hxthread.hpp

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#pragma once
// SPDX-FileCopyrightText: © 2017-2026 Adrian Johnston.
// SPDX-License-Identifier: MIT
// This file is licensed under the MIT license found in the LICENSE.md file.

 
#include "libhatchet.h"
 
// HX_USE_MACROS_WITH_MODULE allows including macros alongside the module.
#if HX_USE_MACROS_WITH_MODULE
#error Header does not provide macros alone.
#endif
#if (HX_USE_THREADS) != 0 && (HX_USE_THREADS) != 1 && (HX_USE_THREADS) != 11
#error HX_USE_THREADS must be 0, 1 or 11. 11 is for using <threads.h>.
#endif
 
#if (HX_USE_THREADS) == 11
#include <threads.h>
#elif HX_USE_THREADS
#include <pthread.h>
#endif
 
#include "hxutility.h"
 
HX_NS_BEGIN_

template<typename T_>
class hxthread_local {
    static_assert(sizeof(T_) <= sizeof(void*),
        "hxthread_local: sizeof(T) must be <= sizeof(void*)");
 
public:
    hxinline hxattr_flatten explicit hxthread_local(void) {
#if (HX_USE_THREADS) == 11
        const int code_ = ::tss_create(&m_key_, 0);
        hxassert_always(code_ == thrd_success, "tss_create %d", code_); (void)code_;
#elif HX_USE_THREADS
        const int code_ = ::pthread_key_create(&m_key_, 0);
        hxassert_always(code_ == 0, "pthread_key_create %s", ::strerror(code_)); (void)code_;
#else
        m_value_ = T_();
#endif
    }

    hxinline hxattr_flatten ~hxthread_local() {
#if (HX_USE_THREADS) == 11
        ::tss_delete(m_key_);
#elif HX_USE_THREADS
        ::pthread_key_delete(m_key_);
#endif
    }

    hxinline hxattr_flatten operator T_(void) {
#if (HX_USE_THREADS) == 11
        return (T_)(intptr_t)::tss_get(m_key_); // NOLINT(google-readability-casting)
#elif HX_USE_THREADS
        return (T_)(intptr_t)::pthread_getspecific(m_key_); // NOLINT(google-readability-casting)
#else
        return m_value_;
#endif
    }

    hxinline hxattr_flatten void operator=(T_ local_) {
#if (HX_USE_THREADS) == 11
        const int code_ = ::tss_set(m_key_, (void*)(intptr_t)local_); // NOLINT(google-readability-casting)
        hxassert_hard(code_ == thrd_success, "tss_set %d", code_); (void)code_;
#elif HX_USE_THREADS
        const int code_ = ::pthread_setspecific(m_key_, (void*)(intptr_t)local_); // NOLINT(google-readability-casting)
        hxassert_hard(code_ == 0, "pthread_setspecific %s", ::strerror(code_)); (void)code_;
#else
        m_value_ = local_;
#endif
    }
 
private:
    explicit hxthread_local(const hxthread_local&) = delete;
    hxthread_local& operator=(const hxthread_local&) = delete;
 
    // No allocation is being made with which to return a pointer to.
    void operator&(void) const = delete;
    void operator&(void) = delete;
 
#if (HX_USE_THREADS) == 11
    ::tss_t m_key_;
#elif HX_USE_THREADS
    ::pthread_key_t m_key_;
#else
    T_ m_value_;
#endif
};

hxinline size_t hxthread_id(void) {
#if (HX_USE_THREADS) == 11
#if defined(_WIN32)
    return static_cast<size_t>(::thrd_current()._Tid);
#else
    return static_cast<size_t>(::thrd_current());
#endif
#elif HX_USE_THREADS
    return static_cast<size_t>(::pthread_self());
#else
    return 0; // Single threaded.
#endif
}
 
// The remaining classes are only available when threading is enabled. Emulating
// pthreads is a little too nutty because it has a range of valid implementations.
#if HX_USE_THREADS

class hxmutex {
public:
    hxinline hxmutex(void) {
#if (HX_USE_THREADS) == 11
        const int code_ = ::mtx_init(&m_mutex_, mtx_plain);
        hxassert_always(code_ == thrd_success, "mtx_init %d", code_); (void)code_;
#else
        const int code_ = ::pthread_mutex_init(&m_mutex_, 0);
        hxassert_always(code_ == 0, "pthread_mutex_init %s", ::strerror(code_)); (void)code_;
#endif
    }

