/workdir/bitcoin/src/validationinterface.h

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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2022 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_VALIDATIONINTERFACE_H
#define BITCOIN_VALIDATIONINTERFACE_H

#include <kernel/chain.h>
#include <kernel/cs_main.h>
#include <primitives/transaction.h> // CTransaction(Ref)
#include <sync.h>

#include <cstddef>
#include <cstdint>
#include <functional>
#include <memory>
#include <vector>

namespace util {
class TaskRunnerInterface;
} // namespace util

class BlockValidationState;
class CBlock;
class CBlockIndex;
struct CBlockLocator;
enum class MemPoolRemovalReason;
struct RemovedMempoolTransactionInfo;
struct NewMempoolTransactionInfo;

/**
 * Implement this to subscribe to events generated in validation and mempool
 *
 * Each CValidationInterface() subscriber will receive event callbacks
 * in the order in which the events were generated by validation and mempool.
 * Furthermore, each ValidationInterface() subscriber may assume that
 * callbacks effectively run in a single thread with single-threaded
 * memory consistency. That is, for a given ValidationInterface()
 * instantiation, each callback will complete before the next one is
 * invoked. This means, for example when a block is connected that the
 * UpdatedBlockTip() callback may depend on an operation performed in
 * the BlockConnected() callback without worrying about explicit
 * synchronization. No ordering should be assumed across
 * ValidationInterface() subscribers.
 */
class CValidationInterface {
protected:
    /**
     * Protected destructor so that instances can only be deleted by derived classes.
     * If that restriction is no longer desired, this should be made public and virtual.
     */
    ~CValidationInterface() = default;
    /**
     * Notifies listeners when the block chain tip advances.
     *
     * When multiple blocks are connected at once, UpdatedBlockTip will be called on the final tip
     * but may not be called on every intermediate tip. If the latter behavior is desired,
     * subscribe to BlockConnected() instead.
     *
     * Called on a background thread. Only called for the active chainstate.
     */
    virtual void UpdatedBlockTip(const CBlockIndex *pindexNew, const CBlockIndex *pindexFork, bool fInitialDownload) {}
    /**
     * Notifies listeners any time the block chain tip changes, synchronously.
     */
    virtual void ActiveTipChange(const CBlockIndex& new_tip, bool is_ibd) {};
    /**
     * Notifies listeners of a transaction having been added to mempool.
     *
     * Called on a background thread.
     */
    virtual void TransactionAddedToMempool(const NewMempoolTransactionInfo& tx, uint64_t mempool_sequence) {}

