Merge branch 'validator-enhancements' into testnet-client

validator_client/Cargo.toml

@@ -12,7 +12,6 @@ path = "src/main.rs"
 name = "validator_client"
 path = "src/lib.rs"
 
-
 [dependencies]
 block_proposer = { path = "../eth2/block_proposer" }
 attester = { path = "../eth2/attester" }

validator_client/src/attestation_producer/beacon_node_attestation.rs

@@ -0,0 +1,23 @@
+//TODO: generalise these enums to the crate
+use crate::block_producer::{BeaconNodeError, PublishOutcome};
+use types::{Attestation, AttestationData, Slot};
+
+/// Defines the methods required to produce and publish attestations on a Beacon Node. Abstracts the
+/// actual beacon node.
+pub trait BeaconNodeAttestation: Send + Sync {
+    /// Request that the node produces the required attestation data.
+    ///
+    fn produce_attestation_data(
+        &self,
+        slot: Slot,
+        shard: u64,
+    ) -> Result<AttestationData, BeaconNodeError>;
+
+    /// Request that the node publishes a attestation.
+    ///
+    /// Returns `true` if the publish was successful.
+    fn publish_attestation(
+        &self,
+        attestation: Attestation,
+    ) -> Result<PublishOutcome, BeaconNodeError>;
+}

validator_client/src/attestation_producer/grpc.rs

@@ -0,0 +1,57 @@
+use super::beacon_node_attestation::BeaconNodeAttestation;
+use crate::block_producer::{BeaconNodeError, PublishOutcome};
+use protos::services_grpc::AttestationServiceClient;
+use ssz::{ssz_encode, Decodable};
+
+use protos::services::{
+    Attestation as GrpcAttestation, ProduceAttestationDataRequest, PublishAttestationRequest,
+};
+use types::{Attestation, AttestationData, Slot};
+
+impl BeaconNodeAttestation for AttestationServiceClient {
+    fn produce_attestation_data(
+        &self,
+        slot: Slot,
+        shard: u64,
+    ) -> Result<AttestationData, BeaconNodeError> {
+        let mut req = ProduceAttestationDataRequest::new();
+        req.set_slot(slot.as_u64());
+        req.set_shard(shard);
+
+        let reply = self
+            .produce_attestation_data(&req)
+            .map_err(|err| BeaconNodeError::RemoteFailure(format!("{:?}", err)))?;
+
+        let (attestation_data, _index) =
+            AttestationData::ssz_decode(reply.get_attestation_data().get_ssz(), 0)
+                .map_err(|_| BeaconNodeError::DecodeFailure)?;
+        Ok(attestation_data)
+    }
+
+    fn publish_attestation(
+        &self,
+        attestation: Attestation,
+    ) -> Result<PublishOutcome, BeaconNodeError> {
+        let mut req = PublishAttestationRequest::new();
+
+        let ssz = ssz_encode(&attestation);
+
+        let mut grpc_attestation = GrpcAttestation::new();
+        grpc_attestation.set_ssz(ssz);
+
+        req.set_attestation(grpc_attestation);
+
+        let reply = self
+            .publish_attestation(&req)
+            .map_err(|err| BeaconNodeError::RemoteFailure(format!("{:?}", err)))?;
+
+        if reply.get_success() {
+            Ok(PublishOutcome::Valid)
+        } else {
+            // TODO: distinguish between different errors
+            Ok(PublishOutcome::InvalidAttestation(
+                "Publish failed".to_string(),
+            ))
+        }
+    }
+}

