampling. Returns an opaque registration info.
- HashtablezInfo* Register();
+using HashtablezSampler =
+ ::absl::profiling_internal::SampleRecorder<HashtablezInfo>;
- // Unregisters the sample.
- void Unregister(HashtablezInfo* sample);
-
- // The dispose callback will be called on all samples the moment they are
- // being unregistered. Only affects samples that are unregistered after the
- // callback has been set.
- // Returns the previous callback.
- using DisposeCallback = void (*)(const HashtablezInfo&);
- DisposeCallback SetDisposeCallback(DisposeCallback f);
-
- // Iterates over all the registered `StackInfo`s. Returning the number of
- // samples that have been dropped.
- int64_t Iterate(const std::function<void(const HashtablezInfo& stack)>& f);
-
- private:
- void PushNew(HashtablezInfo* sample);
- void PushDead(HashtablezInfo* sample);
- HashtablezInfo* PopDead();
-
- std::atomic<size_t> dropped_samples_;
- std::atomic<size_t> size_estimate_;
-
- // Intrusive lock free linked lists for tracking samples.
- //
- // `all_` records all samples (they are never removed from this list) and is
- // terminated with a `nullptr`.
- //
- // `graveyard_.dead` is a circular linked list. When it is empty,
- // `graveyard_.dead == &graveyard`. The list is circular so that
- // every item on it (even the last) has a non-null dead pointer. This allows
- // `Iterate` to determine if a given sample is live or dead using only
- // information on the sample itself.
- //
- // For example, nodes [A, B, C, D, E] with [A, C, E] alive and [B, D] dead
- // looks like this (G is the Graveyard):
- //
- // +---+ +---+ +---+ +---+ +---+
- // all -->| A |--->| B |--->| C |--->| D |--->| E |
- // | | | | | | | | | |
- // +---+ | | +->| |-+ | | +->| |-+ | |
- // | G | +---+ | +---+ | +---+ | +---+ | +---+
- // | | | | | |
- // | | --------+ +--------+ |
- // +---+ |
- // ^ |
- // +--------------------------------------+
- //
- std::atomic<HashtablezInfo*> all_;
- HashtablezInfo graveyard_;
-
- std::atomic<DisposeCallback> dispose_;
-};
+// Returns a global Sampler.
+HashtablezSampler& GlobalHashtablezSampler();
// Enables or disables sampling for Swiss tables.
void SetHashtablezEnabled(bool enabled);
diff --git a/absl/container/internal/hashtablez_sampler_test.cc b/absl/container/internal/hashtablez_sampler_test.cc
index 5f4c83b7..53fcfe6f 100644
--- a/absl/container/internal/hashtablez_sampler_test.cc
+++ b/absl/container/internal/hashtablez_sampler_test.cc
@@ -22,6 +22,7 @@
#include "gtest/gtest.h"
#include "absl/base/attributes.h"
#include "absl/container/internal/have_sse.h"
+#include "absl/profiling/internal/sample_recorder.h"
#include "absl/synchronization/blocking_counter.h"
#include "absl/synchronization/internal/thread_pool.h"
#include "absl/synchronization/mutex.h"
@@ -232,7 +233,7 @@ TEST(HashtablezSamplerTest, Sample) {
}
TEST(HashtablezSamplerTest, Handle) {
- auto& sampler = HashtablezSampler::Global();
+ auto& sampler = GlobalHashtablezSampler();
HashtablezInfoHandle h(sampler.Register());
auto* info = HashtablezInfoHandlePeer::GetInfo(&h);
info->hashes_bitwise_and.store(0x12345678, std::memory_order_relaxed);
diff --git a/absl/container/internal/raw_hash_set_test.cc b/absl/container/internal/raw_hash_set_test.cc
index 4fb31fad..4012a3aa 100644
--- a/absl/container/internal/raw_hash_set_test.cc
+++ b/absl/container/internal/raw_hash_set_test.cc
@@ -2038,7 +2038,7 @@ TEST(RawHashSamplerTest, Sample) {
SetHashtablezEnabled(true);
SetHashtablezSampleParameter(100);
- auto& sampler = HashtablezSampler::Global();
+ auto& sampler = GlobalHashtablezSampler();
size_t start_size = 0;
std::unordered_set<const HashtablezInfo*> preexisting_info;
start_size += sampler.Iterate([&](const HashtablezInfo& info) {
@@ -2076,7 +2076,7 @@ TEST(RawHashSamplerTest, DoNotSampleCustomAllocators) {
SetHashtablezEnabled(true);
SetHashtablezSampleParameter(100);
- auto& sampler = HashtablezSampler::Global();
+ auto& sampler = GlobalHashtablezSampler();
size_t start_size = 0;
start_size += sampler.Iterate([&](const HashtablezInfo&) { ++start_size; });
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-20 17:52:57 +0000