1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
|
// 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/options.h"
#include "rocksdb/slice.h"
using ROCKSDB_NAMESPACE::DB;
using ROCKSDB_NAMESPACE::Options;
using ROCKSDB_NAMESPACE::PinnableSlice;
using ROCKSDB_NAMESPACE::ReadOptions;
using ROCKSDB_NAMESPACE::Status;
using ROCKSDB_NAMESPACE::WriteBatch;
using ROCKSDB_NAMESPACE::WriteOptions;
#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;
}
|
