Ejemplo n.º 1
0
Archivo: rados.c Proyecto: Nikolo/uwsgi
static int uwsgi_rados_read_async(struct wsgi_request *wsgi_req, rados_ioctx_t ctx, const char *key, uint64_t off, uint64_t remains, size_t bufsize, int timeout) {
	int ret = -1;
	char *buf = uwsgi_malloc(UMIN(remains, bufsize));

	struct uwsgi_rados_io *urio = &urados.urio[wsgi_req->async_id];
	// increase request counter
	pthread_mutex_lock(&urio->mutex);
	urio->rid++;
	pthread_mutex_unlock(&urio->mutex);

	while(remains > 0) {
		struct uwsgi_rados_cb *urcb = uwsgi_malloc(sizeof(struct uwsgi_rados_cb));
		// map the current request id to the callback
		urcb->rid = urio->rid;
		// map urio to the callback
		urcb->urio = urio;


		rados_completion_t comp;
		if (rados_aio_create_completion(urcb, uwsgi_rados_read_async_cb, NULL, &comp) < 0) {
			free(urcb);
			break;
		}
		// trigger an async read
		if (rados_aio_read(ctx, key, comp, buf, UMIN(remains, bufsize), off) < 0) {
			free(urcb);
			rados_aio_release(comp);
			break;
		}
		// wait for the callback to be executed
		if (uwsgi.wait_read_hook(urio->fds[0], timeout) <= 0) {
			rados_aio_release(comp);
			break;
		}
		char ack = 1;
		if (read(urio->fds[0], &ack, 1) != 1) {
			rados_aio_release(comp);
			uwsgi_error("uwsgi_rados_read_async()/read()");
			break;
		}
		int rlen = -1;	
		if (rados_aio_is_complete_and_cb(comp)) {
			rlen = rados_aio_get_return_value(comp);
		}
		rados_aio_release(comp);
		if (rlen <= 0) break;
		if (uwsgi_response_write_body_do(wsgi_req, buf, rlen)) break;
		remains -= rlen;
		off += rlen;
	}

	free(buf);
	if (remains == 0) ret = 0;

	pthread_mutex_lock(&urio->mutex);
	// increase the counter again
	urio->rid++;
	pthread_mutex_unlock(&urio->mutex);
	return ret;	
}
Ejemplo n.º 2
0
static int uwsgi_rados_read_async(struct wsgi_request *wsgi_req, rados_ioctx_t *ctx, const char *key, size_t remains) {
	uint64_t off = 0;
	char buf[8192];
	struct uwsgi_rados_async_io aio;
	int ret = -1;
	if (pipe(aio.fd)) {
		uwsgi_error("uwsgi_rados_read_async()/pipe()");
		return -1;
	}
	aio.rlen = -1;
	rados_completion_t comp;
	if (rados_aio_create_completion(&aio, uwsgi_rados_read_async_cb, NULL, &comp) < 0) goto end;
	
	while(remains > 0) {
		// trigger an async read
		if (rados_aio_read(ctx, key, comp, buf, 8192, off) < 0) goto end;
		// wait for the callback to be executed
		if (uwsgi.wait_read_hook(aio.fd[0], urados.timeout) <= 0) goto end;
		if (aio.rlen <= 0) goto end;	
		if (uwsgi_response_write_body_do(wsgi_req, buf, aio.rlen)) goto end;
		remains -= aio.rlen;
	}
	ret = 0;
end:
	rados_aio_release(&comp);
	close(aio.fd[0]);
	close(aio.fd[1]);
	return ret;	
}
Ejemplo n.º 3
0
Archivo: rados.c Proyecto: Nikolo/uwsgi
static int uwsgi_rados_delete(struct wsgi_request *wsgi_req, rados_ioctx_t ctx, char *key, int timeout) {
	if (uwsgi.async < 1) {
		return rados_remove(ctx, key); 
	}
	struct uwsgi_rados_io *urio = &urados.urio[wsgi_req->async_id];
	int ret = -1;
        // increase request counter
        pthread_mutex_lock(&urio->mutex);
        urio->rid++;
        pthread_mutex_unlock(&urio->mutex);

