Revert of [Tracing] V8 Tracing Controller

src/libplatform/tracing/trace-buffer.cc

-// Copyright 2016 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/libplatform/tracing/trace-buffer.h"
-
-namespace v8 {
-namespace platform {
-namespace tracing {
-
-TraceBufferRingBuffer::TraceBufferRingBuffer(size_t max_chunks,
-                                             TraceWriter* trace_writer)
-    : max_chunks_(max_chunks) {
-  trace_writer_.reset(trace_writer);
-  chunks_.resize(max_chunks);
-}
-
-TraceBufferRingBuffer::~TraceBufferRingBuffer() {}
-
-TraceObject* TraceBufferRingBuffer::AddTraceEvent(uint64_t* handle) {
-  base::LockGuard<base::Mutex> guard(&mutex_);
-  if (is_empty_ || chunks_[chunk_index_]->IsFull()) {
-    chunk_index_ = is_empty_ ? 0 : NextChunkIndex(chunk_index_);
-    is_empty_ = false;
-    auto& chunk = chunks_[chunk_index_];
-    if (chunk) {
-      chunk->Reset(current_chunk_seq_++);
-    } else {
-      chunk.reset(new TraceBufferChunk(current_chunk_seq_++));
-    }
-  }
-  auto& chunk = chunks_[chunk_index_];
-  size_t event_index;
-  TraceObject* trace_object = chunk->AddTraceEvent(&event_index);
-  *handle = MakeHandle(chunk_index_, chunk->seq(), event_index);
-  return trace_object;
-}
-
-TraceObject* TraceBufferRingBuffer::GetEventByHandle(uint64_t handle) {
-  base::LockGuard<base::Mutex> guard(&mutex_);
-  size_t chunk_index, event_index;
-  uint32_t chunk_seq;
-  ExtractHandle(handle, &chunk_index, &chunk_seq, &event_index);
-  if (chunk_index >= chunks_.size()) return NULL;
-  auto& chunk = chunks_[chunk_index];
-  if (!chunk || chunk->seq() != chunk_seq) return NULL;
-  return chunk->GetEventAt(event_index);
-}
-
-bool TraceBufferRingBuffer::Flush() {
-  base::LockGuard<base::Mutex> guard(&mutex_);
-  // This flushes all the traces stored in the buffer.
-  if (!is_empty_) {
-    for (size_t i = NextChunkIndex(chunk_index_);; i = NextChunkIndex(i)) {
-      if (auto& chunk = chunks_[i]) {
-        for (size_t j = 0; j < chunk->size(); ++j) {
-          trace_writer_->AppendTraceEvent(chunk->GetEventAt(j));
-        }
-      }
-      if (i == chunk_index_) break;
-    }
-  }
-  trace_writer_->Flush();
-  // This resets the trace buffer.
-  is_empty_ = true;
-  return true;
-}
-
-uint64_t TraceBufferRingBuffer::MakeHandle(size_t chunk_index,
-                                           uint32_t chunk_seq,
-                                           size_t event_index) const {
-  return static_cast<uint64_t>(chunk_seq) * Capacity() +
-         chunk_index * TraceBufferChunk::kChunkSize + event_index;
-}
-
-void TraceBufferRingBuffer::ExtractHandle(uint64_t handle, size_t* chunk_index,
-                                          uint32_t* chunk_seq,
-                                          size_t* event_index) const {
-  *chunk_seq = static_cast<uint32_t>(handle / Capacity());
-  size_t indices = handle % Capacity();
-  *chunk_index = indices / TraceBufferChunk::kChunkSize;
-  *event_index = indices % TraceBufferChunk::kChunkSize;
-}
-
-size_t TraceBufferRingBuffer::NextChunkIndex(size_t index) const {
-  if (++index >= max_chunks_) index = 0;
-  return index;
-}
-
-TraceBufferChunk::TraceBufferChunk(uint32_t seq) : seq_(seq) {}
-
-void TraceBufferChunk::Reset(uint32_t new_seq) {
-  next_free_ = 0;
-  seq_ = new_seq;
-}
-
-TraceObject* TraceBufferChunk::AddTraceEvent(size_t* event_index) {
-  *event_index = next_free_++;
-  return &chunk_[*event_index];
-}
-
-TraceBuffer* TraceBuffer::CreateTraceBufferRingBuffer(
-    size_t max_chunks, TraceWriter* trace_writer) {
-  return new TraceBufferRingBuffer(max_chunks, trace_writer);
-}
-
-}  // namespace tracing
-}  // namespace platform
-}  // namespace v8