lnav/src/base/future_util.hh

71 lines
2.4 KiB
C++

/**
* Copyright (c) 2020, Timothy Stack
*
* 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 Timothy Stack 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 REGENTS 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 THE REGENTS OR CONTRIBUTORS 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 lnav_future_util_hh
#define lnav_future_util_hh
#include <deque>
#include <future>
template<class T>
std::future<std::decay_t<T>> make_ready_future( T&& t ) {
std::promise<std::decay_t<T>> pr;
auto r = pr.get_future();
pr.set_value(std::forward<T>(t));
return r;
}
template<typename T>
class future_queue {
public:
explicit future_queue(std::function<void(const T&)> processor)
: fq_processor(processor) {};
~future_queue() {
this->pop_to();
}
void push_back(std::future<T>&& f) {
this->fq_deque.emplace_back(std::move(f));
this->pop_to(8);
}
void pop_to(size_t size = 0) {
while (this->fq_deque.size() > size) {
this->fq_processor(this->fq_deque.front().get());
this->fq_deque.pop_front();
}
}
std::function<void(const T&)> fq_processor;
std::deque<std::future<T>> fq_deque;
};
#endif