OOScriptTimer.m

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/*
 
OOScriptTimer.m
 
 
Oolite
Copyright (C) 2004-2013 Giles C Williams and contributors
 
This program 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; either version 2
of the License, or (at your option) any later version.
 
This program 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 this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
MA 02110-1301, USA.
 
*/
 
#import "OOScriptTimer.h"
#import "Universe.h"
#import "OOLogging.h"
#import "OOPriorityQueue.h"
 
 
static OOPriorityQueue  *sTimers;
 
// During an update, new timers must be deferred to avoid an infinite loop.
static BOOL             sUpdating;
static NSMutableArray   *sDeferredTimers;
 
 
@implementation OOScriptTimer
 
- (id) initWithNextTime:(OOTimeAbsolute)nextTime
               interval:(OOTimeDelta)interval
{
    OOTimeAbsolute          now;
    
    if ((self = [super init]))
    {
        if (interval <= 0.0)  interval = -1.0;
        
        now = [UNIVERSE getTime];
        if (nextTime < 0.0)  nextTime = now + interval;
        if (nextTime < now && interval < 0)
        {
            // Negative or old nextTime and negative interval = meaningless.
            [self release];
            self = nil;
        }
        else
        {
            _nextTime = nextTime;
            _interval = interval;
            _hasBeenRun = NO;
        }
    }
    
    return self;
}
 
    // Sets nextTime to current time + delay.
- (id) initOneShotTimerWithDelay:(OOTimeDelta)delay
{
    return [self initWithNextTime:[UNIVERSE getTime] + delay interval:-1.0];
}
 
 
- (void) dealloc
{
    if (_isScheduled)  [self unscheduleTimer];
    
    [super dealloc];
}
 
 
- (NSString *) descriptionComponents
{
    NSString                    *intervalDesc = nil;
    
    if (_interval <= 0.0)  intervalDesc = @"one-shot";
    else  intervalDesc = [NSString stringWithFormat:@"interval: %g", _interval];
        
    return [NSString stringWithFormat:@"nextTime: %g, %@, %srunning", _nextTime, intervalDesc, _isScheduled ? "" : "not "];
}
 
 
- (OOTimeAbsolute)nextTime
{
    return _nextTime;
}
 
 
- (BOOL)setNextTime:(OOTimeAbsolute)nextTime
{
    if (_isScheduled)  return NO;
    
    _nextTime = nextTime;
    return YES;
}
 
 
- (OOTimeDelta)interval
{
    return _interval;
}
 
 
- (void)setInterval:(OOTimeDelta)interval
{
    if (interval <= 0.0)  interval = -1.0;
    _interval = interval;
}
 
 
- (void) timerFired
{
    OOLogGenericSubclassResponsibility();
}
 
 
- (BOOL) scheduleTimer
{
    if (_isScheduled)  return YES;
    if (![self isValidForScheduling])  return NO;
    
    if (EXPECT(!sUpdating))
    {
        if (EXPECT_NOT(sTimers == nil))  sTimers = [[OOPriorityQueue alloc] initWithComparator:@selector(compareByNextFireTime:)];
        [sTimers addObject:self];
    }
    else
    {
        if (sDeferredTimers == nil)  sDeferredTimers = [[NSMutableArray alloc] init];
        [sDeferredTimers addObject:self];
    }
    
    _isScheduled = YES;
    return YES;
}
 
 
- (void) unscheduleTimer
{
    [sTimers removeExactObject:self];
    _isScheduled = NO;
    _hasBeenRun = NO;
}
 
 
- (BOOL) isScheduled
{
    return _isScheduled;
}
 
 
+ (void) updateTimers
{
    OOScriptTimer       *timer = nil;
    OOTimeAbsolute      now;
    
    sUpdating = YES;
    
    now = [UNIVERSE getTime];
    for (;;)
    {
        timer = [sTimers peekAtNextObject];
        if (timer == nil || now < [timer nextTime])  break;
        
        [sTimers removeNextObject];
        
        // Must fire before rescheduling so that the timer callback can stop itself. -- Ahruman 2011-01-01
        [timer timerFired];
        
        timer->_hasBeenRun = YES;
        
        if (timer->_isScheduled)
        {
            timer->_isScheduled = NO;
            [timer scheduleTimer];
        }
    }
    
    if (sDeferredTimers != nil)
    {
        [sTimers addObjects:sDeferredTimers];
        DESTROY(sDeferredTimers);
    }
    
    sUpdating = NO;
}
 
 
+ (void) noteGameReset
{
    NSArray             *timers = nil;
    OOScriptTimer       *timer = nil;
    
    // Intermediate array is required so we don't get stuck in an endless loop over reinserted timers. Note that -sortedObjects also clears the queue!
    timers = [sTimers sortedObjects];
    foreach (timer, timers)
    {
        timer->_isScheduled = NO;
    }
}
 
 
- (BOOL) isValidForScheduling
{
    OOTimeAbsolute      now;
    double              scaled;
    
    now = [UNIVERSE getTime];
    if (_nextTime <= now)
    {
        if (_interval <= 0.0 && _hasBeenRun)  return NO;    // One-shot timer which has expired
        
        // Move _nextTime to the closest future time that's a multiple of _interval
        scaled = (now - _nextTime) / _interval;
        scaled = ceil(scaled);
        _nextTime += scaled * _interval;
        if (_nextTime <= now && _hasBeenRun) 
        {
            // Should only happen if _nextTime is exactly equal to now after previous stuff
            _nextTime += _interval;
        }
    }
    
    return YES;
}
 
- (NSComparisonResult) compareByNextFireTime:(OOScriptTimer *)other
{
    OOTimeAbsolute      otherTime = -INFINITY;
    
    @try
    {
        if (other != nil)  otherTime = [other nextTime];
    }
    @catch (NSException *exception)
    {
        OOLog(kOOLogException, @"\n\n***** Ignoring Timer Exception: %@ : %@ *****\n\n",[exception name], [exception reason]);
    }
    
    if (_nextTime < otherTime) return NSOrderedAscending;
    else if (_nextTime > otherTime) return NSOrderedDescending;
    else  return NSOrderedSame;
}
 
@end