#include <stdio.h>
#include "dinningph.h"
DiningPh::DiningPh() {
dp = new Lock();
for ( int i = 0; i < 5; i++ ) {
self[ i ] = new Condition();
state[ i ] = Thinking;
}
}
DiningPh::~DiningPh() {
for ( int i = 0; i < 5; i++ ) {
delete self[ i ];
}
delete dp;
}
void DiningPh::pickup( long who ) {
dp->Acquire();
state[ who ] = Hungry;
test( who );
if ( state[ who ] == Hungry )
self[ who ]->Wait( dp );
dp->Release();
}
void DiningPh::putdown( long who ) {
dp->Acquire();
state[ who ] = Thinking;
test( (who + 4) % 5 );
test( (who + 1) % 5 );
dp->Release();
}
void DiningPh::test( long i ) {
if ( ( state[ (i + 4) % 5 ] != Eating ) &&
( state[ i ] == Hungry ) &&
( state[ (i + 1) % 5] != Eating ) ) {
state[ i ] = Eating;
self[ i ]->Signal( dp );
}
}
void DiningPh::print() {
for ( int i = 0; i < 5; i++ ) {
printf( "Philosopher %d is %s \n", i + 1, (state[i]==Hungry)?"Hungry":(state[i]==Thinking)?"Thinking":"Eating");
}
}
