// Copyright 2015 The Chromium 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 "base/trace_event/trace_buffer.h"
#include <memory>
#include <utility>
#include <vector>
#include "base/macros.h"
#include "base/trace_event/heap_profiler.h"
#include "base/trace_event/trace_event_impl.h"
namespace base {
namespace trace_event {
namespace {
class TraceBufferRingBuffer : public TraceBuffer {
public:
TraceBufferRingBuffer(size_t max_chunks)
: max_chunks_(max_chunks),
recyclable_chunks_queue_(new size_t[queue_capacity()]),
queue_head_(0),
queue_tail_(max_chunks),
current_iteration_index_(0),
current_chunk_seq_(1) {
chunks_.reserve(max_chunks);
for (size_t i = 0; i < max_chunks; ++i)
recyclable_chunks_queue_[i] = i;
}
std::unique_ptr<TraceBufferChunk> GetChunk(size_t* index) override {
HEAP_PROFILER_SCOPED_IGNORE;
// Because the number of threads is much less than the number of chunks,
// the queue should never be empty.
DCHECK(!QueueIsEmpty());
*index = recyclable_chunks_queue_[queue_head_];
queue_head_ = NextQueueIndex(queue_head_);
current_iteration_index_ = queue_head_;
if (*index >= chunks_.size())
chunks_.resize(*index + 1);
TraceBufferChunk* chunk = chunks_[*index].release();
chunks_[*index] = NULL; // Put NULL in the slot of a in-flight chunk.
if (chunk)
chunk->Reset(current_chunk_seq_++);
else
chunk = new TraceBufferChunk(current_chunk_seq_++);
return std::unique_ptr<TraceBufferChunk>(chunk);
}
void ReturnChunk(size_t index,
std::unique_ptr<TraceBufferChunk> chunk) override {
// When this method is called, the queue should not be full because it
// can contain all chunks including the one to be returned.
DCHECK(!QueueIsFull());
DCHECK(chunk);
DCHECK_LT(index, chunks_.size());
DCHECK(!chunks_[index]);
chunks_[index] = std::move(chunk);
recyclable_chunks_queue_[queue_tail_] = index;
queue_tail_ = NextQueueIndex(queue_tail_);
}
bool IsFull() const override { return false; }
size_t Size() const override {
// This is approximate because not all of the chunks are full.
return chunks_.size() * TraceBufferChunk::kTraceBufferChunkSize;
}
size_t Capacity() const override {
return max_chunks_ * TraceBufferChunk::kTraceBufferChunkSize;
}
TraceEvent* GetEventByHandle(TraceEventHandle handle) override {
if (handle.chunk_index >= chunks_.size())
return NULL;
TraceBufferChunk* chunk = chunks_[handle.chunk_index].get();
if (!chunk || chunk->seq() != handle.chunk_seq)
return NULL;
return chunk->GetEventAt(handle.event_index);
}
const TraceBufferChunk* NextChunk() override {
if (chunks_.empty())
return NULL;
while (current_iteration_index_ != queue_tail_) {
size_t chunk_index = recyclable_chunks_queue_[current_iteration_index_];
current_iteration_index_ = NextQueueIndex(current_iteration_index_);
if (chunk_index >= chunks_.size()) // Skip uninitialized chunks.
continue;
DCHECK(chunks_[chunk_index]);
return chunks_[chunk_index].get();
}
return NULL;
}
void EstimateTraceMemoryOverhead(
TraceEventMemoryOverhead* overhead) override {
overhead->Add("TraceBufferRingBuffer", sizeof(*this));
for (size_t queue_index = queue_head_; queue_index != queue_tail_;
queue_index = NextQueueIndex(queue_index)) {
size_t chunk_index = recyclable_chunks_queue_[queue_index];
if (chunk_index >= chunks_.size()) // Skip uninitialized chunks.
