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// Copyright (c) 2000-2003 Intel Corporation 
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#include "TimerThread.h"
#include <assert.h>

/****************************************************************************
 * Function: FreeTimerEvent
 *
 *  Description:
 *      Deallocates a dynamically allocated TimerEvent.
 *  Parameters:
 *      TimerEvent *event - must be allocated with CreateTimerEvent
 *****************************************************************************/
static void
FreeTimerEvent( TimerThread * timer,
                TimerEvent * event )
{

    assert( timer != NULL );

    FreeListFree( &timer->freeEvents, event );
}

/****************************************************************************
 * Function: TimerThreadWorker
 *
 *  Description:
 *      Implements timer thread.
 *      Waits for next event to occur and schedules
 *      associated job into threadpool.
 *      Internal Only.
 *  Parameters:
 *      void * arg -> is cast to TimerThread *
 *****************************************************************************/
static void *
TimerThreadWorker( void *arg )
{
    TimerThread *timer = ( TimerThread * ) arg;
    ListNode *head = NULL;

    TimerEvent *nextEvent = NULL;

    time_t currentTime = 0;
    time_t nextEventTime = 0;
    struct timespec timeToWait;

    int tempId;

    assert( timer != NULL );

    ithread_mutex_lock( &timer->mutex );

    while( 1 )
    {

        //mutex should always be locked at top of loop

        //Check for shutdown

        if( timer->shutdown )
        {

            timer->shutdown = 0;
            ithread_cond_signal( &timer->condition );
            ithread_mutex_unlock( &timer->mutex );
            return NULL;

        }

        nextEvent = NULL;

        //Get the next event if possible
        if( timer->eventQ.size > 0 )
        {
            head = ListHead( &timer->eventQ );

            nextEvent = ( TimerEvent * ) head->item;
            nextEventTime = nextEvent->eventTime;
        }

        currentTime = time( NULL );

        //If time has elapsed, schedule job

        if( ( nextEvent != NULL ) && ( currentTime >= nextEventTime ) )
        {

            if( nextEvent->persistent ) {

                ThreadPoolAddPersistent( timer->tp, &nextEvent->job,
                                         &tempId );
            } else {

                ThreadPoolAdd( timer->tp, &nextEvent->job, &tempId );
            }

            ListDelNode( &timer->eventQ, head, 0 );
            FreeTimerEvent( timer, nextEvent );

            continue;

        }

        if( nextEvent != NULL ) {
            timeToWait.tv_nsec = 0;
            timeToWait.tv_sec = nextEvent->eventTime;

            ithread_cond_timedwait( &timer->condition, &timer->mutex,
                                    &timeToWait );

        } else {
            ithread_cond_wait( &timer->condition, &timer->mutex );
        }

    }
}

/****************************************************************************
 * Function: CalculateEventTime
 *
 *  Description:
 *      Calculates the appropriate timeout in absolute seconds since
 *      Jan 1, 1970
 *      Internal Only.
 *  Parameters:
 *      time_t *timeout - timeout
 *      
 *****************************************************************************/
static int
CalculateEventTime( time_t * timeout,
                    TimeoutType type )
{
    time_t now;

    assert( timeout != NULL );

    if( type == ABS_SEC )
        return 0;
    else if( type == REL_SEC ) {
        time( &now );
        ( *timeout ) += now;
        return 0;
    }

    return -1;

}

/****************************************************************************
 * Function: CreateTimerEvent
 *
 *  Description:
 *      Creates a Timer Event. (Dynamically allocated)
 *      Internal to timer thread.
 *  Parameters:
 *      func - thread function to run.
 *      arg - argument to function.
 *      priority - priority of job.
 *      eventTime - the absoule time of the event
 *                  in seconds from Jan, 1970
 *      id - id of job
 *      
 *  Returns:
 *      TimerEvent * on success, NULL on failure.
 ****************************************************************************/
static TimerEvent *
CreateTimerEvent( TimerThread * timer,
                  ThreadPoolJob * job,
                  Duration persistent,
                  time_t eventTime,
                  int id )
{
    TimerEvent *temp = NULL;

    assert( timer != NULL );
    assert( job != NULL );

