A backend used for the NodeStore. More...

#include <Backend.h>

Inheritance diagram for xrpl::NodeStore::Backend:

[legend]

Public Member Functions
virtual	~Backend ()=default
	Destroy the backend.

virtual std::string	getName ()=0
	Get the human-readable name of this backend.

virtual std::optional< std::size_t >	getBlockSize () const
	Get the block size for backends that support it.

virtual void	open (bool createIfMissing=true)=0
	Open the backend.

virtual bool	isOpen ()=0
	Returns true is the database is open.

virtual void	open (bool createIfMissing, uint64_t appType, uint64_t uid, uint64_t salt)
	Open the backend.

virtual void	close ()=0
	Close the backend.

virtual Status	fetch (void const key, std::shared_ptr< NodeObject > pObject)=0
	Fetch a single object.

virtual std::pair< std::vector< std::shared_ptr< NodeObject > >, Status >	fetchBatch (std::vector< uint256 const * > const &hashes)=0
	Fetch a batch synchronously.

virtual void	store (std::shared_ptr< NodeObject > const &object)=0
	Store a single object.

virtual void	storeBatch (Batch const &batch)=0
	Store a group of objects.

virtual void	sync ()=0

virtual void	for_each (std::function< void(std::shared_ptr< NodeObject >)> f)=0
	Visit every object in the database This is usually called during import.

virtual int	getWriteLoad ()=0
	Estimate the number of write operations pending.

virtual void	setDeletePath ()=0
	Remove contents on disk upon destruction.

virtual void	verify ()
	Perform consistency checks on database.

virtual int	fdRequired () const =0
	Returns the number of file descriptors the backend expects to need.

Detailed Description

A backend used for the NodeStore.

The NodeStore uses a swappable backend so that other database systems can be tried. Different databases may offer various features such as improved performance, fault tolerant or distributed storage, or all in-memory operation.

A given instance of a backend is fixed to a particular key size.

Definition at line 20 of file Backend.h.

Constructor & Destructor Documentation

◆ ~Backend()

virtual xrpl::NodeStore::Backend::~Backend ( )

virtualdefault

Destroy the backend.

All open files are closed and flushed. If there are batched writes or other tasks scheduled, they will be completed before this call returns.

Member Function Documentation

◆ getName()

virtual std::string xrpl::NodeStore::Backend::getName ( )

pure virtual

Get the human-readable name of this backend.

This is used for diagnostic output.

Implemented in xrpl::NodeStore::MemoryBackend, xrpl::NodeStore::NuDBBackend, and xrpl::NodeStore::NullBackend.

◆ getBlockSize()

virtual std::optional< std::size_t > xrpl::NodeStore::Backend::getBlockSize ( ) const

virtual

Get the block size for backends that support it.

Reimplemented in xrpl::NodeStore::NuDBBackend.

Definition at line 40 of file Backend.h.

◆ open() [1/2]

virtual void xrpl::NodeStore::Backend::open ( bool createIfMissing = true )

pure virtual

Open the backend.

Parameters

createIfMissing Create the database files if necessary. This allows the caller to catch exceptions.

Implemented in xrpl::NodeStore::NuDBBackend, xrpl::NodeStore::NullBackend, and xrpl::NodeStore::MemoryBackend.

◆ isOpen()

virtual bool xrpl::NodeStore::Backend::isOpen ( )

pure virtual

Returns true is the database is open.

Implemented in xrpl::NodeStore::MemoryBackend, xrpl::NodeStore::NuDBBackend, and xrpl::NodeStore::NullBackend.

◆ open() [2/2]

virtual void xrpl::NodeStore::Backend::open	(	bool	createIfMissing,
		uint64_t	appType,
		uint64_t	uid,
		uint64_t	salt
	)

virtual

Open the backend.

Parameters

createIfMissing	Create the database files if necessary.
appType	Deterministic appType used to create a backend.
uid	Deterministic uid used to create a backend.
salt	Deterministic salt used to create a backend.

Exceptions

std::runtime_error is function is called not for NuDB backend.

Reimplemented in xrpl::NodeStore::NuDBBackend.

Definition at line 65 of file Backend.h.

◆ close()

virtual void xrpl::NodeStore::Backend::close ( )

pure virtual

Close the backend.

This allows the caller to catch exceptions.