validator_client/src/attestation_producer/mod.rs

@@ -0,0 +1,165 @@
+mod beacon_node_attestation;
+mod grpc;
+
+use std::sync::Arc;
+use types::{ChainSpec, Domain, Fork};
+//TODO: Move these higher up in the crate
+use super::block_producer::{BeaconNodeError, PublishOutcome, ValidatorEvent};
+use crate::signer::Signer;
+use beacon_node_attestation::BeaconNodeAttestation;
+use slog::{error, info, warn};
+use ssz::TreeHash;
+use types::{
+    AggregateSignature, Attestation, AttestationData, AttestationDataAndCustodyBit,
+    AttestationDuty, Bitfield,
+};
+
+//TODO: Group these errors at a crate level
+#[derive(Debug, PartialEq)]
+pub enum Error {
+    BeaconNodeError(BeaconNodeError),
+}
+
+impl From<BeaconNodeError> for Error {
+    fn from(e: BeaconNodeError) -> Error {
+        Error::BeaconNodeError(e)
+    }
+}
+
+/// This struct contains the logic for requesting and signing beacon attestations for a validator. The
+/// validator can abstractly sign via the Signer trait object.
+pub struct AttestationProducer<'a, B: BeaconNodeAttestation, S: Signer> {
+    /// The current fork.
+    pub fork: Fork,
+    /// The attestation duty to perform.
+    pub duty: AttestationDuty,
+    /// The current epoch.
+    pub spec: Arc<ChainSpec>,
+    /// The beacon node to connect to.
+    pub beacon_node: Arc<B>,
+    /// The signer to sign the block.
+    pub signer: &'a S,
+}
+
+impl<'a, B: BeaconNodeAttestation, S: Signer> AttestationProducer<'a, B, S> {
+    /// Handle outputs and results from attestation production.
+    pub fn handle_produce_attestation(&mut self, log: slog::Logger) {
+        match self.produce_attestation() {
+            Ok(ValidatorEvent::AttestationProduced(_slot)) => {
+                info!(log, "Attestation produced"; "Validator" => format!("{}", self.signer))
+            }
+            Err(e) => error!(log, "Attestation production error"; "Error" => format!("{:?}", e)),
+            Ok(ValidatorEvent::SignerRejection(_slot)) => {
+                error!(log, "Attestation production error"; "Error" => "Signer could not sign the attestation".to_string())
+            }
+            Ok(ValidatorEvent::SlashableAttestationNotProduced(_slot)) => {
+                error!(log, "Attestation production error"; "Error" => "Rejected the attestation as it could have been slashed".to_string())
+            }
+            Ok(ValidatorEvent::PublishAttestationFailed) => {
+                error!(log, "Attestation production error"; "Error" => "Beacon node was unable to publish an attestation".to_string())
+            }
+            Ok(ValidatorEvent::InvalidAttestation) => {
+                error!(log, "Attestation production error"; "Error" => "The signed attestation was invalid".to_string())
+            }
+            Ok(v) => {
+                warn!(log, "Unknown result for attestation production"; "Error" => format!("{:?}",v))
+            }
+        }
+    }
+
+    /// Produce an attestation, sign it and send it back
+    ///
+    /// Assumes that an attestation is required at this slot (does not check the duties).
+    ///
+    /// Ensures the message is not slashable.
+    ///
+    /// !!! UNSAFE !!!
+    ///
+    /// The slash-protection code is not yet implemented. There is zero protection against
+    /// slashing.
+    pub fn produce_attestation(&mut self) -> Result<ValidatorEvent, Error> {
+        let epoch = self.duty.slot.epoch(self.spec.slots_per_epoch);
+
+        let attestation = self
+            .beacon_node
+            .produce_attestation_data(self.duty.slot, self.duty.shard)?;
+        if self.safe_to_produce(&attestation) {
+            let domain = self.spec.get_domain(epoch, Domain::Attestation, &self.fork);
+            if let Some(attestation) = self.sign_attestation(attestation, self.duty, domain) {
+                match self.beacon_node.publish_attestation(attestation) {
+                    Ok(PublishOutcome::InvalidAttestation(_string)) => {
+                        Ok(ValidatorEvent::InvalidAttestation)
+                    }
+                    Ok(PublishOutcome::Valid) => {
+                        Ok(ValidatorEvent::AttestationProduced(self.duty.slot))
+                    }
+                    Err(_) | Ok(_) => Ok(ValidatorEvent::PublishAttestationFailed),
+                }
+            } else {
+                Ok(ValidatorEvent::SignerRejection(self.duty.slot))
+            }
+        } else {
+            Ok(ValidatorEvent::SlashableAttestationNotProduced(
+                self.duty.slot,
+            ))
+        }
+    }
+
+    /// Consumes an attestation, returning the attestation signed by the validators private key.
+    ///
+    /// Important: this function will not check to ensure the attestation is not slashable. This must be
+    /// done upstream.
+    fn sign_attestation(
+        &mut self,
+        attestation: AttestationData,
+        duties: AttestationDuty,
+        domain: u64,
+    ) -> Option<Attestation> {
+        self.store_produce(&attestation);
+
+        // build the aggregate signature
+        let aggregate_signature = {
+            let message = AttestationDataAndCustodyBit {
+                data: attestation.clone(),
+                custody_bit: false,
+            }
+            .hash_tree_root();
+
+            let sig = self.signer.sign_message(&message, domain)?;
+
+            let mut agg_sig = AggregateSignature::new();
+            agg_sig.add(&sig);
+            agg_sig
+        };
+
+        let mut aggregation_bitfield = Bitfield::with_capacity(duties.committee_len);
+        let custody_bitfield = Bitfield::with_capacity(duties.committee_len);
+        aggregation_bitfield.set(duties.committee_index, true);
+
+        Some(Attestation {
+            aggregation_bitfield,
+            data: attestation,
+            custody_bitfield,
+            aggregate_signature,
+        })
+    }
+
+    /// Returns `true` if signing an attestation is safe (non-slashable).
+    ///
+    /// !!! UNSAFE !!!
+    ///
+    /// Important: this function is presently stubbed-out. It provides ZERO SAFETY.
+    fn safe_to_produce(&self, _attestation: &AttestationData) -> bool {
+        //TODO: Implement slash protection
+        true
+    }
+
+    /// Record that an attestation was produced so that slashable votes may not be made in the future.
+    ///
+    /// !!! UNSAFE !!!
+    ///
+    /// Important: this function is presently stubbed-out. It provides ZERO SAFETY.
+    fn store_produce(&mut self, _attestation: &AttestationData) {
+        // TODO: Implement slash protection
+    }
+}

