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Diffstat (limited to 'src/index/txindex.cpp')
-rw-r--r-- | src/index/txindex.cpp | 286 |
1 files changed, 286 insertions, 0 deletions
diff --git a/src/index/txindex.cpp b/src/index/txindex.cpp new file mode 100644 index 0000000000..c85030e18e --- /dev/null +++ b/src/index/txindex.cpp @@ -0,0 +1,286 @@ +// Copyright (c) 2017-2018 The Bitcoin Core developers +// Distributed under the MIT software license, see the accompanying +// file COPYING or http://www.opensource.org/licenses/mit-license.php. + +#include <index/txindex.h> +#include <shutdown.h> +#include <ui_interface.h> +#include <util.h> +#include <validation.h> + +#include <boost/thread.hpp> + +constexpr char DB_BEST_BLOCK = 'B'; +constexpr char DB_TXINDEX = 't'; +constexpr char DB_TXINDEX_BLOCK = 'T'; + +std::unique_ptr<TxIndex> g_txindex; + +struct CDiskTxPos : public CDiskBlockPos +{ + unsigned int nTxOffset; // after header + + ADD_SERIALIZE_METHODS; + + template <typename Stream, typename Operation> + inline void SerializationOp(Stream& s, Operation ser_action) { + READWRITEAS(CDiskBlockPos, *this); + READWRITE(VARINT(nTxOffset)); + } + + CDiskTxPos(const CDiskBlockPos &blockIn, unsigned int nTxOffsetIn) : CDiskBlockPos(blockIn.nFile, blockIn.nPos), nTxOffset(nTxOffsetIn) { + } + + CDiskTxPos() { + SetNull(); + } + + void SetNull() { + CDiskBlockPos::SetNull(); + nTxOffset = 0; + } +}; + +/** + * Access to the txindex database (indexes/txindex/) + * + * The database stores a block locator of the chain the database is synced to + * so that the TxIndex can efficiently determine the point it last stopped at. + * A locator is used instead of a simple hash of the chain tip because blocks + * and block index entries may not be flushed to disk until after this database + * is updated. + */ +class TxIndex::DB : public BaseIndex::DB +{ +public: + explicit DB(size_t n_cache_size, bool f_memory = false, bool f_wipe = false); + + /// Read the disk location of the transaction data with the given hash. Returns false if the + /// transaction hash is not indexed. + bool ReadTxPos(const uint256& txid, CDiskTxPos& pos) const; + + /// Write a batch of transaction positions to the DB. + bool WriteTxs(const std::vector<std::pair<uint256, CDiskTxPos>>& v_pos); + + /// Migrate txindex data from the block tree DB, where it may be for older nodes that have not + /// been upgraded yet to the new database. + bool MigrateData(CBlockTreeDB& block_tree_db, const CBlockLocator& best_locator); +}; + +TxIndex::DB::DB(size_t n_cache_size, bool f_memory, bool f_wipe) : + BaseIndex::DB(GetDataDir() / "indexes" / "txindex", n_cache_size, f_memory, f_wipe) +{} + +bool TxIndex::DB::ReadTxPos(const uint256 &txid, CDiskTxPos& pos) const +{ + return Read(std::make_pair(DB_TXINDEX, txid), pos); +} + +bool TxIndex::DB::WriteTxs(const std::vector<std::pair<uint256, CDiskTxPos>>& v_pos) +{ + CDBBatch batch(*this); + for (const auto& tuple : v_pos) { + batch.Write(std::make_pair(DB_TXINDEX, tuple.first), tuple.second); + } + return WriteBatch(batch); +} + +/* + * Safely persist a transfer of data from the old txindex database to the new one, and compact the + * range of keys updated. This is used internally by MigrateData. + */ +static void WriteTxIndexMigrationBatches(CDBWrapper& newdb, CDBWrapper& olddb, + CDBBatch& batch_newdb, CDBBatch& batch_olddb, + const std::pair<unsigned char, uint256>& begin_key, + const std::pair<unsigned char, uint256>& end_key) +{ + // Sync new DB changes to disk before deleting from old DB. + newdb.WriteBatch(batch_newdb, /*fSync=*/ true); + olddb.WriteBatch(batch_olddb); + olddb.CompactRange(begin_key, end_key); + + batch_newdb.Clear(); + batch_olddb.Clear(); +} + +bool TxIndex::DB::MigrateData(CBlockTreeDB& block_tree_db, const CBlockLocator& best_locator) +{ + // The prior implementation of txindex was always in sync with block index + // and presence was indicated with a boolean DB flag. If the flag is set, + // this means the txindex from a previous version is valid and in sync with + // the chain tip. The first step of the migration is to unset the flag and + // write the chain hash to a separate key, DB_TXINDEX_BLOCK. After that, the + // index entries are copied over in batches to the new database. Finally, + // DB_TXINDEX_BLOCK is erased from the old database and the block hash is + // written to the new database. + // + // Unsetting the boolean flag ensures that if the node is downgraded to a + // previous version, it will not see a corrupted, partially migrated index + // -- it will see that the txindex is disabled. When the node is upgraded + // again, the migration will pick up where it left off and sync to the block + // with hash DB_TXINDEX_BLOCK. + bool f_legacy_flag = false; + block_tree_db.ReadFlag("txindex", f_legacy_flag); + if (f_legacy_flag) { + if (!block_tree_db.Write(DB_TXINDEX_BLOCK, best_locator)) { + return error("%s: