1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
|
// Copyright (c) 2017-2021 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#ifndef BITCOIN_INDEX_BASE_H
#define BITCOIN_INDEX_BASE_H
#include <dbwrapper.h>
#include <interfaces/chain.h>
#include <threadinterrupt.h>
#include <validationinterface.h>
class CBlock;
class CBlockIndex;
class CChainState;
namespace interfaces {
class Chain;
} // namespace interfaces
struct IndexSummary {
std::string name;
bool synced{false};
int best_block_height{0};
};
/**
* Base class for indices of blockchain data. This implements
* CValidationInterface and ensures blocks are indexed sequentially according
* to their position in the active chain.
*/
class BaseIndex : public CValidationInterface
{
protected:
/**
* The database stores a block locator of the chain the database is synced to
* so that the index 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 DB : public CDBWrapper
{
public:
DB(const fs::path& path, size_t n_cache_size,
bool f_memory = false, bool f_wipe = false, bool f_obfuscate = false);
/// Read block locator of the chain that the index is in sync with.
bool ReadBestBlock(CBlockLocator& locator) const;
/// Write block locator of the chain that the index is in sync with.
void WriteBestBlock(CDBBatch& batch, const CBlockLocator& locator);
};
private:
/// Whether the index is in sync with the main chain. The flag is flipped
/// from false to true once, after which point this starts processing
/// ValidationInterface notifications to stay in sync.
std::atomic<bool> m_synced{false};
/// The last block in the chain that the index is in sync with.
std::atomic<const CBlockIndex*> m_best_block_index{nullptr};
std::thread m_thread_sync;
CThreadInterrupt m_interrupt;
/// Read best block locator and check that data needed to sync has not been pruned.
bool Init();
/// Sync the index with the block index starting from the current best block.
/// Intended to be run in its own thread, m_thread_sync, and can be
/// interrupted with m_interrupt. Once the index gets in sync, the m_synced
/// flag is set and the BlockConnected ValidationInterface callback takes
/// over and the sync thread exits.
void ThreadSync();
/// Write the current index state (eg. chain block locator and subclass-specific items) to disk.
///
/// Recommendations for error handling:
/// If called on a successor of the previous committed best block in the index, the index can
/// continue processing without risk of corruption, though the index state will need to catch up
/// from further behind on reboot. If the new state is not a successor of the previous state (due
/// to a chain reorganization), the index must halt until Commit succeeds or else it could end up
/// getting corrupted.
bool Commit();
virtual bool AllowPrune() const = 0;
protected:
std::unique_ptr<interfaces::Chain> m_chain;
CChainState* m_chainstate{nullptr};
void BlockConnected(const std::shared_ptr<const CBlock>& block, const CBlockIndex* pindex) override;
void ChainStateFlushed(const CBlockLocator& locator) override;
/// Initialize internal state from the database and block index.
[[nodiscard]] virtual bool CustomInit(const std::optional<interfaces::BlockKey>& block) { return true; }
/// Write update index entries for a newly connected block.
[[nodiscard]] virtual bool CustomAppend(const interfaces::BlockInfo& block) { return true; }
/// Virtual method called internally by Commit that can be overridden to atomically
/// commit more index state.
virtual bool CommitInternal(CDBBatch& batch);
/// Rewind index to an earlier chain tip during a chain reorg. The tip must
/// be an ancestor of the current best block.
virtual bool Rewind(const CBlockIndex* current_tip, const CBlockIndex* new_tip);
virtual DB& GetDB() const = 0;
/// Get the name of the index for display in logs.
virtual const char* GetName() const = 0;
/// Update the internal best block index as well as the prune lock.
void SetBestBlockIndex(const CBlockIndex* block);
public:
BaseIndex(std::unique_ptr<interfaces::Chain> chain);
/// Destructor interrupts sync thread if running and blocks until it exits.
virtual ~BaseIndex();
/// Blocks the current thread until the index is caught up to the current
/// state of the block chain. This only blocks if the index has gotten in
/// sync once and only needs to process blocks in the ValidationInterface
/// queue. If the index is catching up from far behind, this method does
/// not block and immediately returns false.
bool BlockUntilSyncedToCurrentChain() const LOCKS_EXCLUDED(::cs_main);
void Interrupt();
/// Start initializes the sync state and registers the instance as a
/// ValidationInterface so that it stays in sync with blockchain updates.
[[nodiscard]] bool Start();
/// Stops the instance from staying in sync with blockchain updates.
void Stop();
/// Get a summary of the index and its state.
IndexSummary GetSummary() const;
};
#endif // BITCOIN_INDEX_BASE_H
|