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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);
// Clean up the whole buffer to avoid encountering a random kEnd
// while enqueuing.
for (int i = 0; i < buffer_size_; ++i) {
buffer_[i] = kClear;
}
buffer_[buffer_size_] = kEnd;
// Layout producer and consumer position pointers each on their own
// cache lines to avoid cache lines thrashing due to simultaneous
// updates of positions by different processor cores.
const int positions_size =
RoundUp(1, kProcessorCacheLineSize) +
RoundUp(static_cast<int>(sizeof(ProducerPosition)),
kProcessorCacheLineSize) +
RoundUp(static_cast<int>(sizeof(ConsumerPosition)),
kProcessorCacheLineSize);
positions_ = NewArray<byte>(positions_size);
producer_pos_ = reinterpret_cast<ProducerPosition*>(
RoundUp(positions_, kProcessorCacheLineSize));
producer_pos_->enqueue_pos = buffer_;
consumer_pos_ = reinterpret_cast<ConsumerPosition*>(
reinterpret_cast<byte*>(producer_pos_) + kProcessorCacheLineSize);
ASSERT(reinterpret_cast<byte*>(consumer_pos_ + 1) <=
positions_ + positions_size);
consumer_pos_->dequeue_chunk_pos = buffer_;
consumer_pos_->dequeue_chunk_poll_pos = buffer_ + producer_consumer_distance_;
consumer_pos_->dequeue_pos = NULL;
}
SamplingCircularQueue::~SamplingCircularQueue() {
DeleteArray(positions_);
DeleteArray(buffer_);
}
void* SamplingCircularQueue::StartDequeue() {
if (consumer_pos_->dequeue_pos != NULL) {
return consumer_pos_->dequeue_pos;
} else {
if (*consumer_pos_->dequeue_chunk_poll_pos != kClear) {
consumer_pos_->dequeue_pos = consumer_pos_->dequeue_chunk_pos;
consumer_pos_->dequeue_end_pos = consumer_pos_->dequeue_pos + chunk_size_;
return consumer_pos_->dequeue_pos;
} else {
return NULL;
}
}
}
void SamplingCircularQueue::FinishDequeue() {
consumer_pos_->dequeue_pos += record_size_;
if (consumer_pos_->dequeue_pos < consumer_pos_->dequeue_end_pos) return;
// Move to next chunk.
consumer_pos_->dequeue_pos = NULL;
*consumer_pos_->dequeue_chunk_pos = kClear;
consumer_pos_->dequeue_chunk_pos += chunk_size_;
WrapPositionIfNeeded(&consumer_pos_->dequeue_chunk_pos);
consumer_pos_->dequeue_chunk_poll_pos += chunk_size_;
WrapPositionIfNeeded(&consumer_pos_->dequeue_chunk_poll_pos);
}
void SamplingCircularQueue::FlushResidualRecords() {
// Eliminate producer / consumer distance.
consumer_pos_->dequeue_chunk_poll_pos = consumer_pos_->dequeue_chunk_pos;
}
} } // namespace v8::internal
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