329 lines
10 KiB
C
329 lines
10 KiB
C
/*
|
|
* server.c
|
|
*
|
|
* Demonstrate a client/server threading model.
|
|
*
|
|
* Special notes: On a Solaris system, call thr_setconcurrency()
|
|
* to allow interleaved thread execution, since threads are not
|
|
* timesliced.
|
|
*/
|
|
#include <pthread.h>
|
|
#include <math.h>
|
|
#include "errors.h"
|
|
|
|
#define CLIENT_THREADS 4 /* Number of clients */
|
|
|
|
#define REQ_READ 1 /* Read with prompt */
|
|
#define REQ_WRITE 2 /* Write */
|
|
#define REQ_QUIT 3 /* Quit server */
|
|
|
|
/*
|
|
* Internal to server "package" -- one for each request.
|
|
*/
|
|
typedef struct request_tag {
|
|
struct request_tag *next; /* Link to next */
|
|
int operation; /* Function code */
|
|
int synchronous; /* Non-zero if synchronous */
|
|
int done_flag; /* Predicate for wait */
|
|
pthread_cond_t done; /* Wait for completion */
|
|
char prompt[32]; /* Prompt string for reads */
|
|
char text[128]; /* Read/write text */
|
|
} request_t;
|
|
|
|
/*
|
|
* Static context for the server
|
|
*/
|
|
typedef struct tty_server_tag {
|
|
request_t *first;
|
|
request_t *last;
|
|
int running;
|
|
pthread_mutex_t mutex;
|
|
pthread_cond_t request;
|
|
} tty_server_t;
|
|
|
|
tty_server_t tty_server = {
|
|
NULL, NULL, 0,
|
|
PTHREAD_MUTEX_INITIALIZER, PTHREAD_COND_INITIALIZER};
|
|
|
|
/*
|
|
* Main program data
|
|
*/
|
|
|
|
int client_threads;
|
|
pthread_mutex_t client_mutex = PTHREAD_MUTEX_INITIALIZER;
|
|
pthread_cond_t clients_done = PTHREAD_COND_INITIALIZER;
|
|
|
|
/*
|
|
* The server start routine. It waits for a request to appear
|
|
* in tty_server.requests using the request condition variable.
|
|
* It processes requests in FIFO order. If a request is marked
|
|
* "synchronous" (synchronous != 0), the server will set done_flag
|
|
* and signal the request's condition variable. The client is
|
|
* responsible for freeing the request. If the request was not
|
|
* synchronous, the server will free the request on completion.
|
|
*/
|
|
void *tty_server_routine (void *arg)
|
|
{
|
|
static pthread_mutex_t prompt_mutex = PTHREAD_MUTEX_INITIALIZER;
|
|
request_t *request;
|
|
int operation, len;
|
|
int status;
|
|
|
|
while (1) {
|
|
status = pthread_mutex_lock (&tty_server.mutex);
|
|
if (status != 0)
|
|
err_abort (status, "Lock server mutex");
|
|
|
|
/*
|
|
* Wait for data
|
|
*/
|
|
while (tty_server.first == NULL) {
|
|
status = pthread_cond_wait (
|
|
&tty_server.request, &tty_server.mutex);
|
|
if (status != 0)
|
|
err_abort (status, "Wait for request");
|
|
}
|
|
request = tty_server.first;
|
|
tty_server.first = request->next;
|
|
if (tty_server.first == NULL)
|
|
tty_server.last = NULL;
|
|
status = pthread_mutex_unlock (&tty_server.mutex);
|
|
if (status != 0)
|
|
err_abort (status, "Unlock server mutex");
|
|
|
|
/*
|
|
* Process the data
|
|
*/
|
|
operation = request->operation;
|
|
switch (operation) {
|
|
case REQ_QUIT:
|
|
break;
|
|
case REQ_READ:
|
|
if (strlen (request->prompt) > 0)
|
|
printf (request->prompt);
|
|
if (fgets (request->text, 128, stdin) == NULL)
|
|
request->text[0] = '\0';
|
|
/*
|
|
* Because fgets returns the newline, and we don't want it,
|
|
* we look for it, and turn it into a null (truncating the
|
|
* input) if found. It should be the last character, if it is
|
|
* there.
