mirror of https://github.com/facebook/rocksdb.git
88 lines
2.5 KiB
C++
88 lines
2.5 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 <cstdio>
|
|
#include <string>
|
|
|
|
#include "rocksdb/db.h"
|
|
#include "rocksdb/slice.h"
|
|
#include "rocksdb/options.h"
|
|
|
|
using namespace ROCKSDB_NAMESPACE;
|
|
|
|
#if defined(OS_WIN)
|
|
std::string kDBPath = "C:\\Windows\\TEMP\\rocksdb_simple_example";
|
|
#else
|
|
std::string kDBPath = "/tmp/rocksdb_simple_example";
|
|
#endif
|
|
|
|
int main() {
|
|
DB* db;
|
|
Options options;
|
|
// Optimize RocksDB. This is the easiest way to get RocksDB to perform well
|
|
options.IncreaseParallelism();
|
|
options.OptimizeLevelStyleCompaction();
|
|
// create the DB if it's not already present
|
|
options.create_if_missing = true;
|
|
|
|
// open DB
|
|
Status s = DB::Open(options, kDBPath, &db);
|
|
assert(s.ok());
|
|
|
|
// Put key-value
|
|
s = db->Put(WriteOptions(), "key1", "value");
|
|
assert(s.ok());
|
|
std::string value;
|
|
// get value
|
|
s = db->Get(ReadOptions(), "key1", &value);
|
|
assert(s.ok());
|
|
assert(value == "value");
|
|
|
|
// atomically apply a set of updates
|
|
{
|
|
WriteBatch batch;
|
|
batch.Delete("key1");
|
|
batch.Put("key2", value);
|
|
s = db->Write(WriteOptions(), &batch);
|
|
}
|
|
|
|
s = db->Get(ReadOptions(), "key1", &value);
|
|
assert(s.IsNotFound());
|
|
|
|
db->Get(ReadOptions(), "key2", &value);
|
|
assert(value == "value");
|
|
|
|
{
|
|
PinnableSlice pinnable_val;
|
|
db->Get(ReadOptions(), db->DefaultColumnFamily(), "key2", &pinnable_val);
|
|
assert(pinnable_val == "value");
|
|
}
|
|
|
|
{
|
|
std::string string_val;
|
|
// If it cannot pin the value, it copies the value to its internal buffer.
|
|
// The intenral buffer could be set during construction.
|
|
PinnableSlice pinnable_val(&string_val);
|
|
db->Get(ReadOptions(), db->DefaultColumnFamily(), "key2", &pinnable_val);
|
|
assert(pinnable_val == "value");
|
|
// If the value is not pinned, the internal buffer must have the value.
|
|
assert(pinnable_val.IsPinned() || string_val == "value");
|
|
}
|
|
|
|
PinnableSlice pinnable_val;
|
|
s = db->Get(ReadOptions(), db->DefaultColumnFamily(), "key1", &pinnable_val);
|
|
assert(s.IsNotFound());
|
|
// Reset PinnableSlice after each use and before each reuse
|
|
pinnable_val.Reset();
|
|
db->Get(ReadOptions(), db->DefaultColumnFamily(), "key2", &pinnable_val);
|
|
assert(pinnable_val == "value");
|
|
pinnable_val.Reset();
|
|
// The Slice pointed by pinnable_val is not valid after this point
|
|
|
|
delete db;
|
|
|
|
return 0;
|
|
}
|