    temp = ( TimerEvent * ) FreeListAlloc( &timer->freeEvents );
    if( temp == NULL )
        return temp;
    temp->job = ( *job );
    temp->persistent = persistent;
    temp->eventTime = eventTime;
    temp->id = id;

    return temp;
}

/************************************************************************
 * Function: TimerThreadInit
 * 
 *  Description:
 *     Initializes and starts timer thread.
 *
 *  Parameters:
 *             timer - valid timer thread pointer.
 *             tp  - valid thread pool to use. Must be
 *                   started. Must be valid for lifetime
 *                   of timer.  Timer must be shutdown
 *                   BEFORE thread pool.
 *  Return:
 *            0 on success, nonzero on failure
 *            Returns error from ThreadPoolAddPersistent if failure.
 ************************************************************************/
int
TimerThreadInit( TimerThread * timer,
                 ThreadPool * tp )
{

    int rc = 0;

    ThreadPoolJob timerThreadWorker;

    assert( timer != NULL );
    assert( tp != NULL );

    if( ( timer == NULL ) || ( tp == NULL ) ) {
        return EINVAL;
    }

    rc += ithread_mutex_init( &timer->mutex, NULL );

    assert( rc == 0 );

    rc += ithread_mutex_lock( &timer->mutex );
    assert( rc == 0 );

    rc += ithread_cond_init( &timer->condition, NULL );
    assert( rc == 0 );

    rc += FreeListInit( &timer->freeEvents, sizeof( TimerEvent ), 100 );
    assert( rc == 0 );

    timer->shutdown = 0;
    timer->tp = tp;
    timer->lastEventId = 0;
    rc += ListInit( &timer->eventQ, NULL, NULL );

    assert( rc == 0 );

    if( rc != 0 ) {
        rc = EAGAIN;
    } else {

        TPJobInit( &timerThreadWorker, TimerThreadWorker, timer );
        TPJobSetPriority( &timerThreadWorker, HIGH_PRIORITY );

        rc = ThreadPoolAddPersistent( tp, &timerThreadWorker, NULL );
    }

    ithread_mutex_unlock( &timer->mutex );

    if( rc != 0 ) {
        ithread_cond_destroy( &timer->condition );
        ithread_mutex_destroy( &timer->mutex );
        FreeListDestroy( &timer->freeEvents );
        ListDestroy( &timer->eventQ, 0 );
    }

    return rc;

}

/************************************************************************
 * Function: TimerThreadSchedule
 * 
 *  Description:
 *     Schedules an event to run at a specified time.
 *
 *  Parameters:
 *             timer - valid timer thread pointer.
 *             time_t - time of event.
 *                      either in absolute seconds,
 *                      or relative seconds in the future.
 *             timeoutType - either ABS_SEC, or REL_SEC.
 *                           if REL_SEC, then the event
 *                           will be scheduled at the
 *                           current time + REL_SEC.
 *             
 *             func - function to schedule
 *             arg - argument to function
 *             priority - priority of job.
 *             id - id of timer event. (out)
 *  Return:
 *            0 on success, nonzero on failure
 *			  EOUTOFMEM if not enough memory to schedule job
 ************************************************************************/
int
TimerThreadSchedule( TimerThread * timer,
                     time_t timeout,
                     TimeoutType type,
                     ThreadPoolJob * job,
                     Duration duration,
                     int *id )
{

    int rc = EOUTOFMEM;
    int found = 0;
    int tempId = 0;

    ListNode *tempNode = NULL;
    TimerEvent *temp = NULL;
    TimerEvent *newEvent = NULL;

    assert( timer != NULL );
    assert( job != NULL );

    if( ( timer == NULL ) || ( job == NULL ) ) {
        return EINVAL;
    }

    CalculateEventTime( &timeout, type );
    ithread_mutex_lock( &timer->mutex );

    if( id == NULL )
        id = &tempId;

