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path: root/util/system/atexit.cpp
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#include "atexit.h" 
#include "atomic.h"
#include "yassert.h" 
#include "spinlock.h" 
#include "thread.h" 
 
#include <util/generic/ylimits.h>
#include <util/generic/utility.h> 
#include <util/generic/deque.h> 
#include <util/generic/queue.h> 
 
#include <tuple> 
 
#include <cstdlib> 
 
namespace { 
    class TAtExit { 
        struct TFunc { 
            TAtExitFunc Func; 
            void* Ctx; 
            size_t Priority; 
            size_t Number; 
        }; 
 
        struct TCmp { 
            inline bool operator()(const TFunc* l, const TFunc* r) const noexcept { 
                return std::tie(l->Priority, l->Number) < std::tie(r->Priority, r->Number); 
            } 
        }; 
 
    public: 
        inline TAtExit() noexcept 
            : FinishStarted_(0) 
        { 
        } 
 
        inline void Finish() noexcept {
            AtomicSet(FinishStarted_, 1);
 
            auto guard = Guard(Lock_); 
 
            while (Items_) { 
                auto c = Items_.top(); 
 
                Y_ASSERT(c);
 
                Items_.pop(); 

                { 
                    auto unguard = Unguard(guard); 

                    try { 
                        c->Func(c->Ctx);
                    } catch (...) { 
                        // ¯\_(ツ)_/¯ 
                    }
                } 
            } 
        } 
 
        inline void Register(TAtExitFunc func, void* ctx, size_t priority) { 
            with_lock (Lock_) { 
                Store_.push_back({func, ctx, priority, Store_.size()});
                Items_.push(&Store_.back()); 
            } 
        } 
 
        inline bool FinishStarted() const {
            return AtomicGet(FinishStarted_);
        }
 
    private: 
        TAdaptiveLock Lock_; 
        TAtomic FinishStarted_;
        TDeque<TFunc> Store_;
        TPriorityQueue<TFunc*, TVector<TFunc*>, TCmp> Items_;
    }; 
 
    static TAtomic atExitLock = 0; 
    static TAtExit* volatile atExitPtr = nullptr;
    alignas(TAtExit) static char atExitMem[sizeof(TAtExit)]; 
 
    static void OnExit() { 
        if (TAtExit* const atExit = AtomicGet(atExitPtr)) {
            atExit->Finish(); 
            atExit->~TAtExit(); 
            AtomicSet(atExitPtr, nullptr);
        } 
    } 
 
    static inline TAtExit* Instance() { 
        if (TAtExit* const atExit = AtomicGet(atExitPtr)) {
            return atExit;
        }
        with_lock (atExitLock) { 
            if (TAtExit* const atExit = AtomicGet(atExitPtr)) {
                return atExit;
            } 
            atexit(OnExit);
            TAtExit* const atExit = new (atExitMem) TAtExit;
            AtomicSet(atExitPtr, atExit);
            return atExit;
        } 
    } 
} 
 
void ManualRunAtExitFinalizers() {
    OnExit();
}

bool ExitStarted() {
    if (TAtExit* const atExit = AtomicGet(atExitPtr)) {
        return atExit->FinishStarted();
    }
    return false;
}

void AtExit(TAtExitFunc func, void* ctx, size_t priority) { 
    Instance()->Register(func, ctx, priority); 
} 
 
void AtExit(TAtExitFunc func, void* ctx) { 
    AtExit(func, ctx, Max<size_t>()); 
} 
 
static void TraditionalCloser(void* ctx) { 
    reinterpret_cast<TTraditionalAtExitFunc>(ctx)();
} 
 
void AtExit(TTraditionalAtExitFunc func) { 
    AtExit(TraditionalCloser, reinterpret_cast<void*>(func));
} 
 
void AtExit(TTraditionalAtExitFunc func, size_t priority) { 
    AtExit(TraditionalCloser, reinterpret_cast<void*>(func), priority);
}