17a0655431
R=yangguo@chromium.org BUG= Review URL: https://codereview.chromium.org/214903002 git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20314 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
92 lines
3.5 KiB
C++
92 lines
3.5 KiB
C++
// Copyright 2010 the V8 project authors. All rights reserved.
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following
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// disclaimer in the documentation and/or other materials provided
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// with the distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived
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// from this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#ifndef V8_CIRCULAR_QUEUE_H_
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#define V8_CIRCULAR_QUEUE_H_
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#include "atomicops.h"
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#include "v8globals.h"
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namespace v8 {
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namespace internal {
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// Lock-free cache-friendly sampling circular queue for large
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// records. Intended for fast transfer of large records between a
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// single producer and a single consumer. If the queue is full,
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// StartEnqueue will return NULL. The queue is designed with
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// a goal in mind to evade cache lines thrashing by preventing
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// simultaneous reads and writes to adjanced memory locations.
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template<typename T, unsigned Length>
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class SamplingCircularQueue {
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public:
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// Executed on the application thread.
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SamplingCircularQueue();
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~SamplingCircularQueue();
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// StartEnqueue returns a pointer to a memory location for storing the next
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// record or NULL if all entries are full at the moment.
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T* StartEnqueue();
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// Notifies the queue that the producer has complete writing data into the
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// memory returned by StartEnqueue and it can be passed to the consumer.
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void FinishEnqueue();
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// Executed on the consumer (analyzer) thread.
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// Retrieves, but does not remove, the head of this queue, returning NULL
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// if this queue is empty. After the record had been read by a consumer,
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// Remove must be called.
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T* Peek();
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void Remove();
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private:
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// Reserved values for the entry marker.
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enum {
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kEmpty, // Marks clean (processed) entries.
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kFull // Marks entries already filled by the producer but not yet
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// completely processed by the consumer.
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};
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struct V8_ALIGNED(PROCESSOR_CACHE_LINE_SIZE) Entry {
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Entry() : marker(kEmpty) {}
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T record;
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Atomic32 marker;
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};
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Entry* Next(Entry* entry);
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Entry buffer_[Length];
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V8_ALIGNED(PROCESSOR_CACHE_LINE_SIZE) Entry* enqueue_pos_;
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V8_ALIGNED(PROCESSOR_CACHE_LINE_SIZE) Entry* dequeue_pos_;
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DISALLOW_COPY_AND_ASSIGN(SamplingCircularQueue);
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};
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} } // namespace v8::internal
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#endif // V8_CIRCULAR_QUEUE_H_
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