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// Copyright 2012 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef V8_LOGGING_COUNTERS_H_
#define V8_LOGGING_COUNTERS_H_
#include <memory>
#include "include/v8.h"
#include "src/base/atomic-utils.h"
#include "src/base/optional.h"
#include "src/base/platform/elapsed-timer.h"
#include "src/base/platform/time.h"
#include "src/common/globals.h"
#include "src/logging/counters-definitions.h"
#include "src/logging/runtime-call-stats.h"
#include "src/objects/code-kind.h"
#include "src/objects/fixed-array.h"
#include "src/objects/objects.h"
#include "src/utils/allocation.h"
namespace v8 {
namespace internal {
// StatsCounters is an interface for plugging into external
// counters for monitoring. Counters can be looked up and
// manipulated by name.
class Counters;
class Isolate;
class StatsTable {
public:
StatsTable(const StatsTable&) = delete;
StatsTable& operator=(const StatsTable&) = delete;
// Register an application-defined function for recording
// subsequent counter statistics.
void SetCounterFunction(CounterLookupCallback f);
// Register an application-defined function to create histograms for
// recording subsequent histogram samples.
void SetCreateHistogramFunction(CreateHistogramCallback f) {
create_histogram_function_ = f;
}
// Register an application-defined function to add a sample
// to a histogram created with CreateHistogram function.
void SetAddHistogramSampleFunction(AddHistogramSampleCallback f) {
add_histogram_sample_function_ = f;
}
bool HasCounterFunction() const { return lookup_function_ != nullptr; }
// Lookup the location of a counter by name. If the lookup
// is successful, returns a non-nullptr pointer for writing the
// value of the counter. Each thread calling this function
// may receive a different location to store it's counter.
// The return value must not be cached and re-used across
// threads, although a single thread is free to cache it.
int* FindLocation(const char* name) {
if (!lookup_function_) return nullptr;
return lookup_function_(name);
}
// Create a histogram by name. If the create is successful,
// returns a non-nullptr pointer for use with AddHistogramSample
// function. min and max define the expected minimum and maximum
// sample values. buckets is the maximum number of buckets
// that the samples will be grouped into.
void* CreateHistogram(const char* name, int min, int max, size_t buckets) {
if (!create_histogram_function_) return nullptr;
return create_histogram_function_(name, min, max, buckets);
}
// Add a sample to a histogram created with the CreateHistogram
// function.
void AddHistogramSample(void* histogram, int sample) {
if (!add_histogram_sample_function_) return;
return add_histogram_sample_function_(histogram, sample);
}
private:
friend class Counters;
explicit StatsTable(Counters* counters);
CounterLookupCallback lookup_function_;
CreateHistogramCallback create_histogram_function_;
AddHistogramSampleCallback add_histogram_sample_function_;
};
// Base class for stats counters.
class StatsCounterBase {
protected:
Counters* counters_;
const char* name_;
int* ptr_;
StatsCounterBase() = default;
StatsCounterBase(Counters* counters, const char* name)
: counters_(counters), name_(name), ptr_(nullptr) {}
void SetLoc(int* loc, int value) { *loc = value; }
void IncrementLoc(int* loc) { (*loc)++; }
void IncrementLoc(int* loc, int value) { (*loc) += value; }
void DecrementLoc(int* loc) { (*loc)--; }
void DecrementLoc(int* loc, int value) { (*loc) -= value; }
V8_EXPORT_PRIVATE int* FindLocationInStatsTable() const;
};
// StatsCounters are dynamically created values which can be tracked in
// the StatsTable. They are designed to be lightweight to create and
// easy to use.
//
// Internally, a counter represents a value in a row of a StatsTable.
