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 both the GPLv2 (found in the
   3 //  COPYING file in the root directory) and Apache 2.0 License
   4 //  (found in the LICENSE.Apache file in the root 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 #if defined(OS_WIN)
  14 #include <Windows.h>
  15 #else
  16 #include <unistd.h>  // sysconf() - get CPU count
  17 #endif
  18
  19 #if defined(OS_WIN)
  20 const char DBPath[] = "C:\\Windows\\TEMP\\rocksdb_c_simple_example";
  21 const char DBBackupPath[] =
  22     "C:\\Windows\\TEMP\\rocksdb_c_simple_example_backup";
  23 #else
  24 const char DBPath[] = "/tmp/rocksdb_c_simple_example";
  25 const char DBBackupPath[] = "/tmp/rocksdb_c_simple_example_backup";
  26 #endif
  27
  28 int main(int argc, char **argv) {
  29   rocksdb_t *db;
  30   rocksdb_backup_engine_t *be;
  31   rocksdb_options_t *options = rocksdb_options_create();
  32   // Optimize RocksDB. This is the easiest way to
  33   // get RocksDB to perform well.
  34 #if defined(OS_WIN)
  35   SYSTEM_INFO system_info;
  36   GetSystemInfo(&system_info);
  37   long cpus = system_info.dwNumberOfProcessors;
  38 #else
  39   long cpus = sysconf(_SC_NPROCESSORS_ONLN);
  40 #endif
  41   // Set # of online cores
  42   rocksdb_options_increase_parallelism(options, (int)(cpus));
  43   rocksdb_options_optimize_level_style_compaction(options, 0);
  44   // create the DB if it's not already present
  45   rocksdb_options_set_create_if_missing(options, 1);
  46
  47   // open DB
  48   char *err = NULL;
  49   db = rocksdb_open(options, DBPath, &err);
  50   assert(!err);
  51
  52   // open Backup Engine that we will use for backing up our database
  53   be = rocksdb_backup_engine_open(options, DBBackupPath, &err);
  54   assert(!err);
  55
  56   // Put key-value
  57   rocksdb_writeoptions_t *writeoptions = rocksdb_writeoptions_create();
  58   const char key[] = "key";
  59   const char *value = "value";
  60   rocksdb_put(db, writeoptions, key, strlen(key), value, strlen(value) + 1,
  61               &err);
  62   assert(!err);
  63   // Get value
  64   rocksdb_readoptions_t *readoptions = rocksdb_readoptions_create();
  65   size_t len;
  66   char *returned_value =
  67       rocksdb_get(db, readoptions, key, strlen(key), &len, &err);
  68   assert(!err);
  69   assert(strcmp(returned_value, "value") == 0);
  70   free(returned_value);
  71
  72   // create new backup in a directory specified by DBBackupPath
  73   rocksdb_backup_engine_create_new_backup(be, db, &err);
  74   assert(!err);
  75
  76   rocksdb_close(db);
  77
  78   // If something is wrong, you might want to restore data from last backup
  79   rocksdb_restore_options_t *restore_options = rocksdb_restore_options_create();
  80   rocksdb_backup_engine_restore_db_from_latest_backup(be, DBPath, DBPath,
  81                                                       restore_options, &err);
  82   assert(!err);
  83   rocksdb_restore_options_destroy(restore_options);
  84
  85   db = rocksdb_open(options, DBPath, &err);
  86   assert(!err);
  87
  88   // cleanup
  89   rocksdb_writeoptions_destroy(writeoptions);
  90   rocksdb_readoptions_destroy(readoptions);
  91   rocksdb_options_destroy(options);
  92   rocksdb_backup_engine_close(be);
  93   rocksdb_close(db);
  94
  95   return 0;
  96 }