safe_ptr.h

#pragma once
#ifndef SAFE_PTR_H
#define SAFE_PTR_H

#include <iostream>
#include <string>
#include <vector>
#include <atomic>
#include <memory>
#include <mutex>
#include <thread>
#include <map>
#include <unordered_map>
#include <condition_variable>
#include <array>
#include <sstream>
#include <cassert>
#include <random>
#include <iomanip>
#include <algorithm>

// Autodetect C++14
#if (__cplusplus >= 201402L || _MSC_VER >= 1900)
#define SHARED_MTX
#include <shared_mutex>
#endif

namespace sf {


    template<typename T, typename mutex_t = std::recursive_mutex, typename x_lock_t = std::unique_lock<mutex_t>,
        typename s_lock_t = std::unique_lock<mutex_t >>
        // std::shared_lock<std::shared_timed_mutex>, when mutex_t = std::shared_timed_mutex
    class safe_ptr {
        protected:
            const std::shared_ptr<T> ptr;   // std::experimental::propagate_const<std::shared_ptr<T>> ptr;  // C++17
            std::shared_ptr<mutex_t> mtx_ptr;

            template<typename req_lock>
            class auto_lock_t {
                T * const ptr;
                req_lock lock;
            public:
                auto_lock_t(auto_lock_t&& o) : ptr(std::move(o.ptr)), lock(std::move(o.lock)) { }
                auto_lock_t(T * const _ptr, mutex_t& _mtx) : ptr(_ptr), lock(_mtx) {}
                T* operator -> () { return ptr; }
                const T* operator -> () const { return ptr; }
            };

            template<typename req_lock>
            class auto_lock_obj_t {
                T * const ptr;
                req_lock lock;
            public:
                auto_lock_obj_t(auto_lock_obj_t&& o) : ptr(std::move(o.ptr)), lock(std::move(o.lock)) { }
                auto_lock_obj_t(T * const _ptr, mutex_t& _mtx) : ptr(_ptr), lock(_mtx) {}
                template<typename arg_t>
                auto operator [] (arg_t &&arg) -> decltype((*ptr)[arg]) { return (*ptr)[arg]; }
            };

            struct no_lock_t { no_lock_t(no_lock_t &&) {} template<typename sometype> no_lock_t(sometype&) {} };
            using auto_nolock_t = auto_lock_obj_t<no_lock_t>;

            T * get_obj_ptr() const { return ptr.get(); }
            mutex_t * get_mtx_ptr() const { return mtx_ptr.get(); }

            template<typename... Args> void lock_shared() const { get_mtx_ptr()->lock_shared(); }
            template<typename... Args> void unlock_shared() const { get_mtx_ptr()->unlock_shared(); }
            void lock() const { get_mtx_ptr()->lock(); }
            void unlock() const { get_mtx_ptr()->unlock(); }
            friend struct link_safe_ptrs;
            template<typename, typename, typename, typename> friend class safe_obj;
            template<typename some_type> friend struct xlocked_safe_ptr;
            template<typename some_type> friend struct slocked_safe_ptr;
            template<typename, typename, size_t, size_t> friend class lock_timed_transaction;
#if (_MSC_VER && _MSC_VER == 1900)
            template<class... mutex_types> friend class std::lock_guard;  // MSVS2015
#else
            template<class mutex_type> friend class std::lock_guard;  // other compilers
#endif
#ifdef SHARED_MTX    
            template<typename mutex_type> friend class std::shared_lock;  // C++14
#endif

        private:
        
            safe_ptr(std::shared_ptr<T> &&ptr, std::shared_ptr<mutex_t> &&mtx_ptr)
                : ptr(std::move(ptr))
                , mtx_ptr(std::move(mtx_ptr))
            {}

        public:
            template<typename... Args>
            static safe_ptr make_safe(Args&&... args) { 
                return safe_ptr(std::make_shared<T>(std::forward<Args>(args)...), std::make_shared<mutex_t>());
            }

            auto_lock_t<x_lock_t> operator -> () { return auto_lock_t<x_lock_t>(get_obj_ptr(), *get_mtx_ptr()); }
            auto_lock_obj_t<x_lock_t> operator * () { return auto_lock_obj_t<x_lock_t>(get_obj_ptr(), *get_mtx_ptr()); }
            const auto_lock_t<s_lock_t> operator -> () const { return auto_lock_t<s_lock_t>(get_obj_ptr(), *get_mtx_ptr()); }
            const auto_lock_obj_t<s_lock_t> operator * () const { return auto_lock_obj_t<s_lock_t>(get_obj_ptr(), *get_mtx_ptr()); }

            typedef mutex_t mtx_t;
            typedef T obj_t;
            typedef x_lock_t xlock_t;
            typedef s_lock_t slock_t;
    };

    template<typename T> using default_safe_ptr = safe_ptr<T, std::recursive_mutex, std::unique_lock<std::recursive_mutex>, std::unique_lock<std::recursive_mutex>>;

