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Use BN for large uints #95

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Feb 11, 2019
Merged

Use BN for large uints #95

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cbf2857
Use BN for large uints
wemeetagain Feb 8, 2019
51a2914
Test isPowerOfTwo up to 2**256 + 1
wemeetagain Feb 8, 2019
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150 changes: 86 additions & 64 deletions beaconChain/helpers/stateTransitionHelpers.ts
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Original file line number Diff line number Diff line change
@@ -1,4 +1,6 @@
import { keccakAsU8a } from "@polkadot/util-crypto";
import BN from "bn.js";

import {
ENTRY_EXIT_DELAY,
EPOCH_LENGTH, GENESIS_EPOCH, LATEST_BLOCK_ROOTS_LENGTH, LATEST_INDEX_ROOTS_LENGTH,
Expand All @@ -9,10 +11,15 @@ import {
} from "../constants";
import {
AttestationData,
BeaconState, Bytes32,
BeaconState,
bytes32,
EpochNumber,
Fork,
SlotNumber, Validator, ValidatorIndex,
SlotNumber,
uint24,
uint64,
Validator,
ValidatorIndex,
} from "../types";

type int = number;
Expand All @@ -24,7 +31,7 @@ type hash32 = Uint8Array;
* @returns {EpochNumber}
*/
export function slotToEpoch(slot: SlotNumber): EpochNumber {
return Math.floor(slot / EPOCH_LENGTH);
return slot.divn(EPOCH_LENGTH);
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}

/**
Expand All @@ -42,7 +49,7 @@ export function getCurrentEpoch(state: BeaconState): EpochNumber {
* @returns {SlotNumber}
*/
export function getEpochStartSlot(epoch: EpochNumber): SlotNumber {
return epoch * EPOCH_LENGTH;
return epoch.muln(EPOCH_LENGTH);
}

/**
Expand All @@ -52,7 +59,7 @@ export function getEpochStartSlot(epoch: EpochNumber): SlotNumber {
* @returns {boolean}
*/
export function isActiveValidator(validator: Validator, epoch: EpochNumber): boolean {
return validator.activationEpoch <= epoch && epoch < validator.exitEpoch;
return validator.activationEpoch.lte(epoch) && epoch.lt(validator.exitEpoch);
}

/**
Expand All @@ -62,9 +69,9 @@ export function isActiveValidator(validator: Validator, epoch: EpochNumber): boo
* @returns {ValidatorIndex[]}
*/
export function getActiveValidatorIndices(validators: Validator[], epoch: EpochNumber): ValidatorIndex[] {
return validators.reduce((accumulator: int[], validator: Validator, index: int) => {
return validators.reduce((accumulator: ValidatorIndex[], validator: Validator, index: int) => {
return isActiveValidator(validator, epoch)
? [...accumulator, index]
? [...accumulator, new BN(index)]
: accumulator;
}, []);
}
Expand All @@ -86,7 +93,7 @@ export function readUIntBE(array: Uint8Array, offset: number, byteLength: number
* @param {hash32} seed
* @returns {T[]} Returns the shuffled values with seed as entropy.
*/
function shuffle<T>(values: T[], seed: Bytes32): T[] {
function shuffle<T>(values: T[], seed: bytes32): T[] {
const valuesCount: int = values.length;
// Entropy is consumed from the seed in 3-byte (24 bit) chunks.
const randBytes: number = 3;
Expand Down Expand Up @@ -191,11 +198,11 @@ export function getEpochCommitteeCount(activeValidatorCount: int): int {
* @param {int} slot
* @returns {int[][]}
*/
export function getShuffling(seed: hash32, validators: Validator[], slot: int): int[][] {
export function getShuffling(seed: hash32, validators: Validator[], slot: SlotNumber): ValidatorIndex[][] {
// Normalizes slot to start of epoch boundary
slot -= slot % EPOCH_LENGTH;
const slotAtEpoch = slot.sub(slot.umod(new BN(EPOCH_LENGTH)));

const activeValidatorIndices = getActiveValidatorIndices(validators, slot);
const activeValidatorIndices = getActiveValidatorIndices(validators, slotAtEpoch);

const committeesPerSlot = getEpochCommitteeCount(activeValidatorIndices.length);

