#include #include #include #include #include #include \"msecond.h\" #include \"random_int.h\" float total_time_spent_waiting = 0.0; int total_number_of_meals = 0; #define semaphore_create(s,v) sem_init( &s, 0, v ) #define semaphore_wait(s) sem_wait( &s ) #define semaphore_signal(s) sem_post( &s ) #define semaphore_release(s) sem_destroy( &s ) typedef sem_t semaphore; semaphore chopstick[NUM_PHILOSOPHERS]; semaphore screen; semaphore mutex; int screen_row[NUM_PHILOSOPHERS] = { 6, 2, 2, 6, 10 }; int screen_col[NUM_PHILOSOPHERS] = { 31, 36, 44, 49, 40 }; int chopstick_row[5] = { 9, 4, 3, 4, 9 }; int chopstick_col[5] = { 35, 33, 40, 47, 45 }; char chopstick_sym[5] = { \'/\', \'\\\\\', \'|\', \'/\', \'\\\\\' }; for ( i = 0; i < NUM_PHILOSOPHERS; i++ ) { position( screen_row[i], screen_col[i] ); printf( \"%d\", i ); position( screen_row[i] + 1, screen_col[i] - 1 ); printf( \"(%d)\", 0 ); position( chopstick_row[i], chopstick_col[i] ); printf( \"%c\", chopstick_sym[i] ); } position_flush( 13, 1 ); } void draw_thinking( int n ) { semaphore_wait( screen ); position( screen_row[n], screen_col[n] ); position_flush( 13, 1 ); semaphore_signal( screen ); } void draw_hungry( int n ) { semaphore_wait( screen ); position( screen_row[n], screen_col[n] ); position_flush( 13, 1 ); semaphore_signal( screen ); } void draw_eating( int n, int eat_count ) { semaphore_wait( screen ); position( screen_row[n], screen_col[n] ); position( screen_row[n] + 1, screen_col[n] - 1 ); printf( \"(%d)\", eat_count ); position_flush( 13, 1 ); semaphore_signal( screen ); } void draw_chopstick_up( int n ) { semaphore_wait( screen ); position( chopstick_row[n], chopstick_col[n] ); printf( \"%c\", \' \' ); position_flush( 13, 1 ); semaphore_signal( screen ); } void draw_chopstick_down( int n ) { semaphore_wait( screen ); position( chopstick_row[n], chopstick_col[n] ); position_flush( 13, 1 ); semaphore_signal( screen ); } void draw_done( int n ) { semaphore_wait( screen ); position( screen_row[n], screen_col[n] ); printf( \"D\" ); position_flush( 13, 1 ); semaphore_signal( screen ); } void chopsticks( int n ) { if ( n % 2 == 0 ) { semaphore_wait( chopstick[(n+1) % NUM_PHILOSOPHERS] ); draw_chopstick_up( (n+1) % NUM_PHILOSOPHERS ); semaphore_wait( chopstick[n] ); draw_chopstick_up( n ); } else { semaphore_wait( chopstick[n] ); draw_chopstick_up( n ); semaphore_wait( chopstick[(n+1) % NUM_PHILOSOPHERS] ); draw_chopstick_up( (n+1) % NUM_PHILOSOPHERS ); } } void release_chopsticks( int n ) { draw_chopstick_down( n ); semaphore_signal( chopstick[n] ); draw_chopstick_down( (n+1) % NUM_PHILOSOPHERS ); semaphore_signal( chopstick[(n+1) % NUM_PHILOSOPHERS] ); } void philosopher( int *philosopher_data ) { int start_time; int eat_count = 0; int total_hungry_time = 0; int became_hungry_time; int n = philosopher_data[0]; int duration = philosopher_data[1]; start_time = msecond(); while( msecond() - start_time < duration * 1000 ) { became_hungry_time = msecond(); draw_hungry( n ); chopsticks( n ); t.

