src/v8/src/profiler/sampling-heap-profiler.cc - cobalt - Git at Google

 // Copyright 2015 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.

 #include "src/profiler/sampling-heap-profiler.h"

 #include <stdint.h>
 #include <memory>
 #include "src/api.h"
 #include "src/base/ieee754.h"
 #include "src/base/utils/random-number-generator.h"
 #include "src/frames-inl.h"
 #include "src/heap/heap.h"
 #include "src/isolate.h"
 #include "src/profiler/strings-storage.h"

 namespace v8 {
 namespace internal {

 // We sample with a Poisson process, with constant average sampling interval.
 // This follows the exponential probability distribution with parameter
 // λ = 1/rate where rate is the average number of bytes between samples.
 //
 // Let u be a uniformly distributed random number between 0 and 1, then
 // next_sample = (- ln u) / λ
 intptr_t SamplingAllocationObserver::GetNextSampleInterval(uint64_t rate) {
   if (FLAG_sampling_heap_profiler_suppress_randomness) {
     return static_cast<intptr_t>(rate);
   }
   double u = random_->NextDouble();
   double next = (-base::ieee754::log(u)) * rate;
   return next < kPointerSize
              ? kPointerSize
              : (next > INT_MAX ? INT_MAX : static_cast<intptr_t>(next));
 }

 // Samples were collected according to a poisson process. Since we have not
 // recorded all allocations, we must approximate the shape of the underlying
 // space of allocations based on the samples we have collected. Given that
 // we sample at rate R, the probability that an allocation of size S will be
 // sampled is 1-exp(-S/R). This function uses the above probability to
 // approximate the true number of allocations with size *size* given that
 // *count* samples were observed.
 v8::AllocationProfile::Allocation SamplingHeapProfiler::ScaleSample(
     size_t size, unsigned int count) {
   double scale = 1.0 / (1.0 - std::exp(-static_cast<double>(size) / rate_));
   // Round count instead of truncating.
   return {size, static_cast<unsigned int>(count * scale + 0.5)};
 }

 SamplingHeapProfiler::SamplingHeapProfiler(
     Heap* heap, StringsStorage* names, uint64_t rate, int stack_depth,
     v8::HeapProfiler::SamplingFlags flags)
     : isolate_(heap->isolate()),
       heap_(heap),
       new_space_observer_(new SamplingAllocationObserver(
           heap_, static_cast<intptr_t>(rate), rate, this,
           heap->isolate()->random_number_generator())),
       other_spaces_observer_(new SamplingAllocationObserver(
           heap_, static_cast<intptr_t>(rate), rate, this,
           heap->isolate()->random_number_generator())),
       names_(names),
       profile_root_(nullptr, "(root)", v8::UnboundScript::kNoScriptId, 0),
       samples_(),
       stack_depth_(stack_depth),
       rate_(rate),
       flags_(flags) {
   CHECK_GT(rate_, 0u);

   heap_->AddAllocationObserversToAllSpaces(other_spaces_observer_.get(),
                                            new_space_observer_.get());
 }


 SamplingHeapProfiler::~SamplingHeapProfiler() {
   heap_->RemoveAllocationObserversFromAllSpaces(other_spaces_observer_.get(),
                                                 new_space_observer_.get());

   for (auto sample : samples_) {
     delete sample;
   }
   std::set<Sample*> empty;
   samples_.swap(empty);
 }


 void SamplingHeapProfiler::SampleObject(Address soon_object, size_t size) {
   DisallowHeapAllocation no_allocation;

   HandleScope scope(isolate_);
   HeapObject* heap_object = HeapObject::FromAddress(soon_object);
   Handle<Object> obj(heap_object, isolate_);

   // Mark the new block as FreeSpace to make sure the heap is iterable while we
   // are taking the sample.
   heap()->CreateFillerObjectAt(soon_object, static_cast<int>(size),
                                ClearRecordedSlots::kNo);

   Local<v8::Value> loc = v8::Utils::ToLocal(obj);