// The row has a 32bit value for each process/thread in the table and also
// a name (stored in the table metadata). Since the storage location can be
// thread-specific, this class cannot be shared across threads. Note: This
// class is not thread safe.
class StatsCounter : public StatsCounterBase {
public:
// Sets the counter to a specific value.
void Set(int value) {
if (int* loc = GetPtr()) SetLoc(loc, value);
}
// Increments the counter.
void Increment() {
if (int* loc = GetPtr()) IncrementLoc(loc);
}
void Increment(int value) {
if (int* loc = GetPtr()) IncrementLoc(loc, value);
}
// Decrements the counter.
void Decrement() {
if (int* loc = GetPtr()) DecrementLoc(loc);
}
void Decrement(int value) {
if (int* loc = GetPtr()) DecrementLoc(loc, value);
}
// Is this counter enabled?
// Returns false if table is full.
bool Enabled() { return GetPtr() != nullptr; }
// Get the internal pointer to the counter. This is used
// by the code generator to emit code that manipulates a
// given counter without calling the runtime system.
int* GetInternalPointer() {
int* loc = GetPtr();
DCHECK_NOT_NULL(loc);
return loc;
}
private:
friend class Counters;
StatsCounter() = default;
StatsCounter(Counters* counters, const char* name)
: StatsCounterBase(counters, name), lookup_done_(false) {}
// Reset the cached internal pointer.
void Reset() { lookup_done_ = false; }
// Returns the cached address of this counter location.
int* GetPtr() {
if (lookup_done_) return ptr_;
lookup_done_ = true;
ptr_ = FindLocationInStatsTable();
return ptr_;
}
bool lookup_done_;
};
// Thread safe version of StatsCounter.
class V8_EXPORT_PRIVATE StatsCounterThreadSafe : public StatsCounterBase {
public:
void Set(int Value);
void Increment();
void Increment(int value);
void Decrement();
void Decrement(int value);
bool Enabled() { return ptr_ != nullptr; }
int* GetInternalPointer() {
DCHECK_NOT_NULL(ptr_);
return ptr_;
}
private:
friend class Counters;
StatsCounterThreadSafe(Counters* counters, const char* name);
void Reset() { ptr_ = FindLocationInStatsTable(); }
base::Mutex mutex_;
DISALLOW_IMPLICIT_CONSTRUCTORS(StatsCounterThreadSafe);
};
// A Histogram represents a dynamically created histogram in the
// StatsTable. Note: This class is thread safe.
class Histogram {
public:
// Add a single sample to this histogram.
void AddSample(int sample);
// Returns true if this histogram is enabled.
bool Enabled() { return histogram_ != nullptr; }
const char* name() const { return name_; }
int min() const { return min_; }
int max() const { return max_; }
int num_buckets() const { return num_buckets_; }
// Asserts that |expected_counters| are the same as the Counters this
// Histogram reports to.
void AssertReportsToCounters(Counters* expected_counters) {
DCHECK_EQ(counters_, expected_counters);
}
protected:
Histogram() = default;
Histogram(const char* name, int min, int max, int num_buckets,
Counters* counters)
: name_(name),
min_(min),
max_(max),
num_buckets_(num_buckets),
histogram_(nullptr),
counters_(counters) {
DCHECK(counters_);
}
Counters* counters() const { return counters_; }
// Reset the cached internal pointer.
void Reset(bool create_new = true) {
histogram_ = create_new ? CreateHistogram() : nullptr;
}
private:
friend class Counters;
void* CreateHistogram() const;
const char* name_;
int min_;
int max_;
int num_buckets_;
void* histogram_;
Counters* counters_;
};
enum class TimedHistogramResolution { MILLISECOND, MICROSECOND };
// A thread safe histogram timer. It also allows distributions of
// nested timed results.
class TimedHistogram : public Histogram {
public:
// Records a TimeDelta::Max() result. Useful to record percentage of tasks
// that never got to run in a given scenario. Log if isolate non-null.
void RecordAbandon(base::ElapsedTimer* timer, Isolate* isolate);
// Add a single sample to this histogram.
V8_EXPORT_PRIVATE void AddTimedSample(base::TimeDelta sample);
#ifdef DEBUG
// Ensures that we don't have nested timers for TimedHistogram per thread, use
// NestedTimedHistogram which correctly pause and resume timers.
