Prototype for invariant check implementations. More...

#include <InvariantCheck.h>

Public Member Functions
	InvariantChecker_PROTOTYPE ()=default

void	visitEntry (bool isDelete, std::shared_ptr< SLE const > const &before, std::shared_ptr< SLE const > const &after)
	called for each ledger entry in the current transaction.

bool	finalize (STTx const &tx, TER const tec, XRPAmount const fee, ReadView const &view, beast::Journal const &j)
	called after all ledger entries have been visited to determine the final status of the check.

Detailed Description

Prototype for invariant check implementations.

THIS CLASS DOES NOT EXIST - or rather it exists in documentation only to communicate the interface required of any invariant checker. Any invariant check implementation should implement the public methods documented here.

Rules for implementing <tt>finalize</tt>

Invariants must run regardless of transaction result

An invariant's finalize method MUST perform meaningful checks even when the transaction has failed (i.e., !isTesSuccess(tec)). The following pattern is almost certainly wrong and must never be used:

// WRONG: skipping all checks on failure defeats the purpose of invariants
if (!isTesSuccess(tec))
    return true;

The entire purpose of invariants is to detect and prevent the impossible. A bug or exploit could cause a failed transaction to mutate ledger state in unexpected ways. Invariants are the last line of defense against such scenarios.

In general: an invariant that expects a domain-specific state change to occur (e.g., a new object being created) should only expect that change when the transaction succeeded. A failed VaultCreate must not have created a Vault. A failed LoanSet must not have created a Loan.

Also be aware that failed transactions, regardless of type, carry no Privileges. Any privilege-gated checks must therefore also be applied to failed transactions.

Definition at line 59 of file InvariantCheck.h.

Constructor & Destructor Documentation

◆ InvariantChecker_PROTOTYPE()

xrpl::InvariantChecker_PROTOTYPE::InvariantChecker_PROTOTYPE ( )

explicitdefault

Member Function Documentation

◆ visitEntry()

void xrpl::InvariantChecker_PROTOTYPE::visitEntry	(	bool	isDelete,
		std::shared_ptr< SLE const > const &	before,
		std::shared_ptr< SLE const > const &	after
	)

called for each ledger entry in the current transaction.

Parameters

isDelete	true if the SLE is being deleted
before	ledger entry before modification by the transaction
after	ledger entry after modification by the transaction

◆ finalize()

bool xrpl::InvariantChecker_PROTOTYPE::finalize	(	STTx const &	tx,
		TER const	tec,
		XRPAmount const	fee,
		ReadView const &	view,
		beast::Journal const &	j
	)

called after all ledger entries have been visited to determine the final status of the check.

This method MUST perform meaningful checks even when tec indicates a failed transaction. See the class-level documentation for the rules governing how failed transactions must be handled.