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| The [https://github.com/libbitcoin/libbitcoin-blockchain libbitcoin-blockchain] library is a dependency of [[Libbitcoin_Node|libbitcoin-node]] and [[Libbitcoin_Server|libbitcoin-server]]. It was originally contained within [[Libbitcoin_Common|libbitcoin]]. | | The [https://github.com/libbitcoin/libbitcoin-blockchain libbitcoin-blockchain] library is a dependency of [[Libbitcoin_Node|libbitcoin-node]] and [[Libbitcoin_Server|libbitcoin-server]]. It was originally contained within [[Libbitcoin_Common|libbitcoin]]. |
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| ==Example==
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| #include <string>
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| #include <bitcoin/blockchain.hpp>
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| // Initialize the blockchain.
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| int main(int argc, char* argv[])
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| {
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| std::string prefix("blockchain");
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| if (argc > 1)
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| prefix = argv[1];
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| bc::chain::initialize_blockchain(prefix);
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| bc::chain::db_paths paths(prefix);
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| constexpr size_t history_height = 0;
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| bc::chain::db_interface interface(paths, { history_height });
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| interface.start();
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| const auto genesis = bc::genesis_block();
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| interface.push(genesis);
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| return 0;
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| }
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| ==Design==
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| The original implementation used [http://leveldb.org LevelDB]. Following a redesign in late 2014 by [[Amir_Taaki|Amir Taaki]] (genjix) the database was replaced by a [https://en.wikipedia.org/wiki/Memory-mapped_file memory-mapped file] implementation. Logical queries are performed using a set of hash tables. The number of hash buckets is optimized to minimize hash collisions, though collisions are accommodated. These changes resulted in a substantial performance increase, near constant time, for queries against the blockchain. Insert performance was not materially affected.
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| [[Image:Libbitcoin-blockchain-gets.png|500px]] [[Image:Libbitcoin-blockchain-gets-normalised.png|500px]]
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| ==Database==
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| The following files constitute the blockchain database non-volatile storage. As of height 350,000 the database consumes approximately 105 GB of disk space.
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| * blocks_lookup
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| * blocks_rows
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| * history_lookup
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| * history_rows
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| * spends
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| * stealth_index
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| * stealth_rows
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| * txs
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| ==Consensus Validation== | | ==Consensus Validation== |
| By default the library depends on the [[Libbitcoin_Consensus|libbitcoin-consensus]] library. This ensures that consensus checks are identical to those implemented by [[Bitcoind|bitcoind]]. By building using the ''--without-consensus'' flag the dependency is avoided and [[Libbitcoin|libbitcoin]] native consensus checks are used instead. | | By default the library depends on the [[Libbitcoin_Consensus|libbitcoin-consensus]] library. This ensures that consensus checks are identical to those implemented by [[Bitcoind|bitcoind]]. By building using the ''--without-consensus'' flag the dependency is avoided and [[Libbitcoin|libbitcoin]] native consensus checks are used instead. |
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| ==Considerations==
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| * There is no mechanical hard drive optimization. The implementation is intended for solid state drives ([http://en.wikipedia.org/wiki/Solid-state_drive SSD]).
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| * There is a possibility of index corruption during hard shutdown. There is no means of detecting corruption aside from catastrophic fault. However given that the entire blockchain is a cache this is not considered significant. Repair can be accomplished by re-synchronizing the blockchain.
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| * Data files are append only, with logical deletions only. Therefore file size is not minimized following blockchain reorganization although the impact is typically small. Defragmentation can be accomplished by re-synchronizing the blockchain.
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| * The database is effectively locked during write operations. As these operations are anticipated on a period of approximately ten minutes this is not typically significant. However during a period of catch-up synchronizing the server can become continuously unresponsive to requests.
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| ==Dependencies== | | ==Dependencies== |
The libbitcoin-blockchain library is a dependency of libbitcoin-node and libbitcoin-server. It was originally contained within libbitcoin.
Consensus Validation
By default the library depends on the libbitcoin-consensus library. This ensures that consensus checks are identical to those implemented by bitcoind. By building using the --without-consensus flag the dependency is avoided and libbitcoin native consensus checks are used instead.
Dependencies
See Also
References