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tuple_server.c

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/*****************************************************************
 *
 * LinuxTuples - an open-source tuple space for Linux clusters
 * Copyright (c) 2003, Will Ware <wware@alum.mit.edu>
 * All rights reserved.
 *
 *    Redistribution and use in source and binary forms, with or
 *    without modification, are permitted provided that the following
 *    conditions are met:
 *
 *    + Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 *    + Redistributions in binary form must reproduce the above
 *    copyright notice, this list of conditions and the following
 *    disclaimer in the documentation and/or other materials provided
 *    with the distribution.
 *
 *    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 *    CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 *    INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 *    MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *    DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 *    CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *    SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 *    LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 *    USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 *    AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 *    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 *    IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 *    THE POSSIBILITY OF SUCH DAMAGE.
 *
 ******************************************************************/

#include <stdio.h>
#include <stdarg.h>
#include <string.h>
#include <stdlib.h>
#include <malloc.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <pthread.h>
#include <semaphore.h>

#include "tuple.h"

sem_t log_sem;

#define LOGPRINTF(fmt,a...)   \
   if (logptr < 8000) { logptr += sprintf(logbuf+logptr, fmt, ##a); }

#define LOGTUPLE(s)    print_tuple(s);


struct ttuple {
        struct tuple *tuple;
        struct ttuple *next;
        struct ttuple *previous;
};

struct ttuple *first_message = NULL;

struct ttuple *last_message = NULL;



#define MAXNUMTHREADS 100

struct context client_list[MAXNUMTHREADS];


sem_t tuple_space_access;

unsigned char num_blocked = 0;

sem_t blocked_sem;

sem_t new_client_sem;


static void
add_tuple_to_space(struct tuple *t)
{
        struct ttuple *s;
        s = malloc(sizeof(struct ttuple));
        if (s == NULL) {
                perror("malloc failed");
                exit(1);
        }
        s->tuple = t;
        s->next = NULL;
        sem_wait(&tuple_space_access);

        if (last_message == NULL)
                first_message = s;
        else
                last_message->next = s;
        s->previous = last_message;
        last_message = s;
        
        while (num_blocked) {
                sem_post(&blocked_sem);
                num_blocked--;
        }
        sem_post(&tuple_space_access);
}



static void
remove_message_from_space(struct ttuple *s)
{
        if (s->previous == NULL && s->next == NULL) {
                /* I am the only message */
                first_message = last_message = NULL;
        }
        else if (s->next == NULL) {
                /* I am the last message */
                last_message = s->previous;
                last_message->next = NULL;
        }
        else if (s->previous == NULL) {
                /* I am the first message */
                first_message = s->next;
                first_message->previous = NULL;
        }
        else {
                /* I have both a previous and a next */
                s->previous->next = s->next;
                s->next->previous = s->previous;
        }
}



static void
kill_this_thread(struct context *arg)
{
        LOGPRINTF("kill thread for socket %d\n", arg->sock);
        arg->thr = -1;
        close(arg->sock);
        pthread_exit(NULL);
}
 


static void
handle_get_read(struct context *ctx,
                struct tuple *s,
                int remove, int blocking)
{
        struct ttuple *p;
        int sock = ctx->sock;

        while (1) {
                sem_wait(&tuple_space_access);
                for (p = first_message; p != NULL; p = p->next) {
                        if (tuples_match(p->tuple, s)) {
                                if (remove) {
                                        remove_message_from_space(p);
                                }
                                sem_post(&tuple_space_access);
                                /* ignore return value of send_tuple,
                                 * if client bails, it's his loss
                                 */
                                sem_wait(&log_sem);
                                LOGPRINTF("Socket %d gets/reads a tuple\n",
                                          sock);
                                // LOGTUPLE(p->tuple);
                                sem_post(&log_sem);
                                if (send_tuple(ctx, p->tuple)) {
                                        /* Assume the client died while blocked.
                                         * If the tuple was removed, put it back.
                                         * Otherwise just kill this thread.
                                         */
                                        DBGPRINTF("remove=%d\n", remove);
                                        if (remove) {
                                                add_tuple_to_space(p->tuple);
                                                destroy_tuple(s);
                                                return;
                                        }
                                }
                                if (remove) {
                                        destroy_tuple(p->tuple);
                                }
                                destroy_tuple(s);
                                return;
                        }
                }
                sem_post(&tuple_space_access);
                // LOGPRINTF("Socket %d couldn't find a matching tuple\n", sock);
                if (blocking) {
                        /* wait for a tuple that might match */
                        num_blocked++;
                        sem_wait(&blocked_sem);
                } else {
                        /* don't wait, return a failure code */
                        int ack = -1;
                        send_chunk(ctx, (char*) &ack, sizeof(int));
                        return;
                }
        }
}