continue;
chunks_[chunk_index]->EstimateTraceMemoryOverhead(overhead);
}
}
private:
bool QueueIsEmpty() const { return queue_head_ == queue_tail_; }
size_t QueueSize() const {
return queue_tail_ > queue_head_
? queue_tail_ - queue_head_
: queue_tail_ + queue_capacity() - queue_head_;
}
bool QueueIsFull() const { return QueueSize() == queue_capacity() - 1; }
size_t queue_capacity() const {
// One extra space to help distinguish full state and empty state.
return max_chunks_ + 1;
}
size_t NextQueueIndex(size_t index) const {
index++;
if (index >= queue_capacity())
index = 0;
return index;
}
size_t max_chunks_;
std::vector<std::unique_ptr<TraceBufferChunk>> chunks_;
std::unique_ptr<size_t[]> recyclable_chunks_queue_;
size_t queue_head_;
size_t queue_tail_;
size_t current_iteration_index_;
uint32_t current_chunk_seq_;
DISALLOW_COPY_AND_ASSIGN(TraceBufferRingBuffer);
};
class TraceBufferVector : public TraceBuffer {
public:
TraceBufferVector(size_t max_chunks)
: in_flight_chunk_count_(0),
current_iteration_index_(0),
max_chunks_(max_chunks) {
chunks_.reserve(max_chunks_);
}
std::unique_ptr<TraceBufferChunk> GetChunk(size_t* index) override {
HEAP_PROFILER_SCOPED_IGNORE;
// This function may be called when adding normal events or indirectly from
// AddMetadataEventsWhileLocked(). We can not DECHECK(!IsFull()) because we
// have to add the metadata events and flush thread-local buffers even if
// the buffer is full.
*index = chunks_.size();
chunks_.push_back(NULL); // Put NULL in the slot of a in-flight chunk.
++in_flight_chunk_count_;
// + 1 because zero chunk_seq is not allowed.
return std::unique_ptr<TraceBufferChunk>(
new TraceBufferChunk(static_cast<uint32_t>(*index) + 1));
}
void ReturnChunk(size_t index,
std::unique_ptr<TraceBufferChunk> chunk) override {
DCHECK_GT(in_flight_chunk_count_, 0u);
DCHECK_LT(index, chunks_.size());
DCHECK(!chunks_[index]);
--in_flight_chunk_count_;
chunks_[index] = chunk.release();
}
bool IsFull() const override { return chunks_.size() >= max_chunks_; }
size_t Size() const override {
// This is approximate because not all of the chunks are full.
return chunks_.size() * TraceBufferChunk::kTraceBufferChunkSize;
}
size_t Capacity() const override {
return max_chunks_ * TraceBufferChunk::kTraceBufferChunkSize;
}
TraceEvent* GetEventByHandle(TraceEventHandle handle) override {
if (handle.chunk_index >= chunks_.size())
return NULL;
TraceBufferChunk* chunk = chunks_[handle.chunk_index];
if (!chunk || chunk->seq() != handle.chunk_seq)
return NULL;
return chunk->GetEventAt(handle.event_index);
}
const TraceBufferChunk* NextChunk() override {
while (current_iteration_index_ < chunks_.size()) {
// Skip in-flight chunks.
const TraceBufferChunk* chunk = chunks_[current_iteration_index_++];
if (chunk)
return chunk;
}
return NULL;
}
void EstimateTraceMemoryOverhead(
TraceEventMemoryOverhead* overhead) override {
const size_t chunks_ptr_vector_allocated_size =
sizeof(*this) + max_chunks_ * sizeof(decltype(chunks_)::value_type);
const size_t chunks_ptr_vector_resident_size =
sizeof(*this) + chunks_.size() * sizeof(decltype(chunks_)::value_type);
overhead->Add("TraceBufferVector", chunks_ptr_vector_allocated_size,
chunks_ptr_vector_resident_size);
for (size_t i = 0; i < chunks_.size(); ++i) {
TraceBufferChunk* chunk = chunks_[i];
// Skip the in-flight (nullptr) chunks. They will be accounted by the
// per-thread-local dumpers, see ThreadLocalEventBuffer::OnMemoryDump.
