cocos_lib/cocos/base/job-system/job-system-dummy/DummyJobGraph.h

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 Copyright (c) 2020-2023 Xiamen Yaji Software Co., Ltd.

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#pragma once

#include "base/Macros.h"
#include "base/memory/Memory.h"
#include "base/std/container/unordered_set.h"
#include "base/std/container/vector.h"

namespace cc {

class DummyJobSystem;

class DummyGraphNode;
class DummyGraph final {
public:
    DummyGraph() = default;
    DummyGraph(const DummyGraph &) = delete;
    DummyGraph(DummyGraph &&) = delete;
    DummyGraph &operator=(const DummyGraph &) = delete;
    DummyGraph &operator=(DummyGraph &&) = delete;
    ~DummyGraph();

    template <class Fn>
    size_t addNode(Fn &&fn);

    void run();
    void link(size_t precede, size_t after);
    void walk(DummyGraphNode *node);
    void clear();

private:
    bool excuted(DummyGraphNode *n) const;

    int _generation{0};
    ccstd::vector<DummyGraphNode *> _nodes;
};

class DummyGraphNodeTaskItf {
public:
    virtual ~DummyGraphNodeTaskItf() = default;
    virtual void execute() = 0;
};

template <class Fn>
class DummyGraphNodeTaskImpl final : public DummyGraphNodeTaskItf {
public:
    explicit DummyGraphNodeTaskImpl(Fn &&t) noexcept;
    DummyGraphNodeTaskImpl(const DummyGraphNodeTaskImpl &) = delete;
    DummyGraphNodeTaskImpl(DummyGraphNodeTaskImpl &&) = delete;
    DummyGraphNodeTaskImpl &operator=(const DummyGraphNodeTaskImpl &) = delete;
    DummyGraphNodeTaskImpl &operator=(DummyGraphNodeTaskImpl &&) = delete;
    ~DummyGraphNodeTaskImpl() override = default;
    inline void execute() override { _task(); }

private:
    Fn _task;
};

class DummyGraphNode final {
public:
    DummyGraphNode() = default;
    DummyGraphNode(const DummyGraphNode &) = delete;
    DummyGraphNode(DummyGraphNode &&) = delete;
    DummyGraphNode &operator=(const DummyGraphNode &) = delete;
    DummyGraphNode &operator=(DummyGraphNode &&) = delete;
    ~DummyGraphNode();

private:
    static void allocChunk();
    static DummyGraphNode *alloc();
    static void free(DummyGraphNode *n);
    static void freeAll();

    void succeed(DummyGraphNode *other);
    void precede(DummyGraphNode *other);
    void reset();

    DummyGraphNodeTaskItf *_callback{nullptr};
    ccstd::unordered_set<DummyGraphNode *> _successors{};
    ccstd::unordered_set<DummyGraphNode *> _predecessors{};
    DummyGraphNode *_next{nullptr};
    int _generation{0};
    friend class DummyGraph;
};

template <class Fn>
DummyGraphNodeTaskImpl<Fn>::DummyGraphNodeTaskImpl(Fn &&t) noexcept : _task(t) {}

template <class Fn>
size_t DummyGraph::addNode(Fn &&fn) {
    DummyGraphNode *n = DummyGraphNode::alloc();
    n->_callback = ccnew DummyGraphNodeTaskImpl<Fn>(std::forward<Fn>(fn));
    n->_generation = _generation;
    _nodes.emplace_back(n);
    return _nodes.size() - 1;
}

// exported declarations

class DummyJobGraph final {
public:
    explicit DummyJobGraph(DummyJobSystem * /*system*/) noexcept {}
    DummyJobGraph(const DummyJobGraph &) = delete;
    DummyJobGraph(DummyJobGraph &&) = delete;
    DummyJobGraph &operator=(const DummyJobGraph &) = delete;
    DummyJobGraph &operator=(DummyJobGraph &&) = delete;
    ~DummyJobGraph() noexcept = default;

    template <typename Function>
    uint32_t createJob(Function &&func) noexcept;

    template <typename Function>
    uint32_t createForEachIndexJob(uint32_t begin, uint32_t end, uint32_t step, Function &&func) noexcept;

    void makeEdge(uint32_t j1, uint32_t j2);

    void run() noexcept;

    inline void waitForAll() { run(); }

private:
    DummyGraph _dummyGraph{};
};

template <typename Function>
uint32_t DummyJobGraph::createJob(Function &&func) noexcept {
    return static_cast<uint32_t>(_dummyGraph.addNode(std::forward<Function>(func)));
}

template <typename Function>
uint32_t DummyJobGraph::createForEachIndexJob(uint32_t begin, uint32_t end, uint32_t step, Function &&func) noexcept {
    return static_cast<uint32_t>(_dummyGraph.addNode([callable = std::forward<Function>(func), first = begin, last = end, step = step]() {
        for (auto i = first; i < last; i += step) {
            callable(i);
        }
    }));
}

} // namespace cc