Merge pull request #233 from sigp/implement-shuffle

Swap BeaconState to v0.2.0 shuffling algorithm

eth2/types/Cargo.toml

@@ -18,7 +18,7 @@ serde_derive = "1.0"
 serde_json = "1.0"
 slog = "^2.2.3"
 ssz = { path = "../utils/ssz" }
-fisher_yates_shuffle = { path = "../utils/fisher_yates_shuffle" }
+swap_or_not_shuffle = { path = "../utils/swap_or_not_shuffle" }
 
 [dev-dependencies]
 env_logger = "0.6.0"

eth2/types/src/beacon_state.rs

@@ -5,15 +5,18 @@ use crate::{
     PendingAttestation, PublicKey, Signature, Slot, Validator,
 };
 use bls::verify_proof_of_possession;
-use fisher_yates_shuffle::shuffle;
 use honey_badger_split::SplitExt;
 use rand::RngCore;
 use serde_derive::Serialize;
 use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use swap_or_not_shuffle::get_permutated_index;
+
+mod tests;
 
 #[derive(Debug, PartialEq)]
 pub enum BeaconStateError {
     EpochOutOfBounds,
+    UnableToShuffle,
     InsufficientRandaoMixes,
     InsufficientValidators,
     InsufficientBlockRoots,
@@ -249,23 +252,36 @@ impl BeaconState {
     /// committee is itself a list of validator indices.
     ///
     /// Spec v0.1
-    pub fn get_shuffling(&self, seed: Hash256, epoch: Epoch, spec: &ChainSpec) -> Vec<Vec<usize>> {
+    pub fn get_shuffling(
+        &self,
+        seed: Hash256,
+        epoch: Epoch,
+        spec: &ChainSpec,
+    ) -> Option<Vec<Vec<usize>>> {
         let active_validator_indices =
             get_active_validator_indices(&self.validator_registry, epoch);
 
         let committees_per_epoch =
             self.get_epoch_committee_count(active_validator_indices.len(), spec);
 
-        // TODO: check that Hash256::from(u64) matches 'int_to_bytes32'.
+        let mut shuffled_active_validator_indices =
-        let seed = seed ^ Hash256::from(epoch.as_u64());
+            Vec::with_capacity(active_validator_indices.len());
-        // TODO: fix `expect` assert.
+        for &i in &active_validator_indices {
-        let shuffled_active_validator_indices =
+            let shuffled_i = get_permutated_index(
-            shuffle(&seed, active_validator_indices).expect("Max validator count exceed!");
+                i,
+                active_validator_indices.len(),
+                &seed[..],
+                spec.shuffle_round_count,
+            )?;
+            shuffled_active_validator_indices[i] = active_validator_indices[shuffled_i]
+        }
 
+        Some(
             shuffled_active_validator_indices
                 .honey_badger_split(committees_per_epoch as usize)
                 .map(|slice: &[usize]| slice.to_vec())
-            .collect()
+                .collect(),
+        )
     }
 
     /// Return the number of committees in the previous epoch.
@@ -401,7 +417,9 @@ impl BeaconState {
                 return Err(BeaconStateError::EpochOutOfBounds);
             };
 
-        let shuffling = self.get_shuffling(seed, shuffling_epoch, spec);
+        let shuffling = self
+            .get_shuffling(seed, shuffling_epoch, spec)
+            .ok_or_else(|| BeaconStateError::UnableToShuffle)?;
         let offset = slot.as_u64() % spec.epoch_length;
         let committees_per_slot = committees_per_epoch / spec.epoch_length;
         let slot_start_shard =
@@ -1064,33 +1082,3 @@ impl<T: RngCore> TestRandom<T> for BeaconState {
         }
     }
 }
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
-    use ssz::ssz_encode;
-
-    #[test]
-    pub fn test_ssz_round_trip() {
-        let mut rng = XorShiftRng::from_seed([42; 16]);
-        let original = BeaconState::random_for_test(&mut rng);
-
-        let bytes = ssz_encode(&original);
-        let (decoded, _) = <_>::ssz_decode(&bytes, 0).unwrap();
-
-        assert_eq!(original, decoded);
-    }
-
-    #[test]
-    pub fn test_hash_tree_root() {
-        let mut rng = XorShiftRng::from_seed([42; 16]);
-        let original = BeaconState::random_for_test(&mut rng);
-
-        let result = original.hash_tree_root();
-
-        assert_eq!(result.len(), 32);
-        // TODO: Add further tests
-        // https://github.com/sigp/lighthouse/issues/170
-    }
-}