#ifdef SHARED_MTX // C++14
    template<typename T> using shared_mutex_safe_ptr =
        safe_ptr< T, std::shared_timed_mutex, std::unique_lock<std::shared_timed_mutex>, std::shared_lock<std::shared_timed_mutex> >;
#endif
    // ---------------------------------------------------------------

    template<typename T, typename mutex_t = std::recursive_mutex, typename x_lock_t = std::unique_lock<mutex_t>,
        typename s_lock_t = std::unique_lock<mutex_t >>
    class safe_obj {
        protected:
            T obj;
            mutable mutex_t mtx;

            T * get_obj_ptr() const { return const_cast<T*>(&obj); }
            mutex_t * get_mtx_ptr() const { return &mtx; }

            template<typename req_lock> using auto_lock_t = typename safe_ptr<T, mutex_t, x_lock_t, s_lock_t>::template auto_lock_t<req_lock>;
            template<typename req_lock> using auto_lock_obj_t = typename safe_ptr<T, mutex_t, x_lock_t, s_lock_t>::template auto_lock_obj_t<req_lock>;
            using auto_nolock_t = typename safe_ptr<T, mutex_t, x_lock_t, s_lock_t>::auto_nolock_t;
            template<typename some_type> friend struct xlocked_safe_ptr;
            template<typename some_type> friend struct slocked_safe_ptr;
        public:
            template<typename... Args>
            safe_obj(Args... args) : obj(args...) {}
            safe_obj(safe_obj const& safe_obj) { std::lock_guard<mutex_t> lock(safe_obj.mtx); obj = safe_obj.obj; }
            explicit operator T() const { s_lock_t lock(mtx); T obj_tmp = obj; return obj_tmp; };

            auto_lock_t<x_lock_t> operator -> () { return auto_lock_t<x_lock_t>(get_obj_ptr(), *get_mtx_ptr()); }
            auto_lock_obj_t<x_lock_t> operator * () { return auto_lock_obj_t<x_lock_t>(get_obj_ptr(), *get_mtx_ptr()); }
            const auto_lock_t<s_lock_t> operator -> () const { return auto_lock_t<s_lock_t>(get_obj_ptr(), *get_mtx_ptr()); }
            const auto_lock_obj_t<s_lock_t> operator * () const { return auto_lock_obj_t<s_lock_t>(get_obj_ptr(), *get_mtx_ptr()); }

            typedef mutex_t mtx_t;
            typedef T obj_t;
            typedef x_lock_t xlock_t;
            typedef s_lock_t slock_t;
    };
    // ---------------------------------------------------------------

    // hide ptr
    template<typename T, typename mutex_t = std::recursive_mutex, typename x_lock_t = std::unique_lock<mutex_t>,
        typename s_lock_t = std::unique_lock<mutex_t >>
    class safe_hide_ptr : protected safe_ptr<T, mutex_t, x_lock_t, s_lock_t> {
        public:
            template<typename... Args> safe_hide_ptr(Args... args) : safe_ptr<T, mutex_t, x_lock_t, s_lock_t>(args...) {}

            friend struct link_safe_ptrs;
            template<typename, typename, size_t, size_t> friend class lock_timed_transaction;
            template<typename some_type> friend struct xlocked_safe_ptr;
            template<typename some_type> friend struct slocked_safe_ptr;

            template<typename req_lock> using auto_lock_t = typename safe_ptr<T, mutex_t, x_lock_t, s_lock_t>::template auto_lock_t<req_lock>;
            template<typename req_lock> using auto_lock_obj_t = typename safe_ptr<T, mutex_t, x_lock_t, s_lock_t>::template auto_lock_obj_t<req_lock>;
            using auto_nolock_t = typename safe_ptr<T, mutex_t, x_lock_t, s_lock_t>::auto_nolock_t;
            typedef mutex_t mtx_t;
            typedef T obj_t;
            typedef x_lock_t xlock_t;
            typedef s_lock_t slock_t;
    };

