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authorMark Benvenuto <mark.benvenuto@mongodb.com>2016-03-31 15:09:29 -0400
committerMark Benvenuto <mark.benvenuto@mongodb.com>2016-03-31 15:09:29 -0400
commit869912de45bfec53f8fd15c4f716b49ac2ca7aa4 (patch)
tree97934f62054ebb1f1c78812196f7c7bded1fc1b3 /src/third_party/boost-1.60.0/boost/thread/latch.hpp
parent319e895cc28b4aade6fa843583e0fd2ea96cd7a0 (diff)
downloadmongo-869912de45bfec53f8fd15c4f716b49ac2ca7aa4.tar.gz
SERVER-17294 Boost 1.60
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+// Distributed under the Boost Software License, Version 1.0. (See
+// accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+// (C) Copyright 2013 Vicente J. Botet Escriba
+
+#ifndef BOOST_THREAD_LATCH_HPP
+#define BOOST_THREAD_LATCH_HPP
+
+#include <boost/thread/detail/config.hpp>
+#include <boost/thread/detail/delete.hpp>
+#include <boost/thread/detail/counter.hpp>
+
+#include <boost/thread/mutex.hpp>
+#include <boost/thread/lock_types.hpp>
+#include <boost/thread/condition_variable.hpp>
+#include <boost/chrono/duration.hpp>
+#include <boost/chrono/time_point.hpp>
+#include <boost/assert.hpp>
+
+#include <boost/config/abi_prefix.hpp>
+
+namespace boost
+{
+ class latch
+ {
+ /// @Requires: count_ must be greater than 0
+ /// Effect: Decrement the count. Unlocks the lock and notify anyone waiting if we reached zero.
+ /// Returns: true if count_ reached the value 0.
+ /// @ThreadSafe ensured by the @c lk parameter
+ bool count_down(unique_lock<mutex> &)
+ /// pre_condition (count_ > 0)
+ {
+ BOOST_ASSERT(count_ > 0);
+ if (--count_ == 0)
+ {
+ ++generation_;
+ //lk.unlock();
+ cond_.notify_all();
+ return true;
+ }
+ return false;
+ }
+ /// Effect: Decrement the count is > 0. Unlocks the lock notify anyone waiting if we reached zero.
+ /// Returns: true if count_ is 0.
+ /// @ThreadSafe ensured by the @c lk parameter
+ bool try_count_down(unique_lock<mutex> &lk)
+ {
+ if (count_ > 0)
+ {
+ return count_down(lk);
+ }
+ return true;
+ }
+ public:
+ BOOST_THREAD_NO_COPYABLE( latch)
+
+ /// Constructs a latch with a given count.
+ latch(std::size_t count) :
+ count_(count), generation_(0)
+ {
+ }
+
+ /// Destructor
+ /// Precondition: No threads are waiting or invoking count_down on @c *this.
+
+ ~latch()
+ {
+
+ }
+
+ /// Blocks until the latch has counted down to zero.
+ void wait()
+ {
+ boost::unique_lock<boost::mutex> lk(mutex_);
+ if (count_ == 0) return;
+ std::size_t generation(generation_);
+ cond_.wait(lk, detail::not_equal(generation, generation_));
+ }
+
+ /// @return true if the internal counter is already 0, false otherwise
+ bool try_wait()
+ {
+ boost::unique_lock<boost::mutex> lk(mutex_);
+ return (count_ == 0);
+ }
+
+ /// try to wait for a specified amount of time is elapsed.
+ /// @return whether there is a timeout or not.
+ template <class Rep, class Period>
+ cv_status wait_for(const chrono::duration<Rep, Period>& rel_time)
+ {
+ boost::unique_lock<boost::mutex> lk(mutex_);
+ if (count_ == 0) return cv_status::no_timeout;
+ std::size_t generation(generation_);
+ return cond_.wait_for(lk, rel_time, detail::not_equal(generation, generation_))
+ ? cv_status::no_timeout
+ : cv_status::timeout;
+ }
+
+ /// try to wait until the specified time_point is reached
+ /// @return whether there were a timeout or not.
+ template <class Clock, class Duration>
+ cv_status wait_until(const chrono::time_point<Clock, Duration>& abs_time)
+ {
+ boost::unique_lock<boost::mutex> lk(mutex_);
+ if (count_ == 0) return cv_status::no_timeout;
+ std::size_t generation(generation_);
+ return cond_.wait_until(lk, abs_time, detail::not_equal(generation, generation_))
+ ? cv_status::no_timeout
+ : cv_status::timeout;
+ }
+
+ /// Decrement the count and notify anyone waiting if we reach zero.
+ /// @Requires count must be greater than 0
+ void count_down()
+ {
+ boost::unique_lock<boost::mutex> lk(mutex_);
+ count_down(lk);
+ }
+ /// Effect: Decrement the count if it is > 0 and notify anyone waiting if we reached zero.
+ /// Returns: true if count_ was 0 or reached 0.
+ bool try_count_down()
+ {
+ boost::unique_lock<boost::mutex> lk(mutex_);
+ return try_count_down(lk);
+ }
+ void signal()
+ {
+ count_down();
+ }
+
+ /// Decrement the count and notify anyone waiting if we reach zero.
+ /// Blocks until the latch has counted down to zero.
+ /// @Requires count must be greater than 0
+ void count_down_and_wait()
+ {
+ boost::unique_lock<boost::mutex> lk(mutex_);
+ std::size_t generation(generation_);
+ if (count_down(lk))
+ {
+ return;
+ }
+ cond_.wait(lk, detail::not_equal(generation, generation_));
+ }
+ void sync()
+ {
+ count_down_and_wait();
+ }
+
+ /// Reset the counter
+ /// #Requires This method may only be invoked when there are no other threads currently inside the count_down_and_wait() method.
+ void reset(std::size_t count)
+ {
+ boost::lock_guard<boost::mutex> lk(mutex_);
+ //BOOST_ASSERT(count_ == 0);
+ count_ = count;
+ }
+
+ private:
+ mutex mutex_;
+ condition_variable cond_;
+ std::size_t count_;
+ std::size_t generation_;
+ };
+
+} // namespace boost
+
+#include <boost/config/abi_suffix.hpp>
+
+#endif