forked from etc/pineapple-src
170 lines
4.9 KiB
C++
Executable file
170 lines
4.9 KiB
C++
Executable file
// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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// (C) Copyright 2013 Vicente J. Botet Escriba
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#ifndef BOOST_THREAD_LATCH_HPP
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#define BOOST_THREAD_LATCH_HPP
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#include <boost/thread/detail/config.hpp>
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#include <boost/thread/detail/delete.hpp>
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#include <boost/thread/detail/counter.hpp>
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#include <boost/thread/mutex.hpp>
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#include <boost/thread/lock_types.hpp>
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#include <boost/thread/condition_variable.hpp>
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#include <boost/chrono/duration.hpp>
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#include <boost/chrono/time_point.hpp>
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#include <boost/assert.hpp>
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#include <boost/config/abi_prefix.hpp>
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namespace boost
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{
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class latch
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{
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/// @Requires: count_ must be greater than 0
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/// Effect: Decrement the count. Unlocks the lock and notify anyone waiting if we reached zero.
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/// Returns: true if count_ reached the value 0.
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/// @ThreadSafe ensured by the @c lk parameter
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bool count_down(unique_lock<mutex> &)
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/// pre_condition (count_ > 0)
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{
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BOOST_ASSERT(count_ > 0);
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if (--count_ == 0)
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{
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++generation_;
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//lk.unlock();
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cond_.notify_all();
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return true;
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}
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return false;
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}
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/// Effect: Decrement the count is > 0. Unlocks the lock notify anyone waiting if we reached zero.
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/// Returns: true if count_ is 0.
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/// @ThreadSafe ensured by the @c lk parameter
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bool try_count_down(unique_lock<mutex> &lk)
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{
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if (count_ > 0)
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{
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return count_down(lk);
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}
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return true;
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}
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public:
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BOOST_THREAD_NO_COPYABLE( latch)
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/// Constructs a latch with a given count.
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latch(std::size_t count) :
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count_(count), generation_(0)
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{
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}
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/// Destructor
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/// Precondition: No threads are waiting or invoking count_down on @c *this.
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~latch()
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{
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}
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/// Blocks until the latch has counted down to zero.
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void wait()
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{
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boost::unique_lock<boost::mutex> lk(mutex_);
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if (count_ == 0) return;
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std::size_t generation(generation_);
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cond_.wait(lk, detail::not_equal(generation, generation_));
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}
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/// @return true if the internal counter is already 0, false otherwise
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bool try_wait()
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{
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boost::unique_lock<boost::mutex> lk(mutex_);
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return (count_ == 0);
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}
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/// try to wait for a specified amount of time is elapsed.
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/// @return whether there is a timeout or not.
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template <class Rep, class Period>
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cv_status wait_for(const chrono::duration<Rep, Period>& rel_time)
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{
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boost::unique_lock<boost::mutex> lk(mutex_);
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if (count_ == 0) return cv_status::no_timeout;
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std::size_t generation(generation_);
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return cond_.wait_for(lk, rel_time, detail::not_equal(generation, generation_))
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? cv_status::no_timeout
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: cv_status::timeout;
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}
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/// try to wait until the specified time_point is reached
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/// @return whether there were a timeout or not.
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template <class Clock, class Duration>
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cv_status wait_until(const chrono::time_point<Clock, Duration>& abs_time)
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{
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boost::unique_lock<boost::mutex> lk(mutex_);
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if (count_ == 0) return cv_status::no_timeout;
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std::size_t generation(generation_);
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return cond_.wait_until(lk, abs_time, detail::not_equal(generation, generation_))
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? cv_status::no_timeout
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: cv_status::timeout;
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}
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/// Decrement the count and notify anyone waiting if we reach zero.
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/// @Requires count must be greater than 0
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void count_down()
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{
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boost::unique_lock<boost::mutex> lk(mutex_);
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count_down(lk);
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}
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/// Effect: Decrement the count if it is > 0 and notify anyone waiting if we reached zero.
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/// Returns: true if count_ was 0 or reached 0.
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bool try_count_down()
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{
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boost::unique_lock<boost::mutex> lk(mutex_);
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return try_count_down(lk);
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}
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void signal()
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{
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count_down();
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}
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/// Decrement the count and notify anyone waiting if we reach zero.
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/// Blocks until the latch has counted down to zero.
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/// @Requires count must be greater than 0
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void count_down_and_wait()
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{
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boost::unique_lock<boost::mutex> lk(mutex_);
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std::size_t generation(generation_);
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if (count_down(lk))
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{
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return;
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}
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cond_.wait(lk, detail::not_equal(generation, generation_));
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}
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void sync()
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{
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count_down_and_wait();
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}
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/// Reset the counter
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/// #Requires This method may only be invoked when there are no other threads currently inside the count_down_and_wait() method.
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void reset(std::size_t count)
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{
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boost::lock_guard<boost::mutex> lk(mutex_);
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//BOOST_ASSERT(count_ == 0);
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count_ = count;
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}
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private:
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mutex mutex_;
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condition_variable cond_;
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std::size_t count_;
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std::size_t generation_;
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};
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} // namespace boost
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#include <boost/config/abi_suffix.hpp>
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#endif
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