rocksdb/examples/c_simple_example.c
Tomasz Posłuszny 8d44d792c3 Make examples work on Windows (#7304)
Summary:
Quick fixes to examples to make it easier to get familiar with RocksDB for Windows users:

- Set proper temporary directory path on Windows for all examples (with C++17 we should start using std::filesystem)
- Fixed typo and got rid of warnings treated as errors in multi_processes_example.cc
- Get number of available cores on Windows in c_simple_example.c
- Add command to remove DB directory for Windows in compaction_filter_example.cc (print error, but carry on with example upon error, because error code is returned if there is no such directory on Windows)

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7304

Reviewed By: jay-zhuang

Differential Revision: D23450900

Pulled By: pdillinger

fbshipit-source-id: 4256134deb6ae6bb267ed1bd69f814842b95f60f
2020-09-01 18:03:50 -07:00

97 lines
3.0 KiB
C

// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include "rocksdb/c.h"
#if defined(OS_WIN)
#include <Windows.h>
#else
#include <unistd.h> // sysconf() - get CPU count
#endif
#if defined(OS_WIN)
const char DBPath[] = "C:\\Windows\\TEMP\\rocksdb_c_simple_example";
const char DBBackupPath[] =
"C:\\Windows\\TEMP\\rocksdb_c_simple_example_backup";
#else
const char DBPath[] = "/tmp/rocksdb_c_simple_example";
const char DBBackupPath[] = "/tmp/rocksdb_c_simple_example_backup";
#endif
int main(int argc, char **argv) {
rocksdb_t *db;
rocksdb_backup_engine_t *be;
rocksdb_options_t *options = rocksdb_options_create();
// Optimize RocksDB. This is the easiest way to
// get RocksDB to perform well.
#if defined(OS_WIN)
SYSTEM_INFO system_info;
GetSystemInfo(&system_info);
long cpus = system_info.dwNumberOfProcessors;
#else
long cpus = sysconf(_SC_NPROCESSORS_ONLN);
#endif
// Set # of online cores
rocksdb_options_increase_parallelism(options, (int)(cpus));
rocksdb_options_optimize_level_style_compaction(options, 0);
// create the DB if it's not already present
rocksdb_options_set_create_if_missing(options, 1);
// open DB
char *err = NULL;
db = rocksdb_open(options, DBPath, &err);
assert(!err);
// open Backup Engine that we will use for backing up our database
be = rocksdb_backup_engine_open(options, DBBackupPath, &err);
assert(!err);
// Put key-value
rocksdb_writeoptions_t *writeoptions = rocksdb_writeoptions_create();
const char key[] = "key";
const char *value = "value";
rocksdb_put(db, writeoptions, key, strlen(key), value, strlen(value) + 1,
&err);
assert(!err);
// Get value
rocksdb_readoptions_t *readoptions = rocksdb_readoptions_create();
size_t len;
char *returned_value =
rocksdb_get(db, readoptions, key, strlen(key), &len, &err);
assert(!err);
assert(strcmp(returned_value, "value") == 0);
free(returned_value);
// create new backup in a directory specified by DBBackupPath
rocksdb_backup_engine_create_new_backup(be, db, &err);
assert(!err);
rocksdb_close(db);
// If something is wrong, you might want to restore data from last backup
rocksdb_restore_options_t *restore_options = rocksdb_restore_options_create();
rocksdb_backup_engine_restore_db_from_latest_backup(be, DBPath, DBPath,
restore_options, &err);
assert(!err);
rocksdb_restore_options_destroy(restore_options);
db = rocksdb_open(options, DBPath, &err);
assert(!err);
// cleanup
rocksdb_writeoptions_destroy(writeoptions);
rocksdb_readoptions_destroy(readoptions);
rocksdb_options_destroy(options);
rocksdb_backup_engine_close(be);
rocksdb_close(db);
return 0;
}