CCoinsView that adds a memory cache for transactions to another CCoinsView. More...

#include <coins.h>

Inheritance diagram for CCoinsViewCache:

Collaboration diagram for CCoinsViewCache:

Classes
class	ResetGuard

Public Member Functions
	CCoinsViewCache (CCoinsView *in_base, bool deterministic=false)

	CCoinsViewCache (const CCoinsViewCache &)=delete
	By deleting the copy constructor, we prevent accidentally using it when one intends to create a cache on top of a base cache. More...

std::optional< Coin >	GetCoin (const COutPoint &outpoint) const override
	Retrieve the Coin (unspent transaction output) for a given outpoint. More...

std::optional< Coin >	PeekCoin (const COutPoint &outpoint) const override
	Retrieve the Coin (unspent transaction output) for a given outpoint, without caching results. More...

bool	HaveCoin (const COutPoint &outpoint) const override
	Just check whether a given outpoint is unspent. More...

uint256	GetBestBlock () const override
	Retrieve the block hash whose state this CCoinsView currently represents. More...

void	SetBestBlock (const uint256 &block_hash)

void	BatchWrite (CoinsViewCacheCursor &cursor, const uint256 &block_hash) override
	Do a bulk modification (multiple Coin changes + BestBlock change). More...

std::unique_ptr< CCoinsViewCursor >	Cursor () const override
	Get a cursor to iterate over the whole state. Implementations may return nullptr. More...

bool	HaveCoinInCache (const COutPoint &outpoint) const
	Check if we have the given utxo already loaded in this cache. More...

const Coin &	AccessCoin (const COutPoint &output) const
	Return a reference to Coin in the cache, or coinEmpty if not found. More...

void	AddCoin (const COutPoint &outpoint, Coin &&coin, bool possible_overwrite)
	Add a coin. More...

void	EmplaceCoinInternalDANGER (COutPoint &&outpoint, Coin &&coin)
	Emplace a coin into cacheCoins without performing any checks, marking the emplaced coin as dirty. More...

bool	SpendCoin (const COutPoint &outpoint, Coin *moveto=nullptr)
	Spend a coin. More...

void	Flush (bool reallocate_cache=true)
	Push the modifications applied to this cache to its base and wipe local state. More...

void	Sync ()
	Push the modifications applied to this cache to its base while retaining the contents of this cache (except for spent coins, which we erase). More...

void	Uncache (const COutPoint &outpoint)
	Removes the UTXO with the given outpoint from the cache, if it is not modified. More...

unsigned int	GetCacheSize () const
	Size of the cache (in number of transaction outputs) More...

size_t	GetDirtyCount () const noexcept
	Number of dirty cache entries (transaction outputs) More...

size_t	DynamicMemoryUsage () const
	Calculate the size of the cache (in bytes) More...

bool	HaveInputs (const CTransaction &tx) const
	Check whether all prevouts of the transaction are present in the UTXO set represented by this view. More...

void	ReallocateCache ()
	Force a reallocation of the cache map. More...

void	SanityCheck () const
	Run an internal sanity check on the cache data structure. *‍/. More...

ResetGuard	CreateResetGuard () noexcept
	Create a scoped guard that will call `Reset()` on this cache when it goes out of scope. More...

Public Member Functions inherited from CCoinsViewBacked
	CCoinsViewBacked (CCoinsView *in_view)

void	SetBackend (CCoinsView &in_view)

std::optional< Coin >	GetCoin (const COutPoint &outpoint) const override
	Retrieve the Coin (unspent transaction output) for a given outpoint. More...

std::optional< Coin >	PeekCoin (const COutPoint &outpoint) const override
	Retrieve the Coin (unspent transaction output) for a given outpoint, without caching results. More...

bool	HaveCoin (const COutPoint &outpoint) const override
	Just check whether a given outpoint is unspent. More...

uint256	GetBestBlock () const override
	Retrieve the block hash whose state this CCoinsView currently represents. More...

std::vector< uint256 >	GetHeadBlocks () const override
	Retrieve the range of blocks that may have been only partially written. More...

void	BatchWrite (CoinsViewCacheCursor &cursor, const uint256 &block_hash) override
	Do a bulk modification (multiple Coin changes + BestBlock change). More...

std::unique_ptr< CCoinsViewCursor >	Cursor () const override
	Get a cursor to iterate over the whole state. Implementations may return nullptr. More...

size_t	EstimateSize () const override
	Estimate database size. More...

