| // Copyright (c) 2011, François Saint-Jacques |
| // 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 the disruptor-- 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 FRANÇOIS SAINT-JACQUES 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. |
| |
| #ifndef CACHE_LINE_SIZE_IN_BYTES // NOLINT |
| #define CACHE_LINE_SIZE_IN_BYTES 64 // NOLINT |
| #endif // NOLINT |
| #define ATOMIC_SEQUENCE_PADDING_LENGTH \ |
| (CACHE_LINE_SIZE_IN_BYTES - sizeof(boost::atomic<int64_t>))/8 |
| #define SEQUENCE_PADDING_LENGTH \ |
| (CACHE_LINE_SIZE_IN_BYTES - sizeof(int64_t))/8 |
| |
| #ifndef DISRUPTOR_SEQUENCE_H_ // NOLINT |
| #define DISRUPTOR_SEQUENCE_H_ // NOLINT |
| |
| #include <boost/atomic.hpp> |
| #include <boost/memory_order.hpp> |
| #include <boost/noncopyable.hpp> |
| #include <vector> |
| #include <limits> |
| using namespace boost; |
| namespace rocketmq { |
| |
| const int64_t kInitialCursorValue = -1L; |
| |
| // Sequence counter. |
| class Sequence:public noncopyable { |
| public: |
| // Construct a sequence counter that can be tracked across threads. |
| // |
| // @param initial_value for the counter. |
| Sequence(int64_t initial_value = kInitialCursorValue) : |
| value_(initial_value) {} |
| |
| // Get the current value of the {@link Sequence}. |
| // |
| // @return the current value. |
| int64_t sequence() const { return value_.load(boost::memory_order_acquire); } |
| |
| // Set the current value of the {@link Sequence}. |
| // |
| // @param the value to which the {@link Sequence} will be set. |
| void set_sequence(int64_t value) { value_.store(value, boost::memory_order_release); } |
| |
| // Increment and return the value of the {@link Sequence}. |
| // |
| // @param increment the {@link Sequence}. |
| // @return the new value incremented. |
| int64_t IncrementAndGet(const int64_t& increment) { |
| return value_.fetch_add(increment, boost::memory_order_release) + increment; |
| } |
| |
| private: |
| // members |
| boost::atomic<int64_t> value_; |
| |
| }; |
| |
| // Cache line padded sequence counter. |
| // |
| // Can be used across threads without worrying about false sharing if a |
| // located adjacent to another counter in memory. |
| class PaddedSequence : public Sequence { |
| public: |
| PaddedSequence(int64_t initial_value = kInitialCursorValue) : |
| Sequence(initial_value) {} |
| |
| //private: |
| // padding |
| //int64_t padding_[ATOMIC_SEQUENCE_PADDING_LENGTH]; |
| |
| }; |
| |
| // Non-atomic sequence counter. |
| // |
| // This counter is not thread safe. |
| class MutableLong { |
| public: |
| MutableLong(int64_t initial_value = kInitialCursorValue) : |
| sequence_(initial_value) {} |
| |
| int64_t sequence() const { return sequence_; } |
| |
| void set_sequence(const int64_t& sequence) { sequence_ = sequence; }; |
| |
| int64_t IncrementAndGet(const int64_t& delta) { sequence_ += delta; return sequence_; } |
| |
| private: |
| volatile int64_t sequence_; |
| }; |
| |
| // Cache line padded non-atomic sequence counter. |
| // |
| // This counter is not thread safe. |
| class PaddedLong : public MutableLong { |
| public: |
| PaddedLong(int64_t initial_value = kInitialCursorValue) : |
| MutableLong(initial_value) {} |
| //private: |
| //int64_t padding_[SEQUENCE_PADDING_LENGTH]; |
| }; |
| |
| int64_t GetMinimumSequence( |
| const std::vector<Sequence*>& sequences) { |
| int64_t minimum = std::numeric_limits<int64_t>::max(); |
| |
| std::vector<Sequence*>::const_iterator it= sequences.begin(); |
| for (;it!=sequences.end();it++) { |
| int64_t sequence = (*it)->sequence(); |
| minimum = minimum < sequence ? minimum : sequence; |
| } |
| |
| return minimum; |
| }; |
| |
| }; // namespace rocketmq |
| |
| #endif // DISRUPTOR_SEQUENCE_H_ NOLINT |