Expand Down Expand Up @@ -236,7 +243,7 @@ export function getCurrentEpochCommitteeCount(state: BeaconState): int {
* @returns {Number}
*/
export function getNextEpochCommitteeCount(state: BeaconState): int {
const nextActiveValidators = getActiveValidatorIndices(state.validatorRegistry, getCurrentEpoch(state) + 1);
const nextActiveValidators = getActiveValidatorIndices(state.validatorRegistry, getCurrentEpoch(state).addn(1));
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return getEpochCommitteeCount(nextActiveValidators.length);
}

Expand All @@ -250,17 +257,17 @@ export function getNextEpochCommitteeCount(state: BeaconState): int {
function getCrosslinkCommitteesAtSlot(state: BeaconState, slot: SlotNumber, registryChange: boolean = false): Array<{ShardNumber, ValidatorIndex}> {
const epoch = slotToEpoch(slot);
const currentEpoch = getCurrentEpoch(state);
const previousEpoch = currentEpoch > GENESIS_EPOCH ? currentEpoch - 1 : currentEpoch;
const nextEpoch = currentEpoch + 1;
const previousEpoch = currentEpoch.gtn(GENESIS_EPOCH) ? currentEpoch.subn(1) : currentEpoch;
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const nextEpoch = currentEpoch.addn(1);
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if (previousEpoch <= epoch && epoch <= nextEpoch) { throw new Error("Slot is too early!"); }

// variables
let committeesPerEpoch;
let seed;
let shufflingEpoch;
let shufflingStartShard;
let currentCommitteesPerEpoch;
let committeesPerEpoch: int;
let seed: bytes32;
let shufflingEpoch: EpochNumber;
let shufflingStartShard: uint64;
let currentCommitteesPerEpoch: int;

if (epoch === previousEpoch) {
committeesPerEpoch = getPreviousEpochCommitteeCount(state);
Expand All @@ -277,11 +284,11 @@ function getCrosslinkCommitteesAtSlot(state: BeaconState, slot: SlotNumber, regi
committeesPerEpoch = getNextEpochCommitteeCount(state);
shufflingEpoch = nextEpoch;

const epochsSinceLastRegistryUpdate = currentEpoch - state.validatorRegistryUpdateEpoch;
const epochsSinceLastRegistryUpdate: BN = currentEpoch.sub(state.validatorRegistryUpdateEpoch);
if (registryChange) {
seed = generateSeed(state, nextEpoch);
shufflingStartShard = (state.currentEpochStartShard + currentCommitteesPerEpoch) % SHARD_COUNT;
} else if (epochsSinceLastRegistryUpdate > 1 && isPowerOfTwo(epochsSinceLastRegistryUpdate)) {
shufflingStartShard = (state.currentEpochStartShard.addn(currentCommitteesPerEpoch)).umod(new BN(SHARD_COUNT));
} else if (epochsSinceLastRegistryUpdate.gtn(1) && isPowerOfTwo(epochsSinceLastRegistryUpdate)) {
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seed = generateSeed(state, nextEpoch);
shufflingStartShard = state.currentEpochStartShard;
} else {
Expand All @@ -290,10 +297,10 @@ function getCrosslinkCommitteesAtSlot(state: BeaconState, slot: SlotNumber, regi
}
}

const shuffling = getShuffling(seed, state.validatorRegistry, shufflingEpoch);
const offset = slot % EPOCH_LENGTH;
const shuffling: ValidatorIndex[][] = getShuffling(seed, state.validatorRegistry, shufflingEpoch);
const offset: int = slot.umod(new BN(EPOCH_LENGTH)).toNumber();
const committeesPerSlot = Math.floor(committeesPerEpoch / EPOCH_LENGTH);
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const slotStartShard = (shufflingStartShard + committeesPerSlot * offset) % SHARD_COUNT;
const slotStartShard = shufflingStartShard.addn(committeesPerSlot * offset).umod(new BN(SHARD_COUNT));
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return Array.apply(null, Array(committeesPerSlot)).map((x, i) => {
return {
Expand All @@ -310,43 +317,43 @@ function getCrosslinkCommitteesAtSlot(state: BeaconState, slot: SlotNumber, regi
* @param {int} slot
* @returns {hash32}
*/
export function getBlockRoot(state: BeaconState, slot: int): Bytes32 {
export function getBlockRoot(state: BeaconState, slot: SlotNumber): bytes32 {
// Returns the block root at a recent ``slot``.
if (state.slot <= slot + LATEST_BLOCK_ROOTS_LENGTH) { throw new Error(); }
if (slot < state.slot) { throw new Error(); }
return state.latestBlockRoots[slot % LATEST_BLOCK_ROOTS_LENGTH];
if (state.slot.lte(slot.addn(LATEST_BLOCK_ROOTS_LENGTH))) { throw new Error(); }
if (slot.lt(state.slot)) { throw new Error(); }
return state.latestBlockRoots[slot.umod(new BN(LATEST_BLOCK_ROOTS_LENGTH)).toNumber()];
}

