/*
 * remote_mutex.c - POSIX mutex implementation.
 * 
 * Authors   Alain   Greiner (2016,2017,2018,2019,2020:)
 *
 * Copyright (c) UPMC Sorbonne Universites
 *
 * This file is part of ALMOS-MKH.
 *
 * ALMOS-MKH is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2.0 of the License.
 *
 * ALMOS-MKH is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with ALMOS-MKH; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <kernel_config.h>
#include <hal_kernel_types.h>
#include <hal_remote.h>
#include <thread.h>
#include <xlist.h>
#include <scheduler.h>
#include <remote_busylock.h>
#include <remote_mutex.h>


/////////////////////////////////////////////////
xptr_t remote_mutex_from_ident( intptr_t  ident )
{
    // get pointer on local process_descriptor
    process_t * process = CURRENT_THREAD->process;

    // get extended pointer on reference process
    xptr_t      ref_xp = process->ref_xp;

    // get cluster and local pointer on reference process 
    cxy_t          ref_cxy = GET_CXY( ref_xp );
    process_t    * ref_ptr = (process_t *)GET_PTR( ref_xp );

    // get extended pointers on mutexes list  
    xptr_t root_xp = XPTR( ref_cxy , &ref_ptr->mutex_root );
    xptr_t lock_xp = XPTR( ref_cxy , &ref_ptr->sync_lock );

    // get lock protecting synchro lists
    remote_queuelock_acquire( lock_xp );
 
    // scan reference process mutex list
    xptr_t           iter_xp;
    xptr_t           mutex_xp;
    cxy_t            mutex_cxy;
    remote_mutex_t * mutex_ptr;
    intptr_t         current;
    bool_t           found = false;
            
    XLIST_FOREACH( root_xp , iter_xp )
    {
        mutex_xp  = XLIST_ELEMENT( iter_xp , remote_mutex_t , list );
        mutex_cxy = GET_CXY( mutex_xp );
        mutex_ptr = (remote_mutex_t *)GET_PTR( mutex_xp );
        current     = (intptr_t)hal_remote_lpt( XPTR( mutex_cxy , &mutex_ptr->ident ) );   
        if( ident == current )
        {
            found = true;
            break;
        }
    }

    // relese lock protecting synchros lists
    remote_queuelock_release( lock_xp );
 
    if( found == false )  return XPTR_NULL;
    else                  return mutex_xp;

}  // end remote_mutex_from_ident()

/////////////////////////////////////////////
error_t remote_mutex_create( intptr_t ident )
{ 
    remote_mutex_t * mutex_ptr;

    // get pointer on local process descriptor
    process_t * process = CURRENT_THREAD->process;

    // get extended pointer on reference process
    xptr_t      ref_xp = process->ref_xp;

    // get reference process cluster and local pointer
    cxy_t       ref_cxy = GET_CXY( ref_xp );
    process_t * ref_ptr = (process_t *)GET_PTR( ref_xp );

    // allocate memory for mutex descriptor in reference cluster
    mutex_ptr = kmem_remote_alloc( ref_cxy , bits_log2(sizeof(remote_mutex_t)) , AF_ZERO );

    if( mutex_ptr == NULL )
    {
       printk("\n[ERROR] in %s : cannot create mutex\n", __FUNCTION__);
       return -1;
    }

    // initialise mutex
    hal_remote_s32 ( XPTR( ref_cxy , &mutex_ptr->taken )   , 0 );
    hal_remote_spt( XPTR( ref_cxy , &mutex_ptr->ident )   , (void *)ident );
    xlist_entry_init( XPTR( ref_cxy , &mutex_ptr->list ) );
    xlist_root_init( XPTR( ref_cxy , &mutex_ptr->root ) );
    hal_remote_s64( XPTR( ref_cxy , &mutex_ptr->owner ) , XPTR_NULL );
    remote_busylock_init( XPTR( ref_cxy , &mutex_ptr->lock ), LOCK_MUTEX_STATE );

    // get root of mutexes list in process, and list_entry in mutex
    xptr_t root_xp = XPTR( ref_cxy , &ref_ptr->mutex_root );
    xptr_t xp_list = XPTR( ref_cxy , &mutex_ptr->list );

    // get lock protecting user synchros lists
    remote_queuelock_acquire( XPTR( ref_cxy , &ref_ptr->sync_lock ) );

    // register mutex in process descriptor 
    xlist_add_first( root_xp , xp_list );

    // release lock protecting user synchros lists
    remote_queuelock_release( XPTR( ref_cxy , &ref_ptr->sync_lock ) );

#if DEBUG_MUTEX
thread_t * this = CURRENT_THREAD;
if( (uint32_t)hal_get_cycles() > DEBUG_MUTEX )
printk("\n[%s] : thread[%x,%x] created mutex(%x,%x)\n",
__FUNCTION__, this->process->pid, this->trdid, local_cxy, mutex_ptr );
#endif


    return 0;