   AllocationNode* node = AddStack();
   node->allocations_[size]++;
   Sample* sample = new Sample(size, node, loc, this);
   samples_.insert(sample);
   sample->global.SetWeak(sample, OnWeakCallback, WeakCallbackType::kParameter);
 }

 void SamplingHeapProfiler::OnWeakCallback(
     const WeakCallbackInfo<Sample>& data) {
   Sample* sample = data.GetParameter();
   AllocationNode* node = sample->owner;
   DCHECK_GT(node->allocations_[sample->size], 0);
   node->allocations_[sample->size]--;
   if (node->allocations_[sample->size] == 0) {
     node->allocations_.erase(sample->size);
     while (node->allocations_.empty() && node->children_.empty() &&
            node->parent_ && !node->parent_->pinned_) {
       AllocationNode* parent = node->parent_;
       AllocationNode::FunctionId id = AllocationNode::function_id(
           node->script_id_, node->script_position_, node->name_);
       parent->children_.erase(id);
       delete node;
       node = parent;
     }
   }
   sample->profiler->samples_.erase(sample);
   delete sample;
 }

 SamplingHeapProfiler::AllocationNode*
 SamplingHeapProfiler::AllocationNode::FindOrAddChildNode(const char* name,
                                                          int script_id,
                                                          int start_position) {
   FunctionId id = function_id(script_id, start_position, name);
   auto it = children_.find(id);
   if (it != children_.end()) {
     DCHECK_EQ(strcmp(it->second->name_, name), 0);
     return it->second;
   }
   auto child = new AllocationNode(this, name, script_id, start_position);
   children_.insert(std::make_pair(id, child));
   return child;
 }

 SamplingHeapProfiler::AllocationNode* SamplingHeapProfiler::AddStack() {
   AllocationNode* node = &profile_root_;

   std::vector<SharedFunctionInfo*> stack;
   JavaScriptFrameIterator it(isolate_);
   int frames_captured = 0;
   bool found_arguments_marker_frames = false;
   while (!it.done() && frames_captured < stack_depth_) {
     JavaScriptFrame* frame = it.frame();
     // If we are materializing objects during deoptimization, inlined
     // closures may not yet be materialized, and this includes the
     // closure on the stack. Skip over any such frames (they'll be
     // in the top frames of the stack). The allocations made in this
     // sensitive moment belong to the formerly optimized frame anyway.
     if (frame->unchecked_function()->IsJSFunction()) {
       SharedFunctionInfo* shared = frame->function()->shared();
       stack.push_back(shared);
       frames_captured++;
     } else {
       found_arguments_marker_frames = true;
     }
     it.Advance();
   }

   if (frames_captured == 0) {
     const char* name = nullptr;
     switch (isolate_->current_vm_state()) {
       case GC:
         name = "(GC)";
         break;
       case PARSER:
         name = "(PARSER)";
         break;
       case COMPILER:
         name = "(COMPILER)";
         break;
       case BYTECODE_COMPILER:
         name = "(BYTECODE_COMPILER)";
         break;
       case OTHER:
         name = "(V8 API)";
         break;
       case EXTERNAL:
         name = "(EXTERNAL)";
         break;
       case IDLE:
         name = "(IDLE)";
         break;
       case JS:
         name = "(JS)";
         break;
     }
     return node->FindOrAddChildNode(name, v8::UnboundScript::kNoScriptId, 0);
   }

   // We need to process the stack in reverse order as the top of the stack is
   // the first element in the list.
   for (auto it = stack.rbegin(); it != stack.rend(); ++it) {
     SharedFunctionInfo* shared = *it;
     const char* name = this->names()->GetFunctionName(shared->DebugName());
     int script_id = v8::UnboundScript::kNoScriptId;
     if (shared->script()->IsScript()) {
       Script* script = Script::cast(shared->script());
       script_id = script->id();
     }
     node = node->FindOrAddChildNode(name, script_id, shared->start_position());
   }

   if (found_arguments_marker_frames) {
     node =
         node->FindOrAddChildNode("(deopt)", v8::UnboundScript::kNoScriptId, 0);
   }

   return node;
 }

 v8::AllocationProfile::Node* SamplingHeapProfiler::TranslateAllocationNode(
     AllocationProfile* profile, SamplingHeapProfiler::AllocationNode* node,
     const std::map<int, Handle<Script>>& scripts) {
   // By pinning the node we make sure its children won't get disposed if
   // a GC kicks in during the tree retrieval.
   node->pinned_ = true;
   Local<v8::String> script_name =
       ToApiHandle<v8::String>(isolate_->factory()->InternalizeUtf8String(""));
   int line = v8::AllocationProfile::kNoLineNumberInfo;
   int column = v8::AllocationProfile::kNoColumnNumberInfo;
   std::vector<v8::AllocationProfile::Allocation> allocations;
   allocations.reserve(node->allocations_.size());
   if (node->script_id_ != v8::UnboundScript::kNoScriptId &&
       scripts.find(node->script_id_) != scripts.end()) {
     // Cannot use std::map<T>::at because it is not available on android.
     auto non_const_scripts =
         const_cast<std::map<int, Handle<Script>>&>(scripts);
     Handle<Script> script = non_const_scripts[node->script_id_];
     if (!script.is_null()) {
       if (script->name()->IsName()) {
         Name* name = Name::cast(script->name());
         script_name = ToApiHandle<v8::String>(
             isolate_->factory()->InternalizeUtf8String(names_->GetName(name)));
       }
       line = 1 + Script::GetLineNumber(script, node->script_position_);
       column = 1 + Script::GetColumnNumber(script, node->script_position_);
     }
   }
   for (auto alloc : node->allocations_) {
     allocations.push_back(ScaleSample(alloc.first, alloc.second));
   }