    /**
     * Notifies listeners of a transaction leaving mempool.
     *
     * This notification fires for transactions that are removed from the
     * mempool for the following reasons:
     *
     * - EXPIRY (expired from mempool after -mempoolexpiry hours)
     * - SIZELIMIT (removed in size limiting if the mempool exceeds -maxmempool megabytes)
     * - REORG (removed during a reorg)
     * - CONFLICT (removed because it conflicts with in-block transaction)
     * - REPLACED (removed due to RBF replacement)
     *
     * This does not fire for transactions that are removed from the mempool
     * because they have been included in a block. Any client that is interested
     * in transactions removed from the mempool for inclusion in a block can learn
     * about those transactions from the MempoolTransactionsRemovedForBlock notification.
     *
     * Transactions that are removed from the mempool because they conflict
     * with a transaction in the new block will have
     * TransactionRemovedFromMempool events fired *before* the BlockConnected
     * event is fired. If multiple blocks are connected in one step, then the
     * ordering could be:
     *
     * - TransactionRemovedFromMempool(tx1 from block A)
     * - TransactionRemovedFromMempool(tx2 from block A)
     * - TransactionRemovedFromMempool(tx1 from block B)
     * - TransactionRemovedFromMempool(tx2 from block B)
     * - BlockConnected(A)
     * - BlockConnected(B)
     *
     * Called on a background thread.
     */
    virtual void TransactionRemovedFromMempool(const CTransactionRef& tx, MemPoolRemovalReason reason, uint64_t mempool_sequence) {}
    /*
     * Notifies listeners of transactions removed from the mempool as
     * as a result of new block being connected.
     * MempoolTransactionsRemovedForBlock will be fired before BlockConnected.
     *
     * Called on a background thread.
     */
    virtual void MempoolTransactionsRemovedForBlock(const std::vector<RemovedMempoolTransactionInfo>& txs_removed_for_block, unsigned int nBlockHeight) {}
    /**
     * Notifies listeners of a block being connected.
     * Provides a vector of transactions evicted from the mempool as a result.
     *
     * Called on a background thread.
     */
    virtual void BlockConnected(ChainstateRole role, const std::shared_ptr<const CBlock> &block, const CBlockIndex *pindex) {}
    /**
     * Notifies listeners of a block being disconnected
     * Provides the block that was disconnected.
     *
     * Called on a background thread. Only called for the active chainstate, since
     * background chainstates should never disconnect blocks.
     */
    virtual void BlockDisconnected(const std::shared_ptr<const CBlock> &block, const CBlockIndex* pindex) {}
    /**
     * Notifies listeners of the new active block chain on-disk.
     *
     * Prior to this callback, any updates are not guaranteed to persist on disk
     * (ie clients need to handle shutdown/restart safety by being able to
     * understand when some updates were lost due to unclean shutdown).
     *
     * When this callback is invoked, the validation changes done by any prior
     * callback are guaranteed to exist on disk and survive a restart, including
     * an unclean shutdown.
     *
     * Provides a locator describing the best chain, which is likely useful for
     * storing current state on disk in client DBs.
     *
     * Called on a background thread.
     */
    virtual void ChainStateFlushed(ChainstateRole role, const CBlockLocator &locator) {}
    /**
     * Notifies listeners of a block validation result.
     * If the provided BlockValidationState IsValid, the provided block
     * is guaranteed to be the current best block at the time the
     * callback was generated (not necessarily now).
     */
    virtual void BlockChecked(const CBlock&, const BlockValidationState&) {}
    /**
     * Notifies listeners that a block which builds directly on our current tip
     * has been received and connected to the headers tree, though not validated yet.
     */
    virtual void NewPoWValidBlock(const CBlockIndex *pindex, const std::shared_ptr<const CBlock>& block) {};
    friend class ValidationSignals;
    friend class ValidationInterfaceTest;
};

class ValidationSignalsImpl;
class ValidationSignals {
private:
    std::unique_ptr<ValidationSignalsImpl> m_internals;

public:
    // The task runner will block validation if it calls its insert method's
    // func argument synchronously. In this class func contains a loop that
    // dispatches a single validation event to all subscribers sequentially.
    explicit ValidationSignals(std::unique_ptr<util::TaskRunnerInterface> task_runner);

    ~ValidationSignals();

    /** Call any remaining callbacks on the calling thread */
    void FlushBackgroundCallbacks();

    size_t CallbacksPending();

    /** Register subscriber */
    void RegisterValidationInterface(CValidationInterface* callbacks);
    /** Unregister subscriber. DEPRECATED. This is not safe to use when the RPC server or main message handler thread is running. */
    void UnregisterValidationInterface(CValidationInterface* callbacks);
    /** Unregister all subscribers */
    void UnregisterAllValidationInterfaces();

    // Alternate registration functions that release a shared_ptr after the last
    // notification is sent. These are useful for race-free cleanup, since
    // unregistration is nonblocking and can return before the last notification is
    // processed.
    /** Register subscriber */
    void RegisterSharedValidationInterface(std::shared_ptr<CValidationInterface> callbacks);
    /** Unregister subscriber */
    void UnregisterSharedValidationInterface(std::shared_ptr<CValidationInterface> callbacks);

    /**
     * Pushes a function to callback onto the notification queue, guaranteeing any
     * callbacks generated prior to now are finished when the function is called.
     *
     * Be very careful blocking on func to be called if any locks are held -
     * validation interface clients may not be able to make progress as they often
     * wait for things like cs_main, so blocking until func is called with cs_main
     * will result in a deadlock (that DEBUG_LOCKORDER will miss).
     */
    void CallFunctionInValidationInterfaceQueue(std::function<void ()> func);