static void
handle_dump_space(struct context *ctx)
{
        struct ttuple *p;
        int num_templates;
        struct tuple **templates = NULL;
        int i, ok, count;
        struct tuple_list *x, *tlist = NULL;

        recv_chunk(ctx, (char*) &num_templates, sizeof(int));

        if (num_templates) {
                templates =
                        (struct tuple **) malloc(num_templates *
                                                 sizeof(struct tuple *));
                if (templates == NULL) {
                        /* ? ? ? ? ? ? */
                        return;
                }
                for (i = 0; i < num_templates; i++) {
                        templates[i] = recv_tuple(ctx);
                        if (templates[i] == NULL) {
                                /* ? ? ? ? ? ? */
                                return;
                        }
                }
        }

        count = 0;
        sem_wait(&tuple_space_access);
        for (p = first_message; p != NULL; p = p->next) {
                ok = 0;
                for (i = 0; i < num_templates; i++) {
                        if (tuples_match(p->tuple, templates[i])) {
                                ok = 1;
                                break;
                        }
                }
                if (ok || num_templates == 0) {
                        x = malloc(sizeof(struct tuple_list));
                        if (x == NULL) {
                                /* ? ? ? ? */
                                return;
                        }
                        x->tup = p->tuple;
                        x->next = tlist;
                        tlist = x;
                        count++;
                }
        }
        sem_post(&tuple_space_access);

        send_chunk(ctx, (char*) &count, sizeof(int));
        for (x = tlist; x != NULL; x = x->next) {
                if (send_tuple(ctx, x->tup)) {
                        /* Assume the client died.
                         */
                        return;
                }
        }

        while (tlist) {
                x = tlist;
                tlist = tlist->next;
                free(x);
        }
}



static void *
client_thread_func(void *varg)
{
        struct context *ctx =
                (struct context *) varg;
        struct tuple *s;
        unsigned int operation;

        if (recv_chunk(ctx, (char*) &operation, sizeof(int))) {
                kill_this_thread(ctx);
        }
        if (operation == PUT) {
                s = recv_tuple(ctx);
                if (s == NULL) {
                        kill_this_thread(ctx);
                }
                sem_wait(&log_sem);
                LOGPRINTF("*******************\n");
                LOGPRINTF("PUT socket=%d  ", ctx->sock);
                LOGTUPLE(s);
                sem_post(&log_sem);
                add_tuple_to_space(s);
                /* send an ack */
                send(ctx->sock, &operation, sizeof(int), MSG_NOSIGNAL);
        }
        else if (operation == GET) {
                s = recv_tuple(ctx);
                if (s == NULL) {
                        kill_this_thread(ctx);
                }
                sem_wait(&log_sem);
                LOGPRINTF("*******************\n");
                LOGPRINTF("GET socket=%d  ", ctx->sock);
                LOGTUPLE(s);
                sem_post(&log_sem);
                handle_get_read(ctx, s, 1, 1);
        }
        else if (operation == READ) {
                s = recv_tuple(ctx);
                if (s == NULL) {
                        kill_this_thread(ctx);
                }
                sem_wait(&log_sem);
                LOGPRINTF("*******************\n");
                LOGPRINTF("READ socket=%d  ", ctx->sock);
                LOGTUPLE(s);
                sem_post(&log_sem);
                handle_get_read(ctx, s, 0, 1);
        }
        else if (operation == GET_NB) {
                s = recv_tuple(ctx);
                if (s == NULL) {
                        kill_this_thread(ctx);
                }
                sem_wait(&log_sem);
                LOGPRINTF("*******************\n");
                LOGPRINTF("GET_NB socket=%d  ", ctx->sock);
                LOGTUPLE(s);
                sem_post(&log_sem);
                handle_get_read(ctx, s, 1, 0);
        }
        else if (operation == READ_NB) {
                s = recv_tuple(ctx);
                if (s == NULL) {
                        kill_this_thread(ctx);
                }
                sem_wait(&log_sem);
                LOGPRINTF("*******************\n");
                LOGPRINTF("READ_NB socket=%d  ", ctx->sock);
                LOGTUPLE(s);
                sem_post(&log_sem);
                handle_get_read(ctx, s, 0, 0);
        }
        else if (operation == DUMP) {
                sem_wait(&log_sem);
                LOGPRINTF("*******************\n");
                LOGPRINTF("DUMP socket=%d\n", ctx->sock);
                sem_post(&log_sem);
                handle_dump_space(ctx);
        }
        else if (operation == LOG) {
                sem_wait(&log_sem);
                send(ctx->sock, logbuf, logptr, MSG_NOSIGNAL);
                logptr = 0;
                sem_post(&log_sem);
                /* kill thread, but don't LOGPRINTF */
                ctx->thr = -1;
                close(ctx->sock);
                pthread_exit(NULL);
        }
        else {
                fprintf(stderr,
                        "Bad operation: %08X\n",
                        (unsigned int) operation);
        }
        kill_this_thread(ctx);
        return NULL;
}