1. #include
#include
#include
#include
#include
#include "msecond.h"
#include "random_int.h"
float total_time_spent_waiting = 0.0;
int total_number_of_meals = 0;
#define semaphore_create(s,v) sem_init( &s, 0, v )
#define semaphore_wait(s) sem_wait( &s )
#define semaphore_signal(s) sem_post( &s )
#define semaphore_release(s) sem_destroy( &s )
typedef sem_t semaphore;
semaphore chopstick[NUM_PHILOSOPHERS];
semaphore screen;
semaphore mutex;
int screen_row[NUM_PHILOSOPHERS] = { 6, 2, 2, 6, 10 };
int screen_col[NUM_PHILOSOPHERS] = { 31, 36, 44, 49, 40 };
int chopstick_row[5] = { 9, 4, 3, 4, 9 };
int chopstick_col[5] = { 35, 33, 40, 47, 45 };
char chopstick_sym[5] = { '/', '', '|', '/', '' };
for ( i = 0; i < NUM_PHILOSOPHERS; i++ )
{
position( screen_row[i], screen_col[i] );
printf( "%d", i );
position( screen_row[i] + 1, screen_col[i] - 1 );
printf( "(%d)", 0 );
position( chopstick_row[i], chopstick_col[i] );
printf( "%c", chopstick_sym[i] );
}
position_flush( 13, 1 );
}
void draw_thinking( int n )

2. {
semaphore_wait( screen );
position( screen_row[n], screen_col[n] );
position_flush( 13, 1 );
semaphore_signal( screen );
}
void draw_hungry( int n )
{
semaphore_wait( screen );
position( screen_row[n], screen_col[n] );
position_flush( 13, 1 );
semaphore_signal( screen );
}
void draw_eating( int n, int eat_count )
{
semaphore_wait( screen );
position( screen_row[n], screen_col[n] );
position( screen_row[n] + 1, screen_col[n] - 1 );
printf( "(%d)", eat_count );
position_flush( 13, 1 );
semaphore_signal( screen );
}
void draw_chopstick_up( int n )
{
semaphore_wait( screen );
position( chopstick_row[n], chopstick_col[n] );
printf( "%c", ' ' );
position_flush( 13, 1 );
semaphore_signal( screen );
}
void draw_chopstick_down( int n )
{
semaphore_wait( screen );
position( chopstick_row[n], chopstick_col[n] );
position_flush( 13, 1 );
semaphore_signal( screen );

3. }
void draw_done( int n )
{
semaphore_wait( screen );
position( screen_row[n], screen_col[n] );
printf( "D" );
position_flush( 13, 1 );
semaphore_signal( screen );
}
void chopsticks( int n )
{
if ( n % 2 == 0 ) {
semaphore_wait( chopstick[(n+1) % NUM_PHILOSOPHERS] );
draw_chopstick_up( (n+1) % NUM_PHILOSOPHERS );
semaphore_wait( chopstick[n] );
draw_chopstick_up( n );
} else {
semaphore_wait( chopstick[n] );
draw_chopstick_up( n );
semaphore_wait( chopstick[(n+1) % NUM_PHILOSOPHERS] );
draw_chopstick_up( (n+1) % NUM_PHILOSOPHERS );
}
}
void release_chopsticks( int n )
{
draw_chopstick_down( n );
semaphore_signal( chopstick[n] );
draw_chopstick_down( (n+1) % NUM_PHILOSOPHERS );
semaphore_signal( chopstick[(n+1) % NUM_PHILOSOPHERS] );
}
void philosopher( int *philosopher_data )
{
int start_time;
int eat_count = 0;

4. int total_hungry_time = 0;
int became_hungry_time;
int n = philosopher_data[0];
int duration = philosopher_data[1];
start_time = msecond();
while( msecond() - start_time < duration * 1000 )
{
became_hungry_time = msecond();
draw_hungry( n );
chopsticks( n );
total_hungry_time += ( msecond() - became_hungry_time );
eat_count++;
draw_eating( n, eat_count );
usleep( 1000L * random_int( MEAN_EAT_TIME ) );
release_chopsticks( n );
draw_thinking( n );
usleep( 1000L * random_int( MEAN_THINK_TIME ) );
}
draw_done( n );
semaphore_wait( mutex );
total_number_of_meals += eat_count;
total_time_spent_waiting += ( total_hungry_time / 1000.0 );
semaphore_signal( mutex );
pthread_exit( NULL );
}
int main( int argc, char *argv[] )
{
pthread_t phil[NUM_PHILOSOPHERS];
int philosopher_data[NUM_PHILOSOPHERS][2];
int duration;
int i;
duration = ( argc > 1 ? atoi( argv[1] ) : 10 );
for ( i = 0; i < NUM_PHILOSOPHERS; i++ )
{