/**
* Return the randao mix at a recent epoch.
* @param {BeaconState} state
* @param {EpochNumber} epoch
* @returns {Bytes32}
* @returns {bytes32}
*/
export function getRandaoMix(state: BeaconState, epoch: EpochNumber): Bytes32 {
if (getCurrentEpoch(state) - LATEST_RANDAO_MIXES_LENGTH < epoch && epoch < getCurrentEpoch(state)) { throw new Error(""); }
return state.latestRandaoMixes[epoch % LATEST_RANDAO_MIXES_LENGTH];
export function getRandaoMix(state: BeaconState, epoch: EpochNumber): bytes32 {
if (getCurrentEpoch(state).subn(LATEST_RANDAO_MIXES_LENGTH).lt(epoch) && epoch.lt(getCurrentEpoch(state))) { throw new Error(""); }
return state.latestRandaoMixes[epoch.umod(new BN(LATEST_RANDAO_MIXES_LENGTH)).toNumber()];
}

/**
* Return the index root at a recent epoch.
* @param {BeaconState} state
* @param {EpochNumber} epoch
* @returns {Bytes32}
* @returns {bytes32}
*/
export function getActiveIndexRoot(state: BeaconState, epoch: EpochNumber): Bytes32 {
if (getCurrentEpoch(state) - LATEST_INDEX_ROOTS_LENGTH + ENTRY_EXIT_DELAY < epoch && epoch < getCurrentEpoch(state) + ENTRY_EXIT_DELAY) { throw new Error(""); }
return state.latestIndexRoots[epoch % LATEST_INDEX_ROOTS_LENGTH];
export function getActiveIndexRoot(state: BeaconState, epoch: EpochNumber): bytes32 {
if (getCurrentEpoch(state).subn(LATEST_INDEX_ROOTS_LENGTH + ENTRY_EXIT_DELAY).lt(epoch) && epoch.lt(getCurrentEpoch(state).addn(ENTRY_EXIT_DELAY))) { throw new Error(""); }
return state.latestIndexRoots[epoch.umod(new BN(LATEST_INDEX_ROOTS_LENGTH)).toNumber()];
}

/**
* Generate a seed for the given epoch.
* @param {BeaconState} state
* @param {EpochNumber} epoch
* @returns {Bytes32}
* @returns {bytes32}
*/
// TODO FINSIH
export function generateSeed(state: BeaconState, epoch: EpochNumber): Bytes32 {
export function generateSeed(state: BeaconState, epoch: EpochNumber): bytes32 {
// return hash(
// getRandaoMix(state, epoch - SEED_LOOKAHEAD) + getActiveIndexRoot(state, epoch))
// )
Expand All @@ -359,18 +366,18 @@ export function generateSeed(state: BeaconState, epoch: EpochNumber): Bytes32 {
* @param {int} slot
* @returns {int}
*/
export function getBeaconProposerIndex(state: BeaconState, slot: int): int {
export function getBeaconProposerIndex(state: BeaconState, slot: SlotNumber): int {
const firstCommittee = getCrosslinkCommitteesAtSlot(state, slot)[0].ValidatorIndex;
return firstCommittee[slot % firstCommittee.length];
return firstCommittee[slot.umod(new BN(firstCommittee.length)).toNumber()];
}

/**
* Merkleize values where the length of values is a power of two and return the Merkle root.
* @param {Bytes32[]} values
* @returns {Bytes32}
* @param {bytes32[]} values
* @returns {bytes32}
*/
// TODO finish
// export function merkleRoot(values: Bytes32[]): Bytes32 {
// export function merkleRoot(values: bytes32[]): bytes32 {
// let o: Uint8Array = new Uint8Array(values.length + 1);
// o.set(values, o.length - 1);
// }
Expand Down Expand Up @@ -401,11 +408,22 @@ export function getBeaconProposerIndex(state: BeaconState, slot: int): int {
* @param {int} value
* @returns {boolean}
*/
export function isPowerOfTwo(value: int): boolean {
if (value < 0) { throw new Error("Value is negative!"); }
if (value >= 2 ** 53) { throw new Error("Values greater or equal to 2 ** 53 are not supported yet!"); }
// TODO: Add support for values that are greater or equal to 2 ** 53
return value === 0 ? false : 2 ** Math.floor(Math.log2(value)) === value;
export function isPowerOfTwo(value: BN): boolean {
if (value.ltn(0)) {
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throw new Error("Value is negative!");
} else if (value.eqn(0)) {
return false;
} else {
// a power of two has only one bit set
let hasBitSet: boolean = false;
for (let i = 0; i < value.bitLength(); i++) {
if (hasBitSet) {
return false;
}
hasBitSet = value.testn(i);
}
return true;
}
}