   profile->nodes().push_back(v8::AllocationProfile::Node(
       {ToApiHandle<v8::String>(
            isolate_->factory()->InternalizeUtf8String(node->name_)),
        script_name, node->script_id_, node->script_position_, line, column,
        std::vector<v8::AllocationProfile::Node*>(), allocations}));
   v8::AllocationProfile::Node* current = &profile->nodes().back();
   // The children map may have nodes inserted into it during translation
   // because the translation may allocate strings on the JS heap that have
   // the potential to be sampled. That's ok since map iterators are not
   // invalidated upon std::map insertion.
   for (auto it : node->children_) {
     current->children.push_back(
         TranslateAllocationNode(profile, it.second, scripts));
   }
   node->pinned_ = false;
   return current;
 }

 v8::AllocationProfile* SamplingHeapProfiler::GetAllocationProfile() {
   if (flags_ & v8::HeapProfiler::kSamplingForceGC) {
     isolate_->heap()->CollectAllGarbage(
         Heap::kNoGCFlags, GarbageCollectionReason::kSamplingProfiler);
   }
   // To resolve positions to line/column numbers, we will need to look up
   // scripts. Build a map to allow fast mapping from script id to script.
   std::map<int, Handle<Script>> scripts;
   {
     Script::Iterator iterator(isolate_);
     while (Script* script = iterator.Next()) {
       scripts[script->id()] = handle(script);
     }
   }
   auto profile = new v8::internal::AllocationProfile();
   TranslateAllocationNode(profile, &profile_root_, scripts);
   return profile;
 }


 }  // namespace internal
 }  // namespace v8
	// Copyright 2015 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.

	#include "src/profiler/sampling-heap-profiler.h"

	#include <stdint.h>
	#include <memory>
	#include "src/api.h"
	#include "src/base/ieee754.h"
	#include "src/base/utils/random-number-generator.h"
	#include "src/frames-inl.h"
	#include "src/heap/heap.h"
	#include "src/isolate.h"
	#include "src/profiler/strings-storage.h"

	namespace v8 {
	namespace internal {

	// We sample with a Poisson process, with constant average sampling interval.
	// This follows the exponential probability distribution with parameter
	// λ = 1/rate where rate is the average number of bytes between samples.
	//
	// Let u be a uniformly distributed random number between 0 and 1, then
	// next_sample = (- ln u) / λ
	intptr_t SamplingAllocationObserver::GetNextSampleInterval(uint64_t rate) {
	if (FLAG_sampling_heap_profiler_suppress_randomness) {
	return static_cast<intptr_t>(rate);
	}
	double u = random_->NextDouble();
	double next = (-base::ieee754::log(u)) * rate;
	return next < kPointerSize
	? kPointerSize
	: (next > INT_MAX ? INT_MAX : static_cast<intptr_t>(next));
	}

	// Samples were collected according to a poisson process. Since we have not
	// recorded all allocations, we must approximate the shape of the underlying
	// space of allocations based on the samples we have collected. Given that
	// we sample at rate R, the probability that an allocation of size S will be
	// sampled is 1-exp(-S/R). This function uses the above probability to
	// approximate the true number of allocations with size size given that
	// count samples were observed.
	v8::AllocationProfile::Allocation SamplingHeapProfiler::ScaleSample(
	size_t size, unsigned int count) {
	double scale = 1.0 / (1.0 - std::exp(-static_cast<double>(size) / rate_));
	// Round count instead of truncating.
	return {size, static_cast<unsigned int>(count * scale + 0.5)};
	}

