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// SPDX-FileCopyrightText: 2012 PPSSPP Project
// SPDX-FileCopyrightText: 2014 Dolphin Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
#pragma once
#include <array>
#include <deque>
namespace Common {
template <class T, unsigned int N>
struct ThreadQueueList {
// TODO(yuriks): If performance proves to be a problem, the std::deques can be replaced with
// (dynamically resizable) circular buffers to remove their overhead when
// inserting and popping.
using Priority = unsigned int;
// Number of priority levels. (Valid levels are [0..NUM_QUEUES).)
static constexpr Priority NUM_QUEUES = N;
ThreadQueueList() {
first = nullptr;
}
// Only for debugging, returns priority level.
[[nodiscard]] Priority contains(const T& uid) const {
for (Priority i = 0; i < NUM_QUEUES; ++i) {
const Queue& cur = queues[i];
if (std::find(cur.data.cbegin(), cur.data.cend(), uid) != cur.data.cend()) {
return i;
}
}
return -1;
}
[[nodiscard]] T get_first() const {
const Queue* cur = first;
while (cur != nullptr) {
if (!cur->data.empty()) {
return cur->data.front();
}
cur = cur->next_nonempty;
}
return T();
}
template <typename UnaryPredicate>
[[nodiscard]] T get_first_filter(UnaryPredicate filter) const {
const Queue* cur = first;
while (cur != nullptr) {
if (!cur->data.empty()) {
for (const auto& item : cur->data) {
if (filter(item))
return item;
}
}
cur = cur->next_nonempty;
}
return T();
}
T pop_first() {
Queue* cur = first;
while (cur != nullptr) {
if (!cur->data.empty()) {
auto tmp = std::move(cur->data.front());
cur->data.pop_front();
return tmp;
}
cur = cur->next_nonempty;
}
return T();
}
T pop_first_better(Priority priority) {
Queue* cur = first;
Queue* stop = &queues[priority];
while (cur < stop) {
if (!cur->data.empty()) {
auto tmp = std::move(cur->data.front());
cur->data.pop_front();
return tmp;
}
cur = cur->next_nonempty;
}
return T();
}
void push_front(Priority priority, const T& thread_id) {
Queue* cur = &queues[priority];
cur->data.push_front(thread_id);
}
void push_back(Priority priority, const T& thread_id) {
Queue* cur = &queues[priority];
cur->data.push_back(thread_id);
}
void move(const T& thread_id, Priority old_priority, Priority new_priority) {
remove(old_priority, thread_id);
prepare(new_priority);
push_back(new_priority, thread_id);
}
void remove(Priority priority, const T& thread_id) {
Queue* const cur = &queues[priority];
const auto iter = std::remove(cur->data.begin(), cur->data.end(), thread_id);
cur->data.erase(iter, cur->data.end());
}
void rotate(Priority priority) {
Queue* cur = &queues[priority];
if (cur->data.size() > 1) {
cur->data.push_back(std::move(cur->data.front()));
cur->data.pop_front();
}
}
void clear() {
queues.fill(Queue());
first = nullptr;
}
[[nodiscard]] bool empty(Priority priority) const {
const Queue* cur = &queues[priority];
return cur->data.empty();
}
void prepare(Priority priority) {
Queue* cur = &queues[priority];
if (cur->next_nonempty == UnlinkedTag())
link(priority);
}
private:
struct Queue {
// Points to the next active priority, skipping over ones that have never been used.
Queue* next_nonempty = UnlinkedTag();
// Double-ended queue of threads in this priority level
std::deque<T> data;
};
/// Special tag used to mark priority levels that have never been used.
static Queue* UnlinkedTag() {
return reinterpret_cast<Queue*>(1);
}
void link(Priority priority) {
Queue* cur = &queues[priority];
for (int i = priority - 1; i >= 0; --i) {
if (queues[i].next_nonempty != UnlinkedTag()) {
cur->next_nonempty = queues[i].next_nonempty;
queues[i].next_nonempty = cur;
return;
}
}
cur->next_nonempty = first;
first = cur;
}
// The first queue that's ever been used.
Queue* first;
// The priority level queues of thread ids.
std::array<Queue, NUM_QUEUES> queues;
};
} // namespace Common
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