--- /dev/null
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation. See file COPYING.
+ * Copyright 2013 Inktank
+ */
+
+// install the librados-dev package to get this
+#include <rados/librados.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+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://docs.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;
+}
Code Review / stor4nfv.git / blobdiff