v8/src/counters.h

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// Copyright 2012 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef V8_COUNTERS_H_
#define V8_COUNTERS_H_
#include "../include/v8.h"
#include "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 StatsTable {
public:
// Register an application-defined function where
// counters can be looked up.
void SetCounterFunction(CounterLookupCallback f) {
lookup_function_ = f;
}
// Register an application-defined function to create
// a histogram for passing to the AddHistogramSample function
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_ != NULL;
}
// Lookup the location of a counter by name. If the lookup
// is successful, returns a non-NULL 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 NULL;
return lookup_function_(name);
}
// Create a histogram by name. If the create is successful,
// returns a non-NULL 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 NULL;
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:
StatsTable();
CounterLookupCallback lookup_function_;
CreateHistogramCallback create_histogram_function_;
AddHistogramSampleCallback add_histogram_sample_function_;
friend class Isolate;
DISALLOW_COPY_AND_ASSIGN(StatsTable);
};
// 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.
//
// This class is designed to be POD initialized. It will be registered with
// the counter system on first use. For example:
// StatsCounter c = { "c:myctr", NULL, false };
struct StatsCounter {
const char* name_;
int* ptr_;
bool lookup_done_;
// Sets the counter to a specific value.
void Set(int value) {
int* loc = GetPtr();
if (loc) *loc = value;
}
// Increments the counter.
void Increment() {
int* loc = GetPtr();
if (loc) (*loc)++;
}
void Increment(int value) {
int* loc = GetPtr();
if (loc)
(*loc) += value;
}
// Decrements the counter.
void Decrement() {
int* loc = GetPtr();
if (loc) (*loc)--;
}
void Decrement(int value) {
int* loc = GetPtr();
if (loc) (*loc) -= value;
}
// Is this counter enabled?
// Returns false if table is full.
bool Enabled() {
return GetPtr() != NULL;
}
// 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();
ASSERT(loc != NULL);
return loc;
}
protected:
// Returns the cached address of this counter location.
int* GetPtr() {
if (lookup_done_) return ptr_;
lookup_done_ = true;
ptr_ = FindLocationInStatsTable();
return ptr_;
}
private:
int* FindLocationInStatsTable() const;
};
// StatsCounterTimer t = { { L"t:foo", NULL, false }, 0, 0 };
struct StatsCounterTimer {
StatsCounter counter_;
int64_t start_time_;
int64_t stop_time_;
// Start the timer.
void Start();
// Stop the timer and record the results.
void Stop();
// Returns true if the timer is running.
bool Running() {
return counter_.Enabled() && start_time_ != 0 && stop_time_ == 0;
}
};
// A Histogram represents a dynamically created histogram in the StatsTable.
//
// This class is designed to be POD initialized. It will be registered with
// the histogram system on first use. For example:
// Histogram h = { "myhist", 0, 10000, 50, NULL, false };
struct Histogram {
const char* name_;
int min_;
int max_;
int num_buckets_;
void* histogram_;
bool lookup_done_;
// Add a single sample to this histogram.
void AddSample(int sample);
// Returns true if this histogram is enabled.
bool Enabled() {
return GetHistogram() != NULL;
}
// Reset the cached internal pointer.
void Reset() {
lookup_done_ = false;
}
protected:
// Returns the handle to the histogram.
void* GetHistogram() {
if (!lookup_done_) {
lookup_done_ = true;
histogram_ = CreateHistogram();
}
return histogram_;
}
private:
void* CreateHistogram() const;
};
// A HistogramTimer allows distributions of results to be created
// HistogramTimer t = { {L"foo", 0, 10000, 50, NULL, false}, 0, 0 };
struct HistogramTimer {
Histogram histogram_;
int64_t start_time_;
int64_t stop_time_;
// Start the timer.
void Start();
// Stop the timer and record the results.
void Stop();
// Returns true if the timer is running.
bool Running() {
return histogram_.Enabled() && (start_time_ != 0) && (stop_time_ == 0);
}
void Reset() {
histogram_.Reset();
}
};
// Helper class for scoping a HistogramTimer.
class HistogramTimerScope BASE_EMBEDDED {
public:
explicit HistogramTimerScope(HistogramTimer* timer) :
timer_(timer) {
timer_->Start();
}
~HistogramTimerScope() {
timer_->Stop();
}
private:
HistogramTimer* timer_;
};
} } // namespace v8::internal
#endif // V8_COUNTERS_H_