// This method assumes that each timer is alternating between stopped and
// started on a single thread. Multiple timers can be active on different
// threads.
bool ToggleRunningState(bool expected_is_running) const;
#endif // DEBUG
protected:
void Stop(base::ElapsedTimer* timer);
void LogStart(Isolate* isolate);
void LogEnd(Isolate* isolate);
friend class Counters;
TimedHistogramResolution resolution_;
TimedHistogram() = default;
TimedHistogram(const char* name, int min, int max,
TimedHistogramResolution resolution, int num_buckets,
Counters* counters)
: Histogram(name, min, max, num_buckets, counters),
resolution_(resolution) {}
};
class NestedTimedHistogramScope;
class PauseNestedTimedHistogramScope;
// A NestedTimedHistogram allows distributions of nested timed results.
class NestedTimedHistogram : public TimedHistogram {
public:
// Note: public for testing purposes only.
NestedTimedHistogram(const char* name, int min, int max,
TimedHistogramResolution resolution, int num_buckets,
Counters* counters)
: TimedHistogram(name, min, max, resolution, num_buckets, counters) {}
private:
friend class Counters;
friend class NestedTimedHistogramScope;
friend class PauseNestedTimedHistogramScope;
inline NestedTimedHistogramScope* Enter(NestedTimedHistogramScope* next) {
NestedTimedHistogramScope* previous = current_;
current_ = next;
return previous;
}
inline void Leave(NestedTimedHistogramScope* previous) {
current_ = previous;
}
NestedTimedHistogramScope* current_ = nullptr;
NestedTimedHistogram() = default;
};
// A histogram timer that can aggregate events within a larger scope.
//
// Intended use of this timer is to have an outer (aggregating) and an inner
// (to be aggregated) scope, where the inner scope measure the time of events,
// and all those inner scope measurements will be summed up by the outer scope.
// An example use might be to aggregate the time spent in lazy compilation
// while running a script.
//
// Helpers:
// - AggregatingHistogramTimerScope, the "outer" scope within which
// times will be summed up.
// - AggregatedHistogramTimerScope, the "inner" scope which defines the
// events to be timed.
class AggregatableHistogramTimer : public Histogram {
public:
// Start/stop the "outer" scope.
void Start() { time_ = base::TimeDelta(); }
void Stop() {
if (time_ != base::TimeDelta()) {
// Only add non-zero samples, since zero samples represent situations
// where there were no aggregated samples added.
AddSample(static_cast<int>(time_.InMicroseconds()));
}
}
// Add a time value ("inner" scope).
void Add(base::TimeDelta other) { time_ += other; }
private:
friend class Counters;
AggregatableHistogramTimer() = default;
AggregatableHistogramTimer(const char* name, int min, int max,
int num_buckets, Counters* counters)
: Histogram(name, min, max, num_buckets, counters) {}
base::TimeDelta time_;
};
// A helper class for use with AggregatableHistogramTimer. This is the
// // outer-most timer scope used with an AggregatableHistogramTimer. It will
// // aggregate the information from the inner AggregatedHistogramTimerScope.
class V8_NODISCARD AggregatingHistogramTimerScope {
public:
explicit AggregatingHistogramTimerScope(AggregatableHistogramTimer* histogram)
: histogram_(histogram) {
histogram_->Start();
}
~AggregatingHistogramTimerScope() { histogram_->Stop(); }
private:
AggregatableHistogramTimer* histogram_;
};
// A helper class for use with AggregatableHistogramTimer, the "inner" scope
// // which defines the events to be timed.
class V8_NODISCARD AggregatedHistogramTimerScope {
public:
explicit AggregatedHistogramTimerScope(AggregatableHistogramTimer* histogram)
: histogram_(histogram) {
timer_.Start();
}
~AggregatedHistogramTimerScope() { histogram_->Add(timer_.Elapsed()); }
private:
base::ElapsedTimer timer_;
AggregatableHistogramTimer* histogram_;
};
// AggretatedMemoryHistogram collects (time, value) sample pairs and turns
// them into time-uniform samples for the backing historgram, such that the
// backing histogram receives one sample every T ms, where the T is controlled
// by the FLAG_histogram_interval.