    /**
     * This is a synonym for the following, which asserts certain locks are not
     * held:
     *     std::promise<void> promise;
     *     CallFunctionInValidationInterfaceQueue([&promise] {
     *         promise.set_value();
     *     });
     *     promise.get_future().wait();
     */
    void SyncWithValidationInterfaceQueue() LOCKS_EXCLUDED(cs_main);

    void UpdatedBlockTip(const CBlockIndex *, const CBlockIndex *, bool fInitialDownload);
    void ActiveTipChange(const CBlockIndex&, bool);
    void TransactionAddedToMempool(const NewMempoolTransactionInfo&, uint64_t mempool_sequence);
    void TransactionRemovedFromMempool(const CTransactionRef&, MemPoolRemovalReason, uint64_t mempool_sequence);
    void MempoolTransactionsRemovedForBlock(const std::vector<RemovedMempoolTransactionInfo>&, unsigned int nBlockHeight);
    void BlockConnected(ChainstateRole, const std::shared_ptr<const CBlock> &, const CBlockIndex *pindex);
    void BlockDisconnected(const std::shared_ptr<const CBlock> &, const CBlockIndex* pindex);
    void ChainStateFlushed(ChainstateRole, const CBlockLocator &);
    void BlockChecked(const CBlock&, const BlockValidationState&);
    void NewPoWValidBlock(const CBlockIndex *, const std::shared_ptr<const CBlock>&);
};