eth2/types/src/beacon_state/tests.rs

@@ -0,0 +1,97 @@
+#![cfg(test)]
+
+use super::*;
+use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
+use crate::{
+    beacon_state::BeaconStateError, BeaconState, ChainSpec, Deposit, DepositData, DepositInput,
+    Eth1Data, Hash256, Keypair,
+};
+use bls::create_proof_of_possession;
+use ssz::ssz_encode;
+
+struct BeaconStateTestBuilder {
+    pub genesis_time: u64,
+    pub initial_validator_deposits: Vec<Deposit>,
+    pub latest_eth1_data: Eth1Data,
+    pub spec: ChainSpec,
+    pub keypairs: Vec<Keypair>,
+}
+
+impl BeaconStateTestBuilder {
+    pub fn with_random_validators(validator_count: usize) -> Self {
+        let genesis_time = 10_000_000;
+        let keypairs: Vec<Keypair> = (0..validator_count)
+            .collect::<Vec<usize>>()
+            .iter()
+            .map(|_| Keypair::random())
+            .collect();
+        let initial_validator_deposits = keypairs
+            .iter()
+            .map(|keypair| Deposit {
+                branch: vec![], // branch verification is not specified.
+                index: 0,       // index verification is not specified.
+                deposit_data: DepositData {
+                    amount: 32_000_000_000, // 32 ETH (in Gwei)
+                    timestamp: genesis_time - 1,
+                    deposit_input: DepositInput {
+                        pubkey: keypair.pk.clone(),
+                        withdrawal_credentials: Hash256::zero(), // Withdrawal not possible.
+                        proof_of_possession: create_proof_of_possession(&keypair),
+                    },
+                },
+            })
+            .collect();
+        let latest_eth1_data = Eth1Data {
+            deposit_root: Hash256::zero(),
+            block_hash: Hash256::zero(),
+        };
+        let spec = ChainSpec::foundation();
+
+        Self {
+            genesis_time,
+            initial_validator_deposits,
+            latest_eth1_data,
+            spec,
+            keypairs,
+        }
+    }
+
+    pub fn build(&self) -> Result<BeaconState, BeaconStateError> {
+        BeaconState::genesis(
+            self.genesis_time,
+            self.initial_validator_deposits.clone(),
+            self.latest_eth1_data.clone(),
+            &self.spec,
+        )
+    }
+}
+
+#[test]
+pub fn can_produce_genesis_block() {
+    let builder = BeaconStateTestBuilder::with_random_validators(2);
+
+    builder.build().unwrap();
+}
+
+#[test]
+pub fn test_ssz_round_trip() {
+    let mut rng = XorShiftRng::from_seed([42; 16]);
+    let original = BeaconState::random_for_test(&mut rng);
+
+    let bytes = ssz_encode(&original);
+    let (decoded, _) = <_>::ssz_decode(&bytes, 0).unwrap();
+
+    assert_eq!(original, decoded);
+}
+
+#[test]
+pub fn test_hash_tree_root() {
+    let mut rng = XorShiftRng::from_seed([42; 16]);
+    let original = BeaconState::random_for_test(&mut rng);
+
+    let result = original.hash_tree_root();
+
+    assert_eq!(result.len(), 32);
+    // TODO: Add further tests
+    // https://github.com/sigp/lighthouse/issues/170
+}

eth2/types/src/beacon_state_tests.rs

@@ -1,72 +0,0 @@
-#[cfg(test)]
-mod tests {
-    use crate::{
-        beacon_state::BeaconStateError, BeaconState, ChainSpec, Deposit, DepositData, DepositInput,
-        Eth1Data, Hash256, Keypair,
-    };
-    use bls::create_proof_of_possession;
-
-    struct BeaconStateTestBuilder {
-        pub genesis_time: u64,
-        pub initial_validator_deposits: Vec<Deposit>,
-        pub latest_eth1_data: Eth1Data,
-        pub spec: ChainSpec,
-        pub keypairs: Vec<Keypair>,
-    }
-
-    impl BeaconStateTestBuilder {
-        pub fn with_random_validators(validator_count: usize) -> Self {
-            let genesis_time = 10_000_000;
-            let keypairs: Vec<Keypair> = (0..validator_count)
-                .collect::<Vec<usize>>()
-                .iter()
-                .map(|_| Keypair::random())
-                .collect();
-            let initial_validator_deposits = keypairs
-                .iter()
-                .map(|keypair| Deposit {
-                    branch: vec![], // branch verification is not specified.
-                    index: 0,       // index verification is not specified.
-                    deposit_data: DepositData {
-                        amount: 32_000_000_000, // 32 ETH (in Gwei)
-                        timestamp: genesis_time - 1,
-                        deposit_input: DepositInput {
-                            pubkey: keypair.pk.clone(),
-                            withdrawal_credentials: Hash256::zero(), // Withdrawal not possible.
-                            proof_of_possession: create_proof_of_possession(&keypair),
-                        },
-                    },
-                })
-                .collect();
-            let latest_eth1_data = Eth1Data {
-                deposit_root: Hash256::zero(),
-                block_hash: Hash256::zero(),
-            };
-            let spec = ChainSpec::foundation();
-
-            Self {
-                genesis_time,
-                initial_validator_deposits,
-                latest_eth1_data,
-                spec,
-                keypairs,
-            }
-        }
-
-        pub fn build(&self) -> Result<BeaconState, BeaconStateError> {
-            BeaconState::genesis(
-                self.genesis_time,
-                self.initial_validator_deposits.clone(),
-                self.latest_eth1_data.clone(),
-                &self.spec,
-            )
-        }
-    }
-
-    #[test]
-    pub fn can_produce_genesis_block() {
-        let builder = BeaconStateTestBuilder::with_random_validators(2);
-
-        builder.build().unwrap();
-    }
-}

eth2/types/src/lib.rs

@@ -7,7 +7,6 @@ pub mod attester_slashing;
 pub mod beacon_block;
 pub mod beacon_block_body;
 pub mod beacon_state;
-pub mod beacon_state_tests;
 pub mod casper_slashing;
 pub mod crosslink;
 pub mod deposit;

eth2/types/src/spec/mod.rs

@@ -17,7 +17,7 @@ pub struct ChainSpec {
     pub beacon_chain_shard_number: u64,
     pub max_indices_per_slashable_vote: u64,
     pub max_withdrawals_per_epoch: u64,
-    pub shuffle_round_count: u64,
+    pub shuffle_round_count: u8,
 
     /*
      *  Deposit contract