        struct uwsgi_rados_cb *urcb = uwsgi_malloc(sizeof(struct uwsgi_rados_cb));
        // map the current request id to the callback
        urcb->rid = urio->rid;
        // map urio to the callback
        urcb->urio = urio;

        rados_completion_t comp;
	// we use the safe cb here
        if (rados_aio_create_completion(urcb, NULL, uwsgi_rados_read_async_cb, &comp) < 0) {
                free(urcb);
                goto end;
        }
        if (rados_aio_remove(ctx, key, comp) < 0) {
                free(urcb);
                rados_aio_release(comp);
                goto end;
        }

        // wait for the callback to be executed
        if (uwsgi.wait_read_hook(urio->fds[0], timeout) <= 0) {
                rados_aio_release(comp);
                goto end;
        }
        char ack = 1;
        if (read(urio->fds[0], &ack, 1) != 1) {
                rados_aio_release(comp);
                uwsgi_error("uwsgi_rados_delete()/read()");
                goto end;
        }

        if (rados_aio_is_safe_and_cb(comp)) {
                ret = rados_aio_get_return_value(comp);
        }
        rados_aio_release(comp);
end:
      	return ret;
}
Ejemplo n.º 4
0
static int testrados(void)
{
	char tmp[32];
	int i, r;
	rados_t cl;

	if (rados_create(&cl, NULL) < 0) {
		printf("error initializing\n");
		return 1;
	}

	if (rados_conf_read_file(cl, NULL)) {
		printf("error reading configuration file\n");
		return 1;
	}

	// Try to set a configuration option that doesn't exist.
	// This should fail.
	if (!rados_conf_set(cl, "config option that doesn't exist",
			"some random value")) {
		printf("error: succeeded in setting nonexistent config option\n");
		return 1;
	}

	if (rados_conf_get(cl, "log to stderr", tmp, sizeof(tmp))) {
		printf("error: failed to read log_to_stderr from config\n");
		return 1;
	}

	// Can we change it?
	if (rados_conf_set(cl, "log to stderr", "2")) {
		printf("error: error setting log_to_stderr\n");
		return 1;
	}
	if (rados_conf_get(cl, "log to stderr", tmp, sizeof(tmp))) {
		printf("error: failed to read log_to_stderr from config\n");
		return 1;
	}
	if (tmp[0] != '2') {
		printf("error: new setting for log_to_stderr failed to take effect.\n");
		return 1;
	}

	if (rados_connect(cl)) {
		printf("error connecting\n");
		return 1;
	}
	if (rados_connect(cl) == 0) {
		printf("second connect attempt didn't return an error\n");
		return 1;
	}

	/* create an io_ctx */
	r = rados_pool_create(cl, "foo");
	printf("rados_pool_create = %d\n", r);

	rados_ioctx_t io_ctx;
	r = rados_ioctx_create(cl, "foo", &io_ctx);
	printf("rados_ioctx_create = %d, io_ctx = %p\n", r, io_ctx);

	/* list all pools */
	{
		int buf_sz = rados_pool_list(cl, NULL, 0);
		printf("need buffer size of %d\n", buf_sz);
		char buf[buf_sz];
		int r = rados_pool_list(cl, buf, buf_sz);
		if (r != buf_sz) {
			printf("buffer size mismatch: got %d the first time, but %d "
			"the second.\n", buf_sz, r);
			return 1;
		}
		const char *b = buf;
		printf("begin pools.\n");
		while (1) {
		if (b[0] == '\0')
		break;
		printf(" pool: '%s'\n", b);
		b += strlen(b) + 1;
		};
		printf("end pools.\n");
	}


	/* stat */
	struct rados_pool_stat_t st;
	r = rados_ioctx_pool_stat(io_ctx, &st);
	printf("rados_ioctx_pool_stat = %d, %lld KB, %lld objects\n", r, (long long)st.num_kb, (long long)st.num_objects);

