Implement circular queues for the C++ version of CPU profiler.

src/circular-queue.cc

Index: src/circular-queue.cc
diff --git a/src/circular-queue.cc b/src/circular-queue.cc
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+// Copyright 2010 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.
+
+#include "v8.h"
+
+#include "circular-queue-inl.h"
+
+namespace v8 {
+namespace internal {
+
+
+SamplingCircularQueue::SamplingCircularQueue(int record_size_in_bytes,
+                                             int desired_chunk_size_in_bytes,
+                                             int buffer_size_in_chunks)
+    : record_size_(record_size_in_bytes / sizeof(Cell)),
+      chunk_size_in_bytes_(desired_chunk_size_in_bytes / record_size_in_bytes *
+                        record_size_in_bytes),
+      chunk_size_(chunk_size_in_bytes_ / sizeof(Cell)),
+      buffer_size_(chunk_size_ * buffer_size_in_chunks),
+      // The distance ensures that producer and consumer never step on
+      // each other's chunks and helps eviction of produced data from
+      // the CPU cache (having that chunk size is bigger than the cache.)
+      producer_consumer_distance_(2 * chunk_size_),
+      buffer_(NewArray<Cell>(buffer_size_ + 1)) {
+  ASSERT(buffer_size_in_chunks > 2);
+  // Only need to keep the first cell of a chunk clean.
+  for (int i = 0; i < buffer_size_; i += chunk_size_) {
+    buffer_[i] = kClear;
+  }
+  buffer_[buffer_size_] = kEnd;
+}
+
+
+SamplingCircularQueue::~SamplingCircularQueue() {
+  DeleteArray(buffer_);
+}
+
+
+void SamplingCircularQueue::SetUpProducer() {
+  producer_key_ = Thread::CreateThreadLocalKey();
+  Thread::SetThreadLocal(producer_key_, buffer_);
+}
+
+
+void SamplingCircularQueue::TearDownProducer() {
+  Thread::DeleteThreadLocalKey(producer_key_);
+}
+
+
+void SamplingCircularQueue::SetUpConsumer() {
+  consumer_key_ = Thread::CreateThreadLocalKey();
+  ConsumerPosition* cp = new ConsumerPosition;
+  cp->dequeue_chunk_pos = buffer_;
+  cp->dequeue_chunk_poll_pos = buffer_ + producer_consumer_distance_;
+  cp->dequeue_pos = NULL;
+  Thread::SetThreadLocal(consumer_key_, cp);
+}
+
+
+void SamplingCircularQueue::TearDownConsumer() {
+  delete reinterpret_cast<ConsumerPosition*>(
+      Thread::GetThreadLocal(consumer_key_));
+  Thread::DeleteThreadLocalKey(consumer_key_);
+}
+
+
+void* SamplingCircularQueue::StartDequeue() {
+  ConsumerPosition* cp = reinterpret_cast<ConsumerPosition*>(
+      Thread::GetThreadLocal(consumer_key_));
+  if (cp->dequeue_pos != NULL) {
+    return cp->dequeue_pos;
+  } else {
+    if (*cp->dequeue_chunk_poll_pos != kClear) {
+      cp->dequeue_pos = cp->dequeue_chunk_pos;
+      cp->dequeue_end_pos = cp->dequeue_pos + chunk_size_;
+      return cp->dequeue_pos;
+    } else {
+      return NULL;
+    }
+  }
+}
+
+
+void SamplingCircularQueue::FinishDequeue() {
+  ConsumerPosition* cp = reinterpret_cast<ConsumerPosition*>(
+      Thread::GetThreadLocal(consumer_key_));
+  cp->dequeue_pos += record_size_;
+  if (cp->dequeue_pos < cp->dequeue_end_pos) return;
+  // Move to next chunk.
+  cp->dequeue_pos = NULL;
+  *cp->dequeue_chunk_pos = kClear;
+  cp->dequeue_chunk_pos += chunk_size_;
+  WrapPositionIfNeeded(&cp->dequeue_chunk_pos);
+  cp->dequeue_chunk_poll_pos += chunk_size_;
+  WrapPositionIfNeeded(&cp->dequeue_chunk_poll_pos);
+}
+
+
+void SamplingCircularQueue::FlushResidualRecords() {
+  ConsumerPosition* cp = reinterpret_cast<ConsumerPosition*>(
+      Thread::GetThreadLocal(consumer_key_));
+  // Eliminate producer / consumer distance.
+  cp->dequeue_chunk_poll_pos = cp->dequeue_chunk_pos;
+}
+
+
+} }  // namespace v8::internal