validator_client/src/attester_service/attestation_grpc_client.rs

@@ -1,44 +0,0 @@
-use protos::services_grpc::AttestationServiceClient;
-use std::sync::Arc;
-
-use attester::{BeaconNode, BeaconNodeError, PublishOutcome};
-use protos::services::ProduceAttestationRequest;
-use types::{AttestationData, FreeAttestation, Slot};
-
-pub struct AttestationGrpcClient {
-    client: Arc<AttestationServiceClient>,
-}
-
-impl AttestationGrpcClient {
-    pub fn new(client: Arc<AttestationServiceClient>) -> Self {
-        Self { client }
-    }
-}
-
-impl BeaconNode for AttestationGrpcClient {
-    fn produce_attestation(
-        &self,
-        slot: Slot,
-        shard: u64,
-    ) -> Result<Option<AttestationData>, BeaconNodeError> {
-        let mut req = ProduceAttestationRequest::new();
-        req.set_slot(slot.as_u64());
-        req.set_shard(shard);
-
-        let reply = self
-            .client
-            .produce_attestation(&req)
-            .map_err(|err| BeaconNodeError::RemoteFailure(format!("{:?}", err)))?;
-
-        // TODO: return correct Attestation
-        Err(BeaconNodeError::DecodeFailure)
-    }
-
-    fn publish_attestation(
-        &self,
-        free_attestation: FreeAttestation,
-    ) -> Result<PublishOutcome, BeaconNodeError> {
-        // TODO: return correct PublishOutcome
-        Err(BeaconNodeError::DecodeFailure)
-    }
-}

