bitset.go

/*
 * The Clear BSD License
 *
 * Copyright (c) 2019 Insolar Technologies
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted (subject to the limitations in the disclaimer below) provided that the following conditions are met:
 *
 *  Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
 *  Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
 *  Neither the name of Insolar Technologies nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
 *
 * NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE GRANTED BY THIS LICENSE. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

package packets

import (
	"github.com/insolar/insolar/core"
	"github.com/pkg/errors"
)

// TriState is state of the communicating node
type TriState uint8

const (
	// Legit is bit indicating OK data from node
	Legit TriState = iota + 1
	// TimedOut is bit indicating that timeout occurred when communicating with node
	TimedOut
	// Fraud is bit indicating that the node is malicious (fraud)
	Fraud
)

// BitSetCell is structure that contains the state of the node
type BitSetCell struct {
	NodeID core.RecordRef
	State  TriState
}

// Possible errors in BitSetMapper
var (
	// ErrBitSetOutOfRange is returned when index passed to IndexToRef function is out of range (ERROR)
	ErrBitSetOutOfRange = errors.New("index out of range")
	// ErrBitSetNodeIsMissing is returned in IndexToRef when we have no information about the node on specified index (SPECIAL CASE)
	ErrBitSetNodeIsMissing = errors.New("no information about node on specified index")
	// ErrBitSetIncorrectNode is returned when an incorrect node is passed to RefToIndex (ERROR)
	ErrBitSetIncorrectNode = errors.New("incorrect node ID")
)

// BitSetMapper contains the mapping from bitset index to node ID (and vice versa)
type BitSetMapper interface {
	// IndexToRef get ID of the node that is stored on the specified internal index
	IndexToRef(index int) (core.RecordRef, error)
	// RefToIndex get bitset internal index where the specified node state is stored
	RefToIndex(nodeID core.RecordRef) (int, error)
	// Length returns required length of the bitset
	Length() int
}

// BitSet is interface
type BitSet interface {
	Serialize() ([]byte, error)
	// GetCells get buckets of bitset
	GetCells(mapper BitSetMapper) ([]BitSetCell, error)
	// GetTristateArray get underlying tristate
	GetTristateArray() ([]TriState, error)
	// ApplyChanges returns copy of the current bitset with changes applied
	ApplyChanges(changes []BitSetCell, mapper BitSetMapper) error
}

// NewBitSet creates bitset from a set of buckets and the mapper. Size == cells count.
func NewBitSet(size int) (BitSet, error) {
	return NewTriStateBitSet(size)
}