//
// More formally: let F be a real-valued function that maps time to sample
// values. We define F as a linear interpolation between adjacent samples. For
// each time interval [x; x + T) the backing histogram gets one sample value
// that is the average of F(t) in the interval.
template <typename Histogram>
class AggregatedMemoryHistogram {
public:
// Note: public for testing purposes only.
explicit AggregatedMemoryHistogram(Histogram* backing_histogram)
: AggregatedMemoryHistogram() {
backing_histogram_ = backing_histogram;
}
// Invariants that hold before and after AddSample if
// is_initialized_ is true:
//
// 1) For we processed samples that came in before start_ms_ and sent the
// corresponding aggregated samples to backing histogram.
// 2) (last_ms_, last_value_) is the last received sample.
// 3) last_ms_ < start_ms_ + FLAG_histogram_interval.
// 4) aggregate_value_ is the average of the function that is constructed by
// linearly interpolating samples received between start_ms_ and last_ms_.
void AddSample(double current_ms, double current_value);
private:
friend class Counters;
AggregatedMemoryHistogram()
: is_initialized_(false),
start_ms_(0.0),
last_ms_(0.0),
aggregate_value_(0.0),
last_value_(0.0),
backing_histogram_(nullptr) {}
double Aggregate(double current_ms, double current_value);
bool is_initialized_;
double start_ms_;
double last_ms_;
double aggregate_value_;
double last_value_;
Histogram* backing_histogram_;
};
template <typename Histogram>
void AggregatedMemoryHistogram<Histogram>::AddSample(double current_ms,
double current_value) {
if (!is_initialized_) {
aggregate_value_ = current_value;
start_ms_ = current_ms;
last_value_ = current_value;
last_ms_ = current_ms;
is_initialized_ = true;
} else {
const double kEpsilon = 1e-6;
const int kMaxSamples = 1000;
if (current_ms < last_ms_ + kEpsilon) {
// Two samples have the same time, remember the last one.
last_value_ = current_value;
} else {
double sample_interval_ms = FLAG_histogram_interval;
double end_ms = start_ms_ + sample_interval_ms;
if (end_ms <= current_ms + kEpsilon) {
// Linearly interpolate between the last_ms_ and the current_ms.
double slope = (current_value - last_value_) / (current_ms - last_ms_);
int i;
// Send aggregated samples to the backing histogram from the start_ms
// to the current_ms.
for (i = 0; i < kMaxSamples && end_ms <= current_ms + kEpsilon; i++) {
double end_value = last_value_ + (end_ms - last_ms_) * slope;
double sample_value;
if (i == 0) {
// Take aggregate_value_ into account.
sample_value = Aggregate(end_ms, end_value);
} else {
// There is no aggregate_value_ for i > 0.
sample_value = (last_value_ + end_value) / 2;
}
backing_histogram_->AddSample(static_cast<int>(sample_value + 0.5));
last_value_ = end_value;
last_ms_ = end_ms;
end_ms += sample_interval_ms;
}
if (i == kMaxSamples) {
// We hit the sample limit, ignore the remaining samples.
aggregate_value_ = current_value;
start_ms_ = current_ms;
} else {
aggregate_value_ = last_value_;
start_ms_ = last_ms_;
}
}
aggregate_value_ = current_ms > start_ms_ + kEpsilon
? Aggregate(current_ms, current_value)
: aggregate_value_;
last_value_ = current_value;
last_ms_ = current_ms;
}
}
}
template <typename Histogram>
double AggregatedMemoryHistogram<Histogram>::Aggregate(double current_ms,
double current_value) {
double interval_ms = current_ms - start_ms_;
double value = (current_value + last_value_) / 2;
// The aggregate_value_ is the average for [start_ms_; last_ms_].
// The value is the average for [last_ms_; current_ms].
