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104 lines
2.0 KiB
104 lines
2.0 KiB
#pragma once
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#include "gp/vfs/process_data.hpp"
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#include <atomic>
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#include <new>
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namespace gp {
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struct topic_list{
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struct node{
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alignas(gp_config::limits::hardware_constructive_interference_size) std::atomic_bool is_locked;
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gp::process_data* value;
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alignas(gp_config::limits::hardware_constructive_interference_size) std::atomic<struct node*> next;
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node()
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{
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is_locked = false;
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value = nullptr;
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next = nullptr;
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}
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node(node&& v)
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{
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v.try_acquire();
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is_locked = false;
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value = gp::move(v.value);
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next = v.next.load();
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}
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bool try_acquire() noexcept {
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bool expected = false;
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return !(is_locked.compare_exchange_strong(expected, true));
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}
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void release() noexcept {
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is_locked.store(false);
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}
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};
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using node_ptr = struct node*;
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using node_ptr_rep = std::atomic<struct node*>;
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topic_list()
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: start{nullptr}
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, end{nullptr}
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{}
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node_ptr_rep start;
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node_ptr_rep end;
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// NODES ARE ACQUIRED ON POP
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node_ptr try_pop() {
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auto ptr = start.load();
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if(!ptr) return nullptr;
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if(ptr->try_acquire()) {
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auto replace = ptr->next.load();
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auto expected = ptr;
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if(end.load() == ptr) {
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replace = nullptr;
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}
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if(start.compare_exchange_strong(expected, replace)) {
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end.store(nullptr);
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return ptr;
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} else {
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return nullptr;
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}
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} else {
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return nullptr;
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}
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}
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// ONLY PUSH ACQUIRED NODES,
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// RELEASE WHEN NO LONGER IN USE
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bool try_push(node_ptr node) {
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node->next.store(nullptr);
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auto ed = end.load();
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if(ed) {
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if(ed->try_acquire()) {
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auto old_ed = ed;
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node->next.store(ed);
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if(end.compare_exchange_strong(ed, node)) {
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node->release();
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old_ed->release();
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return true;
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} else {
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node->release();
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old_ed->release();
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return false;
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}
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} else return false;
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} else {
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if(end.compare_exchange_strong(ed, node)) {
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start.store(node);
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node->release();
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return true;
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} else {
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return false;
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}
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}
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}
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};
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}
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