ceph/src/rocksdb/examples/c_simple_example.c

   1 // Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
   2 // This source code is licensed under the BSD-style license found in the
   3 // LICENSE file in the root directory of this source tree. An additional grant
   4 // of patent rights can be found in the PATENTS file in the same directory.
   5
   6 #include <stdio.h>
   7 #include <string.h>
   8 #include <stdlib.h>
   9 #include <assert.h>
  10
  11 #include "rocksdb/c.h"
  12
  13 #include <unistd.h>  // sysconf() - get CPU count
  14
  15 const char DBPath[] = "/tmp/rocksdb_simple_example";
  16 const char DBBackupPath[] = "/tmp/rocksdb_simple_example_backup";
  17
  18 int main(int argc, char **argv) {
  19   rocksdb_t *db;
  20   rocksdb_backup_engine_t *be;
  21   rocksdb_options_t *options = rocksdb_options_create();
  22   // Optimize RocksDB. This is the easiest way to
  23   // get RocksDB to perform well
  24   long cpus = sysconf(_SC_NPROCESSORS_ONLN);  // get # of online cores
  25   rocksdb_options_increase_parallelism(options, (int)(cpus));
  26   rocksdb_options_optimize_level_style_compaction(options, 0);
  27   // create the DB if it's not already present
  28   rocksdb_options_set_create_if_missing(options, 1);
  29
  30   // open DB
  31   char *err = NULL;
  32   db = rocksdb_open(options, DBPath, &err);
  33   assert(!err);
  34
  35   // open Backup Engine that we will use for backing up our database
  36   be = rocksdb_backup_engine_open(options, DBBackupPath, &err);
  37   assert(!err);
  38
  39   // Put key-value
  40   rocksdb_writeoptions_t *writeoptions = rocksdb_writeoptions_create();
  41   const char key[] = "key";
  42   const char *value = "value";
  43   rocksdb_put(db, writeoptions, key, strlen(key), value, strlen(value) + 1,
  44               &err);
  45   assert(!err);
  46   // Get value
  47   rocksdb_readoptions_t *readoptions = rocksdb_readoptions_create();
  48   size_t len;
  49   char *returned_value =
  50       rocksdb_get(db, readoptions, key, strlen(key), &len, &err);
  51   assert(!err);
  52   assert(strcmp(returned_value, "value") == 0);
  53   free(returned_value);
  54
  55   // create new backup in a directory specified by DBBackupPath
  56   rocksdb_backup_engine_create_new_backup(be, db, &err);
  57   assert(!err);
  58
  59   rocksdb_close(db);
  60
  61   // If something is wrong, you might want to restore data from last backup
  62   rocksdb_restore_options_t *restore_options = rocksdb_restore_options_create();
  63   rocksdb_backup_engine_restore_db_from_latest_backup(be, DBPath, DBPath,
  64                                                       restore_options, &err);
  65   assert(!err);
  66   rocksdb_restore_options_destroy(restore_options);
  67
  68   db = rocksdb_open(options, DBPath, &err);
  69   assert(!err);
  70
  71   // cleanup
  72   rocksdb_writeoptions_destroy(writeoptions);
  73   rocksdb_readoptions_destroy(readoptions);
  74   rocksdb_options_destroy(options);
  75   rocksdb_backup_engine_close(be);
  76   rocksdb_close(db);
  77
  78   return 0;
  79 }