CS360 Final -- December 11, 1999.
Question 4
CS360 Final -- December 11, 1999.
Question 4
Here is a piece of code that serves a socket on cetus3a.cs.utk.edu,
port 15000.
It then allows clients to attach to it and send it 1000
These bytes are
appended to the file outfile and
then the number of characters written to the file so far is sent back to the
This is a simple piece of code:
#include "socketfun.h"
int read1000(int fd, char *chars)
int so_far,
so_far = 0;
while(so_far < 1000) {
i = read(fd, chars+so_far, 1000-so_far);
if (i == 0) return 0;
char chars[1000];
char output[20];
sock = serve_socket("cetus3a", 15000);
if (sock < 0) { perror("serve_socket"); exit(1); }
fout = fopen("outfile", "w");
if (fout == NULL) { perror("fopen(outfile)"); exit(1); }
nchars = 0;
while (1) {
fd = accept_connection(sock);
if (read1000(fd, chars) != 0) {
fwrite(chars, 1, 1000, fout);
nchars += 1000;
sprintf(output, "%d\n", nchars);
write(fd, output, strlen(output));
close(fd);
Part 1: Turn this into threaded code, where a new thread
is created to service each connection.
You will need a mutex
to protect the shared variables.
Try to make sure that you do
not lock the mutex longer than you need to.
Use the skeleton
Don't worry about calling pthread_join().
Were we actually
writing this code, we would use the jthread_create()/jthread_exit()
primitives from the
Part 2: Explain the conditions under which your code will
be more efficient than the above code, and the conditions under
which the two pieces of code perform equally.}