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352 lines
10 KiB
352 lines
10 KiB
// Copyright (c) 2012-2019 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#ifndef BITCOIN_DBWRAPPER_H
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#define BITCOIN_DBWRAPPER_H
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#include <clientversion.h>
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#include <fs.h>
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#include <serialize.h>
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#include <streams.h>
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#include <util/system.h>
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#include <util/strencodings.h>
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#include <leveldb/db.h>
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#include <leveldb/write_batch.h>
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static const size_t DBWRAPPER_PREALLOC_KEY_SIZE = 64;
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static const size_t DBWRAPPER_PREALLOC_VALUE_SIZE = 1024;
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class dbwrapper_error : public std::runtime_error
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{
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public:
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explicit dbwrapper_error(const std::string& msg) : std::runtime_error(msg) {}
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};
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class CDBWrapper;
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/** These should be considered an implementation detail of the specific database.
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*/
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namespace dbwrapper_private {
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/** Handle database error by throwing dbwrapper_error exception.
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*/
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void HandleError(const leveldb::Status& status);
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/** Work around circular dependency, as well as for testing in dbwrapper_tests.
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* Database obfuscation should be considered an implementation detail of the
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* specific database.
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*/
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const std::vector<unsigned char>& GetObfuscateKey(const CDBWrapper &w);
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};
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/** Batch of changes queued to be written to a CDBWrapper */
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class CDBBatch
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{
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friend class CDBWrapper;
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private:
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const CDBWrapper &parent;
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leveldb::WriteBatch batch;
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CDataStream ssKey;
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CDataStream ssValue;
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size_t size_estimate;
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public:
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/**
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* @param[in] _parent CDBWrapper that this batch is to be submitted to
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*/
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explicit CDBBatch(const CDBWrapper &_parent) : parent(_parent), ssKey(SER_DISK, CLIENT_VERSION), ssValue(SER_DISK, CLIENT_VERSION), size_estimate(0) { };
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void Clear()
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{
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batch.Clear();
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size_estimate = 0;
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}
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template <typename K, typename V>
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void Write(const K& key, const V& value)
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{
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ssKey.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
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ssKey << key;
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leveldb::Slice slKey(ssKey.data(), ssKey.size());
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ssValue.reserve(DBWRAPPER_PREALLOC_VALUE_SIZE);
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ssValue << value;
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ssValue.Xor(dbwrapper_private::GetObfuscateKey(parent));
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leveldb::Slice slValue(ssValue.data(), ssValue.size());
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batch.Put(slKey, slValue);
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// LevelDB serializes writes as:
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// - byte: header
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// - varint: key length (1 byte up to 127B, 2 bytes up to 16383B, ...)
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// - byte[]: key
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// - varint: value length
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// - byte[]: value
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// The formula below assumes the key and value are both less than 16k.
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size_estimate += 3 + (slKey.size() > 127) + slKey.size() + (slValue.size() > 127) + slValue.size();
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ssKey.clear();
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ssValue.clear();
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}
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template <typename K>
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void Erase(const K& key)
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{
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ssKey.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
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ssKey << key;
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leveldb::Slice slKey(ssKey.data(), ssKey.size());
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batch.Delete(slKey);
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// LevelDB serializes erases as:
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// - byte: header
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// - varint: key length
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// - byte[]: key
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// The formula below assumes the key is less than 16kB.
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size_estimate += 2 + (slKey.size() > 127) + slKey.size();
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ssKey.clear();
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}
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size_t SizeEstimate() const { return size_estimate; }
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};
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class CDBIterator
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{
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private:
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const CDBWrapper &parent;
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leveldb::Iterator *piter;
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public:
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/**
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* @param[in] _parent Parent CDBWrapper instance.
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* @param[in] _piter The original leveldb iterator.
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*/
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CDBIterator(const CDBWrapper &_parent, leveldb::Iterator *_piter) :
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parent(_parent), piter(_piter) { };
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~CDBIterator();
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bool Valid() const;
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void SeekToFirst();
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template<typename K> void Seek(const K& key) {
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CDataStream ssKey(SER_DISK, CLIENT_VERSION);
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ssKey.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
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ssKey << key;
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leveldb::Slice slKey(ssKey.data(), ssKey.size());
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piter->Seek(slKey);
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}
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void Next();
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template<typename K> bool GetKey(K& key) {
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leveldb::Slice slKey = piter->key();
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try {
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CDataStream ssKey(slKey.data(), slKey.data() + slKey.size(), SER_DISK, CLIENT_VERSION);
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ssKey >> key;
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} catch (const std::exception&) {
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return false;
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}
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return true;
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}
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template<typename V> bool GetValue(V& value) {
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leveldb::Slice slValue = piter->value();
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try {
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CDataStream ssValue(slValue.data(), slValue.data() + slValue.size(), SER_DISK, CLIENT_VERSION);
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ssValue.Xor(dbwrapper_private::GetObfuscateKey(parent));
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ssValue >> value;
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} catch (const std::exception&) {
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return false;
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}
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return true;
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}
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unsigned int GetValueSize() {
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return piter->value().size();
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}
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};
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class CDBWrapper
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{
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friend const std::vector<unsigned char>& dbwrapper_private::GetObfuscateKey(const CDBWrapper &w);
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private:
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//! custom environment this database is using (may be nullptr in case of default environment)
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leveldb::Env* penv;
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//! database options used
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leveldb::Options options;
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//! options used when reading from the database
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leveldb::ReadOptions readoptions;
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//! options used when iterating over values of the database
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leveldb::ReadOptions iteroptions;
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//! options used when writing to the database
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leveldb::WriteOptions writeoptions;
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//! options used when sync writing to the database
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leveldb::WriteOptions syncoptions;
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//! the database itself
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leveldb::DB* pdb;
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//! the name of this database
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std::string m_name;
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//! a key used for optional XOR-obfuscation of the database
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std::vector<unsigned char> obfuscate_key;
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//! the key under which the obfuscation key is stored
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static const std::string OBFUSCATE_KEY_KEY;
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//! the length of the obfuscate key in number of bytes
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static const unsigned int OBFUSCATE_KEY_NUM_BYTES;
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std::vector<unsigned char> CreateObfuscateKey() const;
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public:
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/**
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* @param[in] path Location in the filesystem where leveldb data will be stored.