    // hide obj
    template<typename T, typename mutex_t = std::recursive_mutex, typename x_lock_t = std::unique_lock<mutex_t>,
        typename s_lock_t = std::unique_lock<mutex_t >>
    class safe_hide_obj : protected safe_obj<T, mutex_t, x_lock_t, s_lock_t> {
        public:
            template<typename... Args> safe_hide_obj(Args... args) : safe_obj<T, mutex_t, x_lock_t, s_lock_t>(args...) {}
            explicit operator T() const { return static_cast< safe_obj<T, mutex_t, x_lock_t, s_lock_t> >(*this); };

            friend struct link_safe_ptrs;
            template<typename, typename, size_t, size_t> friend class lock_timed_transaction;
            template<typename some_type> friend struct xlocked_safe_ptr;
            template<typename some_type> friend struct slocked_safe_ptr;

            template<typename req_lock> using auto_lock_t = typename safe_obj<T, mutex_t, x_lock_t, s_lock_t>::template auto_lock_t<req_lock>;
            template<typename req_lock> using auto_lock_obj_t = typename safe_obj<T, mutex_t, x_lock_t, s_lock_t>::template auto_lock_obj_t<req_lock>;
            using auto_nolock_t = typename safe_obj<T, mutex_t, x_lock_t, s_lock_t>::auto_nolock_t;
            typedef mutex_t mtx_t;
            typedef T obj_t;
            typedef x_lock_t xlock_t;
            typedef s_lock_t slock_t;
    };
    // ---------------------------------------------------------------

    struct link_safe_ptrs {
        template<typename T1, typename... Args>
        link_safe_ptrs(T1 &first_ptr, Args&... args) {
            std::lock_guard<T1> lock(first_ptr);
            typedef typename T1::mtx_t mutex_t;
            std::shared_ptr<mutex_t> old_mtxs[] = { args.mtx_ptr ... }; // to unlock before mutexes will be destroyed
            std::shared_ptr<std::lock_guard<mutex_t>> locks[] = { std::make_shared<std::lock_guard<mutex_t>>(*args.mtx_ptr) ... };
            std::shared_ptr<mutex_t> mtxs[] = { (args.mtx_ptr = first_ptr.mtx_ptr) ... };
        }
    };
    // ---------------------------------------------------------------

	enum lock_count_t { lock_once, lock_infinity };

	template<size_t lock_count, typename duration = std::chrono::nanoseconds,
		size_t deadlock_timeout = 100000, size_t spin_iterations = 100>
		class lock_timed_any {
		std::vector<std::shared_ptr<void>> locks_ptr_vec;
		bool success;

		template<typename mtx_t>
		std::unique_lock<mtx_t> try_lock_one(mtx_t &mtx) const {
			std::unique_lock<mtx_t> lock(mtx, std::defer_lock_t());
			for (size_t i = 0; i < spin_iterations; ++i) if (lock.try_lock()) return lock;
			const std::chrono::steady_clock::time_point start_time = std::chrono::steady_clock::now();
			//while (!lock.try_lock_for(duration(deadlock_timeout)))    // only for timed mutexes
			while (!lock.try_lock()) {
				auto const time_remained = duration(deadlock_timeout) - std::chrono::duration_cast<duration>(std::chrono::steady_clock::now() - start_time);
				if (time_remained <= duration(0))
					break;
				else
					std::this_thread::sleep_for(time_remained);
			}
			return lock;
		}

		template<typename mtx_t>
		std::shared_ptr<std::unique_lock<mtx_t>> try_lock_ptr_one(mtx_t &mtx) const {
			return std::make_shared<std::unique_lock<mtx_t>>(try_lock_one(mtx));
		}

		public:
			template<typename... Args>
			lock_timed_any(Args& ...args) {
				do {
					success = true;
					for (auto &lock_ptr : { try_lock_ptr_one(*args.mtx_ptr.get()) ... }) {
						locks_ptr_vec.emplace_back(lock_ptr);
						if (!lock_ptr->owns_lock()) {
							success = false;
							locks_ptr_vec.clear();
							std::this_thread::sleep_for(duration(deadlock_timeout));
							break;
						}
					}
				} while (!success && lock_count == lock_count_t::lock_infinity);
			}

