78 lines
2.5 KiB
C++
78 lines
2.5 KiB
C++
// Copyright (c) 2015 Amanieu d'Antras
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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#ifndef ASYNCXX_H_
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# error "Do not include this header directly, include <async++.h> instead."
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#endif
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namespace async {
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namespace detail {
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// Queue which holds tasks in FIFO order. Note that this queue is not
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// thread-safe and must be protected by a lock.
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class fifo_queue {
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detail::aligned_array<void*, LIBASYNC_CACHELINE_SIZE> items;
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std::size_t head, tail;
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public:
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fifo_queue()
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: items(32), head(0), tail(0) {}
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~fifo_queue()
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{
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// Free any unexecuted tasks
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for (std::size_t i = head; i != tail; i = (i + 1) & (items.size() - 1))
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task_run_handle::from_void_ptr(items[i]);
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}
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// Push a task to the end of the queue
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void push(task_run_handle t)
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{
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// Resize queue if it is full
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if (head == ((tail + 1) & (items.size() - 1))) {
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detail::aligned_array<void*, LIBASYNC_CACHELINE_SIZE> new_items(items.size() * 2);
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for (std::size_t i = 0; i != items.size(); i++)
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new_items[i] = items[(i + head) & (items.size() - 1)];
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head = 0;
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tail = items.size() - 1;
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items = std::move(new_items);
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}
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// Push the item
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items[tail] = t.to_void_ptr();
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tail = (tail + 1) & (items.size() - 1);
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}
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// Pop a task from the front of the queue
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task_run_handle pop()
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{
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// See if an item is available
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if (head == tail)
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return task_run_handle();
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else {
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void* x = items[head];
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head = (head + 1) & (items.size() - 1);
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return task_run_handle::from_void_ptr(x);
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}
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}
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};
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} // namespace detail
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} // namespace async
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