Public Member Functions inherited from CCoinsView
virtual	~CCoinsView ()=default
	As we use CCoinsViews polymorphically, have a virtual destructor. More...

virtual std::optional< Coin >	GetCoin (const COutPoint &outpoint) const =0
	Retrieve the Coin (unspent transaction output) for a given outpoint. More...

virtual std::optional< Coin >	PeekCoin (const COutPoint &outpoint) const =0
	Retrieve the Coin (unspent transaction output) for a given outpoint, without caching results. More...

virtual bool	HaveCoin (const COutPoint &outpoint) const =0
	Just check whether a given outpoint is unspent. More...

virtual uint256	GetBestBlock () const =0
	Retrieve the block hash whose state this CCoinsView currently represents. More...

virtual std::vector< uint256 >	GetHeadBlocks () const =0
	Retrieve the range of blocks that may have been only partially written. More...

virtual void	BatchWrite (CoinsViewCacheCursor &cursor, const uint256 &block_hash)=0
	Do a bulk modification (multiple Coin changes + BestBlock change). More...

virtual std::unique_ptr< CCoinsViewCursor >	Cursor () const =0
	Get a cursor to iterate over the whole state. Implementations may return nullptr. More...

virtual size_t	EstimateSize () const =0
	Estimate database size. More...

Protected Member Functions
void	Reset () noexcept
	Discard all modifications made to this cache without flushing to the base view. More...

virtual std::optional< Coin >	FetchCoinFromBase (const COutPoint &outpoint) const

Protected Attributes
uint256	m_block_hash
	Make mutable so that we can "fill the cache" even from Get-methods declared as "const". More...

CCoinsMapMemoryResource	m_cache_coins_memory_resource {}

CoinsCachePair	m_sentinel

CCoinsMap	cacheCoins

size_t	cachedCoinsUsage {0}

size_t	m_dirty_count {0}

Protected Attributes inherited from CCoinsViewBacked
CCoinsView *	base

Private Member Functions
CCoinsMap::iterator	FetchCoin (const COutPoint &outpoint) const

Private Attributes
const bool	m_deterministic

Detailed Description

CCoinsView that adds a memory cache for transactions to another CCoinsView.

Definition at line 393 of file coins.h.

Constructor & Destructor Documentation

◆ CCoinsViewCache() [1/2]

CCoinsViewCache::CCoinsViewCache	(	CCoinsView *	in_base,
		bool	deterministic = `false`
	)

Definition at line 31 of file coins.cpp.

◆ CCoinsViewCache() [2/2]

CCoinsViewCache::CCoinsViewCache ( const CCoinsViewCache & )

delete

By deleting the copy constructor, we prevent accidentally using it when one intends to create a cache on top of a base cache.

Member Function Documentation

◆ AccessCoin()

const Coin & CCoinsViewCache::AccessCoin ( const COutPoint & output ) const

Return a reference to Coin in the cache, or coinEmpty if not found.

This is more efficient than GetCoin.

Generally, do not hold the reference returned for more than a short scope. While the current implementation allows for modifications to the contents of the cache while holding the reference, this behavior should not be relied on! To be safe, best to not hold the returned reference through any other calls to this cache.

Definition at line 158 of file coins.cpp.

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◆ AddCoin()

void CCoinsViewCache::AddCoin	(	const COutPoint &	outpoint,
		Coin &&	coin,
		bool	possible_overwrite
	)

Add a coin.

Set possible_overwrite to true if an unspent version may already exist in the cache.

Definition at line 68 of file coins.cpp.

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◆ BatchWrite()

void CCoinsViewCache::BatchWrite	(	CoinsViewCacheCursor &	cursor,
		const uint256 &	block_hash
	)

overridevirtual

Do a bulk modification (multiple Coin changes + BestBlock change).

The passed cursor is used to iterate through the coins.

Reimplemented from CCoinsViewBacked.

Definition at line 189 of file coins.cpp.

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◆ CreateResetGuard()

ResetGuard CCoinsViewCache::CreateResetGuard ( )

inlinenoexcept

Create a scoped guard that will call Reset() on this cache when it goes out of scope.

