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;
}
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;
}
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;
}