			explicit operator bool() const throw() { return success; }
			lock_timed_any(lock_timed_any&& other) throw() : locks_ptr_vec(other.locks_ptr_vec) { }
			lock_timed_any(const lock_timed_any&) = delete;
			lock_timed_any& operator=(const lock_timed_any&) = delete;
	};

	using lock_timed_any_once = lock_timed_any<lock_count_t::lock_once>;
	using lock_timed_any_infinity = lock_timed_any<lock_count_t::lock_infinity>;
	// ---------------------------------------------------------------

    template<typename T>
    struct xlocked_safe_ptr {
        T &ref_safe;
        typename T::xlock_t xlock;
        xlocked_safe_ptr(T const& p) : ref_safe(*const_cast<T*>(&p)), xlock(*(ref_safe.get_mtx_ptr())) {}// ++xp;}
        typename T::obj_t* operator -> () { return ref_safe.get_obj_ptr(); }
        typename T::auto_nolock_t operator * () { return typename T::auto_nolock_t(ref_safe.get_obj_ptr(), *ref_safe.get_mtx_ptr()); }
        operator typename T::obj_t() { return ref_safe.obj; } // only for safe_obj
    };

    template<typename T>
    xlocked_safe_ptr<T> xlock_safe_ptr(T const& arg) { return xlocked_safe_ptr<T>(arg); }

    template<typename T>
    struct slocked_safe_ptr {
        T &ref_safe;
        typename T::slock_t slock;
        slocked_safe_ptr(T const& p) : ref_safe(*const_cast<T*>(&p)), slock(*(ref_safe.get_mtx_ptr())) { }//++sp;}
        typename T::obj_t const* operator -> () const { return ref_safe.get_obj_ptr(); }
        const typename T::auto_nolock_t operator * () const { return typename T::auto_nolock_t(ref_safe.get_obj_ptr(), *ref_safe.get_mtx_ptr()); }
        operator typename T::obj_t() const { return ref_safe.obj; } // only for safe_obj
    };

    template<typename T>
    slocked_safe_ptr<T> slock_safe_ptr(T const& arg) { return slocked_safe_ptr<T>(arg); }
    // ---------------------------------------------------------------

    class spinlock_t {
        std::atomic_flag lock_flag;
    public:
        spinlock_t() { lock_flag.clear(); }

        bool try_lock() { return !lock_flag.test_and_set(std::memory_order_acquire); }
        void lock() { for (volatile size_t i = 0; !try_lock(); ++i) if (i % 100000 == 0) std::this_thread::yield(); }
        void unlock() { lock_flag.clear(std::memory_order_release); }
    };
    // ---------------------------------------------------------------

    class recursive_spinlock_t {
        std::atomic_flag lock_flag;
        int64_t recursive_counter;
#if (_WIN32 && _MSC_VER < 1900)
		typedef int64_t thread_id_t;
		std::atomic<thread_id_t> owner_thread_id;
        int64_t get_fast_this_thread_id() {
            static __declspec(thread) int64_t fast_this_thread_id = 0;  // MSVS 2013 thread_local partially supported - only POD
            if (fast_this_thread_id == 0) {
                std::stringstream ss;
                ss << std::this_thread::get_id();   // https://connect.microsoft.com/VisualStudio/feedback/details/1558211
                fast_this_thread_id = std::stoll(ss.str());
			}
            return fast_this_thread_id;
		}
#else
		typedef std::thread::id thread_id_t;
		std::atomic<std::thread::id> owner_thread_id;
        std::thread::id get_fast_this_thread_id() { return std::this_thread::get_id(); }
#endif

    public:
        recursive_spinlock_t() : recursive_counter(0), owner_thread_id(thread_id_t()) { lock_flag.clear(); }

        bool try_lock() {
            if (!lock_flag.test_and_set(std::memory_order_acquire)) {
				owner_thread_id.store(get_fast_this_thread_id(), std::memory_order_release);
            }
            else {
                if (owner_thread_id.load(std::memory_order_acquire) != get_fast_this_thread_id())
                    return false;
            }
            ++recursive_counter;
            return true;
        }

        void lock() {
            for (volatile size_t i = 0; !try_lock(); ++i)
                if (i % 100000 == 0) std::this_thread::yield();
        }

        void unlock() {
            assert(owner_thread_id.load(std::memory_order_acquire) == get_fast_this_thread_id());
            assert(recursive_counter > 0);

            if (--recursive_counter == 0) {
				owner_thread_id.store(thread_id_t(), std::memory_order_release);
                lock_flag.clear(std::memory_order_release);
            }
        }
    };
    // ---------------------------------------------------------------