	/* snapshots */
	r = rados_ioctx_snap_create(io_ctx, "snap1");
	printf("rados_ioctx_snap_create snap1 = %d\n", r);
	rados_snap_t snaps[10];
	r = rados_ioctx_snap_list(io_ctx, snaps, 10);
	for (i=0; i<r; i++) {
		char name[100];
		rados_ioctx_snap_get_name(io_ctx, snaps[i], name, sizeof(name));
		printf("rados_ioctx_snap_list got snap %lld %s\n", (long long)snaps[i], name);
	}
	rados_snap_t snapid;
	r = rados_ioctx_snap_lookup(io_ctx, "snap1", &snapid);
	printf("rados_ioctx_snap_lookup snap1 got %lld, result %d\n", (long long)snapid, r);
	r = rados_ioctx_snap_remove(io_ctx, "snap1");
	printf("rados_ioctx_snap_remove snap1 = %d\n", r);

	/* sync io */
	time_t tm;
	char buf[128], buf2[128];
	time(&tm);
	snprintf(buf, 128, "%s", ctime(&tm));
	const char *oid = "foo_object";
	r = rados_write(io_ctx, oid, buf, strlen(buf) + 1, 0);
	printf("rados_write = %d\n", r);
	r = rados_read(io_ctx, oid, buf2, sizeof(buf2), 0);
	printf("rados_read = %d\n", r);
	if (memcmp(buf, buf2, r))
		printf("*** content mismatch ***\n");

	/* attrs */
	if (do_rados_setxattr(io_ctx, oid, "b", "2"))
		return 1;
	if (do_rados_setxattr(io_ctx, oid, "a", "1"))
		return 1;
	if (do_rados_setxattr(io_ctx, oid, "c", "3"))
		return 1;
	if (do_rados_getxattr(io_ctx, oid, "a", "1"))
		return 1;
	if (do_rados_getxattr(io_ctx, oid, "b", "2"))
		return 1;
	if (do_rados_getxattr(io_ctx, oid, "c", "3"))
		return 1;
	const char *exkeys[] = { "a", "b", "c", NULL };
	const char *exvals[] = { "1", "2", "3", NULL };
	if (do_rados_getxattrs(io_ctx, oid, exkeys, exvals))
		return 1;

	uint64_t size;
	time_t mtime;
	r = rados_stat(io_ctx, oid, &size, &mtime);
	printf("rados_stat size = %lld mtime = %d = %d\n", (long long)size, (int)mtime, r);
	r = rados_stat(io_ctx, "does_not_exist", NULL, NULL);
	printf("rados_stat(does_not_exist) = %d\n", r);

	/* exec */
	rados_exec(io_ctx, oid, "crypto", "md5", buf, strlen(buf) + 1, buf, 128);
	printf("exec result=%s\n", buf);
	r = rados_read(io_ctx, oid, buf2, 128, 0);
	printf("read result=%s\n", buf2);
	printf("size=%d\n", r);

	/* aio */
	rados_completion_t a, b;
	rados_aio_create_completion(0, 0, 0, &a);
	rados_aio_create_completion(0, 0, 0, &b);
	rados_aio_write(io_ctx, "a", a, buf, 100, 0);
	rados_aio_write(io_ctx, "../b/bb_bb_bb\\foo\\bar", b, buf, 100, 0);
	rados_aio_wait_for_safe(a);
	printf("a safe\n");
	rados_aio_wait_for_safe(b);
	printf("b safe\n");
	rados_aio_release(a);
	rados_aio_release(b);

	/* test flush */
	printf("testing aio flush\n");
	rados_completion_t c;
	rados_aio_create_completion(0, 0, 0, &c);
	rados_aio_write(io_ctx, "c", c, buf, 100, 0);
	int safe = rados_aio_is_safe(c);
	printf("a should not yet be safe and ... %s\n", safe ? "is":"is not");
	assert(!safe);
	rados_aio_flush(io_ctx);
	safe = rados_aio_is_safe(c);
	printf("a should be safe and ... %s\n", safe ? "is":"is not");
	assert(safe);
	rados_aio_release(c);
	
	rados_read(io_ctx, "../b/bb_bb_bb\\foo\\bar", buf2, 128, 0);