#endif // BITCOIN_VALIDATIONINTERFACE_H

Coverage Report

Created: 2024-08-21 05:08

Line	Count	Source (jump to first uncovered line)
1		// Copyright (c) 2009-2010 Satoshi Nakamoto
2		// Copyright (c) 2009-2022 The Bitcoin Core developers
3		// Distributed under the MIT software license, see the accompanying
4		// file COPYING or http://www.opensource.org/licenses/mit-license.php.
5
6		#ifndef BITCOIN_VALIDATIONINTERFACE_H
7		#define BITCOIN_VALIDATIONINTERFACE_H
8
9		#include <kernel/chain.h>
10		#include <kernel/cs_main.h>
11		#include <primitives/transaction.h> // CTransaction(Ref)
12		#include <sync.h>
13
14		#include <cstddef>
15		#include <cstdint>
16		#include <functional>
17		#include <memory>
18		#include <vector>
19
20		namespace util {
21		class TaskRunnerInterface;
22		} // namespace util
23
24		class BlockValidationState;
25		class CBlock;
26		class CBlockIndex;
27		struct CBlockLocator;
28		enum class MemPoolRemovalReason;
29		struct RemovedMempoolTransactionInfo;
30		struct NewMempoolTransactionInfo;
31
32		/**
33		* Implement this to subscribe to events generated in validation and mempool
34		*
35		* Each CValidationInterface() subscriber will receive event callbacks
36		* in the order in which the events were generated by validation and mempool.
37		* Furthermore, each ValidationInterface() subscriber may assume that
38		* callbacks effectively run in a single thread with single-threaded
39		* memory consistency. That is, for a given ValidationInterface()
40		* instantiation, each callback will complete before the next one is
41		* invoked. This means, for example when a block is connected that the
42		* UpdatedBlockTip() callback may depend on an operation performed in
43		* the BlockConnected() callback without worrying about explicit
44		* synchronization. No ordering should be assumed across
45		* ValidationInterface() subscribers.
46		*/
47		class CValidationInterface {
48		protected:
49		/**
50		* Protected destructor so that instances can only be deleted by derived classes.
51		* If that restriction is no longer desired, this should be made public and virtual.
52		*/
53		~CValidationInterface() = default;
54		/**
55		* Notifies listeners when the block chain tip advances.
56		*
57		* When multiple blocks are connected at once, UpdatedBlockTip will be called on the final tip
58		* but may not be called on every intermediate tip. If the latter behavior is desired,
59		* subscribe to BlockConnected() instead.
60		*
61		* Called on a background thread. Only called for the active chainstate.
62		*/
63	0	virtual void UpdatedBlockTip(const CBlockIndex pindexNew, const CBlockIndex pindexFork, bool fInitialDownload) {}
64		/**
65		* Notifies listeners any time the block chain tip changes, synchronously.
66		*/
67	0	virtual void ActiveTipChange(const CBlockIndex& new_tip, bool is_ibd) {};
68		/**
69		* Notifies listeners of a transaction having been added to mempool.
70		*
71		* Called on a background thread.
72		*/
73	0	virtual void TransactionAddedToMempool(const NewMempoolTransactionInfo& tx, uint64_t mempool_sequence) {}
74
75		/**
76		* Notifies listeners of a transaction leaving mempool.
77		*
78		* This notification fires for transactions that are removed from the
79		* mempool for the following reasons:
80		*
81		* - EXPIRY (expired from mempool after -mempoolexpiry hours)
82		* - SIZELIMIT (removed in size limiting if the mempool exceeds -maxmempool megabytes)
83		* - REORG (removed during a reorg)
84		* - CONFLICT (removed because it conflicts with in-block transaction)
85		* - REPLACED (removed due to RBF replacement)
86		*
87		* This does not fire for transactions that are removed from the mempool
88		* because they have been included in a block. Any client that is interested
89		* in transactions removed from the mempool for inclusion in a block can learn
90		* about those transactions from the MempoolTransactionsRemovedForBlock notification.
91		*
92		* Transactions that are removed from the mempool because they conflict
93		* with a transaction in the new block will have
94		* TransactionRemovedFromMempool events fired before the BlockConnected
95		* event is fired. If multiple blocks are connected in one step, then the
96		* ordering could be:
97		*
98		* - TransactionRemovedFromMempool(tx1 from block A)
99		* - TransactionRemovedFromMempool(tx2 from block A)
100		* - TransactionRemovedFromMempool(tx1 from block B)
101		* - TransactionRemovedFromMempool(tx2 from block B)
102		* - BlockConnected(A)
103		* - BlockConnected(B)
104		*
105		* Called on a background thread.
106		*/
107	0	virtual void TransactionRemovedFromMempool(const CTransactionRef& tx, MemPoolRemovalReason reason, uint64_t mempool_sequence) {}
108		/*
109		* Notifies listeners of transactions removed from the mempool as
110		* as a result of new block being connected.
111		* MempoolTransactionsRemovedForBlock will be fired before BlockConnected.
112		*
113		* Called on a background thread.
114		*/
115	0	virtual void MempoolTransactionsRemovedForBlock(const std::vector<RemovedMempoolTransactionInfo>& txs_removed_for_block, unsigned int nBlockHeight) {}
116		/**
117		* Notifies listeners of a block being connected.
118		* Provides a vector of transactions evicted from the mempool as a result.
119		*
120		* Called on a background thread.
121		*/
122	0	virtual void BlockConnected(ChainstateRole role, const std::shared_ptr<const CBlock> &block, const CBlockIndex *pindex) {}