// Return the weighted average of the aggregate_value_ and the value.
return aggregate_value_ * ((last_ms_ - start_ms_) / interval_ms) +
value * ((current_ms - last_ms_) / interval_ms);
}
// This file contains all the v8 counters that are in use.
class Counters : public std::enable_shared_from_this<Counters> {
public:
explicit Counters(Isolate* isolate);
// Register an application-defined function for recording
// subsequent counter statistics. Note: Must be called on the main
// thread.
void ResetCounterFunction(CounterLookupCallback f);
// Register an application-defined function to create histograms for
// recording subsequent histogram samples. Note: Must be called on
// the main thread.
void ResetCreateHistogramFunction(CreateHistogramCallback f);
// Register an application-defined function to add a sample
// to a histogram. Will be used in all subsequent sample additions.
// Note: Must be called on the main thread.
void SetAddHistogramSampleFunction(AddHistogramSampleCallback f) {
stats_table_.SetAddHistogramSampleFunction(f);
}
#define HR(name, caption, min, max, num_buckets) \
Histogram* name() { return &name##_; }
HISTOGRAM_RANGE_LIST(HR)
#undef HR
#define HT(name, caption, max, res) \
NestedTimedHistogram* name() { return &name##_; }
NESTED_TIMED_HISTOGRAM_LIST(HT)
NESTED_TIMED_HISTOGRAM_LIST_SLOW(HT)
#undef HT
#define HT(name, caption, max, res) \
TimedHistogram* name() { return &name##_; }
TIMED_HISTOGRAM_LIST(HT)
#undef HT
#define AHT(name, caption) \
AggregatableHistogramTimer* name() { return &name##_; }
AGGREGATABLE_HISTOGRAM_TIMER_LIST(AHT)
#undef AHT
#define HP(name, caption) \
Histogram* name() { return &name##_; }
HISTOGRAM_PERCENTAGE_LIST(HP)
#undef HP
#define HM(name, caption) \
Histogram* name() { return &name##_; }
HISTOGRAM_LEGACY_MEMORY_LIST(HM)
#undef HM
#define SC(name, caption) \
StatsCounter* name() { return &name##_; }
STATS_COUNTER_LIST_1(SC)
STATS_COUNTER_LIST_2(SC)
STATS_COUNTER_NATIVE_CODE_LIST(SC)
#undef SC
#define SC(name, caption) \
StatsCounterThreadSafe* name() { return &name##_; }
STATS_COUNTER_TS_LIST(SC)
#undef SC
// clang-format off
enum Id {
#define RATE_ID(name, caption, max, res) k_##name,
NESTED_TIMED_HISTOGRAM_LIST(RATE_ID)
NESTED_TIMED_HISTOGRAM_LIST_SLOW(RATE_ID)
TIMED_HISTOGRAM_LIST(RATE_ID)
#undef RATE_ID
#define AGGREGATABLE_ID(name, caption) k_##name,
AGGREGATABLE_HISTOGRAM_TIMER_LIST(AGGREGATABLE_ID)
#undef AGGREGATABLE_ID
#define PERCENTAGE_ID(name, caption) k_##name,
HISTOGRAM_PERCENTAGE_LIST(PERCENTAGE_ID)
#undef PERCENTAGE_ID
#define MEMORY_ID(name, caption) k_##name,
HISTOGRAM_LEGACY_MEMORY_LIST(MEMORY_ID)
#undef MEMORY_ID
#define COUNTER_ID(name, caption) k_##name,
STATS_COUNTER_LIST_1(COUNTER_ID)
STATS_COUNTER_LIST_2(COUNTER_ID)
STATS_COUNTER_TS_LIST(COUNTER_ID)
STATS_COUNTER_NATIVE_CODE_LIST(COUNTER_ID)
#undef COUNTER_ID
#define COUNTER_ID(name) kCountOf##name, kSizeOf##name,