|
|
*/
|
|
len = strlen (request->text);
|
|
if (len > 0 && request->text[len-1] == '\n')
|
|
request->text[len-1] = '\0';
|
|
break;
|
|
case REQ_WRITE:
|
|
puts (request->text);
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
if (request->synchronous) {
|
|
status = pthread_mutex_lock (&tty_server.mutex);
|
|
if (status != 0)
|
|
err_abort (status, "Lock server mutex");
|
|
request->done_flag = 1;
|
|
status = pthread_cond_signal (&request->done);
|
|
if (status != 0)
|
|
err_abort (status, "Signal server condition");
|
|
status = pthread_mutex_unlock (&tty_server.mutex);
|
|
if (status != 0)
|
|
err_abort (status, "Unlock server mutex");
|
|
} else
|
|
free (request);
|
|
if (operation == REQ_QUIT)
|
|
break;
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Request an operation
|
|
*/
|
|
void tty_server_request (
|
|
int operation,
|
|
int sync,
|
|
const char *prompt,
|
|
char *string)
|
|
{
|
|
request_t *request;
|
|
int status;
|
|
|
|
status = pthread_mutex_lock (&tty_server.mutex);
|
|
if (status != 0)
|
|
err_abort (status, "Lock server mutex");
|
|
if (!tty_server.running) {
|
|
pthread_t thread;
|
|
pthread_attr_t detached_attr;
|
|
|
|
status = pthread_attr_init (&detached_attr);
|
|
if (status != 0)
|
|
err_abort (status, "Init attributes object");
|
|
status = pthread_attr_setdetachstate (
|
|
&detached_attr, PTHREAD_CREATE_DETACHED);
|
|
if (status != 0)
|
|
err_abort (status, "Set detach state");
|
|
tty_server.running = 1;
|
|
status = pthread_create (&thread, &detached_attr,
|
|
tty_server_routine, NULL);
|
|
if (status != 0)
|
|
err_abort (status, "Create server");
|
|
|
|
/*
|
|
* Ignore an error in destroying the attributes object.
|
|
* It's unlikely to fail, there's nothing useful we can
|
|
* do about it, and it's not worth aborting the program
|
|
* over it.
|
|
*/
|
|
pthread_attr_destroy (&detached_attr);
|
|
}
|
|
|
|
/*
|
|
* Create and initialize a request structure.
|
|
*/
|
|
request = (request_t*)malloc (sizeof (request_t));
|
|
if (request == NULL)
|
|
errno_abort ("Allocate request");
|
|
request->next = NULL;
|
|
request->operation = operation;
|
|
request->synchronous = sync;
|
|
if (sync) {
|
|
request->done_flag = 0;
|
|
status = pthread_cond_init (&request->done, NULL);
|
|
if (status != 0)
|
|
err_abort (status, "Init request condition");
|
|
}
|
|
if (prompt != NULL)
|
|
strncpy (request->prompt, prompt, 32);
|
|
else
|
|
request->prompt[0] = '\0';
|
|
if (operation == REQ_WRITE && string != NULL)
|
|
strncpy (request->text, string, 128);
|
|
else
|
|
request->text[0] = '\0';
|
|
|
|
/*
|
|
* Add the request to the queue, maintaining the first and
|
|
* last pointers.
|
|
*/
|
|
if (tty_server.first == NULL) {
|
|
tty_server.first = request;
|
|
tty_server.last = request;
|
|
} else {
|
|
(tty_server.last)->next = request;
|
|
tty_server.last = request;
|
|
}
|
|
|
|
/*
|
|
* Tell the server that a request is available.
|
|
*/
|
|
status = pthread_cond_signal (&tty_server.request);
|
|
if (status != 0)
|
|
err_abort (status, "Wake server");
|
|
|
|
/*
|
|
* If the request was "synchronous", then wait for a reply.