	/* list objects */
	rados_list_ctx_t h;
	r = rados_objects_list_open(io_ctx, &h);
	printf("rados_list_objects_open = %d, h = %p\n", r, h);
	const char *poolname;
	while (rados_objects_list_next(h, &poolname) == 0)
		printf("rados_list_objects_next got object '%s'\n", poolname);
	rados_objects_list_close(h);

	/* stat */
	r = rados_ioctx_pool_stat(io_ctx, &st);
	printf("rados_stat_pool = %d, %lld KB, %lld objects\n", r, (long long)st.num_kb, (long long)st.num_objects);

	/* delete a pool */
	printf("rados_delete_pool = %d\n", r);
	rados_ioctx_destroy(io_ctx);

	r = rados_pool_delete(cl, "foo");
	printf("rados_ioctx_pool_delete = %d\n", r);

	rados_shutdown(cl);
	return 0;
}
Ejemplo n.º 5
0
Archivo: rados.c Proyecto: Nikolo/uwsgi
static int uwsgi_rados_put(struct wsgi_request *wsgi_req, rados_ioctx_t ctx, char *key, size_t buffer_size, int timeout) {
	struct uwsgi_rados_io *urio = &urados.urio[wsgi_req->async_id];
	size_t remains = wsgi_req->post_cl;
	uint64_t off = 0;
	int ret;
	const char* method;
	int truncate = remains == 0;
#ifdef HAS_RADOS_POOL_REQUIRES_ALIGNMENT2
	if (!truncate && !rados_ioctx_pool_requires_alignment2(ctx, &ret) && ret) {
		uint64_t alignment;
		if (rados_ioctx_pool_required_alignment2(ctx, &alignment)) {
			/* ignore error here */
		} else
#else
	if (!truncate && rados_ioctx_pool_requires_alignment(ctx)) {
		uint64_t alignment = rados_ioctx_pool_required_alignment(ctx);
#endif
		if (buffer_size <= alignment) {
			buffer_size = alignment;
		} else if (buffer_size <= alignment * 2) {
			buffer_size = alignment * 2;
		} else if (alignment) {
			buffer_size -= buffer_size % alignment;
		}
	}
        while(truncate || remains > 0) {
                ssize_t body_len = 0;
                char *body = "\x00";
		if (!truncate) {
			body = uwsgi_request_body_read(wsgi_req, UMIN(remains, buffer_size) , &body_len);
			if (!body || body == uwsgi.empty) goto error;
		} else {
			truncate = 0;
		}
		if (uwsgi.async < 1) {
			if (off == 0) {
				ret = rados_write_full(ctx, key, body, body_len);
				method = "rados_write_full()";
			} else {
				ret = rados_write(ctx, key, body, body_len, off);
				method = "rados_write()";
			}
			if (ret < 0) {
				uwsgi_log("uwsgi_rados_put():%s() %s\n", method, strerror(-ret));
				return -1;
			}
		}
		else {
			// increase request counter
        		pthread_mutex_lock(&urio->mutex);
        		urio->rid++;
        		pthread_mutex_unlock(&urio->mutex);

			struct uwsgi_rados_cb *urcb = uwsgi_malloc(sizeof(struct uwsgi_rados_cb));
        		// map the current request id to the callback
        		urcb->rid = urio->rid;
        		// map urio to the callback
        		urcb->urio = urio;

        		rados_completion_t comp;
			// use safe for write
        		if (rados_aio_create_completion(urcb, NULL, uwsgi_rados_read_async_cb, &comp) < 0) {
                		free(urcb);
                		goto error;
        		}
			if (off == 0) {
				ret = rados_aio_write_full(ctx, key, comp, body, body_len);
				method = "rados_aio_write_full";
			} else {
				ret = rados_aio_write(ctx, key, comp, body, body_len, off);
				method = "rados_aio_write";
			}
			if (ret < 0) {
				uwsgi_log("uwsgi_rados_put():%s() %s\n", method, strerror(-ret));
				free(urcb);
				rados_aio_release(comp);
				goto error;
			}

