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// Copyright (c) 2012-2016 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#ifndef BITCOIN_DBWRAPPER_H
#define BITCOIN_DBWRAPPER_H
#include "clientversion.h"
#include "fs.h"
#include "serialize.h"
#include "streams.h"
#include "util.h"
#include "utilstrencodings.h"
#include "version.h"
#include <leveldb/db.h>
#include <leveldb/write_batch.h>
static const size_t DBWRAPPER_PREALLOC_KEY_SIZE = 64;
static const size_t DBWRAPPER_PREALLOC_VALUE_SIZE = 1024;
class dbwrapper_error : public std::runtime_error
{
public:
dbwrapper_error(const std::string& msg) : std::runtime_error(msg) {}
};
class CDBWrapper;
/** These should be considered an implementation detail of the specific database.
*/
namespace dbwrapper_private {
/** Handle database error by throwing dbwrapper_error exception.
*/
void HandleError(const leveldb::Status& status);
/** Work around circular dependency, as well as for testing in dbwrapper_tests.
* Database obfuscation should be considered an implementation detail of the
* specific database.
*/
const std::vector<unsigned char>& GetObfuscateKey(const CDBWrapper &w);
};
/** Batch of changes queued to be written to a CDBWrapper */
class CDBBatch
{
friend class CDBWrapper;
private:
const CDBWrapper &parent;
leveldb::WriteBatch batch;
CDataStream ssKey;
CDataStream ssValue;
size_t size_estimate;
public:
/**
* @param[in] _parent CDBWrapper that this batch is to be submitted to
*/
CDBBatch(const CDBWrapper &_parent) : parent(_parent), ssKey(SER_DISK, CLIENT_VERSION), ssValue(SER_DISK, CLIENT_VERSION), size_estimate(0) { };
void Clear()
{
batch.Clear();
size_estimate = 0;
}
template <typename K, typename V>
void Write(const K& key, const V& value)
{
ssKey.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
ssKey << key;
leveldb::Slice slKey(ssKey.data(), ssKey.size());
ssValue.reserve(DBWRAPPER_PREALLOC_VALUE_SIZE);
ssValue << value;
ssValue.Xor(dbwrapper_private::GetObfuscateKey(parent));
leveldb::Slice slValue(ssValue.data(), ssValue.size());
batch.Put(slKey, slValue);
// LevelDB serializes writes as:
// - byte: header
// - varint: key length (1 byte up to 127B, 2 bytes up to 16383B, ...)
// - byte[]: key
// - varint: value length
// - byte[]: value
// The formula below assumes the key and value are both less than 16k.
size_estimate += 3 + (slKey.size() > 127) + slKey.size() + (slValue.size() > 127) + slValue.size();
ssKey.clear();
ssValue.clear();
}
template <typename K>
void Erase(const K& key)
{
ssKey.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
ssKey << key;
leveldb::Slice slKey(ssKey.data(), ssKey.size());
batch.Delete(slKey);
// LevelDB serializes erases as:
// - byte: header
// - varint: key length
// - byte[]: key
// The formula below assumes the key is less than 16kB.
size_estimate += 2 + (slKey.size() > 127) + slKey.size();
ssKey.clear();
}
size_t SizeEstimate() const { return size_estimate; }
};
class CDBIterator
{
private:
const CDBWrapper &parent;
leveldb::Iterator *piter;
public:
/**
* @param[in] _parent Parent CDBWrapper instance.
* @param[in] _piter The original leveldb iterator.