Definition at line 545 of file coins.h.

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◆ Cursor()

std::unique_ptr< CCoinsViewCursor > CCoinsViewCache::Cursor ( ) const

inlineoverridevirtual

Get a cursor to iterate over the whole state. Implementations may return nullptr.

Reimplemented from CCoinsViewBacked.

Definition at line 438 of file coins.h.

◆ DynamicMemoryUsage()

size_t CCoinsViewCache::DynamicMemoryUsage ( ) const

Calculate the size of the cache (in bytes)

Definition at line 38 of file coins.cpp.

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◆ EmplaceCoinInternalDANGER()

void CCoinsViewCache::EmplaceCoinInternalDANGER	(	COutPoint &&	outpoint,
		Coin &&	coin
	)

Emplace a coin into cacheCoins without performing any checks, marking the emplaced coin as dirty.

NOT FOR GENERAL USE. Used only when loading coins from a UTXO snapshot.

See also: ChainstateManager::PopulateAndValidateSnapshot()

Definition at line 111 of file coins.cpp.

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◆ FetchCoin()

CCoinsMap::iterator CCoinsViewCache::FetchCoin ( const COutPoint & outpoint ) const

private

Note: this is marked const, but may actually append to cacheCoins, increasing memory usage.

Definition at line 47 of file coins.cpp.

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◆ FetchCoinFromBase()

std::optional< Coin > CCoinsViewCache::FetchCoinFromBase ( const COutPoint & outpoint ) const

protectedvirtual

Reimplemented in CoinsViewOverlay.

Definition at line 42 of file coins.cpp.

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◆ Flush()

void CCoinsViewCache::Flush ( bool reallocate_cache = true )

Push the modifications applied to this cache to its base and wipe local state.

Failure to call this method or Sync() before destruction will cause the changes to be forgotten. If reallocate_cache is false, the cache will retain the same memory footprint after flushing and should be destroyed to deallocate.

Definition at line 260 of file coins.cpp.

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◆ GetBestBlock()

uint256 CCoinsViewCache::GetBestBlock ( ) const

overridevirtual

Retrieve the block hash whose state this CCoinsView currently represents.

Reimplemented from CCoinsViewBacked.

Definition at line 178 of file coins.cpp.

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◆ GetCacheSize()

unsigned int CCoinsViewCache::GetCacheSize ( ) const

Size of the cache (in number of transaction outputs)

Definition at line 306 of file coins.cpp.

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◆ GetCoin()

std::optional< Coin > CCoinsViewCache::GetCoin ( const COutPoint & outpoint ) const

overridevirtual

Retrieve the Coin (unspent transaction output) for a given outpoint.

May populate the cache. Use PeekCoin() to perform a non-caching lookup.

Reimplemented from CCoinsViewBacked.

Definition at line 62 of file coins.cpp.

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◆ GetDirtyCount()

size_t CCoinsViewCache::GetDirtyCount ( ) const

inlinenoexcept

Number of dirty cache entries (transaction outputs)

Definition at line 510 of file coins.h.

◆ HaveCoin()

bool CCoinsViewCache::HaveCoin ( const COutPoint & outpoint ) const

overridevirtual

Just check whether a given outpoint is unspent.

May populate the cache. Use PeekCoin() to perform a non-caching lookup.

Reimplemented from CCoinsViewBacked.

Definition at line 167 of file coins.cpp.

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◆ HaveCoinInCache()

bool CCoinsViewCache::HaveCoinInCache ( const COutPoint & outpoint ) const

Check if we have the given utxo already loaded in this cache.

The semantics are the same as HaveCoin(), but no calls to the backing CCoinsView are made.

Definition at line 173 of file coins.cpp.

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◆ HaveInputs()

bool CCoinsViewCache::HaveInputs ( const CTransaction & tx ) const

Check whether all prevouts of the transaction are present in the UTXO set represented by this view.

Definition at line 310 of file coins.cpp.

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◆ PeekCoin()

std::optional< Coin > CCoinsViewCache::PeekCoin ( const COutPoint & outpoint ) const

overridevirtual

Retrieve the Coin (unspent transaction output) for a given outpoint, without caching results.

Does not populate the cache. Use GetCoin() to cache the result.