    hxinline ~hxmutex(void) {
#if (HX_USE_THREADS) == 11
        ::mtx_destroy(&m_mutex_);
#else
        const int code_ = ::pthread_mutex_destroy(&m_mutex_);
        hxassertf(code_ == 0, "pthread_mutex_destroy %s", ::strerror(code_)); (void)code_;
#endif
    }

    hxinline hxattr_nodiscard bool lock(void) {
#if (HX_USE_THREADS) == 11
        const int code_ = ::mtx_lock(&m_mutex_);
        hxassertf(code_ == thrd_success, "mtx_lock %d", code_);
        return code_ == thrd_success;
#else
        const int code_ = ::pthread_mutex_lock(&m_mutex_);
        hxassertf(code_ == 0 || code_ == EAGAIN, "pthread_mutex_lock %s", ::strerror(code_));
        return code_ == 0;
#endif
    }

    hxinline bool unlock(void) {
#if (HX_USE_THREADS) == 11
        const int code_ = ::mtx_unlock(&m_mutex_);
        hxassertf(code_ == thrd_success, "mtx_unlock %d", code_);
        return code_ == thrd_success;
#else
        const int code_ = ::pthread_mutex_unlock(&m_mutex_);
        hxassertf(code_ == 0, "pthread_mutex_unlock %s", ::strerror(code_));
        return code_ == 0;
#endif
    }

#if (HX_USE_THREADS) == 11
    hxinline ::mtx_t* native_handle(void) { return &m_mutex_; }
#else
    hxinline ::pthread_mutex_t* native_handle(void) { return &m_mutex_; }
#endif
 
private:
    hxmutex(const hxmutex&) = delete;
    hxmutex& operator=(const hxmutex&) = delete;
 
#if (HX_USE_THREADS) == 11
    ::mtx_t m_mutex_;
#else
    ::pthread_mutex_t m_mutex_;
#endif
};

class hxunique_lock {
public:
    hxinline hxunique_lock(hxmutex& mtx_, bool defer_lock_=false)
            : m_mutex_(mtx_), m_owns_(false) {
        if(!defer_lock_) {
            this->lock();
        }
    }

    hxinline ~hxunique_lock(void) {
        if(m_owns_) {
            this->unlock();
        }
    }

    hxinline void lock(void) {
        if(!m_owns_) {
            m_owns_ = m_mutex_.lock();
        }
    }

    hxinline void unlock(void) {
        if(m_owns_) {
            m_mutex_.unlock();
            m_owns_ = false;
        }
    }

    hxinline bool owns_lock(void) const { return m_owns_; }

    hxinline hxmutex& mutex(void) { return m_mutex_; }
 
private:
    hxunique_lock(const hxunique_lock&) = delete;
    hxunique_lock& operator=(const hxunique_lock&) = delete;
    hxmutex& m_mutex_;
    bool m_owns_;
};

class hxcondition_variable {
public:
    hxinline hxcondition_variable(void) {
#if (HX_USE_THREADS) == 11
        const int code_ = ::cnd_init(&m_cond_);
        hxassert_always(code_ == thrd_success, "cnd_init %d", code_); (void)code_;
#else
        const int code_ = ::pthread_cond_init(&m_cond_, 0);
        hxassert_always(code_ == 0, "pthread_cond_init %s", ::strerror(code_)); (void)code_;
#endif
    }

    hxinline ~hxcondition_variable(void) {
#if (HX_USE_THREADS) == 11
        ::cnd_destroy(&m_cond_);
#else
        const int code_ = ::pthread_cond_destroy(&m_cond_);
        hxassertf(code_ == 0, "pthread_cond_destroy %s", ::strerror(code_)); (void)code_;
#endif
    }

    hxinline hxattr_nodiscard bool wait(hxmutex& mutex_) {
#if (HX_USE_THREADS) == 11
        const int code_ = ::cnd_wait(&m_cond_, mutex_.native_handle());
        hxassertf(code_ == thrd_success, "cnd_wait %d", code_);
        return code_ == thrd_success;
#else
        const int code_ = ::pthread_cond_wait(&m_cond_, mutex_.native_handle());
        hxassertf(code_ == 0, "pthread_cond_wait %s", ::strerror(code_));
        return code_ == 0;
#endif
    }

    hxinline hxattr_nodiscard bool wait(hxunique_lock& lock_) {
        return this->wait(lock_.mutex());
    }

    template<typename callable_t_>
    hxinline void wait(hxunique_lock& lock_, callable_t_&& callable_) {
        while(!callable_()) {
            // Failure is undefined as per the standard.
            const bool wait_result_ = this->wait(lock_);
            hxassertf(wait_result_, "wait"); (void)wait_result_;
        }
    }

