source: doc/theses/thierry_delisle_PhD/code/readQ_example/thrdlib/pthread.hpp@ bb7422a

#pragma once

#include <pthread.h>
#include <errno.h>
#include <cstring>
#include <cstdio>
#include <iostream>

#define CHECKED(x) { int err = x; if( err != 0 ) { std::cerr << "KERNEL ERROR: Operation \"" #x "\" return error " << err << " - " << strerror(err) << std::endl; std::abort(); } }

struct __bin_sem_t {
        pthread_mutex_t         lock;
        pthread_cond_t          cond;
        int                     val;

        __bin_sem_t() {
                // Create the mutex with error checking
                pthread_mutexattr_t mattr;
                pthread_mutexattr_init( &mattr );
                pthread_mutexattr_settype( &mattr, PTHREAD_MUTEX_ERRORCHECK_NP);
                pthread_mutex_init(&lock, &mattr);

                pthread_cond_init (&cond, nullptr);
                val = 0;
        }

        ~__bin_sem_t() {
                CHECKED( pthread_mutex_destroy(&lock) );
                CHECKED( pthread_cond_destroy (&cond) );
        }

        void wait() {
                CHECKED( pthread_mutex_lock(&lock) );
                        while(val < 1) {
                                pthread_cond_wait(&cond, &lock);
                        }
                        val -= 1;
                CHECKED( pthread_mutex_unlock(&lock) );
        }

        bool post() {
                bool needs_signal = false;

                CHECKED( pthread_mutex_lock(&lock) );
                        if(val < 1) {
                                val += 1;
                                pthread_cond_signal(&cond);
                                needs_signal = true;
                        }
                CHECKED( pthread_mutex_unlock(&lock) );

                return needs_signal;
        }
};

#undef CHECKED

//--------------------
// Basic types
struct pthread_runner_t {
        pthread_t handle;
        __bin_sem_t sem;
};
typedef pthread_runner_t * thread_t;

static_assert(sizeof(thread_t) == sizeof(void*), "thread_t musst be of same size as void*");

extern "C" {
        //--------------------
        // Basic thread support
        thread_t thrdlib_create( void (*main)( thread_t ) ) {
                thread_t thrd = new pthread_runner_t();
                int r = pthread_create( &thrd->handle, nullptr, (void *(*)(void *))main, thrd );
                if( r != 0 ) std::abort();
                return thrd;
        }

        void thrdlib_join( thread_t handle ) {
                void * ret;
                int r = pthread_join( handle->handle, &ret );
                if( r != 0 ) std::abort();
                delete handle;
        }

        void thrdlib_park( thread_t handle ) {
                handle->sem.wait();
        }

        void thrdlib_unpark( thread_t handle ) {
                handle->sem.post();
        }

        void thrdlib_yield( void ) {
                int r = pthread_yield();
                if( r != 0 ) std::abort();
        }

        //--------------------
        // Basic kernel features
        void thrdlib_init( int ) {}
        void thrdlib_clean( void ) {}
}