INSTANCE_TYPE_LIST(COUNTER_ID)
#undef COUNTER_ID
#define COUNTER_ID(name) kCountOfCODE_TYPE_##name, \
kSizeOfCODE_TYPE_##name,
CODE_KIND_LIST(COUNTER_ID)
#undef COUNTER_ID
#define COUNTER_ID(name) kCountOfFIXED_ARRAY__##name, \
kSizeOfFIXED_ARRAY__##name,
FIXED_ARRAY_SUB_INSTANCE_TYPE_LIST(COUNTER_ID)
#undef COUNTER_ID
stats_counter_count
};
// clang-format on
#ifdef V8_RUNTIME_CALL_STATS
RuntimeCallStats* runtime_call_stats() { return &runtime_call_stats_; }
WorkerThreadRuntimeCallStats* worker_thread_runtime_call_stats() {
return &worker_thread_runtime_call_stats_;
}
#else // V8_RUNTIME_CALL_STATS
RuntimeCallStats* runtime_call_stats() { return nullptr; }
WorkerThreadRuntimeCallStats* worker_thread_runtime_call_stats() {
return nullptr;
}
#endif // V8_RUNTIME_CALL_STATS
private:
friend class StatsTable;
friend class StatsCounterBase;
friend class Histogram;
friend class NestedTimedHistogramScope;
int* FindLocation(const char* name) {
return stats_table_.FindLocation(name);
}
void* CreateHistogram(const char* name, int min, int max, size_t buckets) {
return stats_table_.CreateHistogram(name, min, max, buckets);
}
void AddHistogramSample(void* histogram, int sample) {
stats_table_.AddHistogramSample(histogram, sample);
}
Isolate* isolate() { return isolate_; }
#define HR(name, caption, min, max, num_buckets) Histogram name##_;
HISTOGRAM_RANGE_LIST(HR)
#undef HR
#define HT(name, caption, max, res) NestedTimedHistogram name##_;
NESTED_TIMED_HISTOGRAM_LIST(HT)
NESTED_TIMED_HISTOGRAM_LIST_SLOW(HT)
#undef HT
#define HT(name, caption, max, res) TimedHistogram name##_;
TIMED_HISTOGRAM_LIST(HT)
#undef HT
#define AHT(name, caption) AggregatableHistogramTimer name##_;
AGGREGATABLE_HISTOGRAM_TIMER_LIST(AHT)
#undef AHT
#define HP(name, caption) Histogram name##_;
HISTOGRAM_PERCENTAGE_LIST(HP)
#undef HP
#define HM(name, caption) Histogram name##_;
HISTOGRAM_LEGACY_MEMORY_LIST(HM)
#undef HM
#define SC(name, caption) StatsCounter name##_;
STATS_COUNTER_LIST_1(SC)
STATS_COUNTER_LIST_2(SC)
STATS_COUNTER_NATIVE_CODE_LIST(SC)
#undef SC
#define SC(name, caption) StatsCounterThreadSafe name##_;
STATS_COUNTER_TS_LIST(SC)
#undef SC
#define SC(name) \
StatsCounter size_of_##name##_; \
StatsCounter count_of_##name##_;
INSTANCE_TYPE_LIST(SC)
#undef SC
#define SC(name) \
StatsCounter size_of_CODE_TYPE_##name##_; \
StatsCounter count_of_CODE_TYPE_##name##_;
CODE_KIND_LIST(SC)
#undef SC
#define SC(name) \
StatsCounter size_of_FIXED_ARRAY_##name##_; \
StatsCounter count_of_FIXED_ARRAY_##name##_;
FIXED_ARRAY_SUB_INSTANCE_TYPE_LIST(SC)
#undef SC
#ifdef V8_RUNTIME_CALL_STATS
RuntimeCallStats runtime_call_stats_;
WorkerThreadRuntimeCallStats worker_thread_runtime_call_stats_;
#endif
Isolate* isolate_;
StatsTable stats_table_;
DISALLOW_IMPLICIT_CONSTRUCTORS(Counters);
};
} // namespace internal
} // namespace v8
#endif // V8_LOGGING_COUNTERS_H_
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