if (chunk)
chunk->EstimateTraceMemoryOverhead(overhead);
}
}
private:
size_t in_flight_chunk_count_;
size_t current_iteration_index_;
size_t max_chunks_;
ScopedVector<TraceBufferChunk> chunks_;
DISALLOW_COPY_AND_ASSIGN(TraceBufferVector);
};
} // namespace
TraceBufferChunk::TraceBufferChunk(uint32_t seq) : next_free_(0), seq_(seq) {}
TraceBufferChunk::~TraceBufferChunk() {}
void TraceBufferChunk::Reset(uint32_t new_seq) {
for (size_t i = 0; i < next_free_; ++i)
chunk_[i].Reset();
next_free_ = 0;
seq_ = new_seq;
cached_overhead_estimate_.reset();
}
TraceEvent* TraceBufferChunk::AddTraceEvent(size_t* event_index) {
DCHECK(!IsFull());
*event_index = next_free_++;
return &chunk_[*event_index];
}
void TraceBufferChunk::EstimateTraceMemoryOverhead(
TraceEventMemoryOverhead* overhead) {
if (!cached_overhead_estimate_) {
cached_overhead_estimate_.reset(new TraceEventMemoryOverhead);
// When estimating the size of TraceBufferChunk, exclude the array of trace
// events, as they are computed individually below.
cached_overhead_estimate_->Add("TraceBufferChunk",
sizeof(*this) - sizeof(chunk_));
}
const size_t num_cached_estimated_events =
cached_overhead_estimate_->GetCount("TraceEvent");
DCHECK_LE(num_cached_estimated_events, size());
if (IsFull() && num_cached_estimated_events == size()) {
overhead->Update(*cached_overhead_estimate_);
return;
}
for (size_t i = num_cached_estimated_events; i < size(); ++i)
chunk_[i].EstimateTraceMemoryOverhead(cached_overhead_estimate_.get());
if (IsFull()) {
cached_overhead_estimate_->AddSelf();
} else {
// The unused TraceEvents in |chunks_| are not cached. They will keep
// changing as new TraceEvents are added to this chunk, so they are
// computed on the fly.
const size_t num_unused_trace_events = capacity() - size();
overhead->Add("TraceEvent (unused)",
num_unused_trace_events * sizeof(TraceEvent));
}
overhead->Update(*cached_overhead_estimate_);
}
TraceResultBuffer::OutputCallback
TraceResultBuffer::SimpleOutput::GetCallback() {
return Bind(&SimpleOutput::Append, Unretained(this));
}
void TraceResultBuffer::SimpleOutput::Append(
const std::string& json_trace_output) {
json_output += json_trace_output;
}
TraceResultBuffer::TraceResultBuffer() : append_comma_(false) {}
TraceResultBuffer::~TraceResultBuffer() {}
void TraceResultBuffer::SetOutputCallback(
const OutputCallback& json_chunk_callback) {
output_callback_ = json_chunk_callback;
}
void TraceResultBuffer::Start() {
append_comma_ = false;
output_callback_.Run("[");
}
void TraceResultBuffer::AddFragment(const std::string& trace_fragment) {
if (append_comma_)
output_callback_.Run(",");
append_comma_ = true;
output_callback_.Run(trace_fragment);
}
void TraceResultBuffer::Finish() {
output_callback_.Run("]");
}
TraceBuffer* TraceBuffer::CreateTraceBufferRingBuffer(size_t max_chunks) {
return new TraceBufferRingBuffer(max_chunks);
}
TraceBuffer* TraceBuffer::CreateTraceBufferVectorOfSize(size_t max_chunks) {
return new TraceBufferVector(max_chunks);
}
} // namespace trace_event
} // namespace base