}  // end remote_mutex_create()

////////////////////////////////////////////
void remote_mutex_destroy( xptr_t mutex_xp )
{
    // get pointer on local process descriptor
    process_t * process = CURRENT_THREAD->process;

    // get extended pointer on reference process
    xptr_t      ref_xp = process->ref_xp;

    // get reference process cluster and local pointer
    cxy_t       ref_cxy = GET_CXY( ref_xp );
    process_t * ref_ptr = (process_t *)GET_PTR( ref_xp );

    // get mutex cluster and local pointer
    cxy_t            mutex_cxy = GET_CXY( mutex_xp );
    remote_mutex_t * mutex_ptr = (remote_mutex_t *)GET_PTR( mutex_xp );

    // get lock protecting user synchros lists
    remote_queuelock_acquire( XPTR( ref_cxy , &ref_ptr->sync_lock ) );

    // remove mutex from reference process xlist
    xlist_unlink( XPTR( mutex_cxy , &mutex_ptr->list ) );

    // release lock protecting user synchros lists
    remote_queuelock_release( XPTR( ref_cxy , &ref_ptr->sync_lock ) );

    // release memory allocated for mutex descriptor
    kmem_remote_free( mutex_cxy , mutex_ptr , bits_log2(sizeof(remote_mutex_t)) );

}  // end remote_mutex_destroy()

/////////////////////////////////////////
void remote_mutex_lock( xptr_t mutex_xp )
{ 
    // get cluster and pointers on calling thread
    cxy_t            caller_cxy = local_cxy;
    thread_t       * caller_ptr = CURRENT_THREAD;
    xptr_t           caller_xp  = XPTR( caller_cxy , caller_ptr );

    // check calling thread can yield
    thread_assert_can_yield( caller_ptr , __FUNCTION__ );

    // get cluster and local pointer on mutex
    remote_mutex_t * mutex_ptr = GET_PTR( mutex_xp );
    cxy_t            mutex_cxy = GET_CXY( mutex_xp );

    // get extended pointers on mutex fields 
    xptr_t           taken_xp = XPTR( mutex_cxy , &mutex_ptr->taken );
    xptr_t           owner_xp = XPTR( mutex_cxy , &mutex_ptr->owner );
    xptr_t           root_xp  = XPTR( mutex_cxy , &mutex_ptr->root );
    xptr_t           lock_xp  = XPTR( mutex_cxy , &mutex_ptr->lock );

    while( 1 )
    {
        // get busylock protecting mutex state
        remote_busylock_acquire( lock_xp );

        // test mutex state
        if( hal_remote_l32( taken_xp ) == 0 )                 // success
        {
            // register calling thread as mutex owner
            hal_remote_s64( owner_xp , caller_xp );

            // update mutex state
            hal_remote_s32( taken_xp , 1 );

#if DEBUG_MUTEX
thread_t * this = CURRENT_THREAD;
if( (uint32_t)hal_get_cycles() > DEBUG_MUTEX )
printk("\n[%s] thread[%x,%x] SUCCESS on mutex(%x,%x)\n",
__FUNCTION__, this->process->pid, this->trdid, mutex_cxy, mutex_ptr );
#endif

            // release busylock protecting mutex state
            remote_busylock_release( lock_xp ); 

             return;
        }
        else                                                 //  already taken
        {
            // block the calling thread   
            thread_block( caller_xp , THREAD_BLOCKED_USERSYNC );

            // register calling thread in mutex waiting queue
            xptr_t entry_xp = XPTR( caller_cxy , &caller_ptr->wait_xlist );
            xlist_add_last( root_xp , entry_xp );

#if DEBUG_MUTEX
thread_t * this = CURRENT_THREAD;
if( (uint32_t)hal_get_cycles() > DEBUG_MUTEX )
printk("\n[%s] thread[%x,%x] BLOCKED on mutex(%x,%x)\n",
__FUNCTION__, this->process->pid, this->trdid, mutex_cxy, mutex_ptr );
#endif

            // release busylock protecting mutex state
            remote_busylock_release( lock_xp ); 

            // deschedule calling thread
            sched_yield("blocked on mutex");
        }
    }  
}  // end remote_mutex_lock()

//////////////////////////////////////////////
error_t remote_mutex_unlock( xptr_t mutex_xp )
{
    // memory barrier before mutex release
    hal_fence();

    // get cluster and local pointer on mutex
    remote_mutex_t * mutex_ptr = GET_PTR( mutex_xp );
    cxy_t            mutex_cxy = GET_CXY( mutex_xp );

    // get cluster and pointers on calling thread
    cxy_t            caller_cxy = local_cxy;
    thread_t       * caller_ptr = CURRENT_THREAD;
    xptr_t           caller_xp  = XPTR( caller_cxy , caller_ptr );

