ceph/examples/librbd/hello_world.cc

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3 /*
   4  * Ceph - scalable distributed file system
   5  *
   6  * This is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License version 2.1, as published by the Free Software
   9  * Foundation. See file COPYING.
  10  */
  11
  12 // install the librados-dev and librbd package to get this
  13 #include <rados/librados.hpp>
  14 #include <rbd/librbd.hpp>
  15 #include <iostream>
  16 #include <string>
  17 #include <sstream>
  18
  19 int main(int argc, const char **argv)
  20 {
  21   int ret = 0;
  22
  23   // we will use all of these below
  24   const char *pool_name = "hello_world_pool";
  25   std::string hello("hello world!");
  26   std::string object_name("hello_object");
  27   librados::IoCtx io_ctx;
  28
  29   // first, we create a Rados object and initialize it
  30   librados::Rados rados;
  31   {
  32     ret = rados.init("admin"); // just use the client.admin keyring
  33     if (ret < 0) { // let's handle any error that might have come back
  34       std::cerr << "couldn't initialize rados! error " << ret << std::endl;
  35       ret = EXIT_FAILURE;
  36       goto out;
  37     } else {
  38       std::cout << "we just set up a rados cluster object" << std::endl;
  39     }
  40   }
  41
  42   /*
  43    * Now we need to get the rados object its config info. It can
  44    * parse argv for us to find the id, monitors, etc, so let's just
  45    * use that.
  46    */
  47   {
  48     ret = rados.conf_parse_argv(argc, argv);
  49     if (ret < 0) {
  50       // This really can't happen, but we need to check to be a good citizen.
  51       std::cerr << "failed to parse config options! error " << ret << std::endl;
  52       ret = EXIT_FAILURE;
  53       goto out;
  54     } else {
  55       std::cout << "we just parsed our config options" << std::endl;
  56       // We also want to apply the config file if the user specified
  57       // one, and conf_parse_argv won't do that for us.
  58       for (int i = 0; i < argc; ++i) {
  59         if ((strcmp(argv[i], "-c") == 0) || (strcmp(argv[i], "--conf") == 0)) {
  60           ret = rados.conf_read_file(argv[i+1]);
  61           if (ret < 0) {
  62             // This could fail if the config file is malformed, but it'd be hard.
  63             std::cerr << "failed to parse config file " << argv[i+1]
  64                       << "! error" << ret << std::endl;
  65             ret = EXIT_FAILURE;
  66             goto out;
  67           }
  68           break;
  69         }
  70       }
  71     }
  72   }
  73
  74   /*
  75    * next, we actually connect to the cluster
  76    */
  77   {
  78     ret = rados.connect();
  79     if (ret < 0) {
  80       std::cerr << "couldn't connect to cluster! error " << ret << std::endl;
  81       ret = EXIT_FAILURE;
  82       goto out;
  83     } else {
  84       std::cout << "we just connected to the rados cluster" << std::endl;
  85     }
  86   }
  87
  88   /*
  89    * let's create our own pool instead of scribbling over real data.
  90    * Note that this command creates pools with default PG counts specified
  91    * by the monitors, which may not be appropriate for real use -- it's fine
  92    * for testing, though.
  93    */
  94   {
  95     ret = rados.pool_create(pool_name);
  96     if (ret < 0) {
  97       std::cerr << "couldn't create pool! error " << ret << std::endl;
  98       return EXIT_FAILURE;
  99     } else {
 100       std::cout << "we just created a new pool named " << pool_name << std::endl;
 101     }
 102   }
 103
 104   /*
 105    * create an "IoCtx" which is used to do IO to a pool
 106    */
 107   {
 108     ret = rados.ioctx_create(pool_name, io_ctx);
 109     if (ret < 0) {
 110       std::cerr << "couldn't set up ioctx! error " << ret << std::endl;
 111       ret = EXIT_FAILURE;
 112       goto out;
 113     } else {
 114       std::cout << "we just created an ioctx for our pool" << std::endl;
 115     }
 116   }
 117
 118   /*
 119    * create an rbd image and write data to it
 120    */
 121   {
 122     std::string name = "librbd_test";
 123     uint64_t size = 2 << 20;
 124     int order = 0;
 125     librbd::RBD rbd;
 126     librbd::Image image;
 127
 128     ret = rbd.create(io_ctx, name.c_str(), size, &order);
 129     if (ret < 0) {
 130       std::cerr << "couldn't create an rbd image! error " << ret << std::endl;
 131       ret = EXIT_FAILURE;
 132       goto out;
 133     } else {
 134       std::cout << "we just created an rbd image" << std::endl;
 135     }
 136
 137     ret = rbd.open(io_ctx, image, name.c_str(), NULL);
 138     if (ret < 0) {
 139       std::cerr << "couldn't open the rbd image! error " << ret << std::endl;
 140       ret = EXIT_FAILURE;
 141       goto out;
 142     } else {
 143       std::cout << "we just opened the rbd image" << std::endl;
 144     }
 145
 146     int TEST_IO_SIZE = 512;
 147     char test_data[TEST_IO_SIZE + 1];
 148     int i;
 149
 150     for (i = 0; i < TEST_IO_SIZE; ++i) {
 151       test_data[i] = (char) (rand() % (126 - 33) + 33);
 152     }
 153     test_data[TEST_IO_SIZE] = '\0';
 154
 155     size_t len = strlen(test_data);
 156     ceph::bufferlist bl;
 157     bl.append(test_data, len);
 158
 159     ret = image.write(0, len, bl);
 160     if (ret < 0) {
 161       std::cerr << "couldn't write to the rbd image! error " << ret << std::endl;
 162       ret = EXIT_FAILURE;
 163       goto out;
 164     } else {
 165       std::cout << "we just wrote data to our rbd image " << std::endl;
 166     }
 167
 168     /*
 169      * let's read the image and compare it to the data we wrote
 170      */
 171     ceph::bufferlist bl_r;
 172     int read;
 173     read = image.read(0, TEST_IO_SIZE, bl_r);
 174     if (read < 0) {
 175       std::cerr << "we couldn't read data from the image! error" << std::endl;
 176       ret = EXIT_FAILURE;
 177       goto out;
 178     }
 179
 180     std::string bl_res(bl_r.c_str(), read);
 181
 182     int res = memcmp(bl_res.c_str(), test_data, TEST_IO_SIZE);
 183     if (res != 0) {
 184       std::cerr << "what we read didn't match expected! error" << std::endl;
 185     } else {
 186       std::cout << "we read our data on the image successfully" << std::endl;
 187     }
 188
 189     image.close();
 190
 191     /*
 192      *let's now delete the image
 193      */
 194     ret = rbd.remove(io_ctx, name.c_str());
 195     if (ret < 0) {
 196       std::cerr << "failed to delete rbd image! error " << ret << std::endl;
 197       ret = EXIT_FAILURE;
 198       goto out;
 199     } else {
 200       std::cout << "we just deleted our rbd image " << std::endl;
 201     }
 202   }
 203
 204   ret = EXIT_SUCCESS;
 205   out:
 206   /*
 207    * And now we're done, so let's remove our pool and then
 208    * shut down the connection gracefully.
 209    */
 210   int delete_ret = rados.pool_delete(pool_name);
 211   if (delete_ret < 0) {
 212     // be careful not to
 213     std::cerr << "We failed to delete our test pool!" << std::endl;
 214     ret = EXIT_FAILURE;
 215   }
 216
 217   rados.shutdown();
 218
 219   return ret;
 220 }