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ConcurrentBoundedQueue: move if nothrow assign possible. copy otherwise

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This commit is contained in:
Pavel Kartavyy 2016-08-23 17:01:45 +03:00
parent 457109ac71
commit 6647ba628f
1 changed files with 31 additions and 8 deletions
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39
dbms/include/DB/Common/ConcurrentBoundedQueue.h
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@ -8,6 +8,35 @@
#include <DB/Core/Types.h>
namespace detail
{
template <class T, bool is_nothrow_move_assignable = std::is_nothrow_move_assignable<T>::value>
struct MoveOrCopyIfThrow;
template <class T>
struct MoveOrCopyIfThrow<T, true>
{
void operator()(T && src, T & dst) const
{
dst = std::forward<T>(src);
}
};
template <class T>
struct MoveOrCopyIfThrow<T, false>
{
void operator()(T && src, T & dst) const
{
dst = src;
}
};
template <class T>
void moveOrCopyIfThrow(T && src, T & dst)
{
MoveOrCopyIfThrow<T>()(std::forward<T>(src), dst);
}
};
/** Очень простая thread-safe очередь ограниченной длины.
* Если пытаться вынуть элемент из пустой очереди, то поток блокируется, пока очередь не станет непустой.
@ -53,10 +82,7 @@ public:
fill_count.wait();
{
Poco::ScopedLock<Poco::FastMutex> lock(mutex);
if (std::is_nothrow_move_assignable<T>::value)
x = std::move(queue.front());
else
x = queue.front();
detail::moveOrCopyIfThrow(std::move(queue.front()), x);
queue.pop();
}
empty_count.set();
@ -97,10 +123,7 @@ public:
{
{
Poco::ScopedLock<Poco::FastMutex> lock(mutex);
if (std::is_nothrow_move_assignable<T>::value)
x = std::move(queue.front());
else
x = queue.front();
detail::moveOrCopyIfThrow(std::move(queue.front()), x);
queue.pop();
}
empty_count.set();