    // contention free shared mutex (same-lock-type is recursive for X->X, X->S or S->S locks), but (S->X - is UB)
    template<unsigned contention_free_count = 36, bool shared_flag = false>
    class contention_free_shared_mutex {
		std::atomic<bool> want_x_lock;
        //struct cont_free_flag_t { alignas(std::hardware_destructive_interference_size) std::atomic<int> value; cont_free_flag_t() { value = 0; } }; // C++17
		struct cont_free_flag_t { char tmp[60]; std::atomic<int> value; cont_free_flag_t() { value = 0; } };   // tmp[] to avoid false sharing
        typedef std::array<cont_free_flag_t, contention_free_count> array_slock_t;
        
		const std::shared_ptr<array_slock_t> shared_locks_array_ptr;  // 0 - unregistred, 1 registred & free, 2... - busy
		char avoid_falsesharing_1[64];

        array_slock_t &shared_locks_array;
		char avoid_falsesharing_2[64];

		int recursive_xlock_count;


		enum index_op_t { unregister_thread_op, get_index_op, register_thread_op };

#if (_WIN32 && _MSC_VER < 1900) // only for MSVS 2013
        typedef int64_t thread_id_t;
		std::atomic<thread_id_t> owner_thread_id;
        std::array<int64_t, contention_free_count> register_thread_array;
        int64_t get_fast_this_thread_id() {
            static __declspec(thread) int64_t fast_this_thread_id = 0;  // MSVS 2013 thread_local partially supported - only POD
            if (fast_this_thread_id == 0) {
                std::stringstream ss;
                ss << std::this_thread::get_id();   // https://connect.microsoft.com/VisualStudio/feedback/details/1558211
                fast_this_thread_id = std::stoll(ss.str());
            }
            return fast_this_thread_id;
        }

		int get_or_set_index(index_op_t index_op = get_index_op, int set_index = -1) {
			if (index_op == get_index_op) {  // get index
				auto const thread_id = get_fast_this_thread_id();

				for (size_t i = 0; i < register_thread_array.size(); ++i) {
					if (register_thread_array[i] == thread_id) {
						set_index = i;   // thread already registred                
						break;
					}
				}
			}
			else if (index_op == register_thread_op) {  // register thread
				register_thread_array[set_index] = get_fast_this_thread_id();
			}
			return set_index;
		}

#else
		typedef std::thread::id thread_id_t;
		std::atomic<std::thread::id> owner_thread_id;
		std::thread::id get_fast_this_thread_id() { return std::this_thread::get_id(); }

        struct unregister_t {
            int thread_index;
            std::shared_ptr<array_slock_t> array_slock_ptr;
            unregister_t(int index, std::shared_ptr<array_slock_t> const& ptr) : thread_index(index), array_slock_ptr(ptr) {}
            unregister_t(unregister_t &&src) : thread_index(src.thread_index), array_slock_ptr(std::move(src.array_slock_ptr)) {}
            ~unregister_t() { if (array_slock_ptr.use_count() > 0) (*array_slock_ptr)[thread_index].value--; }
        };

        int get_or_set_index(index_op_t index_op = get_index_op, int set_index = -1) {
            thread_local static std::unordered_map<void *, unregister_t> thread_local_index_hashmap;
            // get thread index - in any cases
            auto it = thread_local_index_hashmap.find(this);
            if (it != thread_local_index_hashmap.cend())
                set_index = it->second.thread_index;

            if (index_op == unregister_thread_op) {  // unregister thread
                if (shared_locks_array[set_index].value == 1) // if isn't shared_lock now
                    thread_local_index_hashmap.erase(this);
                else
                    return -1;
            }
            else if (index_op == register_thread_op) {  // register thread
                thread_local_index_hashmap.emplace(this, unregister_t(set_index, shared_locks_array_ptr));

                // remove info about deleted contfree-mutexes
                for (auto it = thread_local_index_hashmap.begin(), ite = thread_local_index_hashmap.end(); it != ite;) {
                    if (it->second.array_slock_ptr->at(it->second.thread_index).value < 0)    // if contfree-mtx was deleted
                        it = thread_local_index_hashmap.erase(it);
                    else
                        ++it;
                }
            }
            return set_index;
        }

