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+// 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;
+
+std::string kDBPath = "/tmp/rocksdb_simple_example";
+
+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;
+ 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;
+}