validator_client/src/attester_service/mod.rs

@@ -1,54 +0,0 @@
-mod attestation_grpc_client;
-use attester::{Attester, BeaconNode, DutiesReader, PollOutcome as AttesterPollOutcome, Signer};
-use slog::{error, info, warn, Logger};
-use slot_clock::SlotClock;
-use std::time::Duration;
-
-pub use self::attestation_grpc_client::AttestationGrpcClient;
-
-pub struct AttesterService<T: SlotClock, U: BeaconNode, V: DutiesReader, W: Signer> {
-    pub attester: Attester<T, U, V, W>,
-    pub poll_interval_millis: u64,
-    pub log: Logger,
-}
-
-impl<T: SlotClock, U: BeaconNode, V: DutiesReader, W: Signer> AttesterService<T, U, V, W> {
-    /// Run a loop which polls the Attester each `poll_interval_millis` millseconds.
-    ///
-    /// Logs the results of the polls.
-    pub fn run(&mut self) {
-        loop {
-            match self.attester.poll() {
-                Err(error) => {
-                    error!(self.log, "Attester poll error"; "error" => format!("{:?}", error))
-                }
-                Ok(AttesterPollOutcome::AttestationProduced(slot)) => {
-                    info!(self.log, "Produced Attestation"; "slot" => slot)
-                }
-                Ok(AttesterPollOutcome::SlashableAttestationNotProduced(slot)) => {
-                    warn!(self.log, "Slashable attestation was not produced"; "slot" => slot)
-                }
-                Ok(AttesterPollOutcome::AttestationNotRequired(slot)) => {
-                    info!(self.log, "Attestation not required"; "slot" => slot)
-                }
-                Ok(AttesterPollOutcome::ProducerDutiesUnknown(slot)) => {
-                    error!(self.log, "Attestation duties unknown"; "slot" => slot)
-                }
-                Ok(AttesterPollOutcome::SlotAlreadyProcessed(slot)) => {
-                    warn!(self.log, "Attempted to re-process slot"; "slot" => slot)
-                }
-                Ok(AttesterPollOutcome::BeaconNodeUnableToProduceAttestation(slot)) => {
-                    error!(self.log, "Beacon node unable to produce attestation"; "slot" => slot)
-                }
-                Ok(AttesterPollOutcome::SignerRejection(slot)) => {
-                    error!(self.log, "The cryptographic signer refused to sign the attestation"; "slot" => slot)
-                }
-                Ok(AttesterPollOutcome::ValidatorIsUnknown(slot)) => {
-                    error!(self.log, "The Beacon Node does not recognise the validator"; "slot" => slot)
-                }
-            };
-
-            std::thread::sleep(Duration::from_millis(self.poll_interval_millis));
-        }
-    }
-}

validator_client/src/block_producer/beacon_node_block.rs

@@ -0,0 +1,31 @@
+use types::{BeaconBlock, Signature, Slot};
+#[derive(Debug, PartialEq, Clone)]
+pub enum BeaconNodeError {
+    RemoteFailure(String),
+    DecodeFailure,
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum PublishOutcome {
+    Valid,
+    InvalidBlock(String),
+    InvalidAttestation(String),
+}
+
+/// Defines the methods required to produce and publish blocks on a Beacon Node. Abstracts the
+/// actual beacon node.
+pub trait BeaconNodeBlock: Send + Sync {
+    /// Request that the node produces a block.
+    ///
+    /// Returns Ok(None) if the Beacon Node is unable to produce at the given slot.
+    fn produce_beacon_block(
+        &self,
+        slot: Slot,
+        randao_reveal: &Signature,
+    ) -> Result<Option<BeaconBlock>, BeaconNodeError>;
+
+    /// Request that the node publishes a block.
+    ///
+    /// Returns `true` if the publish was successful.
+    fn publish_beacon_block(&self, block: BeaconBlock) -> Result<PublishOutcome, BeaconNodeError>;
+}

validator_client/src/block_producer/grpc.rs

@@ -1,4 +1,4 @@
-use block_proposer::{BeaconNode, BeaconNodeError, PublishOutcome};
+use super::beacon_node_block::*;
 use protos::services::{
     BeaconBlock as GrpcBeaconBlock, ProduceBeaconBlockRequest, PublishBeaconBlockRequest,
 };
@@ -7,6 +7,7 @@ use ssz::{decode, ssz_encode};
 use std::sync::Arc;
 use types::{BeaconBlock, Signature, Slot};
 