5. if ( semaphore_create( chopstick[i], 1 ) < 0 ) {
fprintf( stderr, "cannot create chopstick semaphore " );
exit( 1 );
}
}
if ( semaphore_create( screen, 1 ) < 0 ) {
fprintf( stderr, "cannot create screen semaphore " );
exit( 1 );
}
if ( semaphore_create( mutex, 1 ) < 0 ) {
fprintf( stderr, "cannot create mutex semaphore " );
exit( 1 );
}
screen_print();
for ( i = 0; i < NUM_PHILOSOPHERS; i++ )
{
philosopher_data[i][0] = i;
philosopher_data[i][1] = duration;
if ( pthread_create( &phil[i], NULL, (void *(*)(void *)) &philosopher,
&philosopher_data[i] ) != 0 ) {
fprintf( stderr, "cannot create thread for philosopher %d ", i );
exit( 1 );
}
}
for ( i = 0; i < NUM_PHILOSOPHERS; i++ )
{
pthread_join( phil[i], NULL );
}
for ( i = 0; i < NUM_PHILOSOPHERS; i++ )
{
semaphore_release( chopstick[i] );
}
semaphore_release( screen );
semaphore_release( mutex );
position( 13, 1 );
printf( "Total meals served = %d ", total_number_of_meals );

6. printf( "Average hungry time = %f ",
total_time_spent_waiting / total_number_of_meals );
return 0;
}
Solution
#include
#include
#include
#include
#include
#include "msecond.h"
#include "random_int.h"
float total_time_spent_waiting = 0.0;
int total_number_of_meals = 0;
#define semaphore_create(s,v) sem_init( &s, 0, v )
#define semaphore_wait(s) sem_wait( &s )
#define semaphore_signal(s) sem_post( &s )
#define semaphore_release(s) sem_destroy( &s )
typedef sem_t semaphore;
semaphore chopstick[NUM_PHILOSOPHERS];
semaphore screen;
semaphore mutex;
int screen_row[NUM_PHILOSOPHERS] = { 6, 2, 2, 6, 10 };
int screen_col[NUM_PHILOSOPHERS] = { 31, 36, 44, 49, 40 };
int chopstick_row[5] = { 9, 4, 3, 4, 9 };
int chopstick_col[5] = { 35, 33, 40, 47, 45 };
char chopstick_sym[5] = { '/', '', '|', '/', '' };
for ( i = 0; i < NUM_PHILOSOPHERS; i++ )
{
position( screen_row[i], screen_col[i] );
printf( "%d", i );
position( screen_row[i] + 1, screen_col[i] - 1 );
printf( "(%d)", 0 );

7. position( chopstick_row[i], chopstick_col[i] );
printf( "%c", chopstick_sym[i] );
}
position_flush( 13, 1 );
}
void draw_thinking( int n )
{
semaphore_wait( screen );
position( screen_row[n], screen_col[n] );
position_flush( 13, 1 );
semaphore_signal( screen );
}
void draw_hungry( int n )
{
semaphore_wait( screen );
position( screen_row[n], screen_col[n] );
position_flush( 13, 1 );
semaphore_signal( screen );
}
void draw_eating( int n, int eat_count )
{
semaphore_wait( screen );
position( screen_row[n], screen_col[n] );
position( screen_row[n] + 1, screen_col[n] - 1 );
printf( "(%d)", eat_count );
position_flush( 13, 1 );
semaphore_signal( screen );
}
void draw_chopstick_up( int n )
{
semaphore_wait( screen );
position( chopstick_row[n], chopstick_col[n] );
printf( "%c", ' ' );
position_flush( 13, 1 );
semaphore_signal( screen );
}