*/
CDBIterator(const CDBWrapper &_parent, leveldb::Iterator *_piter) :
parent(_parent), piter(_piter) { };
~CDBIterator();
bool Valid();
void SeekToFirst();
template<typename K> void Seek(const K& key) {
CDataStream ssKey(SER_DISK, CLIENT_VERSION);
ssKey.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
ssKey << key;
leveldb::Slice slKey(ssKey.data(), ssKey.size());
piter->Seek(slKey);
}
void Next();
template<typename K> bool GetKey(K& key) {
leveldb::Slice slKey = piter->key();
try {
CDataStream ssKey(slKey.data(), slKey.data() + slKey.size(), SER_DISK, CLIENT_VERSION);
ssKey >> key;
} catch (const std::exception&) {
return false;
}
return true;
}
template<typename V> bool GetValue(V& value) {
leveldb::Slice slValue = piter->value();
try {
CDataStream ssValue(slValue.data(), slValue.data() + slValue.size(), SER_DISK, CLIENT_VERSION);
ssValue.Xor(dbwrapper_private::GetObfuscateKey(parent));
ssValue >> value;
} catch (const std::exception&) {
return false;
}
return true;
}
unsigned int GetValueSize() {
return piter->value().size();
}
};
class CDBWrapper
{
friend const std::vector<unsigned char>& dbwrapper_private::GetObfuscateKey(const CDBWrapper &w);
private:
//! custom environment this database is using (may be nullptr 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;
//! a key used for optional XOR-obfuscation of the database
std::vector<unsigned char> obfuscate_key;
//! the key under which the obfuscation key is stored
static const std::string OBFUSCATE_KEY_KEY;
//! the length of the obfuscate key in number of bytes
static const unsigned int OBFUSCATE_KEY_NUM_BYTES;
std::vector<unsigned char> CreateObfuscateKey() const;
public:
/**
* @param[in] path Location in the filesystem where leveldb data will be stored.
* @param[in] nCacheSize Configures various leveldb cache settings.
* @param[in] fMemory If true, use leveldb's memory environment.
* @param[in] fWipe If true, remove all existing data.
* @param[in] obfuscate If true, store data obfuscated via simple XOR. If false, XOR
* with a zero'd byte array.
*/
CDBWrapper(const fs::path& path, size_t nCacheSize, bool fMemory = false, bool fWipe = false, bool obfuscate = false);
~CDBWrapper();
template <typename K, typename V>
bool Read(const K& key, V& value) const
{
CDataStream ssKey(SER_DISK, CLIENT_VERSION);
ssKey.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
ssKey << key;
leveldb::Slice slKey(ssKey.data(), 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());
dbwrapper_private::HandleError(status);
}
try {
CDataStream ssValue(strValue.data(), strValue.data() + strValue.size(), SER_DISK, CLIENT_VERSION);
ssValue.Xor(obfuscate_key);
ssValue >> value;
} catch (const std::exception&) {
return false;
}
return true;
}
template <typename K, typename V>
bool Write(const K& key, const V& value, bool fSync = false)
{
CDBBatch batch(*this);
batch.Write(key, value);
return WriteBatch(batch, fSync);
}
template <typename K>
bool Exists(const K& key) const
{
CDataStream ssKey(SER_DISK, CLIENT_VERSION);
ssKey.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
ssKey << key;
leveldb::Slice slKey(ssKey.data(), 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());
dbwrapper_private::HandleError(status);
}
return true;
}
template <typename K>
bool Erase(const K& key, bool fSync = false)
{
CDBBatch batch(*this);
batch.Erase(key);
return WriteBatch(batch, fSync);
}
bool WriteBatch(CDBBatch& batch, bool fSync = false);
// not available for LevelDB; provide for compatibility with BDB
bool Flush()
{
return true;
}
bool Sync()
{
CDBBatch batch(*this);
return WriteBatch(batch, true);
}
CDBIterator *NewIterator()
{
return new CDBIterator(*this, pdb->NewIterator(iteroptions));
}
/**
* Return true if the database managed by this class contains no entries.
*/
bool IsEmpty();
template<typename K>
size_t EstimateSize(const K& key_begin, const K& key_end) const
{
CDataStream ssKey1(SER_DISK, CLIENT_VERSION), ssKey2(SER_DISK, CLIENT_VERSION);
ssKey1.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
ssKey2.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
ssKey1 << key_begin;
ssKey2 << key_end;
leveldb::Slice slKey1(ssKey1.data(), ssKey1.size());
leveldb::Slice slKey2(ssKey2.data(), ssKey2.size());
uint64_t size = 0;
leveldb::Range range(slKey1, slKey2);
pdb->GetApproximateSizes(&range, 1, &size);
return size;
}
/**
* Compact a certain range of keys in the database.
*/
template<typename K>
void CompactRange(const K& key_begin, const K& key_end) const
{
CDataStream ssKey1(SER_DISK, CLIENT_VERSION), ssKey2(SER_DISK, CLIENT_VERSION);
ssKey1.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
ssKey2.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
ssKey1 << key_begin;
ssKey2 << key_end;
leveldb::Slice slKey1(ssKey1.data(), ssKey1.size());
leveldb::Slice slKey2(ssKey2.data(), ssKey2.size());
pdb->CompactRange(&slKey1, &slKey2);
}
};
#endif // BITCOIN_DBWRAPPER_H