    hxinline bool notify_one(void) {
#if (HX_USE_THREADS) == 11
        const int code_ = ::cnd_signal(&m_cond_);
        hxassertf(code_ == thrd_success, "cnd_signal %d", code_);
        return code_ == thrd_success;
#else
        const int code_ = ::pthread_cond_signal(&m_cond_);
        hxassertf(code_ == 0, "pthread_cond_signal %s", ::strerror(code_));
        return code_ == 0;
#endif
    }

    hxinline bool notify_all(void) {
#if (HX_USE_THREADS) == 11
        const int code_ = ::cnd_broadcast(&m_cond_);
        hxassertf(code_ == thrd_success, "cnd_broadcast %d", code_);
        return code_ == thrd_success;
#else
        const int code_ = ::pthread_cond_broadcast(&m_cond_);
        hxassertf(code_ == 0, "pthread_cond_broadcast %s", ::strerror(code_));
        return code_ == 0;
#endif
    }

#if (HX_USE_THREADS) == 11
    hxinline ::cnd_t* native_handle(void) { return &m_cond_; }
#else
    hxinline ::pthread_cond_t* native_handle(void) { return &m_cond_; }
#endif
 
private:
    hxcondition_variable(const hxcondition_variable&) = delete;
    hxcondition_variable& operator=(const hxcondition_variable&) = delete;
 
#if (HX_USE_THREADS) == 11
    ::cnd_t m_cond_;
#else
    ::pthread_cond_t m_cond_;
#endif
};

class hxthread {
public:
#if (HX_USE_THREADS) == 11
    using return_t = int;
#else
    using return_t = void*;
#endif

    hxinline hxthread(void) : m_thread_(), m_joinable_(false) { }

    template<typename parameter_t_>
    hxinline explicit hxthread(return_t (*entry_point_)(parameter_t_*), parameter_t_* parameter_)
            : hxthread() {
        this->start(entry_point_, parameter_);
    }

    hxinline ~hxthread(void) {
        hxassert_hard(!this->joinable(), "thread_busy");
    }

    template<typename parameter_t_>
    hxinline void start(return_t (*entry_point_)(parameter_t_*), parameter_t_* parameter_) {
        hxassertf(!this->joinable(), "thread_busy");
 
        // Stay on the right side of the C++ standard by avoiding assumptions
        // about pointer representations. The parameter is being reinterpreted
        // twice instead of cast once and reinterpreted back.
        static_assert(sizeof(void*) == sizeof(parameter_t_*), "Incompatible pointer sizes");
 
        void* reinterpreted_parameter_ = hxnull;
        ::memcpy(&reinterpreted_parameter_, &parameter_, sizeof(void*)); // NOLINT(bugprone-bitwise-pointer-cast)
#if (HX_USE_THREADS) == 11
        const int code_ = ::thrd_create(&m_thread_,
            reinterpret_cast<entry_point_function_t_>(entry_point_), reinterpreted_parameter_);
        hxassert_always(code_ == thrd_success, "thrd_create %d", code_); (void)code_;
#else
        const int code_ = ::pthread_create(&m_thread_, 0,
            reinterpret_cast<entry_point_function_t_>(entry_point_), reinterpreted_parameter_);
        hxassert_always(code_ == 0, "pthread_create %s", ::strerror(code_)); (void)code_;
#endif
        m_joinable_ = true;
    }

    hxinline hxattr_nodiscard bool joinable(void) const { return m_joinable_; }

    hxinline void join(void) {
        hxassertf(this->joinable(), "task_idle");
#if (HX_USE_THREADS) == 11
        const int code_ = ::thrd_join(m_thread_, hxnull);
        hxassert_always(code_ == thrd_success, "thrd_join %d", code_);
        (void)code_;
#else
        const int code_ = ::pthread_join(m_thread_, 0);
        hxassert_always(code_ == 0, "pthread_join %s", ::strerror(code_));
        (void)code_;
#endif
        m_joinable_ = false;
    }
 
private:
    using entry_point_function_t_ = return_t (*)(void*);
 
    hxthread(const hxthread&) = delete;
    hxthread& operator=(const hxthread&) = delete;
 
#if (HX_USE_THREADS) == 11
    ::thrd_t m_thread_;
#else
    ::pthread_t m_thread_;
#endif
    bool m_joinable_;
};
 
#endif // HX_USE_THREADS
HX_NS_END_