	SamplingHeapProfiler::SamplingHeapProfiler(
	Heap* heap, StringsStorage* names, uint64_t rate, int stack_depth,
	v8::HeapProfiler::SamplingFlags flags)
	: isolate_(heap->isolate()),
	heap_(heap),
	new_space_observer_(new SamplingAllocationObserver(
	heap_, static_cast<intptr_t>(rate), rate, this,
	heap->isolate()->random_number_generator())),
	other_spaces_observer_(new SamplingAllocationObserver(
	heap_, static_cast<intptr_t>(rate), rate, this,
	heap->isolate()->random_number_generator())),
	names_(names),
	profile_root_(nullptr, "(root)", v8::UnboundScript::kNoScriptId, 0),
	samples_(),
	stack_depth_(stack_depth),
	rate_(rate),
	flags_(flags) {
	CHECK_GT(rate_, 0u);

	heap_->AddAllocationObserversToAllSpaces(other_spaces_observer_.get(),
	new_space_observer_.get());
	}


	SamplingHeapProfiler::~SamplingHeapProfiler() {
	heap_->RemoveAllocationObserversFromAllSpaces(other_spaces_observer_.get(),
	new_space_observer_.get());

	for (auto sample : samples_) {
	delete sample;
	}
	std::set<Sample*> empty;
	samples_.swap(empty);
	}


	void SamplingHeapProfiler::SampleObject(Address soon_object, size_t size) {
	DisallowHeapAllocation no_allocation;

	HandleScope scope(isolate_);
	HeapObject* heap_object = HeapObject::FromAddress(soon_object);
	Handle<Object> obj(heap_object, isolate_);

	// Mark the new block as FreeSpace to make sure the heap is iterable while we
	// are taking the sample.
	heap()->CreateFillerObjectAt(soon_object, static_cast<int>(size),
	ClearRecordedSlots::kNo);

	Local<v8::Value> loc = v8::Utils::ToLocal(obj);

	AllocationNode* node = AddStack();
	node->allocations_[size]++;
	Sample* sample = new Sample(size, node, loc, this);
	samples_.insert(sample);
	sample->global.SetWeak(sample, OnWeakCallback, WeakCallbackType::kParameter);
	}

	void SamplingHeapProfiler::OnWeakCallback(
	const WeakCallbackInfo<Sample>& data) {
	Sample* sample = data.GetParameter();
	AllocationNode* node = sample->owner;
	DCHECK_GT(node->allocations_[sample->size], 0);
	node->allocations_[sample->size]--;
	if (node->allocations_[sample->size] == 0) {
	node->allocations_.erase(sample->size);
	while (node->allocations_.empty() && node->children_.empty() &&
	node->parent_ && !node->parent_->pinned_) {
	AllocationNode* parent = node->parent_;
	AllocationNode::FunctionId id = AllocationNode::function_id(
	node->script_id_, node->script_position_, node->name_);
	parent->children_.erase(id);
	delete node;
	node = parent;
	}
	}
	sample->profiler->samples_.erase(sample);
	delete sample;
	}

	SamplingHeapProfiler::AllocationNode*
	SamplingHeapProfiler::AllocationNode::FindOrAddChildNode(const char* name,
	int script_id,
	int start_position) {
	FunctionId id = function_id(script_id, start_position, name);
	auto it = children_.find(id);
	if (it != children_.end()) {
	DCHECK_EQ(strcmp(it->second->name_, name), 0);
	return it->second;
	}
	auto child = new AllocationNode(this, name, script_id, start_position);
	children_.insert(std::make_pair(id, child));
	return child;
	}

	SamplingHeapProfiler::AllocationNode* SamplingHeapProfiler::AddStack() {
	AllocationNode* node = &profile_root_;

	std::vector<SharedFunctionInfo*> stack;
	JavaScriptFrameIterator it(isolate_);
	int frames_captured = 0;
	bool found_arguments_marker_frames = false;
	while (!it.done() && frames_captured < stack_depth_) {
	JavaScriptFrame* frame = it.frame();
	// If we are materializing objects during deoptimization, inlined
	// closures may not yet be materialized, and this includes the
	// closure on the stack. Skip over any such frames (they'll be
	// in the top frames of the stack). The allocations made in this
	// sensitive moment belong to the formerly optimized frame anyway.
	if (frame->unchecked_function()->IsJSFunction()) {
	SharedFunctionInfo* shared = frame->function()->shared();
	stack.push_back(shared);
	frames_captured++;
	} else {
	found_arguments_marker_frames = true;
	}
	it.Advance();
	}

	if (frames_captured == 0) {
	const char* name = nullptr;
	switch (isolate_->current_vm_state()) {
	case GC:
	name = "(GC)";
	break;
	case PARSER:
	name = "(PARSER)";
	break;
	case COMPILER:
	name = "(COMPILER)";
	break;
	case BYTECODE_COMPILER:
	name = "(BYTECODE_COMPILER)";
	break;
	case OTHER:
	name = "(V8 API)";
	break;
	case EXTERNAL:
	name = "(EXTERNAL)";
	break;
	case IDLE:
	name = "(IDLE)";
	break;
	case JS:
	name = "(JS)";
	break;
	}
	return node->FindOrAddChildNode(name, v8::UnboundScript::kNoScriptId, 0);
	}

