Complete the following code. The goal is to implement the producer-consumer problem. You are expected to extend the provided C code to synchronize the thread operations consumer() and producer() such that an underflow and overflow of the queue is prevented. You are not allowed to change the code for implementing the queue operations, that is the code between lines 25 and 126 as shown in the screenshot. You must complete the missing parts as shown in the screenshot as well as complete the missing codes of producer and consumer. #include #include #include #include #include #include #include #include #define MAX_LENGTH_CAP 100 #define INIT -127 #define UNDERFLOW (0x80 + 0x02) #define OVERFLOW 0x80 + 0x01 #define BADPTR (0x80 + 0x03) #define CONSUMER_TERMINATION_PROBABILITY 40 #define PRODUCER_TERMINATION_PROBABILITY 30 // ============= LOCKED ============ //sem_t ACCESS; // use a mutex instead of a binary semaphore pthread_mutex_t ACCESS = PTHREAD_MUTEX_INITIALIZER; sem_t *FULLSPOTS; sem_t *EMPTYSPOTS; struct timespec remaining; struct timespec requested_time; struct Queue{ unsignedint head; unsignedint tail; unsignedint length; int8_t* data; }; void enqueue(struct Queue *q, char x) { if(q==NULL) { printf("\nequeue()>> bad queue pointer %x\n", BADPTR); return; } if ( q->head == (q->tail + 1) % q->length){ printf("\nenqueue()>> Attempt to overflow the queue at %p was prevented.\n", q); } else{ // Why is the following commented code wrong (hint: checking for the underflow condition): // wrong: q->tail = (q->tail+1) % q->length; q->data[q->tail] = x; q->data[q->tail-1] = x; // because arrays start at index 0 but our queue starts at index 1 we should write q->data[q->tail-1] = x; // now we must increment the tail if(q->tail == q->length){ q->tail = 1; } else{ q->tail = q->tail + 1; // this line must happen before enqueue is interruption } } } char dequeue(struct Queue *q) { char val; if(q==NULL) { printf("\ndequeue()>> bad queue pointer %x\n", BADPTR); return (char) BADPTR; } if(q->head == q->tail){ printf("\ndequeue()>> Attempt to underflow the queue at %p was prevented.\n", q); return (char) UNDERFLOW; } else{ if(!q->data) // as a rule, we always check pointers before we access them { printf("dequeue()>> bad data pointer %x\n", BADPTR); return (char) BADPTR; } val = q->data[q->head-1]; // because arrays start at index 0 but our queue starts at index 1 we should write q->data[q->head-1]; q->data[q->head-1] = INIT; if (q->head == q->length){ q->head = 1; } else{ q->head = q->head + 1; } } return (char) val; } void build(struct Queue **q, unsigned int length) { printf("\nbuild()>> Building a queue of length %d", length); if( (length == 0) || (length > MAX_LENGTH_CAP) ) { printf("\nbuild()>> Invalid length."); return; } struct Queue *ptr=NULL; if ( ! (ptr = (struct Queue*) malloc(sizeof(struct Queue))) ) { printf("\nbuild()>> Failed to allocate memory for the structure."); return; } printf("\nbuild()>> Allocated memory for the structure at the address %p", ptr); if ((ptr->data = (int8_t*) malloc(length*sizeof(int8_t)) ) == NULL ) { printf("\nbuild()>> Failed to allocate memory of size %lu for queue's data", length * sizeof(char)); } ptr->length = length; ptr->head = 1; ptr->tail = 1; printf("\nbuild()>> Initialize all elements of data to %d\n", (int8_t) INIT); for (int i=0; idata[i] = (int8_t) INIT; *q = ptr; } // ================= UNLOCKED ==================== void *producer( void *qptr ) { } void *consumer( void *qptr) { pthread_exit(0); } void closeup(void); int main(int argc, const char * argv[]) { return0; } void closeup(void)