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* @param[in] nCacheSize Configures various leveldb cache settings.
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* @param[in] fMemory If true, use leveldb's memory environment.
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* @param[in] fWipe If true, remove all existing data.
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* @param[in] obfuscate If true, store data obfuscated via simple XOR. If false, XOR
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* with a zero'd byte array.
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*/
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CDBWrapper(const fs::path& path, size_t nCacheSize, bool fMemory = false, bool fWipe = false, bool obfuscate = false);
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~CDBWrapper();
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CDBWrapper(const CDBWrapper&) = delete;
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CDBWrapper& operator=(const CDBWrapper&) = delete;
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template <typename K, typename V>
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bool Read(const K& key, V& value) const
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{
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CDataStream ssKey(SER_DISK, CLIENT_VERSION);
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ssKey.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
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ssKey << key;
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leveldb::Slice slKey(ssKey.data(), ssKey.size());
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std::string strValue;
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leveldb::Status status = pdb->Get(readoptions, slKey, &strValue);
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if (!status.ok()) {
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if (status.IsNotFound())
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return false;
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LogPrintf("LevelDB read failure: %s\n", status.ToString());
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dbwrapper_private::HandleError(status);
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}
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try {
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CDataStream ssValue(strValue.data(), strValue.data() + strValue.size(), SER_DISK, CLIENT_VERSION);
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ssValue.Xor(obfuscate_key);
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ssValue >> value;
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} catch (const std::exception&) {
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return false;
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}
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return true;
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}
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template <typename K, typename V>
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bool Write(const K& key, const V& value, bool fSync = false)
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{
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CDBBatch batch(*this);
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batch.Write(key, value);
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return WriteBatch(batch, fSync);
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}
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template <typename K>
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bool Exists(const K& key) const
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{
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CDataStream ssKey(SER_DISK, CLIENT_VERSION);
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ssKey.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
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ssKey << key;
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leveldb::Slice slKey(ssKey.data(), ssKey.size());
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std::string strValue;
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leveldb::Status status = pdb->Get(readoptions, slKey, &strValue);
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if (!status.ok()) {
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if (status.IsNotFound())
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return false;
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LogPrintf("LevelDB read failure: %s\n", status.ToString());
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dbwrapper_private::HandleError(status);
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}
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return true;
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}
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template <typename K>
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bool Erase(const K& key, bool fSync = false)
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{
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CDBBatch batch(*this);
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batch.Erase(key);
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return WriteBatch(batch, fSync);
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}
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bool WriteBatch(CDBBatch& batch, bool fSync = false);
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// Get an estimate of LevelDB memory usage (in bytes).
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size_t DynamicMemoryUsage() const;
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// not available for LevelDB; provide for compatibility with BDB
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bool Flush()
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{
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return true;
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}
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bool Sync()
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{
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CDBBatch batch(*this);
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return WriteBatch(batch, true);
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}
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CDBIterator *NewIterator()
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{
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return new CDBIterator(*this, pdb->NewIterator(iteroptions));
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}
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/**
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* Return true if the database managed by this class contains no entries.
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*/
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bool IsEmpty();
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template<typename K>
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size_t EstimateSize(const K& key_begin, const K& key_end) const
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{
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CDataStream ssKey1(SER_DISK, CLIENT_VERSION), ssKey2(SER_DISK, CLIENT_VERSION);
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ssKey1.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
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ssKey2.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
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ssKey1 << key_begin;
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ssKey2 << key_end;
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leveldb::Slice slKey1(ssKey1.data(), ssKey1.size());
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leveldb::Slice slKey2(ssKey2.data(), ssKey2.size());
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uint64_t size = 0;
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leveldb::Range range(slKey1, slKey2);
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pdb->GetApproximateSizes(&range, 1, &size);
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return size;
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}
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/**
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* Compact a certain range of keys in the database.
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*/
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template<typename K>
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void CompactRange(const K& key_begin, const K& key_end) const
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{
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CDataStream ssKey1(SER_DISK, CLIENT_VERSION), ssKey2(SER_DISK, CLIENT_VERSION);
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ssKey1.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
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ssKey2.reserve(DBWRAPPER_PREALLOC_KEY_SIZE);
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ssKey1 << key_begin;
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ssKey2 << key_end;
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leveldb::Slice slKey1(ssKey1.data(), ssKey1.size());
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leveldb::Slice slKey2(ssKey2.data(), ssKey2.size());
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pdb->CompactRange(&slKey1, &slKey2);
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}
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};
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#endif // BITCOIN_DBWRAPPER_H
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