123		/**
124		* Notifies listeners of a block being disconnected
125		* Provides the block that was disconnected.
126		*
127		* Called on a background thread. Only called for the active chainstate, since
128		* background chainstates should never disconnect blocks.
129		*/
130	0	virtual void BlockDisconnected(const std::shared_ptr<const CBlock> &block, const CBlockIndex* pindex) {}
131		/**
132		* Notifies listeners of the new active block chain on-disk.
133		*
134		* Prior to this callback, any updates are not guaranteed to persist on disk
135		* (ie clients need to handle shutdown/restart safety by being able to
136		* understand when some updates were lost due to unclean shutdown).
137		*
138		* When this callback is invoked, the validation changes done by any prior
139		* callback are guaranteed to exist on disk and survive a restart, including
140		* an unclean shutdown.
141		*
142		* Provides a locator describing the best chain, which is likely useful for
143		* storing current state on disk in client DBs.
144		*
145		* Called on a background thread.
146		*/
147	0	virtual void ChainStateFlushed(ChainstateRole role, const CBlockLocator &locator) {}
148		/**
149		* Notifies listeners of a block validation result.
150		* If the provided BlockValidationState IsValid, the provided block
151		* is guaranteed to be the current best block at the time the
152		* callback was generated (not necessarily now).
153		*/
154	0	virtual void BlockChecked(const CBlock&, const BlockValidationState&) {}
155		/**
156		* Notifies listeners that a block which builds directly on our current tip
157		* has been received and connected to the headers tree, though not validated yet.
158		*/
159	0	virtual void NewPoWValidBlock(const CBlockIndex *pindex, const std::shared_ptr<const CBlock>& block) {};
160		friend class ValidationSignals;
161		friend class ValidationInterfaceTest;
162		};
163
164		class ValidationSignalsImpl;
165		class ValidationSignals {
166		private:
167		std::unique_ptr<ValidationSignalsImpl> m_internals;
168
169		public:
170		// The task runner will block validation if it calls its insert method's
171		// func argument synchronously. In this class func contains a loop that
172		// dispatches a single validation event to all subscribers sequentially.
173		explicit ValidationSignals(std::unique_ptr<util::TaskRunnerInterface> task_runner);
174
175		~ValidationSignals();
176
177		/** Call any remaining callbacks on the calling thread */
178		void FlushBackgroundCallbacks();
179
180		size_t CallbacksPending();
181
182		/** Register subscriber */
183		void RegisterValidationInterface(CValidationInterface* callbacks);
184		/** Unregister subscriber. DEPRECATED. This is not safe to use when the RPC server or main message handler thread is running. */
185		void UnregisterValidationInterface(CValidationInterface* callbacks);
186		/** Unregister all subscribers */
187		void UnregisterAllValidationInterfaces();
188
189		// Alternate registration functions that release a shared_ptr after the last
190		// notification is sent. These are useful for race-free cleanup, since
191		// unregistration is nonblocking and can return before the last notification is
192		// processed.
193		/** Register subscriber */
194		void RegisterSharedValidationInterface(std::shared_ptr<CValidationInterface> callbacks);
195		/** Unregister subscriber */
196		void UnregisterSharedValidationInterface(std::shared_ptr<CValidationInterface> callbacks);
197
198		/**
199		* Pushes a function to callback onto the notification queue, guaranteeing any
200		* callbacks generated prior to now are finished when the function is called.
201		*
202		* Be very careful blocking on func to be called if any locks are held -
203		* validation interface clients may not be able to make progress as they often
204		* wait for things like cs_main, so blocking until func is called with cs_main
205		* will result in a deadlock (that DEBUG_LOCKORDER will miss).
206		*/
207		void CallFunctionInValidationInterfaceQueue(std::function<void ()> func);
208
209		/**
210		* This is a synonym for the following, which asserts certain locks are not
211		* held:
212		* std::promise<void> promise;
213		* CallFunctionInValidationInterfaceQueue([&promise] {
214		* promise.set_value();
215		* });
216		* promise.get_future().wait();
217		*/
218		void SyncWithValidationInterfaceQueue() LOCKS_EXCLUDED(cs_main);
219
220		void UpdatedBlockTip(const CBlockIndex , const CBlockIndex , bool fInitialDownload);
221		void ActiveTipChange(const CBlockIndex&, bool);
222		void TransactionAddedToMempool(const NewMempoolTransactionInfo&, uint64_t mempool_sequence);
223		void TransactionRemovedFromMempool(const CTransactionRef&, MemPoolRemovalReason, uint64_t mempool_sequence);
224		void MempoolTransactionsRemovedForBlock(const std::vector<RemovedMempoolTransactionInfo>&, unsigned int nBlockHeight);
225		void BlockConnected(ChainstateRole, const std::shared_ptr<const CBlock> &, const CBlockIndex *pindex);
226		void BlockDisconnected(const std::shared_ptr<const CBlock> &, const CBlockIndex* pindex);
227		void ChainStateFlushed(ChainstateRole, const CBlockLocator &);
228		void BlockChecked(const CBlock&, const BlockValidationState&);
229		void NewPoWValidBlock(const CBlockIndex *, const std::shared_ptr<const CBlock>&);
230		};
231
232		#endif // BITCOIN_VALIDATIONINTERFACE_H