aboutsummaryrefslogtreecommitdiff
path: root/src/leveldbwrapper.h
blob: b4cc53b50bf19f7abaec8c8b1b137c6cca314890 (plain)
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
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
// Copyright (c) 2012-2013 The Bitcoin developers
// Distributed under the MIT/X11 software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#ifndef BITCOIN_LEVELDBWRAPPER_H
#define BITCOIN_LEVELDBWRAPPER_H

#include "serialize.h"
#include "util.h"

#include <leveldb/db.h>
#include <leveldb/write_batch.h>

#include <boost/filesystem/path.hpp>

class leveldb_error : public std::runtime_error
{
public:
    leveldb_error(const std::string &msg) : std::runtime_error(msg) {}
};

void HandleError(const leveldb::Status &status) throw(leveldb_error);

// Batch of changes queued to be written to a CLevelDBWrapper
class CLevelDBBatch
{
    friend class CLevelDBWrapper;

private:
    leveldb::WriteBatch batch;

public:
    template<typename K, typename V> void Write(const K& key, const V& value) {
        CDataStream ssKey(SER_DISK, CLIENT_VERSION);
        ssKey.reserve(ssKey.GetSerializeSize(key));
        ssKey << key;
        leveldb::Slice slKey(&ssKey[0], ssKey.size());

        CDataStream ssValue(SER_DISK, CLIENT_VERSION);
        ssValue.reserve(ssValue.GetSerializeSize(value));
        ssValue << value;
        leveldb::Slice slValue(&ssValue[0], ssValue.size());

        batch.Put(slKey, slValue);
    }

    template<typename K> void Erase(const K& key) {
        CDataStream ssKey(SER_DISK, CLIENT_VERSION);
        ssKey.reserve(ssKey.GetSerializeSize(key));
        ssKey << key;
        leveldb::Slice slKey(&ssKey[0], ssKey.size());

        batch.Delete(slKey);
    }
};

class CLevelDBWrapper
{
private:
    // custom environment this database is using (may be NULL in case of default environment)
    leveldb::Env *penv;

    // database options used
    leveldb::Options options;

    // options used when reading from the database
    leveldb::ReadOptions readoptions;

    // options used when iterating over values of the database
    leveldb::ReadOptions iteroptions;

    // options used when writing to the database
    leveldb::WriteOptions writeoptions;

    // options used when sync writing to the database
    leveldb::WriteOptions syncoptions;

    // the database itself
    leveldb::DB *pdb;

public:
    CLevelDBWrapper(const boost::filesystem::path &path, size_t nCacheSize, bool fMemory = false, bool fWipe = false);
    ~CLevelDBWrapper();

    template<typename K, typename V> bool Read(const K& key, V& value) throw(leveldb_error) {
        CDataStream ssKey(SER_DISK, CLIENT_VERSION);
        ssKey.reserve(ssKey.GetSerializeSize(key));
        ssKey << key;
        leveldb::Slice slKey(&ssKey[0], ssKey.size());

        std::string strValue;
        leveldb::Status status = pdb->Get(readoptions, slKey, &strValue);
        if (!status.ok()) {
            if (status.IsNotFound())
                return false;
            LogPrintf("LevelDB read failure: %s\n", status.ToString().c_str());
            HandleError(status);
        }
        try {
            CDataStream ssValue(strValue.data(), strValue.data() + strValue.size(), SER_DISK, CLIENT_VERSION);
            ssValue >> value;
        } catch(std::exception &e) {
            return false;
        }
        return true;
    }

    template<typename K, typename V> bool Write(const K& key, const V& value, bool fSync = false) throw(leveldb_error) {
        CLevelDBBatch batch;
        batch.Write(key, value);
        return WriteBatch(batch, fSync);
    }

    template<typename K> bool Exists(const K& key) throw(leveldb_error) {
        CDataStream ssKey(SER_DISK, CLIENT_VERSION);
        ssKey.reserve(ssKey.GetSerializeSize(key));
        ssKey << key;
        leveldb::Slice slKey(&ssKey[0], ssKey.size());

        std::string strValue;
        leveldb::Status status = pdb->Get(readoptions, slKey, &strValue);
        if (!status.ok()) {
            if (status.IsNotFound())
                return false;
            LogPrintf("LevelDB read failure: %s\n", status.ToString().c_str());
            HandleError(status);
        }
        return true;
    }

    template<typename K> bool Erase(const K& key, bool fSync = false) throw(leveldb_error) {
        CLevelDBBatch batch;
        batch.Erase(key);
        return WriteBatch(batch, fSync);
    }

    bool WriteBatch(CLevelDBBatch &batch, bool fSync = false) throw(leveldb_error);

    // not available for LevelDB; provide for compatibility with BDB
    bool Flush() {
        return true;
    }

    bool Sync() throw(leveldb_error) {
        CLevelDBBatch batch;
        return WriteBatch(batch, true);
    }

    // not exactly clean encapsulation, but it's easiest for now
    leveldb::Iterator *NewIterator() {
        return pdb->NewIterator(iteroptions);
    }
};

#endif // BITCOIN_LEVELDBWRAPPER_H