	// We need to process the stack in reverse order as the top of the stack is
	// the first element in the list.
	for (auto it = stack.rbegin(); it != stack.rend(); ++it) {
	SharedFunctionInfo* shared = *it;
	const char* name = this->names()->GetFunctionName(shared->DebugName());
	int script_id = v8::UnboundScript::kNoScriptId;
	if (shared->script()->IsScript()) {
	Script* script = Script::cast(shared->script());
	script_id = script->id();
	}
	node = node->FindOrAddChildNode(name, script_id, shared->start_position());
	}

	if (found_arguments_marker_frames) {
	node =
	node->FindOrAddChildNode("(deopt)", v8::UnboundScript::kNoScriptId, 0);
	}

	return node;
	}

	v8::AllocationProfile::Node* SamplingHeapProfiler::TranslateAllocationNode(
	AllocationProfile* profile, SamplingHeapProfiler::AllocationNode* node,
	const std::map<int, Handle<Script>>& scripts) {
	// By pinning the node we make sure its children won't get disposed if
	// a GC kicks in during the tree retrieval.
	node->pinned_ = true;
	Local<v8::String> script_name =
	ToApiHandle<v8::String>(isolate_->factory()->InternalizeUtf8String(""));
	int line = v8::AllocationProfile::kNoLineNumberInfo;
	int column = v8::AllocationProfile::kNoColumnNumberInfo;
	std::vector<v8::AllocationProfile::Allocation> allocations;
	allocations.reserve(node->allocations_.size());
	if (node->script_id_ != v8::UnboundScript::kNoScriptId &&
	scripts.find(node->script_id_) != scripts.end()) {
	// Cannot use std::map<T>::at because it is not available on android.
	auto non_const_scripts =
	const_cast<std::map<int, Handle<Script>>&>(scripts);
	Handle<Script> script = non_const_scripts[node->script_id_];
	if (!script.is_null()) {
	if (script->name()->IsName()) {
	Name* name = Name::cast(script->name());
	script_name = ToApiHandle<v8::String>(
	isolate_->factory()->InternalizeUtf8String(names_->GetName(name)));
	}
	line = 1 + Script::GetLineNumber(script, node->script_position_);
	column = 1 + Script::GetColumnNumber(script, node->script_position_);
	}
	}
	for (auto alloc : node->allocations_) {
	allocations.push_back(ScaleSample(alloc.first, alloc.second));
	}

	profile->nodes().push_back(v8::AllocationProfile::Node(
	{ToApiHandle<v8::String>(
	isolate_->factory()->InternalizeUtf8String(node->name_)),
	script_name, node->script_id_, node->script_position_, line, column,
	std::vector<v8::AllocationProfile::Node*>(), allocations}));
	v8::AllocationProfile::Node* current = &profile->nodes().back();
	// The children map may have nodes inserted into it during translation
	// because the translation may allocate strings on the JS heap that have
	// the potential to be sampled. That's ok since map iterators are not
	// invalidated upon std::map insertion.
	for (auto it : node->children_) {
	current->children.push_back(
	TranslateAllocationNode(profile, it.second, scripts));
	}
	node->pinned_ = false;
	return current;
	}

	v8::AllocationProfile* SamplingHeapProfiler::GetAllocationProfile() {
	if (flags_ & v8::HeapProfiler::kSamplingForceGC) {
	isolate_->heap()->CollectAllGarbage(
	Heap::kNoGCFlags, GarbageCollectionReason::kSamplingProfiler);
	}
	// To resolve positions to line/column numbers, we will need to look up
	// scripts. Build a map to allow fast mapping from script id to script.
	std::map<int, Handle<Script>> scripts;
	{
	Script::Iterator iterator(isolate_);
	while (Script* script = iterator.Next()) {
	scripts[script->id()] = handle(script);
	}
	}
	auto profile = new v8::internal::AllocationProfile();
	TranslateAllocationNode(profile, &profile_root_, scripts);
	return profile;
	}


	} // namespace internal
	} // namespace v8