    // get extended pointers on mutex fields 
    xptr_t           taken_xp = XPTR( mutex_cxy , &mutex_ptr->taken );
    xptr_t           owner_xp = XPTR( mutex_cxy , &mutex_ptr->owner );
    xptr_t           root_xp  = XPTR( mutex_cxy , &mutex_ptr->root );
    xptr_t           lock_xp  = XPTR( mutex_cxy , &mutex_ptr->lock );

    // get busylock protecting mutex state
    remote_busylock_acquire( lock_xp );
    
    // check calling thread is mutex owner
    if( hal_remote_l64( owner_xp ) != caller_xp )
    {
        // release busylock protecting mutex state
        remote_busylock_release( lock_xp );

        return 0xFFFFFFFF;
    }

#if DEBUG_MUTEX
thread_t * this = CURRENT_THREAD;
if( (uint32_t)hal_get_cycles() > DEBUG_MUTEX )
printk("\n[%s] thread[%x,%x] EXIT / mutex(%x,%x)\n",
__FUNCTION__, this->process->pid, this->trdid, mutex_cxy, mutex_ptr );
#endif

    // update owner field, 
    hal_remote_s64( owner_xp , XPTR_NULL );

    // update taken field
    hal_remote_s32( taken_xp , 0 );

    // unblock first waiting thread if waiting list non empty
    if( xlist_is_empty( root_xp ) == false )
    {
        // get extended pointer on first waiting thread
        xptr_t     thread_xp  = XLIST_FIRST( root_xp , thread_t , wait_xlist );
        thread_t * thread_ptr = GET_PTR( thread_xp );
        cxy_t      thread_cxy = GET_CXY( thread_xp );

#if DEBUG_MUTEX
if( (uint32_t)hal_get_cycles() > DEBUG_MUTEX )
{
trdid_t     trdid   = hal_remote_l32( XPTR( thread_cxy , &thread_ptr->trdid ) );
process_t * process = hal_remote_lpt( XPTR( thread_cxy , &thread_ptr->process ) );
pid_t       pid     = hal_remote_l32( XPTR( thread_cxy , &process->pid ) );
printk("\n[%s] thread[%x,%x] UNBLOCK thread %x in process %d / mutex(%x,%x)\n",
__FUNCTION__, this->process->pid, this->trdid, trdid, pid, mutex_cxy, mutex_ptr );
}
#endif

        // remove this thread from waiting queue
        xlist_unlink( XPTR( thread_cxy , &thread_ptr->wait_xlist ) );

        // unblock first waiting thread
        thread_unblock( thread_xp , THREAD_BLOCKED_USERSYNC ); 
    }
    
    // release busylock protecting mutex state
    remote_busylock_release( lock_xp );

    return 0;

}  // end remote_mutex_unlock()

///////////////////////////////////////////////
error_t remote_mutex_trylock( xptr_t mutex_xp )
{
    // get cluster and local pointer on mutex
    remote_mutex_t * mutex_ptr = GET_PTR( mutex_xp );
    cxy_t            mutex_cxy = GET_CXY( mutex_xp );

    // get cluster and pointers on calling thread
    cxy_t            caller_cxy = local_cxy;
    thread_t       * caller_ptr = CURRENT_THREAD;
    xptr_t           caller_xp  = XPTR( caller_cxy , caller_ptr );

    // get extended pointers on mutex fields 
    xptr_t           taken_xp = XPTR( mutex_cxy , &mutex_ptr->taken );
    xptr_t           owner_xp = XPTR( mutex_cxy , &mutex_ptr->owner );
    xptr_t           lock_xp  = XPTR( mutex_cxy , &mutex_ptr->lock );

    // get busylock protecting mutex state
    remote_busylock_acquire( lock_xp );

    // test mutex state
    if( hal_remote_l32( taken_xp ) == 0 )                 // success
    {
        // register calling thread as mutex owner
        hal_remote_s64( owner_xp , caller_xp );

        // update mutex state
        hal_remote_s32( taken_xp , 1 );

#if DEBUG_MUTEX
thread_t * this = CURRENT_THREAD;
if( (uint32_t)hal_get_cycles() > DEBUG_QUEUELOCK )
printk("\n[%s] SUCCESS for thread[%x,%x] / mutex(%x,%x)\n",
__FUNCTION__, this->process->pid, this->trdid, mutex_cxy, mutex_ptr );
#endif
        // release busylock protecting mutex state
        remote_busylock_release( lock_xp ); 

        return 0;
    }
    else                                                 //  already taken
    {

#if DEBUG_MUTEX
thread_t * this = CURRENT_THREAD;
if( (uint32_t)hal_get_cycles() > DEBUG_QUEUELOCK )
printk("\n[%s] FAILURE for thread[%x,%x] / mutex(%x,%x)\n",
__FUNCTION__, this->process->pid, this->trdid, mutex_cxy, mutex_ptr );
#endif
        // release busylock protecting mutex state
        remote_busylock_release( lock_xp ); 

        return 0xFFFFFFFF;
    }
}  // end remote_mutex_trylock()