        		// wait for the callback to be executed
        		if (uwsgi.wait_read_hook(urio->fds[0], timeout) <= 0) {
                		rados_aio_release(comp);
                		goto error;
        		}
        		char ack = 1;
        		if (read(urio->fds[0], &ack, 1) != 1) {
                		rados_aio_release(comp);
                		uwsgi_error("uwsgi_rados_read_async()/read()");
                		goto error;
        		}

        		if (rados_aio_is_safe_and_cb(comp)) {
				ret = rados_aio_get_return_value(comp);
				if (ret < 0) {
					uwsgi_log("uwsgi_rados_put():%s() %s\n", method, strerror(-ret));
                			rados_aio_release(comp);
					goto error;
				}
				
        		}
        		rados_aio_release(comp);
		}
		remains -= body_len;
		off += body_len;
        }	

	return 0;

error:
	return -1;
}

// async stat
static int uwsgi_rados_async_stat(struct uwsgi_rados_io *urio, rados_ioctx_t ctx, const char *key, uint64_t *stat_size, time_t *stat_mtime, int timeout) {
	int ret = -1;
        // increase request counter
        pthread_mutex_lock(&urio->mutex);
        urio->rid++;
        pthread_mutex_unlock(&urio->mutex);

	struct uwsgi_rados_cb *urcb = uwsgi_malloc(sizeof(struct uwsgi_rados_cb));
        // map the current request id to the callback
        urcb->rid = urio->rid;
        // map urio to the callback
        urcb->urio = urio;

	rados_completion_t comp;
	if (rados_aio_create_completion(urcb, uwsgi_rados_read_async_cb, NULL, &comp) < 0) {
        	free(urcb);
		goto end;
	}
	if (rados_aio_stat(ctx, key, comp, stat_size, stat_mtime) < 0) {
		free(urcb);
                rados_aio_release(comp);
		goto end;
	}	

	// wait for the callback to be executed
        if (uwsgi.wait_read_hook(urio->fds[0], timeout) <= 0) {
        	rados_aio_release(comp);
		goto end;
        }
        char ack = 1;
        if (read(urio->fds[0], &ack, 1) != 1) {
        	rados_aio_release(comp);
                uwsgi_error("uwsgi_rados_read_async()/read()");
		goto end;
        }

	if (rados_aio_is_complete_and_cb(comp)) {
        	ret = rados_aio_get_return_value(comp);
        }
        rados_aio_release(comp);

end:
	return ret;
}
Ejemplo n.º 6
0
int main(int argc, const char **argv)
{
  int ret = 0;

  // we will use all of these below
  const char *pool_name = "hello_world_pool";
  const char* hello = "hello world!";
  const char* object_name = "hello_object";
  rados_ioctx_t io_ctx = NULL;
  int pool_created = 0;

  // first, we create a Rados object and initialize it
  rados_t rados = NULL;
  {
    ret = rados_create(&rados, "admin"); // just use the client.admin keyring
    if (ret < 0) { // let's handle any error that might have come back
      printf("couldn't initialize rados! error %d\n", ret);
      ret = EXIT_FAILURE;
      goto out;
    } else {
      printf("we just set up a rados cluster object\n");
    }
  }

  /*
   * Now we need to get the rados object its config info. It can
   * parse argv for us to find the id, monitors, etc, so let's just
   * use that.
   */
  {
    ret = rados_conf_parse_argv(rados, argc, argv);
    if (ret < 0) {
      // This really can't happen, but we need to check to be a good citizen.
      printf("failed to parse config options! error %d\n", ret);
      ret = EXIT_FAILURE;
      goto out;
    } else {
      printf("we just parsed our config options\n");
      // We also want to apply the config file if the user specified
      // one, and conf_parse_argv won't do that for us.
      int i;
      for (i = 0; i < argc; ++i) {
  	if ((strcmp(argv[i], "-c") == 0) || (strcmp(argv[i], "--conf") == 0)) {
  	  ret = rados_conf_read_file(rados, argv[i+1]);
  	  if (ret < 0) {
  	    // This could fail if the config file is malformed, but it'd be hard.
	    printf("failed to parse config file %s! error %d\n", argv[i+1], ret);
  	    ret = EXIT_FAILURE;
  	    goto out;
  	  }
  	  break;
  	}
      }
    }
  }

