1 // Copyright (c) 2017-present The Limenka developers
2 // Distributed under the MIT software license, see the accompanying
3 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
4 5 #ifndef LIMENKA_INDEX_BASE_H
6 #define LIMENKA_INDEX_BASE_H
7 8 #include <dbwrapper.h>
9 #include <interfaces/chain.h>
10 #include <interfaces/types.h>
11 #include <util/string.h>
12 #include <util/threadinterrupt.h>
13 #include <util/translation.h>
14 #include <validationinterface.h>
15 16 #include <string>
17 18 class CBlock;
19 class CBlockIndex;
20 class Chainstate;
21 class ChainstateManager;
22 namespace interfaces {
23 class Chain;
24 } // namespace interfaces
25 26 struct IndexSummary {
27 std::string name;
28 bool synced{false};
29 int best_block_height{0};
30 uint256 best_block_hash;
31 };
32 33 /**
34 * Base class for indices of blockchain data. This implements
35 * CValidationInterface and ensures blocks are indexed sequentially according
36 * to their position in the active chain.
37 *
38 * In the presence of multiple chainstates (i.e. if a UTXO snapshot is loaded),
39 * only the background "IBD" chainstate will be indexed to avoid building the
40 * index out of order. When the background chainstate completes validation, the
41 * index will be reinitialized and indexing will continue.
42 */
43 class BaseIndex : public CValidationInterface
44 {
45 protected:
46 /**
47 * The database stores a block locator of the chain the database is synced to
48 * so that the index can efficiently determine the point it last stopped at.
49 * A locator is used instead of a simple hash of the chain tip because blocks
50 * and block index entries may not be flushed to disk until after this database
51 * is updated.
52 */
53 class DB : public CDBWrapper
54 {
55 public:
56 DB(const fs::path& path, size_t n_cache_size,
57 bool f_memory = false, bool f_wipe = false, bool f_obfuscate = false);
58 59 /// Read block locator of the chain that the index is in sync with.
60 bool ReadBestBlock(CBlockLocator& locator) const;
61 62 /// Write block locator of the chain that the index is in sync with.
63 void WriteBestBlock(CDBBatch& batch, const CBlockLocator& locator);
64 };
65 66 private:
67 /// Whether the index has been initialized or not.
68 std::atomic<bool> m_init{false};
69 /// Whether the index is in sync with the main chain. The flag is flipped
70 /// from false to true once, after which point this starts processing
71 /// ValidationInterface notifications to stay in sync.
72 ///
73 /// Note that this will latch to true *immediately* upon startup if
74 /// `m_chainstate->m_chain` is empty, which will be the case upon startup
75 /// with an empty datadir if, e.g., `-txindex=1` is specified.
76 std::atomic<bool> m_synced{false};
77 78 /// The last block in the chain that the index is in sync with.
79 std::atomic<const CBlockIndex*> m_best_block_index{nullptr};
80 81 std::thread m_thread_sync;
82 CThreadInterrupt m_interrupt;
83 84 /// Write the current index state (eg. chain block locator and subclass-specific items) to disk.
85 ///
86 /// Recommendations for error handling:
87 /// If called on a successor of the previous committed best block in the index, the index can
88 /// continue processing without risk of corruption, though the index state will need to catch up
89 /// from further behind on reboot. If the new state is not a successor of the previous state (due
90 /// to a chain reorganization), the index must halt until Commit succeeds or else it could end up
91 /// getting corrupted.
92 bool Commit();
93 94 /// Loop over disconnected blocks and call CustomRewind.
95 bool Rewind(const CBlockIndex* current_tip, const CBlockIndex* new_tip);
96 97 virtual bool AllowPrune() const = 0;
98 99 template <typename... Args>
100 void FatalErrorf(util::ConstevalFormatString<sizeof...(Args)> fmt, const Args&... args);
101 102 protected:
103 std::unique_ptr<interfaces::Chain> m_chain;
104 Chainstate* m_chainstate{nullptr};
105 const std::string m_name;
106 107 void BlockConnected(ChainstateRole role, const std::shared_ptr<const CBlock>& block, const CBlockIndex* pindex) override;
108 109 void ChainStateFlushed(ChainstateRole role, const CBlockLocator& locator) override;
110 111 /// Initialize internal state from the database and block index.
112 [[nodiscard]] virtual bool CustomInit(const std::optional<interfaces::BlockRef>& block) { return true; }
113 114 /// Write update index entries for a newly connected block.
115 [[nodiscard]] virtual bool CustomAppend(const interfaces::BlockInfo& block) { return true; }
116 117 /// Virtual method called internally by Commit that can be overridden to atomically
118 /// commit more index state.
119 virtual bool CustomCommit(CDBBatch& batch) { return true; }
120 121 /// Rewind index to an earlier chain tip during a chain reorg. The tip must
122 /// be an ancestor of the current best block.
123 [[nodiscard]] virtual bool CustomRewind(const interfaces::BlockRef& current_tip, const interfaces::BlockRef& new_tip) { return true; }
124 125 virtual DB& GetDB() const = 0;
126 127 /// Update the internal best block index as well as the prune lock.
128 void SetBestBlockIndex(const CBlockIndex* block);
129 130 public:
131 BaseIndex(std::unique_ptr<interfaces::Chain> chain, std::string name);
132 /// Destructor interrupts sync thread if running and blocks until it exits.
133 virtual ~BaseIndex();
134 135 /// Get the name of the index for display in logs.
136 const std::string& GetName() const LIFETIMEBOUND { return m_name; }
137 138 /// Get the action the user should take to disable this index, including the verb
139 /// (e.g., "set -txindex=0" or "remove 'basic' from -blockfilterindex").
140 virtual bilingual_str GetDisableAction() const = 0;
141 142 /// Blocks the current thread until the index is caught up to the current
143 /// state of the block chain. This only blocks if the index has gotten in
144 /// sync once and only needs to process blocks in the ValidationInterface
145 /// queue. If the index is catching up from far behind, this method does
146 /// not block and immediately returns false.
147 bool BlockUntilSyncedToCurrentChain() const LOCKS_EXCLUDED(::cs_main);
148 149 void Interrupt();
150 151 /// Initializes the sync state and registers the instance to the
152 /// validation interface so that it stays in sync with blockchain updates.
153 [[nodiscard]] bool Init();
154 155 /// Starts the initial sync process on a background thread.
156 [[nodiscard]] bool StartBackgroundSync();
157 158 /// Sync the index with the block index starting from the current best block.
159 /// Intended to be run in its own thread, m_thread_sync, and can be
160 /// interrupted with m_interrupt. Once the index gets in sync, the m_synced
161 /// flag is set and the BlockConnected ValidationInterface callback takes
162 /// over and the sync thread exits.
163 void Sync();
164 165 /// Stops the instance from staying in sync with blockchain updates.
166 void Stop();
167 168 /// Get a summary of the index and its state.
169 IndexSummary GetSummary() const;
170 };
171 172 #endif // LIMENKA_INDEX_BASE_H
173