mutator

Documentation

Overview

Package mutator defines the operations to transform mutations into changes in the map as well as operations to write and read mutations to and from the database.

Index

• Variables
• type Mutation
• type Mutator

Variables

var (
	// MaxMutationSize represent the maximum allowed mutation size in bytes.
	MaxMutationSize = 16 * 1024
	// ErrReplay occurs when two mutations acting on the same entry & epoch
	// occur.
	ErrReplay = errors.New("mutation replay")
	// ErrSize occurs when the mutation size is larger than the allowed upper
	// bound.
	ErrSize = errors.New("mutation is too large")
	// ErrPreviousHash occurs when the mutation the hash of the previous
	// entry provided in the mutation does not match the previous entry
	// itself.
	ErrPreviousHash = errors.New("previous entry hash does not match the hash provided in the mutation")
	// ErrMissingKey occurs when a mutation does not have authorized keys.
	ErrMissingKey = errors.New("missing authorized key(s)")
	// ErrInvalidSig occurs when either the current or previous update entry
	// signature verification fails.
	ErrInvalidSig = errors.New("invalid signature")
)

Types

type Mutation

type Mutation interface {
	// ReadRange reads all mutations for a specific given mapID and sequence
	// range. The range is identified by a starting sequence number and a
	// count. Note that startSequence is not included in the result.
	// ReadRange stops when endSequence or count is reached, whichever comes
	// first. ReadRange also returns the maximum sequence number read.
	ReadRange(txn transaction.Txn, startSequence, endSequence uint64, count int32) (uint64, []*tpb.SignedKV, error)
	// ReadAll reads all mutations starting from the given sequence number.
	// Note that startSequence is not included in the result. ReadAll also
	// returns the maximum sequence number read.
	ReadAll(txn transaction.Txn, startSequence uint64) (uint64, []*tpb.SignedKV, error)
	// Write saves the mutation in the database. Write returns the sequence
	// number that is written.
	Write(txn transaction.Txn, mutation *tpb.SignedKV) (uint64, error)
}

Mutation reads and writes mutations to the database. TODO: Add mapID to this interface to support multiple maps per server.

type Mutator

type Mutator interface {
	// CheckMutation verifies that this is a valid mutation for this item.
	CheckMutation(value, mutation []byte) error
	// Mutate applies mutation to value
	Mutate(value, mutation []byte) ([]byte, error)
}

Mutator verifies mutations and transforms values in the map.