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#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <pthread.h>
#include "uthash.h"
#undef uthash_noexpand_fyi
#define uthash_noexpand_fyi(tbl) fprintf(stderr,"warning: bucket expansion inhibited\n")
#define LOOPS 100000
typedef struct {
int i;
UT_hash_handle hh;
} elt;
elt *elts=NULL; /* this is our hash table which two threads will use */
pthread_rwlock_t lock;
void *thread_routine_r( void *arg ) {
int i;
long num_found=0;
elt *e;
for(i=0;i<LOOPS;i++) {
if (pthread_rwlock_rdlock(&lock) != 0) {
fprintf(stderr,"can't acquire read lock\n");
exit(-1);
}
HASH_FIND_INT(elts, &i, e);
if (e) num_found++;
pthread_rwlock_unlock(&lock);
}
return (void*)num_found;
}
void *thread_routine_w( void *arg ) {
int i;
long num_deld=0;
elt *e;
for(i=0;i<LOOPS;i++) {
if (pthread_rwlock_wrlock(&lock) != 0) {
fprintf(stderr,"can't acquire write lock\n");
exit(-1);
}
HASH_FIND_INT(elts, &i, e);
if (e) {
/* HASH_DEL(elts, e); */
/* num_deld++; */
} else {
e = malloc(sizeof(elt));
if (!e) exit(-1);
e->i = i;
HASH_ADD_INT(elts, i, e);
}
pthread_rwlock_unlock(&lock);
}
return (void*)num_deld;
}
int main() {
unsigned i;
long num_added=0;
int status;
pthread_t thread_r1,thread_r2,thread_w1,thread_w2;
void *thread_result;
elt tmp, *e;
if (pthread_rwlock_init(&lock,NULL) != 0) {
fprintf(stderr,"lock init failed\n");
exit(-1);
}
if (( status = pthread_create( &thread_r1, NULL, thread_routine_r, NULL) )) {
printf("failure: status %d\n", status);
exit(-1);
}
if (( status = pthread_create( &thread_r2, NULL, thread_routine_r, NULL) )) {
printf("failure: status %d\n", status);
exit(-1);
}
if (( status = pthread_create( &thread_w1, NULL, thread_routine_w, NULL) )) {
printf("failure: status %d\n", status);
exit(-1);
}
if (( status = pthread_create( &thread_w2, NULL, thread_routine_w, NULL) )) {
printf("failure: status %d\n", status);
exit(-1);
}
status = pthread_join( thread_r1, &thread_result );
printf("thread result: %d %ld\n", status, (long)thread_result);
status = pthread_join( thread_r2, &thread_result );
printf("thread result: %d %ld\n", status, (long)thread_result);
status = pthread_join( thread_w1, &thread_result );
printf("thread result: %d %ld\n", status, (long)thread_result);
status = pthread_join( thread_w2, &thread_result );
printf("thread result: %d %ld\n", status, (long)thread_result);
i = HASH_COUNT(elts);
printf("final count of items in hash: %u\n", i);
if (pthread_rwlock_destroy(&lock) != 0) {
fprintf(stderr,"lock destroy failed\n");
exit(-1);
}
}
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