  /*
   * next, we actually connect to the cluster
   */
  {
    ret = rados_connect(rados);
    if (ret < 0) {
      printf("couldn't connect to cluster! error %d\n", ret);
      ret = EXIT_FAILURE;
      goto out;
    } else {
      printf("we just connected to the rados cluster\n");
    }
  }

  /*
   * let's create our own pool instead of scribbling over real data.
   * Note that this command creates pools with default PG counts specified
   * by the monitors, which may not be appropriate for real use -- it's fine
   * for testing, though.
   */
  {
    ret = rados_pool_create(rados, pool_name);
    if (ret < 0) {
      printf("couldn't create pool! error %d\n", ret);
      return EXIT_FAILURE;
    } else {
      printf("we just created a new pool named %s\n", pool_name);
    }
    pool_created = 1;
  }

  /*
   * create an "IoCtx" which is used to do IO to a pool
   */
  {
    ret = rados_ioctx_create(rados, pool_name, &io_ctx);
    if (ret < 0) {
      printf("couldn't set up ioctx! error %d\n", ret);
      ret = EXIT_FAILURE;
      goto out;
    } else {
      printf("we just created an ioctx for our pool\n");
    }
  }

  /*
   * now let's do some IO to the pool! We'll write "hello world!" to a
   * new object.
   */
  {
    /*
     * now that we have the data to write, let's send it to an object.
     * We'll use the synchronous interface for simplicity.
     */
    ret = rados_write_full(io_ctx, object_name, hello, strlen(hello));
    if (ret < 0) {
      printf("couldn't write object! error %d\n", ret);
      ret = EXIT_FAILURE;
      goto out;
    } else {
      printf("we just wrote new object %s, with contents '%s'\n", object_name, hello);
    }
  }

  /*
   * now let's read that object back! Just for fun, we'll do it using
   * async IO instead of synchronous. (This would be more useful if we
   * wanted to send off multiple reads at once; see
   * http://ceph.com/docs/master/rados/api/librados/#asychronous-io )
   */
  {
    int read_len = 4194304; // this is way more than we need
    char* read_buf = malloc(read_len + 1); // add one for the terminating 0 we'll add later
    if (!read_buf) {
      printf("couldn't allocate read buffer\n");
      ret = EXIT_FAILURE;
      goto out;
    }
    // allocate the completion from librados
    rados_completion_t read_completion;
    ret = rados_aio_create_completion(NULL, NULL, NULL, &read_completion);
    if (ret < 0) {
      printf("couldn't create completion! error %d\n", ret);
      ret = EXIT_FAILURE;
      free(read_buf);
      goto out;
    } else {
      printf("we just created a new completion\n");
    }
    // send off the request.
    ret = rados_aio_read(io_ctx, object_name, read_completion, read_buf, read_len, 0);
    if (ret < 0) {
      printf("couldn't start read object! error %d\n", ret);
      ret = EXIT_FAILURE;
      free(read_buf);
      rados_aio_release(read_completion);
      goto out;
    }
    // wait for the request to complete, and check that it succeeded.
    rados_aio_wait_for_complete(read_completion);
    ret = rados_aio_get_return_value(read_completion);
    if (ret < 0) {
      printf("couldn't read object! error %d\n", ret);
      ret = EXIT_FAILURE;
      free(read_buf);
      rados_aio_release(read_completion);
      goto out;
    } else {
      read_buf[ret] = 0; // null-terminate the string
      printf("we read our object %s, and got back %d bytes with contents\n%s\n", object_name, ret, read_buf);
    }

    free(read_buf);
    rados_aio_release(read_completion);
  }

  /*
   * We can also use xattrs that go alongside the object.
   */
  {
    const char* version = "1";
    ret = rados_setxattr(io_ctx, object_name, "version", version, strlen(version));
    if (ret < 0) {
      printf("failed to set xattr version entry! error %d\n", ret);
      ret = EXIT_FAILURE;
      goto out;
    } else {
      printf("we set the xattr 'version' on our object!\n");
    }
  }