Complete the following code. The goal is to implement the producer-consumer problem. You are expected to extend the provided C code to synchronize the thread operations consumer() and producer() such that an underflow and overflow of the queue is prevented. You are not allowed to change the code for implementing the queue operations, that is the code between lines 25 and 126 as shown in the screenshot. You must complete the missing parts as shown in the screenshot as well as complete the missing codes of producer and consumer. #include #include #include #include #include #include #include #include #define MAX_LENGTH_CAP 100 #define INIT -127 #define UNDERFLOW (0x80 + 0x02) #define OVERFLOW 0x80 + 0x01 #define BADPTR (0x80 + 0x03) #define CONSUMER_TERMINATION_PROBABILITY 40 #define PRODUCER_TERMINATION_PROBABILITY 30 // ============= LOCKED ============ //sem_t ACCESS; // use a mutex instead of a binary semaphore pthread_mutex_t ACCESS = PTHREAD_MUTEX_INITIALIZER; sem_t *FULLSPOTS; sem_t *EMPTYSPOTS; struct timespec remaining; struct timespec requested_time; struct Queue{ unsignedint head; unsignedint tail; unsignedint length; int8_t* data; }; void enqueue(struct Queue *q, char x) { if(q==NULL) { printf("\nequeue()>> bad queue pointer %x\n", BADPTR); return; } if ( q->head == (q->tail + 1) % q->length){ printf("\nenqueue()>> Attempt to overflow the queue at %p was prevented.\n", q); } else{ // Why is the following commented code wrong (hint: checking for the underflow condition): // wrong: q->tail = (q->tail+1) % q->length; q->data[q->tail] = x; q->data[q->tail-1] = x; // because arrays start at index 0 but our queue starts at index 1 we should write q->data[q->tail-1] = x; // now we must increment the tail if(q->tail == q->length){ q->tail = 1; } else{ q->tail = q->tail + 1; // this line must happen before enqueue is interruption } } } char dequeue(struct Queue *q) { char val; if(q==NULL) { printf("\ndequeue()>> bad queue pointer %x\n", BADPTR); return (char) BADPTR; } if(q->head == q->tail){ printf("\ndequeue()>> Attempt to underflow the queue at %p was prevented.\n", q); return (char) UNDERFLOW; } else{ if(!q->data) // as a rule, we always check pointers before we access them { printf("dequeue()>> bad data pointer %x\n", BADPTR); return (char) BADPTR; } val = q->data[q->head-1]; // because arrays start at index 0 but our queue starts at index 1 we should write q->data[q->head-1]; q->data[q->head-1] = INIT; if (q->head == q->length){ q->head = 1; } else{ q->head = q->head + 1; } } return (char) val; } void build(struct Queue **q, unsigned int length) { printf("\nbuild()>> Building a queue of length %d", length); if( (length == 0) || (length > MAX_LENGTH_CAP) ) { printf("\nbuild()>> Invalid length."); return; } struct Queue *ptr=NULL; if ( ! (ptr = (struct Queue*) malloc(sizeof(struct Queue))) ) { printf("\nbuild()>> Failed to allocate memory for the structure."); return; } printf("\nbuild()>> Allocated memory for the structure at the address %p", ptr); if ((ptr->data = (int8_t*) malloc(length*sizeof(int8_t)) ) == NULL ) { printf("\nbuild()>> Failed to allocate memory of size %lu for queue's data", length * sizeof(char)); } ptr->length = length; ptr->head = 1; ptr->tail = 1; printf("\nbuild()>> Initialize all elements of data to %d\n", (int8_t) INIT); for (int i=0; idata[i] = (int8_t) INIT; *q = ptr; } // ================= UNLOCKED ==================== void *producer( void *qptr ) { } void *consumer( void *qptr) { pthread_exit(0); } void closeup(void); int main(int argc, const char * argv[]) { return0; } void closeup(void)
Database System Concepts
7th Edition
ISBN:9780078022159
Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Chapter1: Introduction
Section: Chapter Questions
Problem 1PE
Related questions
Question
100%
Complete the following code. The goal is to implement the producer-consumer problem. You are expected to extend the provided C code to synchronize the thread operations consumer() and producer() such that an underflow and overflow of the queue is prevented. You are not allowed to change the code for implementing the queue operations, that is the code between lines 25 and 126 as shown in the screenshot. You must complete the missing parts as shown in the screenshot as well as complete the missing codes of producer and consumer.