    ( *id ) = INVALID_EVENT_ID;

    newEvent = CreateTimerEvent( timer, job, duration, timeout,
                                 timer->lastEventId );

    if( newEvent == NULL ) {
        ithread_mutex_unlock( &timer->mutex );
        return rc;
    }

    tempNode = ListHead( &timer->eventQ );
    //add job to Q
    //Q is ordered by eventTime
    //with the head of the Q being the next event

    while( tempNode != NULL ) {
        temp = ( TimerEvent * ) tempNode->item;
        if( temp->eventTime >= timeout )
        {

            if( ListAddBefore( &timer->eventQ, newEvent, tempNode ) !=
                NULL )
                rc = 0;
            found = 1;
            break;

        }
        tempNode = ListNext( &timer->eventQ, tempNode );
    }

    //add to the end of Q
    if( !found ) {

        if( ListAddTail( &timer->eventQ, newEvent ) != NULL )
            rc = 0;

    }
    //signal change in Q
    if( rc == 0 ) {

        ithread_cond_signal( &timer->condition );
    } else {
        FreeTimerEvent( timer, newEvent );
    }
    ( *id ) = timer->lastEventId++;
    ithread_mutex_unlock( &timer->mutex );

    return rc;
}

/************************************************************************
 * Function: TimerThreadRemove
 * 
 *  Description:
 *     Removes an event from the timer Q.
 *     Events can only be removed 
 *     before they have been placed in the
 *     thread pool.
 *
 *  Parameters:
 *             timer - valid timer thread pointer.
 *             id - id of event to remove.
 *             out - space for returned job (Can be NULL)
 *  Return:
 *            0 on success.
 *            INVALID_EVENT_ID on error.
 *
 ************************************************************************/
int
TimerThreadRemove( TimerThread * timer,
                   int id,
                   ThreadPoolJob * out )
{
    int rc = INVALID_EVENT_ID;
    ListNode *tempNode = NULL;
    TimerEvent *temp = NULL;

    assert( timer != NULL );

    if( timer == NULL ) {
        return EINVAL;
    }

    ithread_mutex_lock( &timer->mutex );

    tempNode = ListHead( &timer->eventQ );

    while( tempNode != NULL ) {
        temp = ( TimerEvent * ) tempNode->item;
        if( temp->id == id )
        {

            ListDelNode( &timer->eventQ, tempNode, 0 );
            if( out != NULL )
                ( *out ) = temp->job;
            FreeTimerEvent( timer, temp );
            rc = 0;
            break;
        }
        tempNode = ListNext( &timer->eventQ, tempNode );
    }

    ithread_mutex_unlock( &timer->mutex );
    return rc;
}

/************************************************************************
 * Function: TimerThreadShutdown
 * 
 *  Description:
 *    Shutdown the timer thread
 *    Events scheduled in the future will NOT be run.
 *    Timer thread should be shutdown BEFORE it's associated
 *    thread pool.
 *  Returns:
 *    returns 0 if succesfull,
 *            nonzero otherwise.
 *            Always returns 0.
 ***********************************************************************/
int
TimerThreadShutdown( TimerThread * timer )
{
    ListNode *tempNode2 = NULL;
    ListNode *tempNode = NULL;

    assert( timer != NULL );

    if( timer == NULL ) {
        return EINVAL;
    }

    ithread_mutex_lock( &timer->mutex );

    timer->shutdown = 1;
    tempNode = ListHead( &timer->eventQ );

    //Delete nodes in Q
    //call registered free function 
    //on argument
    while( tempNode != NULL ) {
        TimerEvent *temp = ( TimerEvent * ) tempNode->item;

        tempNode2 = ListNext( &timer->eventQ, tempNode );
        ListDelNode( &timer->eventQ, tempNode, 0 );
        if( temp->job.free_func ) {
            temp->job.free_func( temp->job.arg );
        }
        FreeTimerEvent( timer, temp );
        tempNode = tempNode2;
    }

    ListDestroy( &timer->eventQ, 0 );
    FreeListDestroy( &timer->freeEvents );

    ithread_cond_broadcast( &timer->condition );

    while( timer->shutdown )    //wait for timer thread to shutdown
    {
        ithread_cond_wait( &timer->condition, &timer->mutex );
    }

    ithread_mutex_unlock( &timer->mutex );

    //destroy condition
    while( ithread_cond_destroy( &timer->condition ) != 0 ) {
    }

    //destroy mutex
    while( ithread_mutex_destroy( &timer->mutex ) != 0 ) {
    }

    return 0;
}