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/*
diningPhilosophers.h
Five hungry philosophers testing locks and threads
This program loops indefinitely.
Copyright (C) 1996 Free Software Foundation, Inc.
Author: Scott Christley <scottc@net-community.com>
Date: 1996
This file is part of the GNUstep Application Kit Library.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library 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
Library General Public License for more details.
If you are interested in a warranty or support for this source code,
contact Scott Christley <scottc@net-community.com> for more information.
You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free
Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <Foundation/NSLock.h>
#include <Foundation/NSThread.h>
// Conditions
#define NO_FOOD 1
#define FOOD_SERVED 2
// NSLocks ... umm I mean forks
id forks[5];
//
// A class of hungry philosophers
//
@interface Philosopher : NSObject
{
int chair;
}
// Instance methods
- (void)sitAtChair:(int)position;
- (int)chair;
@end
@implementation Philosopher
// Instance methods
- (void)sitAtChair:(int)position
{
int i;
// Sit down
chair = position;
// Its a constant battle to feed yourself
while (1)
{
// Get the fork to our left
[forks[chair] lockWhenCondition:FOOD_SERVED];
// Get the fork to our right
[forks[(chair + 1) % 5] lockWhenCondition:FOOD_SERVED];
// Start eating!
printf("Philosopher %d can start eating.\n", chair);
for (i = 0;i < 100000; ++i)
{
if ((i % 10000) == 0)
printf("Philosopher %d is eating.\n", chair);
}
// Done eating
printf("Philosopher %d is done eating.\n", chair);
// Drop the fork to our left
[forks[chair] unlock];
// Drop the fork to our right
[forks[(chair + 1) % 5] unlock];
// Wait until we are hungry again
for (i = 0;i < 1000000 * (chair + 1); ++i) ;
}
// We never get here, but this is what we should do
[NSThread exit];
}
- (int)chair
{
return chair;
}
@end
//
// my main for the test app
//
int main()
{
int i;
id p[5];
#ifdef WIN32
// Initialize ourselves in Obj-C runtime
init_diningPhilosophers();
#endif
// Create the locks
for (i = 0;i < 5; ++i)
{
forks[i] = [[NSConditionLock alloc]
initWithCondition:NO_FOOD];
[forks[i] lock];
}
// Create the philosophers
for (i = 0;i < 5; ++i)
p[i] = [[Philosopher alloc] init];
// Have them sit at the table
for (i = 0;i < 5; ++i)
[NSThread detachNewThreadSelector:@selector(sitAtChair:)
toTarget:p[i] withObject: (id)i];
// Now let them all eat
for (i = 0;i < 5; ++i)
[forks[i] unlockWithCondition:FOOD_SERVED];
while (1);
}
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