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h>
#include <pthread.h>
#include <semaphore.h>
#include <errno.h>
#include <fcntl.h>
#define MAX_LENGTH_CAP 100
#define INIT -127
#define UNDERFLOW (0x80 + 0x02)
#define OVERFLOW 0x80 + 0x01
#define BADPTR (0x80 + 0x03)
#define CONSUMER_TERMINATION_PROBABILITY 40
#define PRODUCER_TERMINATION_PROBABILITY 30
// ============= LOCKED ============
//sem_t ACCESS; // use a mutex instead of a binary semaphore
pthread_mutex_t ACCESS = PTHREAD_MUTEX_INITIALIZER;
sem_t *FULLSPOTS;
sem_t *EMPTYSPOTS;
struct timespec remaining;
struct timespec requested_time;
struct Queue{
unsignedint head;
unsignedint tail;
unsignedint length;
int8_t* data;
};
void enqueue(struct Queue *q, char x)
{
if(q==NULL)
{
printf("\nequeue()>> bad queue pointer %x\n", BADPTR);
return;
}
if ( q->head == (q->tail + 1) % q->length){
printf("\nenqueue()>> Attempt to overflow the queue at %p was prevented.\n", q);
}
else{
// Why is the following commented code wrong (hint: checking for the underflow condition):
// wrong: q->tail = (q->tail+1) % q->length; q->data[q->tail] = x;
q->data[q->tail-1] = x; // because arrays start at index 0 but our queue starts at index 1 we should write q->data[q->tail-1] = x;
// now we must increment the tail
if(q->tail == q->length){
q->tail = 1;
}
else{
q->tail = q->tail + 1; // this line must happen before enqueue is interruption
}
}
}
char dequeue(struct Queue *q)
{
char val;
if(q==NULL)
{
printf("\ndequeue()>> bad queue pointer %x\n", BADPTR);
return (char) BADPTR;
}
if(q->head == q->tail){
printf("\ndequeue()>> Attempt to underflow the queue at %p was prevented.\n", q);
return (char) UNDERFLOW;
}
else{
if(!q->data) // as a rule, we always check pointers before we access them
{
printf("dequeue()>> bad data pointer %x\n", BADPTR);
return (char) BADPTR;
}
val = q->data[q->head-1]; // because arrays start at index 0 but our queue starts at index 1 we should write q->data[q->head-1];
q->data[q->head-1] = INIT;
if (q->head == q->length){
q->head = 1;
}
else{
q->head = q->head + 1;
}
}
return (char) val;
}
void build(struct Queue **q, unsigned int length)
{
printf("\nbuild()>> Building a queue of length %d", length);
if( (length == 0) || (length > MAX_LENGTH_CAP) )
{
printf("\nbuild()>> Invalid length.");
return;
}
struct Queue *ptr=NULL;
if ( ! (ptr = (struct Queue*) malloc(sizeof(struct Queue))) )
{
printf("\nbuild()>> Failed to allocate memory for the structure.");
return;
}
printf("\nbuild()>> Allocated memory for the structure at the address %p", ptr);
if ((ptr->data = (int8_t*) malloc(length*sizeof(int8_t)) ) == NULL )
{
printf("\nbuild()>> Failed to allocate memory of size %lu for queue's data", length * sizeof(char));
}
ptr->length = length;
ptr->head = 1;
ptr->tail = 1;
printf("\nbuild()>> Initialize all elements of data to %d\n", (int8_t) INIT);
for (int i=0; i<length; i++)
ptr->data[i] = (int8_t) INIT;
*q = ptr;
}
// ================= UNLOCKED ====================
void *producer( void *qptr )
{
}
void *consumer( void *qptr)
{
pthread_exit(0);
}
void closeup(void);
int main(int argc, const char * argv[])
{
return0;
}
void closeup(void)
{
}
Transcribed Image Text:C main.c> producer(void *)
327
128 void *producer(void *ptr)
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main.c> producer(void *)
179 void *consumer( void *qptr)
180 {
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while (1)
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printf("\n+++++++++++++PRODUCER BEGIN++++++++++++++++++");
printf("\nproducer() >>Wait for EMPTYSPOTS.");
enqueue ((struct Queue *) qptr, pthread_self()); //thread-id will be sized to fit into the queue element int8_t
pthread_mutex_unlock( &ACCESS );
printf("\n+++++++++++++PRODUCER END++++++++++++++++++++\n\n");
requested_time.tv_nsec= rand()*5* 100000000; // up to 400 miliseconds
requested_time.tv_sec= 5;
}
nanosleep (&requested_time, &remaining);
if (rand() PRODUCER_TERMINATION PROBABILITY == 1){
printf("\n
-PRODUCER CANCELLING-
---"); // What will happen to the consumers? Wait infinitely().