Implemented in xrpl::NodeStore::MemoryBackend, xrpl::NodeStore::NuDBBackend, and xrpl::NodeStore::NullBackend.

◆ fetch()

virtual Status xrpl::NodeStore::Backend::fetch	(	void const *	key,
		std::shared_ptr< NodeObject > *	pObject
	)

pure virtual

Fetch a single object.

If the object is not found or an error is encountered, the result will indicate the condition.

Note: This will be called concurrently.

Parameters

key	A pointer to the key data.
pObject	[out] The created object if successful.

Returns: The result of the operation.

Implemented in xrpl::NodeStore::NullBackend, xrpl::NodeStore::NuDBBackend, and xrpl::NodeStore::MemoryBackend.

◆ fetchBatch()

virtual std::pair< std::vector< std::shared_ptr< NodeObject > >, Status > xrpl::NodeStore::Backend::fetchBatch ( std::vector< uint256 const * > const & hashes )

pure virtual

Fetch a batch synchronously.

Implemented in xrpl::NodeStore::MemoryBackend, xrpl::NodeStore::NuDBBackend, and xrpl::NodeStore::NullBackend.

◆ store()

virtual void xrpl::NodeStore::Backend::store ( std::shared_ptr< NodeObject > const & object )

pure virtual

Store a single object.

Depending on the implementation this may happen immediately or deferred using a scheduled task.

Note: This will be called concurrently.

Parameters

object The object to store.

Implemented in xrpl::NodeStore::NuDBBackend, xrpl::NodeStore::MemoryBackend, and xrpl::NodeStore::NullBackend.

◆ storeBatch()

virtual void xrpl::NodeStore::Backend::storeBatch ( Batch const & batch )

pure virtual

Store a group of objects.

Note: This function will not be called concurrently with itself or store.

Implemented in xrpl::NodeStore::MemoryBackend, xrpl::NodeStore::NuDBBackend, and xrpl::NodeStore::NullBackend.

◆ sync()

virtual void xrpl::NodeStore::Backend::sync ( )

pure virtual

Implemented in xrpl::NodeStore::MemoryBackend, xrpl::NodeStore::NuDBBackend, and xrpl::NodeStore::NullBackend.

◆ for_each()

virtual void xrpl::NodeStore::Backend::for_each ( std::function< void(std::shared_ptr< NodeObject >)> f )

pure virtual

Visit every object in the database This is usually called during import.

Note: This routine will not be called concurrently with itself or other methods.

See also: import

Implemented in xrpl::NodeStore::MemoryBackend, xrpl::NodeStore::NuDBBackend, and xrpl::NodeStore::NullBackend.

◆ getWriteLoad()

virtual int xrpl::NodeStore::Backend::getWriteLoad ( )

pure virtual

Estimate the number of write operations pending.

Implemented in xrpl::NodeStore::MemoryBackend, xrpl::NodeStore::NuDBBackend, and xrpl::NodeStore::NullBackend.

◆ setDeletePath()

virtual void xrpl::NodeStore::Backend::setDeletePath ( )

pure virtual

Remove contents on disk upon destruction.

Implemented in xrpl::NodeStore::MemoryBackend, xrpl::NodeStore::NuDBBackend, and xrpl::NodeStore::NullBackend.

◆ verify()

virtual void xrpl::NodeStore::Backend::verify ( )

virtual

Perform consistency checks on database.

This method is implemented only by NuDBBackend. It is not yet called anywhere, but it might be a good idea to one day call it at startup to avert a crash.

Reimplemented in xrpl::NodeStore::NuDBBackend.

Definition at line 136 of file Backend.h.

◆ fdRequired()

virtual int xrpl::NodeStore::Backend::fdRequired ( ) const

pure virtual

Returns the number of file descriptors the backend expects to need.

Implemented in xrpl::NodeStore::MemoryBackend, xrpl::NodeStore::NuDBBackend, and xrpl::NodeStore::NullBackend.

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ ~Backend()

Member Function Documentation

◆ getName()

◆ getBlockSize()

◆ open() [1/2]

◆ isOpen()

◆ open() [2/2]

◆ close()

◆ fetch()

◆ fetchBatch()

◆ store()

◆ storeBatch()

◆ sync()

◆ for_each()

◆ getWriteLoad()

◆ setDeletePath()

◆ verify()

◆ fdRequired()