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Diffstat (limited to 'examples/librbd/hello_world.cc')
| -rw-r--r-- | examples/librbd/hello_world.cc | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/examples/librbd/hello_world.cc b/examples/librbd/hello_world.cc new file mode 100644 index 000000000..f21c45f20 --- /dev/null +++ b/examples/librbd/hello_world.cc @@ -0,0 +1,220 @@ +// -*- 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. + */ + +// install the librados-dev and librbd package to get this +#include <rados/librados.hpp> +#include <rbd/librbd.hpp> +#include <iostream> +#include <string> +#include <sstream> + +int main(int argc, const char **argv) +{ + int ret = 0; + + // we will use all of these below + const char *pool_name = "hello_world_pool"; + std::string hello("hello world!"); + std::string object_name("hello_object"); + librados::IoCtx io_ctx; + + // first, we create a Rados object and initialize it + librados::Rados rados; + { + ret = rados.init("admin"); // just use the client.admin keyring + if (ret < 0) { // let's handle any error that might have come back + std::cerr << "couldn't initialize rados! error " << ret << std::endl; + ret = EXIT_FAILURE; + goto out; + } else { + std::cout << "we just set up a rados cluster object" << std::endl; + } + } + + /* + * 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(argc, argv); + if (ret < 0) { + // This really can't happen, but we need to check to be a good citizen. + std::cerr << "failed to parse config options! error " << ret << std::endl; + ret = EXIT_FAILURE; + goto out; + } else { + std::cout << "we just parsed our config options" << std::endl; + // We also want to apply the config file if the user specified + // one, and conf_parse_argv won't do that for us. + for (int i = 0; i < argc; ++i) { + if ((strcmp(argv[i], "-c") == 0) || (strcmp(argv[i], "--conf") == 0)) { + ret = rados.conf_read_file(argv[i+1]); + if (ret < 0) { + // This could fail if the config file is malformed, but it'd be hard. + std::cerr << "failed to parse config file " << argv[i+1] + << "! error" << ret << std::endl; + ret = EXIT_FAILURE; + goto out; + } + break; + } + } + } + } + + /* + * next, we actually connect to the cluster + */ + { + ret = rados.connect(); + if (ret < 0) { + std::cerr << "couldn't connect to cluster! error " << ret << std::endl; + ret = EXIT_FAILURE; + goto out; + } else { + std::cout << "we just connected to the rados cluster" << std::endl; + } + } + + /* + * 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(pool_name); + if (ret < 0) { + std::cerr << "couldn't create pool! error " << ret << std::endl; + return EXIT_FAILURE; + } else { + std::cout << "we just created a new pool named " << pool_name << std::endl; + } + } + + /* + * create an "IoCtx" which is used to do IO to a pool + */ + { + ret = rados.ioctx_create(pool_name, io_ctx); + if (ret < 0) { + std::cerr << "couldn't set up ioctx! error " << ret << std::endl; + ret = EXIT_FAILURE; + goto out; + } else { + std::cout << "we just created an ioctx for our pool" << std::endl; + } + } + + /* + * create an rbd image and write data to it + */ + { + std::string name = "librbd_test"; + uint64_t size = 2 << 20; + int order = 0; + librbd::RBD rbd; + librbd::Image image; + + ret = rbd.create(io_ctx, name.c_str(), size, &order); + if (ret < 0) { + std::cerr << "couldn't create an rbd image! error " << ret << std::endl; + ret = EXIT_FAILURE; + goto out; + } else { + std::cout << "we just created an rbd image" << std::endl; + } + + ret = rbd.open(io_ctx, image, name.c_str(), NULL); + if (ret < 0) { + std::cerr << "couldn't open the rbd image! error " << ret << std::endl; + ret = EXIT_FAILURE; + goto out; + } else { + std::cout << "we just opened the rbd image" << std::endl; + } + + int TEST_IO_SIZE = 512; + char test_data[TEST_IO_SIZE + 1]; + int i; + + for (i = 0; i < TEST_IO_SIZE; ++i) { + test_data[i] = (char) (rand() % (126 - 33) + 33); + } + test_data[TEST_IO_SIZE] = '\0'; + + size_t len = strlen(test_data); + ceph::bufferlist bl; + bl.append(test_data, len); + + ret = image.write(0, len, bl); + if (ret < 0) { + std::cerr << "couldn't write to the rbd image! error " << ret << std::endl; + ret = EXIT_FAILURE; + goto out; + } else { + std::cout << "we just wrote data to our rbd image " << std::endl; + } + + /* + * let's read the image and compare it to the data we wrote + */ + ceph::bufferlist bl_r; + int read; + read = image.read(0, TEST_IO_SIZE, bl_r); + if (read < 0) { + std::cerr << "we couldn't read data from the image! error" << std::endl; + ret = EXIT_FAILURE; + goto out; + } + + std::string bl_res(bl_r.c_str(), read); + + int res = memcmp(bl_res.c_str(), test_data, TEST_IO_SIZE); + if (res != 0) { + std::cerr << "what we read didn't match expected! error" << std::endl; + } else { + std::cout << "we read our data on the image successfully" << std::endl; + } + + image.close(); + + /* + *let's now delete the image + */ + ret = rbd.remove(io_ctx, name.c_str()); + if (ret < 0) { + std::cerr << "failed to delete rbd image! error " << ret << std::endl; + ret = EXIT_FAILURE; + goto out; + } else { + std::cout << "we just deleted our rbd image " << std::endl; + } + } + + ret = EXIT_SUCCESS; + out: + /* + * And now we're done, so let's remove our pool and then + * shut down the connection gracefully. + */ + int delete_ret = rados.pool_delete(pool_name); + if (delete_ret < 0) { + // be careful not to + std::cerr << "We failed to delete our test pool!" << std::endl; + ret = EXIT_FAILURE; + } + + rados.shutdown(); + + return ret; +} |