printf("\n\n\nProducer>>Thread %lu terminates normally. What will happen to the consumers?\n", pthread_self());
pthread_cancel(pthread_self());
pthread_exit(0); // Code will not be executed because of the infinite loop
while (1)
printf("\n-
-CONSUMER BEGINN-
printf("\nconsumer() >>Wait for FULLSPOTS.");
Complete this part. You may find some hints in the lines below
printf("\nconsumer()>>Wait for ACCESS.");
// TODD: Complete error checking for pthread_mutex_lock and pthread_mutex_unlock
similar to the error-checking for sem_wait() and sem_post() in this subprogram
pthread_mutex_lock( &ACCESS );
printf("\nConsumer reports %d ", dequeue (qptr));
pthread_mutex_unlock( &ACCESS );
Figure 3 Producer Template
Complete this part. You may find some hints in the lines below
printf("\n\n\nConsumer>>Abnormal Termination will follow because of an attempt to sem post (EMPTYSPOTS) with errno %d\n", errno);
perror("sem_post");
exit(EXIT_FAILURE);
printf("\n-
{
-CONSUMER END-
requested_time.tv_nsec= rand()*5* 100000000;
requested_time.tv_sec = 2 +rand()*3; // 2.. 4 seconds
nanosleep (&requested_time,&remaining);
printf("\n-
printf("\nCONSUMER EXITING-▬▬▬▬▬▬▬
pthread_exit(0);
You can modify these numbers only. If you did, report it in your table that
if(rand()*CONSUMER_TERMINATION PROBABILITY == 1)
CONSUMER CANCELLING--
-"); // What will happen to the producers? Wait infinitely().
printf("\n\n\nConsumer>>Thread %lu terminates normally. What will happen to the producers?\n", pthread_self());
pthread_cancel(pthread_self());
\n\n\n");
Optional. 5% Bonus
"); //never reached
You can modify the values of
requested_time.tv_nsec and requested_time.tv_sec
Figure 4 Consumer Template
![Au
#include <pthread.h>
14 #include <semaphore.h>
15 #include <errno.h>
16 #include <fcntl.h>
17 #define MAX_LENGTH_CAP 100 You can modify MAX LENGTH_CAP
18
#define INIT -127
#define UNDERFLOW (0x80+ 0x02)
#define OVERFLOW 0x80+ 0x01
19
26
21
23
24
25
#define BADPTR (0x80 + 0x03)
#define CONSUMER_TERMINATION_PROBABILITY 40
#define PRODUCER_TERMINATION PROBABILITY 30
28
sem_t *FULLSPOTS;
sem_t *EMPTYSPOTS;
30
struct timespec remaining;
31 struct timespec requested_time;
32> struct Queue (-
//sem_t ACCESS; // use a mutex instead of a binary semaphore
pthread_mutex_t ACCESS = PTHREAD_MUTEX_INITIALIZER;
39
40 > void enqueue (struct Queue *q, char x) -
65 char dequeue (struct Queue *q) -
97 > void build (struct Queue **q, unsigned int length) -
125
126 //
127
128 > void *producer( void *qptr)-
179
180 > void *consumer( void *qptr)-
225
226 void closeup (void);
227> int main(int argc, const char * argv[])-
308
309> void closeup (void) -
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void closeup (void);
int main(int argc, const char * argv[])
struct Queue *qptr = NULL;
build (&qptr, q_test_size);
(&attr);
}
pthread_t thread [6]; // declares the identifier for the thread we will create.
