Move genesis code into its own crate

beacon_chain/genesis/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "genesis"
+version = "0.1.0"
+authors = ["Paul Hauner <paul@paulhauner.com>"]
+
+[dependencies]
+bls = { path = "../utils/bls"  }
+spec = { path = "../spec"  }
+types = { path = "../types"  }
+validator_induction = { path = "../validator_induction"  }
+validator_shuffling = { path = "../validator_shuffling"  }

beacon_chain/genesis/src/beacon_state.rs

@@ -0,0 +1,172 @@
+use spec::ChainSpec;
+use types::{
+    BeaconState, CrosslinkRecord, ForkData, Hash256, ValidatorRegistration, ValidatorStatus,
+};
+use validator_induction::ValidatorInductor;
+use validator_shuffling::{shard_and_committees_for_cycle, ValidatorAssignmentError};
+
+#[derive(Debug, PartialEq)]
+pub enum Error {
+    NoValidators,
+    ValidationAssignmentError(ValidatorAssignmentError),
+    NotImplemented,
+}
+
+pub fn genesis_beacon_state(
+    spec: &ChainSpec,
+    initial_validators: &[ValidatorRegistration],
+    genesis_time: u64,
+    processed_pow_receipt_root: &Hash256,
+) -> Result<BeaconState, Error> {
+    /*
+     * Parse the ValidatorRegistrations into ValidatorRecords and induct them.
+     *
+     * Ignore any records which fail proof-of-possession or are invalid.
+     */
+    let validators = {
+        let mut inductor = ValidatorInductor::new(0, spec.shard_count, vec![]);
+        for registration in initial_validators {
+            let _ = inductor.induct(&registration, ValidatorStatus::Active);
+        }
+        inductor.to_vec()
+    };
+
+    /*
+     * Assign the validators to shards, using all zeros as the seed.
+     *
+     * Crystallizedstate stores two cycles, so we simply repeat the same assignment twice.
+     */
+    let _shard_and_committee_for_slots = {
+        let mut a = shard_and_committees_for_cycle(&[0; 32], &validators, 0, &spec)?;
+        let mut b = a.clone();
+        a.append(&mut b);
+        a
+    };
+
+    let initial_crosslink = CrosslinkRecord {
+        slot: spec.initial_slot_number,
+        shard_block_root: spec.zero_hash,
+    };
+
+    Ok(BeaconState {
+        /*
+         * Misc
+         */
+        slot: spec.initial_slot_number,
+        genesis_time,
+        fork_data: ForkData {
+            pre_fork_version: spec.initial_fork_version,
+            post_fork_version: spec.initial_fork_version,
+            fork_slot: spec.initial_slot_number,
+        },
+        /*
+         * Validator registry
+         */
+        validator_registry: validators,
+        validator_registry_latest_change_slot: spec.initial_slot_number,
+        validator_registry_exit_count: 0,
+        validator_registry_delta_chain_tip: spec.zero_hash,
+        /*
+         * Randomness and committees
+         */
+        randao_mix: spec.zero_hash,
+        next_seed: spec.zero_hash,
+        shard_committees_at_slots: vec![],
+        persistent_committees: vec![],
+        persistent_committee_reassignments: vec![],
+        /*
+         * Finality
+         */
+        previous_justified_slot: spec.initial_slot_number,
+        justified_slot: spec.initial_slot_number,
+        justification_bitfield: 0,
+        finalized_slot: spec.initial_slot_number,
+        /*
+         * Recent state
+         */
+        latest_crosslinks: vec![initial_crosslink; spec.shard_count as usize],
+        latest_block_roots: vec![spec.zero_hash; spec.epoch_length as usize],
+        latest_penalized_exit_balances: vec![],
+        latest_attestations: vec![],
+        /*
+         * PoW receipt root
+         */
+        processed_pow_receipt_root: *processed_pow_receipt_root,
+        candidate_pow_receipt_roots: vec![],
+    })
+}
+
+impl From<ValidatorAssignmentError> for Error {
+    fn from(e: ValidatorAssignmentError) -> Error {
+        Error::ValidationAssignmentError(e)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    extern crate bls;
+    extern crate validator_induction;
+
+    use self::bls::{create_proof_of_possession, Keypair};
+    use super::*;
+    use types::{Address, Hash256, ValidatorRegistration};
+
+    // TODO: enhance these tests.
+    // https://github.com/sigp/lighthouse/issues/117
+
+    fn random_registration() -> ValidatorRegistration {
+        let keypair = Keypair::random();
+        ValidatorRegistration {
+            pubkey: keypair.pk.clone(),
+            withdrawal_shard: 0,
+            withdrawal_address: Address::random(),
+            randao_commitment: Hash256::random(),
+            proof_of_possession: create_proof_of_possession(&keypair),
+        }
+    }
+
+    fn random_registrations(n: usize) -> Vec<ValidatorRegistration> {
+        let mut output = Vec::with_capacity(n);
+        for _ in 0..n {
+            output.push(random_registration())
+        }
+        output
+    }
+
+    #[test]
+    fn test_genesis() {
+        let spec = ChainSpec::foundation();
+        let genesis_time = 42;
+        let initial_validators = random_registrations(4);
+        let processed_pow_receipt_root = Hash256::from("pow_root".as_bytes());
+
+        let state = genesis_beacon_state(
+            &spec,
+            &initial_validators,
+            genesis_time,
+            &processed_pow_receipt_root,
+        ).unwrap();
+
+        assert_eq!(state.validator_registry.len(), 4);
+    }
+
+    #[test]
+    fn test_genesis_bad_validator() {
+        let spec = ChainSpec::foundation();
+        let genesis_time = 42;
+        let mut initial_validators = random_registrations(5);
+        let processed_pow_receipt_root = Hash256::from("pow_root".as_bytes());
+
+        let random_kp = Keypair::random();
+        initial_validators[4].proof_of_possession = create_proof_of_possession(&random_kp);
+
+        let state = genesis_beacon_state(
+            &spec,
+            &initial_validators,
+            genesis_time,
+            &processed_pow_receipt_root,
+        ).unwrap();
+
+        assert_eq!(state.validator_registry.len(), 4);
+    }
+}

beacon_chain/genesis/src/lib.rs

@@ -0,0 +1,7 @@
+extern crate spec;
+extern crate types;
+extern crate validator_induction;
+extern crate validator_shuffling;
+
+pub mod beacon_state;
+