| // 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 |
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| // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| #ifndef V8_CIRCULAR_QUEUE_H_ |
| #define V8_CIRCULAR_QUEUE_H_ |
| |
| #include "v8globals.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| |
| // Lock-free cache-friendly sampling circular queue for large |
| // records. Intended for fast transfer of large records between a |
| // single producer and a single consumer. If the queue is full, |
| // StartEnqueue will return NULL. The queue is designed with |
| // a goal in mind to evade cache lines thrashing by preventing |
| // simultaneous reads and writes to adjanced memory locations. |
| template<typename T, unsigned Length> |
| class SamplingCircularQueue { |
| public: |
| // Executed on the application thread. |
| SamplingCircularQueue(); |
| ~SamplingCircularQueue(); |
| |
| // StartEnqueue returns a pointer to a memory location for storing the next |
| // record or NULL if all entries are full at the moment. |
| T* StartEnqueue(); |
| // Notifies the queue that the producer has complete writing data into the |
| // memory returned by StartEnqueue and it can be passed to the consumer. |
| void FinishEnqueue(); |
| |
| // Executed on the consumer (analyzer) thread. |
| // Retrieves, but does not remove, the head of this queue, returning NULL |
| // if this queue is empty. After the record had been read by a consumer, |
| // Remove must be called. |
| T* Peek(); |
| void Remove(); |
| |
| private: |
| // Reserved values for the entry marker. |
| enum { |
| kEmpty, // Marks clean (processed) entries. |
| kFull // Marks entries already filled by the producer but not yet |
| // completely processed by the consumer. |
| }; |
| |
| struct V8_ALIGNED(PROCESSOR_CACHE_LINE_SIZE) Entry { |
| Entry() : marker(kEmpty) {} |
| T record; |
| Atomic32 marker; |
| }; |
| |
| Entry* Next(Entry* entry); |
| |
| Entry buffer_[Length]; |
| V8_ALIGNED(PROCESSOR_CACHE_LINE_SIZE) Entry* enqueue_pos_; |
| V8_ALIGNED(PROCESSOR_CACHE_LINE_SIZE) Entry* dequeue_pos_; |
| |
| DISALLOW_COPY_AND_ASSIGN(SamplingCircularQueue); |
| }; |
| |
| |
| } } // namespace v8::internal |
| |
| #endif // V8_CIRCULAR_QUEUE_H_ |