pthread_attr_t attr;
int iret [6];
int q_test_size = 5;
perror("sem_open");
exit (EXIT_FAILURE);
if
You can modify these two constants
for test and experimentation
closeup();
FULLSPOTS = (sem_t*) sem_open("/FULLSPOTS", O_CREAT 10_EXCL, 0644,
if
perror("sem_open");
exit (EXIT_FAILURE);
LOCKED
====== UNLOCKED
EMPTYSPOTS = sem_open("/EMPTYSPOTS", O_CREATIO_EXCL, 0644,
Don't modify this code segment
closeup();
if (qptr->data) free(qptr->data);
if(qptr) free (qptr);
printf("\n");
return 0;
266
267
268
269> void closeup (void) --
}
int x=0;
for(; x<5; x++) {
iret [x] = pthread_create(&thread [x], &attr, producer, qptr); // creat 5 producers
if (!iret [x]) // check for success
printf("PRODUCER_%d was created successfully.", x);
> TOTAL
}
iret [x] = pthread_create(&thread [x], &attr, consumer, qptr); // ctreate one consumer
if (!iret [x])
printf("CONSUMER_%d was created successfully.", x);
for(int x=0; x<6; x++) // Wait for all threads; verify the for-loop
Aa ab, No results
main ⁰A⁰
Figure 2 You must complete the missing parts. between lines 226 - 261 as shown in this screenshot
> TOTAL](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Ff9be1d69-a222-4ca1-8ade-d83f4256e548%2Fd0a0fb79-aa00-41ff-9a93-92943c38df24%2Frye39dq_processed.png&w=3840&q=75)
Transcribed Image Text:Au
#include <pthread.h>
14 #include <semaphore.h>
15 #include <errno.h>
16 #include <fcntl.h>
17 #define MAX_LENGTH_CAP 100 You can modify MAX LENGTH_CAP
18
#define INIT -127
#define UNDERFLOW (0x80+ 0x02)
#define OVERFLOW 0x80+ 0x01
19
26
21
23
24
25
#define BADPTR (0x80 + 0x03)
#define CONSUMER_TERMINATION_PROBABILITY 40
#define PRODUCER_TERMINATION PROBABILITY 30
28
sem_t *FULLSPOTS;
sem_t *EMPTYSPOTS;
30
struct timespec remaining;
31 struct timespec requested_time;
32> struct Queue (-
//sem_t ACCESS; // use a mutex instead of a binary semaphore
pthread_mutex_t ACCESS = PTHREAD_MUTEX_INITIALIZER;
39
40 > void enqueue (struct Queue *q, char x) -
65 char dequeue (struct Queue *q) -
97 > void build (struct Queue **q, unsigned int length) -
125
126 //
127
128 > void *producer( void *qptr)-
179
180 > void *consumer( void *qptr)-
225
226 void closeup (void);
227> int main(int argc, const char * argv[])-
308
309> void closeup (void) -
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void closeup (void);
int main(int argc, const char * argv[])
struct Queue *qptr = NULL;
build (&qptr, q_test_size);
(&attr);
}
pthread_t thread [6]; // declares the identifier for the thread we will create.
pthread_attr_t attr;
int iret [6];
int q_test_size = 5;
perror("sem_open");
exit (EXIT_FAILURE);
if
You can modify these two constants
for test and experimentation
closeup();
FULLSPOTS = (sem_t*) sem_open("/FULLSPOTS", O_CREAT 10_EXCL, 0644,
if
perror("sem_open");
exit (EXIT_FAILURE);
LOCKED
====== UNLOCKED
EMPTYSPOTS = sem_open("/EMPTYSPOTS", O_CREATIO_EXCL, 0644,
Don't modify this code segment
closeup();
if (qptr->data) free(qptr->data);
if(qptr) free (qptr);
printf("\n");
return 0;
266
267
268
269> void closeup (void) --
}
int x=0;
for(; x<5; x++) {
iret [x] = pthread_create(&thread [x], &attr, producer, qptr); // creat 5 producers
if (!iret [x]) // check for success
printf("PRODUCER_%d was created successfully.", x);
> TOTAL
}
iret [x] = pthread_create(&thread [x], &attr, consumer, qptr); // ctreate one consumer
if (!iret [x])
printf("CONSUMER_%d was created successfully.", x);
for(int x=0; x<6; x++) // Wait for all threads; verify the for-loop
Aa ab, No results
main ⁰A⁰
Figure 2 You must complete the missing parts. between lines 226 - 261 as shown in this screenshot
> TOTAL
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