llist_threads_rw.c

linux thread programe

/********************************************************
 * An example source module to accompany...
 *
 * "Using POSIX Threads: Programming with Pthreads"
 *     by Brad nichols, Dick Buttlar, Jackie Farrell
 *     O'Reilly & Associates, Inc.
 *
 ********************************************************
 * llist_threads_rw.c --
 *
 * Linked list library with reader/writer locks for
 * threads support
 */

#include "llist_threads_rw.h"
#include <stdio.h>
#include <stdlib.h>


int llist_init (llist_t *llistp) 
{
  int rtn;

  llistp->first = NULL;
  if ((rtn = pthread_rdwr_init_np(&(llistp->rwlock), NULL)) !=0)
    fprintf(stderr, "pthread_rdwr_init_np error %d",rtn), exit(1);
  return 0;
}

int llist_insert_data (int index, void *datap, llist_t *llistp) 
{
  llist_node_t *cur, *prev, *new;
  int found = FALSE;

  pthread_rdwr_wlock_np(&(llistp->rwlock));

  for (cur=prev=llistp->first; cur != NULL; prev=cur, cur=cur->nextp) {
    if (cur->index == index) {
      free(cur->datap);
      cur->datap = datap;
      found=TRUE;
      break;
    }
    else if (cur->index > index){
      break;
    }
  }
  if (!found) {
    new = (llist_node_t *)malloc(sizeof(llist_node_t));
    new->index = index;
    new->datap = datap;
    new->nextp = cur;
    if (cur==llistp->first)
      llistp->first = new;
    else
      prev->nextp = new;
  }

  pthread_rdwr_wunlock_np(&(llistp->rwlock));

  return 0;
}
int llist_remove_data(int index, void **datapp, llist_t *llistp) 
{
  llist_node_t *cur, *prev;

  /* Initialize to "not found" */
  *datapp = NULL;

  pthread_rdwr_wlock_np(&(llistp->rwlock));

  for (cur=prev=llistp->first; cur != NULL; prev=cur, cur=cur->nextp) {
    if (cur->index == index) {
      *datapp = cur->datap;
      prev->nextp = cur->nextp;
      free(cur);
      break;
    }
    else if (cur->index > index){
      break;
    }
  }

  pthread_rdwr_wunlock_np(&(llistp->rwlock));

  return 0;
}
int llist_find_data(int index, void **datapp, llist_t *llistp) 
{
  llist_node_t *cur, *prev;

  /* Initialize to "not found" */
  *datapp = NULL;

  pthread_rdwr_rlock_np(&(llistp->rwlock));

  /* Look through index for our entry */
  for (cur=prev=llistp->first; cur != NULL; prev=cur, cur=cur->nextp) {
    if (cur->index == index) {
      *datapp = cur->datap; 
      break;
    }
    else if (cur->index > index){
      break;
    }
  }

  pthread_rdwr_runlock_np(&(llistp->rwlock));

  return 0;
}
int llist_change_data(int index, void *datap, llist_t *llistp)
{
  llist_node_t *cur, *prev;
  int status = -1; /* assume failure */

  pthread_rdwr_wlock_np(&(llistp->rwlock));

  for (cur=prev=llistp->first; cur != NULL; prev=cur, cur=cur->nextp) {
    if (cur->index == index) {
      cur->datap = datap;
      prev->nextp = cur->nextp;
      free(cur);
      status = 0;
      break;
    }
    else if (cur->index > index){
      break;
    }
  }

  pthread_rdwr_wunlock_np(&(llistp->rwlock));

  return status;
}
int llist_show(llist_t *llistp)
{
  llist_node_t *cur;

  pthread_rdwr_rlock_np(&(llistp->rwlock));

  printf (" Linked list contains : \n");
  for (cur=llistp->first; cur != NULL; cur=cur->nextp) {
    printf ("Index: %d\tData: %s \n", cur->index, (char *)cur->datap);    
  }

  pthread_rdwr_runlock_np(&(llistp->rwlock));

  return 0; 
}