#endif

        public:
            contention_free_shared_mutex() :
                shared_locks_array_ptr(std::make_shared<array_slock_t>()), shared_locks_array(*shared_locks_array_ptr), want_x_lock(false), recursive_xlock_count(0),
				owner_thread_id(thread_id_t()) {}

            ~contention_free_shared_mutex() {
                for (auto &i : shared_locks_array) i.value = -1;
            }


            bool unregister_thread() { return get_or_set_index(unregister_thread_op) >= 0; }

            int register_thread() {
                int cur_index = get_or_set_index();

                if (cur_index == -1) {
                    if (shared_locks_array_ptr.use_count() <= (int)shared_locks_array.size())  // try once to register thread
                    {
                        for (size_t i = 0; i < shared_locks_array.size(); ++i) {
                            int unregistred_value = 0;
                            if (shared_locks_array[i].value == 0)
                                if (shared_locks_array[i].value.compare_exchange_strong(unregistred_value, 1)) {
                                    cur_index = i;
                                    get_or_set_index(register_thread_op, cur_index);   // thread registred success
                                    break;
                                }
                        }
                        //std::cout << "\n thread_id = " << std::this_thread::get_id() << ", register_thread_index = " << cur_index <<
                        //    ", shared_locks_array[cur_index].value = " << shared_locks_array[cur_index].value << std::endl;
                    }
                }
                return cur_index;
            }

            void lock_shared() {
                int const register_index = register_thread();

                if (register_index >= 0) {
                    int recursion_depth = shared_locks_array[register_index].value.load(std::memory_order_acquire);
                    assert(recursion_depth >= 1);

                    if (recursion_depth > 1)
                        shared_locks_array[register_index].value.store(recursion_depth + 1, std::memory_order_release); // if recursive -> release
                    else {
                        shared_locks_array[register_index].value.store(recursion_depth + 1, std::memory_order_seq_cst); // if first -> sequential
                        while (want_x_lock.load(std::memory_order_seq_cst)) {
                            shared_locks_array[register_index].value.store(recursion_depth, std::memory_order_seq_cst);
                            for (volatile size_t i = 0; want_x_lock.load(std::memory_order_seq_cst); ++i) 
								if (i % 100000 == 0) std::this_thread::yield();
                            shared_locks_array[register_index].value.store(recursion_depth + 1, std::memory_order_seq_cst);
                        }
                    }
                    // (shared_locks_array[register_index] == 2 && want_x_lock == false) ||     // first shared lock
                    // (shared_locks_array[register_index] > 2)                                 // recursive shared lock
                }
                else {
					if (owner_thread_id.load(std::memory_order_acquire) != get_fast_this_thread_id()) {
						size_t i = 0;
						for (bool flag = false; !want_x_lock.compare_exchange_weak(flag, true, std::memory_order_seq_cst); flag = false)
							if (++i % 100000 == 0) std::this_thread::yield();
						owner_thread_id.store(get_fast_this_thread_id(), std::memory_order_release);
					}
					++recursive_xlock_count;
                }
            }

            void unlock_shared() {
                int const register_index = get_or_set_index();

                if (register_index >= 0) {
                    int const recursion_depth = shared_locks_array[register_index].value.load(std::memory_order_acquire);
                    assert(recursion_depth > 1);

                    shared_locks_array[register_index].value.store(recursion_depth - 1, std::memory_order_release);
                }
                else {
					if (--recursive_xlock_count == 0) {
						owner_thread_id.store(decltype(owner_thread_id)(), std::memory_order_release);
						want_x_lock.store(false, std::memory_order_release);
					}
                }
            }

            void lock() {
                // forbidden upgrade S-lock to X-lock - this is an excellent opportunity to get deadlock
                int const register_index = get_or_set_index();
                if (register_index >= 0)
                    assert(shared_locks_array[register_index].value.load(std::memory_order_acquire) == 1);

				if (owner_thread_id.load(std::memory_order_acquire) != get_fast_this_thread_id()) {
					size_t i = 0;
					for (bool flag = false; !want_x_lock.compare_exchange_weak(flag, true, std::memory_order_seq_cst); flag = false)
						if (++i % 1000000 == 0) std::this_thread::yield();

					owner_thread_id.store(get_fast_this_thread_id(), std::memory_order_release);

					for (auto &i : shared_locks_array)
						while (i.value.load(std::memory_order_seq_cst) > 1);
				}