|
|
*/
|
|
if (sync) {
|
|
while (!request->done_flag) {
|
|
status = pthread_cond_wait (
|
|
&request->done, &tty_server.mutex);
|
|
if (status != 0)
|
|
err_abort (status, "Wait for sync request");
|
|
}
|
|
if (operation == REQ_READ) {
|
|
if (strlen (request->text) > 0)
|
|
strcpy (string, request->text);
|
|
else
|
|
string[0] = '\0';
|
|
}
|
|
status = pthread_cond_destroy (&request->done);
|
|
if (status != 0)
|
|
err_abort (status, "Destroy request condition");
|
|
free (request);
|
|
}
|
|
status = pthread_mutex_unlock (&tty_server.mutex);
|
|
if (status != 0)
|
|
err_abort (status, "Unlock mutex");
|
|
}
|
|
|
|
/*
|
|
* Client routine -- multiple copies will request server.
|
|
*/
|
|
void *client_routine (void *arg)
|
|
{
|
|
int my_number = (int)arg, loops;
|
|
char prompt[32];
|
|
char string[128], formatted[128];
|
|
int status;
|
|
|
|
sprintf (prompt, "Client %d> ", my_number);
|
|
while (1) {
|
|
tty_server_request (REQ_READ, 1, prompt, string);
|
|
if (strlen (string) == 0)
|
|
break;
|
|
for (loops = 0; loops < 4; loops++) {
|
|
sprintf (
|
|
formatted, "(%d#%d) %s", my_number, loops, string);
|
|
tty_server_request (REQ_WRITE, 0, NULL, formatted);
|
|
sleep (1);
|
|
}
|
|
}
|
|
status = pthread_mutex_lock (&client_mutex);
|
|
if (status != 0)
|
|
err_abort (status, "Lock client mutex");
|
|
client_threads--;
|
|
if (client_threads <= 0) {
|
|
status = pthread_cond_signal (&clients_done);
|
|
if (status != 0)
|
|
err_abort (status, "Signal clients done");
|
|
}
|
|
status = pthread_mutex_unlock (&client_mutex);
|
|
if (status != 0)
|
|
err_abort (status, "Unlock client mutex");
|
|
return NULL;
|
|
}
|
|
|
|
int main (int argc, char *argv[])
|
|
{
|
|
pthread_t thread;
|
|
int count;
|
|
int status;
|
|
|
|
#ifdef sun
|
|
/*
|
|
* On Solaris 2.5, threads are not timesliced. To ensure
|
|
* that our threads can run concurrently, we need to
|
|
* increase the concurrency level to CLIENT_THREADS.
|
|
*/
|
|
DPRINTF (("Setting concurrency level to %d\n", CLIENT_THREADS));
|
|
thr_setconcurrency (CLIENT_THREADS);
|
|
#endif
|
|
|
|
/*
|
|
* Create CLIENT_THREADS clients.
|
|
*/
|
|
client_threads = CLIENT_THREADS;
|
|
for (count = 0; count < client_threads; count++) {
|
|
status = pthread_create (&thread, NULL,
|
|
client_routine, (void*)count);
|
|
if (status != 0)
|
|
err_abort (status, "Create client thread");
|
|
}
|
|
status = pthread_mutex_lock (&client_mutex);
|
|
if (status != 0)
|
|
err_abort (status, "Lock client mutex");
|
|
while (client_threads > 0) {
|
|
status = pthread_cond_wait (&clients_done, &client_mutex);
|
|
if (status != 0)
|
|
err_abort (status, "Wait for clients to finish");
|
|
}
|
|
status = pthread_mutex_unlock (&client_mutex);
|
|
if (status != 0)
|
|
err_abort (status, "Unlock client mutex");
|
|
printf ("All clients done\n");
|
|
tty_server_request (REQ_QUIT, 1, NULL, NULL);
|
|
return 0;
|
|
}
|