+//TODO: Remove this new type. Do not need to wrap
 /// A newtype designed to wrap the gRPC-generated service so the `BeaconNode` trait may be
 /// implemented upon it.
 pub struct BeaconBlockGrpcClient {
@@ -19,7 +20,7 @@ impl BeaconBlockGrpcClient {
     }
 }
 
-impl BeaconNode for BeaconBlockGrpcClient {
+impl BeaconNodeBlock for BeaconBlockGrpcClient {
     /// Request a Beacon Node (BN) to produce a new block at the supplied slot.
     ///
     /// Returns `None` if it is not possible to produce at the supplied slot. For example, if the
@@ -27,17 +28,20 @@ impl BeaconNode for BeaconBlockGrpcClient {
     fn produce_beacon_block(
         &self,
         slot: Slot,
-        // TODO: use randao_reveal, when proto APIs have been updated.
-        _randao_reveal: &Signature,
+        randao_reveal: &Signature,
     ) -> Result<Option<BeaconBlock>, BeaconNodeError> {
+        // request a beacon block from the node
         let mut req = ProduceBeaconBlockRequest::new();
         req.set_slot(slot.as_u64());
+        req.set_randao_reveal(ssz_encode(randao_reveal));
 
+        //TODO: Determine if we want an explicit timeout
         let reply = self
             .client
             .produce_beacon_block(&req)
             .map_err(|err| BeaconNodeError::RemoteFailure(format!("{:?}", err)))?;
 
+        // format the reply
         if reply.has_block() {
             let block = reply.get_block();
             let ssz = block.get_ssz();
@@ -59,7 +63,6 @@ impl BeaconNode for BeaconBlockGrpcClient {
 
         let ssz = ssz_encode(&block);
 
-        // TODO: this conversion is incomplete; fix it.
         let mut grpc_block = GrpcBeaconBlock::new();
         grpc_block.set_ssz(ssz);
 
@@ -71,7 +74,7 @@ impl BeaconNode for BeaconBlockGrpcClient {
             .map_err(|err| BeaconNodeError::RemoteFailure(format!("{:?}", err)))?;
 
         if reply.get_success() {
-            Ok(PublishOutcome::ValidBlock)
+            Ok(PublishOutcome::Valid)
         } else {
             // TODO: distinguish between different errors
             Ok(PublishOutcome::InvalidBlock("Publish failed".to_string()))