  /*
   * And if we want to be really cool, we can do multiple things in a single
   * atomic operation. For instance, we can update the contents of our object
   * and set the version at the same time.
   */
  {
    const char* content = "v2";
    rados_write_op_t write_op = rados_create_write_op();
    if (!write_op) {
      printf("failed to allocate write op\n");
      ret = EXIT_FAILURE;
      goto out;
    }
    rados_write_op_write_full(write_op, content, strlen(content));
    const char* version = "2";
    rados_write_op_setxattr(write_op, "version", version, strlen(version));
    ret = rados_write_op_operate(write_op, io_ctx, object_name, NULL, 0);
    if (ret < 0) {
      printf("failed to do compound write! error %d\n", ret);
      ret = EXIT_FAILURE;
      rados_release_write_op(write_op);
      goto out;
    } else {
      printf("we overwrote our object %s with contents\n%s\n", object_name, content);
    }
    rados_release_write_op(write_op);
  }

  /*
   * And to be even cooler, we can make sure that the object looks the
   * way we expect before doing the write! Notice how this attempt fails
   * because the xattr differs.
   */
  {
    rados_write_op_t failed_write_op = rados_create_write_op();
    if (!failed_write_op) {
      printf("failed to allocate write op\n");
      ret = EXIT_FAILURE;
      goto out;
    }
    const char* content = "v2";
    const char* version = "2";
    const char* old_version = "1";
    rados_write_op_cmpxattr(failed_write_op, "version", LIBRADOS_CMPXATTR_OP_EQ, old_version, strlen(old_version));
    rados_write_op_write_full(failed_write_op, content, strlen(content));
    rados_write_op_setxattr(failed_write_op, "version", version, strlen(version));
    ret = rados_write_op_operate(failed_write_op, io_ctx, object_name, NULL, 0);
    if (ret < 0) {
      printf("we just failed a write because the xattr wasn't as specified\n");
    } else {
      printf("we succeeded on writing despite an xattr comparison mismatch!\n");
      ret = EXIT_FAILURE;
      rados_release_write_op(failed_write_op);
      goto out;
    }
    rados_release_write_op(failed_write_op);

    /*
     * Now let's do the update with the correct xattr values so it
     * actually goes through
     */
    content = "v3";
    old_version = "2";
    version = "3";
    rados_write_op_t update_op = rados_create_write_op();
    if (!failed_write_op) {
      printf("failed to allocate write op\n");
      ret = EXIT_FAILURE;
      goto out;
    }
    rados_write_op_cmpxattr(update_op, "version", LIBRADOS_CMPXATTR_OP_EQ, old_version, strlen(old_version));
    rados_write_op_write_full(update_op, content, strlen(content));
    rados_write_op_setxattr(update_op, "version", version, strlen(version));
    ret = rados_write_op_operate(update_op, io_ctx, object_name, NULL, 0);
    if (ret < 0) {
      printf("failed to do a compound write update! error %d\n", ret);
      ret = EXIT_FAILURE;
      rados_release_write_op(update_op);
      goto out;
    } else {
      printf("we overwrote our object %s following an xattr test with contents\n%s\n", object_name, content);
    }
    rados_release_write_op(update_op);
  }

  ret = EXIT_SUCCESS;

 out:
  if (io_ctx) {
    rados_ioctx_destroy(io_ctx);
  }

  if (pool_created) {
    /*
     * And now we're done, so let's remove our pool and then
     * shut down the connection gracefully.
     */
    int delete_ret = rados_pool_delete(rados, pool_name);
    if (delete_ret < 0) {
      // be careful not to
      printf("We failed to delete our test pool!\n");
      ret = EXIT_FAILURE;
    }
  }

  rados_shutdown(rados);

  return ret;
}