cannot write block indicator", __func__); + } + if (!block_tree_db.WriteFlag("txindex", false)) { + return error("%s: cannot write block index db flag", __func__); + } + } + + CBlockLocator locator; + if (!block_tree_db.Read(DB_TXINDEX_BLOCK, locator)) { + return true; + } + + int64_t count = 0; + LogPrintf("Upgrading txindex database... [0%%]\n"); + uiInterface.ShowProgress(_("Upgrading txindex database"), 0, true); + int report_done = 0; + const size_t batch_size = 1 << 24; // 16 MiB + + CDBBatch batch_newdb(*this); + CDBBatch batch_olddb(block_tree_db); + + std::pair<unsigned char, uint256> key; + std::pair<unsigned char, uint256> begin_key{DB_TXINDEX, uint256()}; + std::pair<unsigned char, uint256> prev_key = begin_key; + + bool interrupted = false; + std::unique_ptr<CDBIterator> cursor(block_tree_db.NewIterator()); + for (cursor->Seek(begin_key); cursor->Valid(); cursor->Next()) { + boost::this_thread::interruption_point(); + if (ShutdownRequested()) { + interrupted = true; + break; + } + + if (!cursor->GetKey(key)) { + return error("%s: cannot get key from valid cursor", __func__); + } + if (key.first != DB_TXINDEX) { + break; + } + + // Log progress every 10%. + if (++count % 256 == 0) { + // Since txids are uniformly random and traversed in increasing order, the high 16 bits + // of the hash can be used to estimate the current progress. + const uint256& txid = key.second; + uint32_t high_nibble = + (static_cast<uint32_t>(*(txid.begin() + 0)) << 8) + + (static_cast<uint32_t>(*(txid.begin() + 1)) << 0); + int percentage_done = (int)(high_nibble * 100.0 / 65536.0 + 0.5); + + uiInterface.ShowProgress(_("Upgrading txindex database"), percentage_done, true); + if (report_done < percentage_done/10) { + LogPrintf("Upgrading txindex database... [%d%%]\n", percentage_done); + report_done = percentage_done/10; + } + } + + CDiskTxPos value; + if (!cursor->GetValue(value)) { + return error("%s: cannot parse txindex record", __func__); + } + batch_newdb.Write(key, value); + batch_olddb.Erase(key); + + if (batch_newdb.SizeEstimate() > batch_size || batch_olddb.SizeEstimate() > batch_size) { + // NOTE: it's OK to delete the key pointed at by the current DB cursor while iterating + // because LevelDB iterators are guaranteed to provide a consistent view of the + // underlying data, like a lightweight snapshot. + WriteTxIndexMigrationBatches(*this, block_tree_db, + batch_newdb, batch_olddb, + prev_key, key); + prev_key = key; + } + } + + // If these final DB batches complete the migration, write the best block + // hash marker to the new database and delete from the old one. This signals + // that the former is fully caught up to that point in the blockchain and + // that all txindex entries have been removed from the latter. + if (!interrupted) { + batch_olddb.Erase(DB_TXINDEX_BLOCK); + batch_newdb.Write(DB_BEST_BLOCK, locator); + } + + WriteTxIndexMigrationBatches(*this, block_tree_db, + batch_newdb, batch_olddb, + begin_key, key); + + if (interrupted) { + LogPrintf("[CANCELLED].\n"); + return false; + } + + uiInterface.ShowProgress("", 100, false); + + LogPrintf("[DONE].\n"); + return true; +} + +TxIndex::TxIndex(size_t n_cache_size, bool f_memory, bool f_wipe) + : m_db(MakeUnique<TxIndex::DB>(n_cache_size, f_memory, f_wipe)) +{} + +TxIndex::~TxIndex() {} + +bool TxIndex::Init() +{ + LOCK(cs_main); + + // Attempt to migrate txindex from the old database to the new one. Even if + // chain_tip is null, the node could be reindexing and we still want to + // delete txindex records in the old database. + if (!m_db->MigrateData(*pblocktree, chainActive.GetLocator())) { + return false; + } + + return BaseIndex::Init(); +} + +bool TxIndex::WriteBlock(const CBlock& block, const CBlockIndex* pindex) +{ + CDiskTxPos pos(pindex->GetBlockPos(), GetSizeOfCompactSize(block.vtx.size())); + std::vector<std::pair<uint256, CDiskTxPos>> vPos; + vPos.reserve(block.vtx.size()); + for (const auto& tx : block.vtx) { + vPos.emplace_back(tx->GetHash(), pos); + pos.nTxOffset += ::GetSerializeSize(*tx, SER_DISK, CLIENT_VERSION); + } + return m_db->WriteTxs(vPos); +} + +BaseIndex::DB& TxIndex::GetDB() const { return *m_db; } + +bool TxIndex::FindTx(const uint256& tx_hash, uint256& block_hash, CTransactionRef& tx) const +{ + CDiskTxPos postx; + if (!m_db->ReadTxPos(tx_hash, postx)) { + return false; + } + + CAutoFile file(OpenBlockFile(postx, true), SER_DISK, CLIENT_VERSION); + if (file.IsNull()) { + return error("%s: OpenBlockFile failed", __func__); + } + CBlockHeader header; + try { + file >> header; + if (fseek(file.Get(), postx.nTxOffset, SEEK_CUR)) { + return error("%s: fseek(...) failed", __func__); + } + file >> tx; + } catch (const std::exception& e) { + return error("%s: Deserialize or I/O error - %s", __func__, e.what()); + } + if (tx->GetHash() != tx_hash) { + return error("%s: txid mismatch", __func__); + } + block_hash = header.GetHash(); + return true; +} |