/**
Expand All @@ -416,7 +434,11 @@ export function isPowerOfTwo(value: int): boolean {
*/
export function getEffectiveBalance(state: BeaconState, index: int): int {
// Returns the effective balance (also known as "balance at stake") for a ``validator`` with the given ``index``.
return Math.min(state.validatorBalances[index], MAX_DEPOSIT_AMOUNT);
if (state.validatorBalances[index].ltn(MAX_DEPOSIT_AMOUNT)) {
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return state.validatorBalances[index].toNumber();
} else {
return MAX_DEPOSIT_AMOUNT;
}
}

/**
Expand All @@ -425,8 +447,8 @@ export function getEffectiveBalance(state: BeaconState, index: int): int {
* @param {EpochNumber} epoch
* @returns {Number}
*/
export function getForkVersion(fork: Fork, epoch: EpochNumber): int {
return epoch < fork.epoch ? fork.previousVersion : fork.currentVersion;
export function getForkVersion(fork: Fork, epoch: EpochNumber): uint64 {
return epoch.lt(fork.epoch) ? fork.previousVersion : fork.currentVersion;
}

/**
Expand All @@ -436,8 +458,8 @@ export function getForkVersion(fork: Fork, epoch: EpochNumber): int {
* @param {int} domainType
* @returns {Number}
*/
export function getDomain(fork: Fork, epoch: EpochNumber, domainType: int): int {
return (getForkVersion(fork, epoch) * 2 ** 32) + domainType;
export function getDomain(fork: Fork, epoch: EpochNumber, domainType: int): uint64 {
return getForkVersion(fork, epoch).muln(2 ** 32).addn(domainType);
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}

// TODO finish
Expand All @@ -461,9 +483,9 @@ export function getDomain(fork: Fork, epoch: EpochNumber, domainType: int): int
* @returns {boolean}
*/
export function isDoubleVote(attestationData1: AttestationData, attestationData2: AttestationData): boolean {
const targetEpoch1: int = slotToEpoch(attestationData1.slot);
const targetEpoch2: int = slotToEpoch(attestationData2.slot);
return targetEpoch1 === targetEpoch2;
const targetEpoch1: EpochNumber = slotToEpoch(attestationData1.slot);
const targetEpoch2: EpochNumber = slotToEpoch(attestationData2.slot);
return targetEpoch1.eq(targetEpoch2);
}

/**
Expand All @@ -473,13 +495,13 @@ export function isDoubleVote(attestationData1: AttestationData, attestationData2
* @returns {boolean}
*/
export function isSurroundVote(attestationData1: AttestationData, attestationData2: AttestationData): boolean {
const sourceEpoch1: int = attestationData1.justifiedEpoch;
const sourceEpoch2: int = attestationData2.justifiedEpoch;
const targetEpoch1: int = slotToEpoch(attestationData1.slot);
const targetEpoch2: int = slotToEpoch(attestationData2.slot);
const sourceEpoch1: EpochNumber = attestationData1.justifiedEpoch;
const sourceEpoch2: EpochNumber = attestationData2.justifiedEpoch;
const targetEpoch1: EpochNumber = slotToEpoch(attestationData1.slot);
const targetEpoch2: EpochNumber = slotToEpoch(attestationData2.slot);
return (
(sourceEpoch1 < sourceEpoch2) &&
(targetEpoch2 < targetEpoch1)
sourceEpoch1.lt(sourceEpoch2) &&
targetEpoch2.lt(targetEpoch1)
);
}

Expand All @@ -505,5 +527,5 @@ export function intSqrt(n: int): int {
* @returns {EpochNumber}
*/
export function getEntryExitEffectEpoch(epoch: EpochNumber): EpochNumber {
return epoch + 1 + ENTRY_EXIT_DELAY;
return epoch.addn(1 + ENTRY_EXIT_DELAY);
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}
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