8. void draw_chopstick_down( int n )
{
semaphore_wait( screen );
position( chopstick_row[n], chopstick_col[n] );
position_flush( 13, 1 );
semaphore_signal( screen );
}
void draw_done( int n )
{
semaphore_wait( screen );
position( screen_row[n], screen_col[n] );
printf( "D" );
position_flush( 13, 1 );
semaphore_signal( screen );
}
void chopsticks( int n )
{
if ( n % 2 == 0 ) {
semaphore_wait( chopstick[(n+1) % NUM_PHILOSOPHERS] );
draw_chopstick_up( (n+1) % NUM_PHILOSOPHERS );
semaphore_wait( chopstick[n] );
draw_chopstick_up( n );
} else {
semaphore_wait( chopstick[n] );
draw_chopstick_up( n );
semaphore_wait( chopstick[(n+1) % NUM_PHILOSOPHERS] );
draw_chopstick_up( (n+1) % NUM_PHILOSOPHERS );
}
}
void release_chopsticks( int n )
{
draw_chopstick_down( n );
semaphore_signal( chopstick[n] );
draw_chopstick_down( (n+1) % NUM_PHILOSOPHERS );

9. semaphore_signal( chopstick[(n+1) % NUM_PHILOSOPHERS] );
}
void philosopher( int *philosopher_data )
{
int start_time;
int eat_count = 0;
int total_hungry_time = 0;
int became_hungry_time;
int n = philosopher_data[0];
int duration = philosopher_data[1];
start_time = msecond();
while( msecond() - start_time < duration * 1000 )
{
became_hungry_time = msecond();
draw_hungry( n );
chopsticks( n );
total_hungry_time += ( msecond() - became_hungry_time );
eat_count++;
draw_eating( n, eat_count );
usleep( 1000L * random_int( MEAN_EAT_TIME ) );
release_chopsticks( n );
draw_thinking( n );
usleep( 1000L * random_int( MEAN_THINK_TIME ) );
}
draw_done( n );
semaphore_wait( mutex );
total_number_of_meals += eat_count;
total_time_spent_waiting += ( total_hungry_time / 1000.0 );
semaphore_signal( mutex );
pthread_exit( NULL );
}
int main( int argc, char *argv[] )
{
pthread_t phil[NUM_PHILOSOPHERS];

10. int philosopher_data[NUM_PHILOSOPHERS][2];
int duration;
int i;
duration = ( argc > 1 ? atoi( argv[1] ) : 10 );
for ( i = 0; i < NUM_PHILOSOPHERS; i++ )
{
if ( semaphore_create( chopstick[i], 1 ) < 0 ) {
fprintf( stderr, "cannot create chopstick semaphore " );
exit( 1 );
}
}
if ( semaphore_create( screen, 1 ) < 0 ) {
fprintf( stderr, "cannot create screen semaphore " );
exit( 1 );
}
if ( semaphore_create( mutex, 1 ) < 0 ) {
fprintf( stderr, "cannot create mutex semaphore " );
exit( 1 );
}
screen_print();
for ( i = 0; i < NUM_PHILOSOPHERS; i++ )
{
philosopher_data[i][0] = i;
philosopher_data[i][1] = duration;
if ( pthread_create( &phil[i], NULL, (void *(*)(void *)) &philosopher,
&philosopher_data[i] ) != 0 ) {
fprintf( stderr, "cannot create thread for philosopher %d ", i );
exit( 1 );
}
}
for ( i = 0; i < NUM_PHILOSOPHERS; i++ )
{
pthread_join( phil[i], NULL );
}
for ( i = 0; i < NUM_PHILOSOPHERS; i++ )
{

11. semaphore_release( chopstick[i] );
}
semaphore_release( screen );
semaphore_release( mutex );
position( 13, 1 );
printf( "Total meals served = %d ", total_number_of_meals );
printf( "Average hungry time = %f ",
total_time_spent_waiting / total_number_of_meals );
return 0;
}