				++recursive_xlock_count;
            }

            void unlock() {
                assert(recursive_xlock_count > 0);
				if (--recursive_xlock_count == 0) {
					owner_thread_id.store(decltype(owner_thread_id)(), std::memory_order_release);
					want_x_lock.store(false, std::memory_order_release);
				}
            }
    };

    template<typename mutex_t>
    struct shared_lock_guard {
        mutex_t &ref_mtx;
        shared_lock_guard(mutex_t &mtx) : ref_mtx(mtx) { ref_mtx.lock_shared(); }
        ~shared_lock_guard() { ref_mtx.unlock_shared(); }
    };

    using default_contention_free_shared_mutex = contention_free_shared_mutex<>;

    template<typename T> using contfree_safe_ptr = safe_ptr<T, contention_free_shared_mutex<>,
        std::unique_lock<contention_free_shared_mutex<>>, shared_lock_guard<contention_free_shared_mutex<>> >;
    // ---------------------------------------------------------------

    // safe partitioned map
    template<typename key_t, typename val_t, template<class> class safe_ptr_t = default_safe_ptr,
        typename container_t = std::map<key_t, val_t>, typename part_t = std::map<key_t, safe_ptr_t<container_t>> >
    class safe_map_partitioned_t
    {
        using safe_container_t = safe_ptr_t<container_t>;
        typedef typename part_t::iterator part_iterator;
        typedef typename part_t::const_iterator const_part_iterator;
        std::shared_ptr<part_t> partition;

    public:
        typedef std::vector<std::pair<key_t, val_t>> result_vector_t;

        safe_map_partitioned_t() : partition(std::make_shared<part_t>()) { partition->emplace(key_t(), container_t()); }

        safe_map_partitioned_t(const key_t start, const key_t end, const key_t step) : partition(std::make_shared<part_t>()) {
            for (key_t i = start; i <= end; i += step) partition->emplace(i, container_t());
        }

        safe_map_partitioned_t(std::initializer_list<key_t> const& il) : partition(std::make_shared<part_t>()) {
            for (auto &i : il) partition->emplace(i, container_t());
        }

        part_iterator part_it(key_t const& k) { auto it = partition->lower_bound(k); if (it == partition->cend()) --it; return it; }
        const_part_iterator part_it(key_t const& k) const { auto it = partition->lower_bound(k); if (it == partition->cend()) --it; return it; }
        safe_container_t& part(key_t const& k) { return part_it(k)->second; }
        const safe_container_t& part(key_t const& k) const { return part_it(k)->second; }
        slocked_safe_ptr<safe_container_t> read_only_part(key_t const& k) const { return slock_safe_ptr(part(k)); }

        void get_range_equal(const key_t& key, result_vector_t &result_vec) const {
            result_vec.clear();
            auto slock_container = slock_safe_ptr(part(key));
            for (auto it = slock_container->lower_bound(key); it != slock_container->upper_bound(key); ++it)
                result_vec.emplace_back(*it);
        }

        void get_range_lower_upper(const key_t& low, const key_t& up, result_vector_t &result_vec) const {
            result_vec.clear();
            auto const& const_part = *partition;
            auto end_it = (const_part.upper_bound(up) == const_part.cend()) ? const_part.cend() : std::next(const_part.upper_bound(up), 1);
            auto it = const_part.lower_bound(low);
            if (it == const_part.cend()) --it;
            for (; it != end_it; ++it)
                result_vec.insert(result_vec.end(), it->second->lower_bound(low), it->second->upper_bound(up));
        }

        void erase_lower_upper(const key_t& low, const key_t& up) {
            auto end_it = (partition->upper_bound(up) == partition->end()) ? partition->end() : std::next(partition->upper_bound(up), 1);
            for (auto it = part_it(low); it != end_it; ++it)
                it->second->erase(it->second->lower_bound(low), it->second->upper_bound(up));
        }

        template<typename T, typename... Args> void emplace(T const& key, Args const&&...args) {
            part(key)->emplace(key, args...);
        }

        size_t size() const {
            size_t size = 0;
            for (auto it = partition->begin(); it != partition->end(); ++it) size += it->second->size();
            return size;
        }
        size_t erase(key_t const& key) throw() { return part(key)->erase(key); }
        void clear() { for (auto it = partition->begin(); it != partition->end(); ++it) it->second->clear(); }
    };
    // ---------------------------------------------------------------


}


#endif // #ifndef SAFE_PTR_H