int
main(int argc, char *argv[])
{
        int i, server_sock;
        int portnumber, status;
        int reuseaddr;
        struct sockaddr_in addr;
        pthread_attr_t detached;

        i_am_server = 1;
        reuseaddr = 1;
        
        if (argc < 2) {
                /* help message */
                fprintf(stderr, "Need a port number as a cmd line arg\n");
                exit(1);
        }

        pthread_attr_init(&detached);
        pthread_attr_setdetachstate(&detached, 1);
        
        portnumber = atoi(argv[1]);
        server_sock = socket(AF_INET, SOCK_STREAM, 0);
        if (server_sock < 0) {
                fprintf(stderr, __FILE__ " line %d\n", __LINE__);
                perror("Can't create socket");
                exit(1);
        }

        setsockopt(server_sock, SOL_SOCKET, SO_REUSEADDR,
                   &reuseaddr, sizeof(int));

        /* Open network listening socket */
        memset(&addr, 0, sizeof(addr));
        addr.sin_family = AF_INET;
        addr.sin_addr.s_addr = INADDR_ANY;
        addr.sin_port = htons(portnumber);
        
        status = bind(server_sock,
                      (struct sockaddr *)&addr,
                      sizeof(struct sockaddr_in));
        if (status < 0) {
                fprintf(stderr, __FILE__ " line %d\n", __LINE__);
                perror("bind() failed");
                exit(1);
        }
        
        status = listen(server_sock, 1);
        if (status < 0) {
                fprintf(stderr, __FILE__ " line %d\n", __LINE__);
                perror("listen() failed");
                exit(1);
        }

        for (i = 0; i < MAXNUMTHREADS; i++) {
                client_list[i].thr = -1;
        }

        sem_init(&tuple_space_access, 0, 1);
        sem_init(&blocked_sem, 0, 0);
        sem_init(&log_sem, 0, 1);
        sem_init(&new_client_sem, 0, 1);

        while (1) {
                struct context ctx;
                ctx.sock = accept(server_sock, NULL, NULL);
                sem_wait(&new_client_sem);
                for (i = 0; i < MAXNUMTHREADS; i++)
                        if (client_list[i].thr == -1) {
                                client_list[i] = ctx;
                                if (pthread_create(&client_list[i].thr,
                                                   &detached,
                                                   client_thread_func,
                                                   &client_list[i])
                                    != 0) {
                                        fprintf(stderr,
                                                "Threads are hosed\n");
                                        EXIT();
                                }
                                break;
                        }
                sem_post(&new_client_sem);
                /* Handle case where i == MAXNUMTHREADS, no threads
                 * available in our array.
                 */
        }
        
        return 0;
}

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