predicates

Documentation

Index

• Constants
• func ExtractPredicate(predicateBytes []byte) (*predicates.Predicate, error)
• func ExtractPubKey(ownerProof []byte) ([]byte, error)
• type GasMeter
• type PredicateEngine
• type PredicateEngines
  • func Dispatcher(engines ...PredicateEngine) (PredicateEngines, error)
  • func (pe PredicateEngines) Add(engine PredicateEngine) error
  • func (pe PredicateEngines) Execute(ctx context.Context, predicate types.PredicateBytes, args []byte, ...) (bool, error)
• type PredicateExecutor
• type PredicateRunner
  • func NewPredicateRunner(executor PredicateExecutor) PredicateRunner
• type TxContext

Constants

const MaxPredicateBinSize = 65536

Functions

func ExtractPredicate

func ExtractPredicate(predicateBytes []byte) (*predicates.Predicate, error)

func ExtractPubKey

func ExtractPubKey(ownerProof []byte) ([]byte, error)

Types

type GasMeter

type GasMeter interface {
	GasAvailable() uint64
	SpendGas(gas uint64) error
	CalculateCost() uint64
}

type PredicateEngine

type PredicateEngine interface {
	// ID unique ID of the engine, this is used to dispatch predicates (predicate.Tag == engine.ID)
	// to the engine which is supposed to evaluate it.
	ID() uint64

	// Execute executes given predicate
	Execute(ctx context.Context, predicate *predicates.Predicate, args []byte, sigBytesFn func() ([]byte, error), env TxContext) (bool, error)
}

type PredicateEngines

type PredicateEngines map[uint64]func(ctx context.Context, predicate *predicates.Predicate, args []byte, sigBytesFn func() ([]byte, error), env TxContext) (bool, error)

func Dispatcher

func Dispatcher(engines ...PredicateEngine) (PredicateEngines, error)

Dispatcher creates collection of predicate engines

func (PredicateEngines) Add

func (pe PredicateEngines) Add(engine PredicateEngine) error

func (PredicateEngines) Execute

func (pe PredicateEngines) Execute(ctx context.Context, predicate types.PredicateBytes, args []byte, sigBytesFn func() ([]byte, error), env TxContext) (bool, error)

Execute decodes predicate from binary representation and dispatches it to appropriate predicate executor.

type PredicateExecutor

type PredicateExecutor func(ctx context.Context, predicate types.PredicateBytes, args []byte, sigBytesFn func() ([]byte, error), env TxContext) (bool, error)

type PredicateRunner

type PredicateRunner func(predicate types.PredicateBytes, args []byte, sigBytesFn func() ([]byte, error), env TxContext) error

func NewPredicateRunner

func NewPredicateRunner(

	executor PredicateExecutor,
) PredicateRunner

NewPredicateRunner is a helper to refactor predicate support - provide implementation which is common for most tx systems and "translates" between two interfaces:

• currently tx handlers do not have context.Context to pass to the predicate engine so wrapper returned doesn't require it and passes context.Background() to the predicate engine;
• currently tx systems do not differentiate between predicate evaluating to "false" vs returning error (ie invalid predicate or arguments) so wrapper returns error in case the predicate evaluates to "false".

type TxContext

type TxContext interface {
	GasMeter
	GetUnit(id types.UnitID, committed bool) (*state.Unit, error)
	CurrentRound() uint64
	TrustBase(epoch uint64) (types.RootTrustBase, error)
	TransactionOrder() (*types.TransactionOrder, error)
}

TxContext environment where predicate runs (AKA transaction execution context) This is meant to provide the predicate engine with access to the tx system which processes the transaction.