veriblock-pop-cpp
C++11 Libraries for leveraging VeriBlock Proof-Of-Proof blockchain technology.
Adding persistence

Table of Contents

Overview

ALT block storage should be modified to store VeriBlock related data.

1. Add PayloadsProvider.

We should add a PayloadsProvider for the VeriBlock library. The main idea of such class is that we reuse the existing ALT blockchain database. Our library allows to use the native implementation of the database. We implement it with PayloadsProvider class which is inherited from the altintegration::PayloadsStorage class.

Payloads provider: https://github.com/VeriBlock/vbk-ri-btc/blob/master/src/vbk/adaptors/payloads_provider.hpp. Copy this file to your project.

Block provider: https://github.com/VeriBlock/vbk-ri-btc/blob/master/src/vbk/adaptors/block_provider.hpp. Copy this file to your project.

Note
These adaptors rely heavily on Bitcoin structures such as CDBWrapper and CDBIterator. Other blockchains should use own adaptors or other means for storing VeriBlock related data.

2. Create wrappers for the persistence API.

https://github.com/VeriBlock/vbk-ri-btc/blob/master/src/vbk/pop_service.hpp

// Copyright (c) 2019-2022 Xenios SEZC
// https://www.veriblock.org
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#ifndef BITCOIN_SRC_VBK_POP_SERVICE_HPP
#define BITCOIN_SRC_VBK_POP_SERVICE_HPP
#include "pop_common.hpp"
#include <vbk/adaptors/payloads_provider.hpp>
#include <vbk/util.hpp>
class CBlockTreeDB;
class CDBBatch;
class CDBIterator;
class CDBWrapper;
namespace VeriBlock {
void InitPopContext(CDBWrapper& db);
bool hasPopData(CBlockTreeDB& db);
altintegration::PopData getPopData();
void saveTrees(CDBBatch* batch);
bool loadTrees(CDBWrapper& db);
} // namespace VeriBlock
#endif //BITCOIN_SRC_VBK_POP_SERVICE_HPP
altintegration::PopData
Represents ALT block body of POP-related info.
Definition: popdata.hpp:27

https://github.com/VeriBlock/vbk-ri-btc/blob/master/src/vbk/pop_service.cpp

// Copyright (c) 2019-2022 Xenios SEZC
// https://www.veriblock.org
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <chain.h>
#include <chainparams.h>
#include <consensus/validation.h>
#include <dbwrapper.h>
#include <shutdown.h>
#include <validation.h>
#include <vbk/adaptors/payloads_provider.hpp>
#include <veriblock/storage/util.hpp>
#ifdef WIN32
#include <boost/thread/interruption.hpp>
#endif //WIN32
#include "pop_service.hpp"
#include <utility>
#include <vbk/adaptors/block_provider.hpp>
#include <vbk/pop_common.hpp>
namespace VeriBlock {
void InitPopContext(CDBWrapper& db)
{
auto payloads_provider = std::make_shared<PayloadsProvider>(db);
SetPop(payloads_provider);
}
bool hasPopData(CBlockTreeDB& db)
{
return db.Exists(tip_key<altintegration::BtcBlock>()) &&
db.Exists(tip_key<altintegration::VbkBlock>()) &&
db.Exists(tip_key<altintegration::AltBlock>());
}
void saveTrees(CDBBatch* batch)
{
AssertLockHeld(cs_main);
VeriBlock::BlockBatch b(*batch);
altintegration::SaveAllTrees(*GetPop().altTree, b);
}
bool loadTrees(CDBWrapper& db)
{
altintegration::ValidationState state;
BlockReader reader(db);
if (!altintegration::LoadAllTrees(GetPop(), reader, state)) {
return error("%s: failed to load trees %s", __func__, state.toString());
}
return true;
}
altintegration::ValidationState
Class that is used for storing validation state.
Definition: validation_state.hpp:28
Note
You can copy provided pop_service.hpp and pop_service.cpp files and comment out everything but storage related API.

3. Initialize VeriBlock storage during ALT blockchain initialization process.

https://github.com/VeriBlock/vbk-ri-btc/blob/master/src/init.cpp

+#include <vbk/pop_service.hpp>

method Shutdown

threadGroup.interrupt_all();
threadGroup.join_all();
+ VeriBlock::StopPop();

method AppInitMain

pblocktree.reset();
pblocktree.reset(new CBlockTreeDB(nBlockTreeDBCache, false, fReset));
+ VeriBlock::InitPopContext(*pblocktree);

https://github.com/VeriBlock/vbk-ri-btc/blob/master/src/txdb.cpp

#include <boost/thread.hpp>
+#include <vbk/pop_service.hpp>

method CBlockTreeDB::WriteBatchSync

}
+
+ // write BTC/VBK/ALT blocks
+ VeriBlock::saveTrees(&batch);
return WriteBatch(batch, true);

https://github.com/VeriBlock/vbk-ri-btc/blob/master/src/validation.cpp

#include <warnings.h>
+#include <vbk/pop_service.hpp>
+#include <vbk/pop_common.hpp>
+#include <vbk/util.hpp>

method BlockManager::LoadBlockIndex

return false;
+ bool hasPopData = VeriBlock::hasPopData(blocktree);
+
+ if (!hasPopData) {
+ LogPrintf("BTC/VBK/ALT tips not found... skipping block index loading\n");
+ return true;
+ }
+
// Calculate nChainWork

method BlockManager::LoadBlockIndex

if (pindex->IsValid(BLOCK_VALID_TREE) && (pindexBestHeader == nullptr || CBlockIndexWorkComparator()(pindexBestHeader, pindex)))
pindexBestHeader = pindex;
}
+
+ // get best chain from ALT tree and update vBTC's best chain
+ {
+ AssertLockHeld(cs_main);
+
+ // load blocks
+ if(!VeriBlock::loadTrees(blocktree)) {
+ return false;
+ }
}

4. Update the constructor of the TestingSetup struct.

https://github.com/VeriBlock/vbk-ri-btc/blob/master/src/test/util/setup_common.cpp

method TestingSetup::TestingSetup

pblocktree.reset(new CBlockTreeDB(1 << 20, true));
+ VeriBlock::InitPopContext(*pblocktree);

method TestingSetup::~TestingSetup

threadGroup.interrupt_all();
threadGroup.join_all();
+ VeriBlock::StopPop();

method TestChain100Setup::TestChain100Setup

+ assert(ChainActive().Tip() != nullptr);
+ assert(ChainActive().Tip()->nHeight == 100);
+ assert(BlockIndex().size() == 101);

5. Restore VeriBlock block hash from the storage - do not recalculate it if possible.

https://github.com/VeriBlock/vbk-ri-btc/blob/master/src/dbwrapper.h

+// VeriBlock: put VBK block hash in the block index
+template <>
+inline bool CDBIterator::GetValue(altintegration::BlockIndex<altintegration::VbkBlock>& 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));
+ std::pair<char, altintegration::VbkBlock::hash_t> key;
+ if (!GetKey(key)) return false;
+ UnserializeWithHash(ssValue, value, key.second);
+ } catch (const std::exception&) {
+ return false;
+ }
+ return true;
+}
altintegration::BlockIndex
A node in a block tree.
Definition: block_index.hpp:31

6. Add pop_service.cpp to the makefile.

https://github.com/VeriBlock/vbk-ri-btc/blob/master/src/Makefile.am

libbitcoin_server_a_SOURCES = \
+ vbk/pop_service.hpp \
+ vbk/pop_service.cpp \
addrdb.cpp \