/*

 * Copyright (c) 2021, kleines Filmröllchen <filmroellchen@serenityos.org>.

 *

 * SPDX-License-Identifier: BSD-2-Clause

 */

#pragma once

#include <AK/Function.h>

#include <LibThreading/Mutex.h>

#include <pthread.h>

#include <sys/types.h>

namespace Threading {

// A signaling condition variable that wraps over the pthread_cond_* APIs.

class ConditionVariable {

    friend class Mutex;

public:

    ConditionVariable(Mutex& to_wait_on)

        : m_to_wait_on(to_wait_on)

    {

        auto result = pthread_cond_init(&m_condition, nullptr);

        VERIFY(result == 0);

    }

    ALWAYS_INLINE ~ConditionVariable()

    {

        auto result = pthread_cond_destroy(&m_condition);

        VERIFY(result == 0);

    }

    // As with pthread APIs, the mutex must be locked or undefined behavior ensues.

    ALWAYS_INLINE void wait()

    {

        auto result = pthread_cond_wait(&m_condition, &m_to_wait_on.m_mutex);

        VERIFY(result == 0);

    }

    ALWAYS_INLINE void wait_while(Function<bool()> condition)

    {

        while (condition())

            wait();

    }

    // Release at least one of the threads waiting on this variable.

    ALWAYS_INLINE void signal()

    {

        auto result = pthread_cond_signal(&m_condition);

        VERIFY(result == 0);

    }

    // Release all of the threads waiting on this variable.

    ALWAYS_INLINE void broadcast()

    {

        auto result = pthread_cond_broadcast(&m_condition);

        VERIFY(result == 0);

    }

private:

    pthread_cond_t m_condition;

    Mutex& m_to_wait_on;

};

}