Reimplemented from CCoinsViewBacked.

Definition at line 23 of file coins.cpp.

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◆ ReallocateCache()

void CCoinsViewCache::ReallocateCache ( )

Force a reallocation of the cache map.

This is required when downsizing the cache because the map's allocator may be hanging onto a lot of memory despite having called .clear().

See: https://stackoverflow.com/questions/42114044/how-to-release-unordered-map-memory

Definition at line 322 of file coins.cpp.

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◆ Reset()

void CCoinsViewCache::Reset ( )

protectednoexcept

Discard all modifications made to this cache without flushing to the base view.

This can be used to efficiently reuse a cache instance across multiple operations.

Definition at line 283 of file coins.cpp.

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◆ SanityCheck()

void CCoinsViewCache::SanityCheck ( ) const

Run an internal sanity check on the cache data structure. *‍/.

Definition at line 332 of file coins.cpp.

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◆ SetBestBlock()

void CCoinsViewCache::SetBestBlock ( const uint256 & block_hash )

Definition at line 184 of file coins.cpp.

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◆ SpendCoin()

bool CCoinsViewCache::SpendCoin	(	const COutPoint &	outpoint,
		Coin *	moveto = `nullptr`
	)

Spend a coin.

Pass moveto in order to get the deleted data. If no unspent output exists for the passed outpoint, this call has no effect.

Definition at line 132 of file coins.cpp.

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◆ Sync()

void CCoinsViewCache::Sync ( )

Push the modifications applied to this cache to its base while retaining the contents of this cache (except for spent coins, which we erase).

Failure to call this method or Flush() before destruction will cause the changes to be forgotten.

Definition at line 272 of file coins.cpp.

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◆ Uncache()

void CCoinsViewCache::Uncache ( const COutPoint & outpoint )

Removes the UTXO with the given outpoint from the cache, if it is not modified.

Definition at line 291 of file coins.cpp.

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Member Data Documentation

◆ cacheCoins

CCoinsMap CCoinsViewCache::cacheCoins

mutableprotected

Definition at line 407 of file coins.h.

◆ cachedCoinsUsage

size_t CCoinsViewCache::cachedCoinsUsage {0}

mutableprotected

Definition at line 410 of file coins.h.

◆ m_block_hash

uint256 CCoinsViewCache::m_block_hash

mutableprotected

Make mutable so that we can "fill the cache" even from Get-methods declared as "const".

Definition at line 403 of file coins.h.

◆ m_cache_coins_memory_resource

CCoinsMapMemoryResource CCoinsViewCache::m_cache_coins_memory_resource {}

mutableprotected

Definition at line 404 of file coins.h.

◆ m_deterministic

const bool CCoinsViewCache::m_deterministic

private

Definition at line 396 of file coins.h.

◆ m_dirty_count

size_t CCoinsViewCache::m_dirty_count {0}

mutableprotected

Definition at line 412 of file coins.h.

◆ m_sentinel

CoinsCachePair CCoinsViewCache::m_sentinel

mutableprotected

Definition at line 406 of file coins.h.

The documentation for this class was generated from the following files:

src/coins.h
src/coins.cpp

Classes

Public Member Functions

Protected Member Functions

Protected Attributes

Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ CCoinsViewCache() [1/2]

◆ CCoinsViewCache() [2/2]

Member Function Documentation

◆ AccessCoin()

◆ AddCoin()

◆ BatchWrite()

◆ CreateResetGuard()

◆ Cursor()

◆ DynamicMemoryUsage()

◆ EmplaceCoinInternalDANGER()

◆ FetchCoin()

◆ FetchCoinFromBase()

◆ Flush()

◆ GetBestBlock()

◆ GetCacheSize()

◆ GetCoin()

◆ GetDirtyCount()

◆ HaveCoin()

◆ HaveCoinInCache()

◆ HaveInputs()

◆ PeekCoin()

◆ ReallocateCache()

◆ Reset()

◆ SanityCheck()

◆ SetBestBlock()

◆ SpendCoin()

◆ Sync()

◆ Uncache()

Member Data Documentation

◆ cacheCoins

◆ cachedCoinsUsage

◆ m_block_hash

◆ m_cache_coins_memory_resource

◆ m_deterministic

◆ m_dirty_count

◆ m_sentinel