validator_client/src/block_producer/mod.rs

@@ -0,0 +1,242 @@
+mod beacon_node_block;
+mod grpc;
+
+use self::beacon_node_block::BeaconNodeBlock;
+pub use self::beacon_node_block::{BeaconNodeError, PublishOutcome};
+pub use self::grpc::BeaconBlockGrpcClient;
+use crate::signer::Signer;
+use slog::{error, info, warn};
+use ssz::{SignedRoot, TreeHash};
+use std::sync::Arc;
+use types::{BeaconBlock, ChainSpec, Domain, Fork, Slot};
+
+#[derive(Debug, PartialEq)]
+pub enum Error {
+    BeaconNodeError(BeaconNodeError),
+}
+
+#[derive(Debug, PartialEq)]
+pub enum ValidatorEvent {
+    /// A new block was produced.
+    BlockProduced(Slot),
+    /// A new attestation was produced.
+    AttestationProduced(Slot),
+    /// A block was not produced as it would have been slashable.
+    SlashableBlockNotProduced(Slot),
+    /// An attestation was not produced as it would have been slashable.
+    SlashableAttestationNotProduced(Slot),
+    /// The Beacon Node was unable to produce a block at that slot.
+    BeaconNodeUnableToProduceBlock(Slot),
+    /// The signer failed to sign the message.
+    SignerRejection(Slot),
+    /// Publishing an attestation failed.
+    PublishAttestationFailed,
+    /// Beacon node rejected the attestation.
+    InvalidAttestation,
+}
+
+/// This struct contains the logic for requesting and signing beacon blocks for a validator. The
+/// validator can abstractly sign via the Signer trait object.
+pub struct BlockProducer<'a, B: BeaconNodeBlock, S: Signer> {
+    /// The current fork.
+    pub fork: Fork,
+    /// The current slot to produce a block for.
+    pub slot: Slot,
+    /// The current epoch.
+    pub spec: Arc<ChainSpec>,
+    /// The beacon node to connect to.
+    pub beacon_node: Arc<B>,
+    /// The signer to sign the block.
+    pub signer: &'a S,
+}
+
+impl<'a, B: BeaconNodeBlock, S: Signer> BlockProducer<'a, B, S> {
+    /// Handle outputs and results from block production.
+    pub fn handle_produce_block(&mut self, log: slog::Logger) {
+        match self.produce_block() {
+            Ok(ValidatorEvent::BlockProduced(_slot)) => {
+                info!(log, "Block produced"; "Validator" => format!("{}", self.signer))
+            }
+            Err(e) => error!(log, "Block production error"; "Error" => format!("{:?}", e)),
+            Ok(ValidatorEvent::SignerRejection(_slot)) => {
+                error!(log, "Block production error"; "Error" => "Signer Could not sign the block".to_string())
+            }
+            Ok(ValidatorEvent::SlashableBlockNotProduced(_slot)) => {
+                error!(log, "Block production error"; "Error" => "Rejected the block as it could have been slashed".to_string())
+            }
+            Ok(ValidatorEvent::BeaconNodeUnableToProduceBlock(_slot)) => {
+                error!(log, "Block production error"; "Error" => "Beacon node was unable to produce a block".to_string())
+            }
+            Ok(v) => {
+                warn!(log, "Unknown result for block production"; "Error" => format!("{:?}",v))
+            }
+        }
+    }
+
+    /// Produce a block at some slot.
+    ///
+    /// Assumes that a block is required at this slot (does not check the duties).
+    ///
+    /// Ensures the message is not slashable.
+    ///
+    /// !!! UNSAFE !!!
+    ///
+    /// The slash-protection code is not yet implemented. There is zero protection against
+    /// slashing.
+    pub fn produce_block(&mut self) -> Result<ValidatorEvent, Error> {
+        let epoch = self.slot.epoch(self.spec.slots_per_epoch);
+
+        let message = epoch.hash_tree_root();
+        let randao_reveal = match self.signer.sign_message(
+            &message,
+            self.spec.get_domain(epoch, Domain::Randao, &self.fork),
+        ) {
+            None => return Ok(ValidatorEvent::SignerRejection(self.slot)),
+            Some(signature) => signature,
+        };
+
+        if let Some(block) = self
+            .beacon_node
+            .produce_beacon_block(self.slot, &randao_reveal)?
+        {
+            if self.safe_to_produce(&block) {
+                let domain = self.spec.get_domain(epoch, Domain::BeaconBlock, &self.fork);
+                if let Some(block) = self.sign_block(block, domain) {
+                    self.beacon_node.publish_beacon_block(block)?;
+                    Ok(ValidatorEvent::BlockProduced(self.slot))
+                } else {
+                    Ok(ValidatorEvent::SignerRejection(self.slot))
+                }
+            } else {
+                Ok(ValidatorEvent::SlashableBlockNotProduced(self.slot))
+            }
+        } else {
+            Ok(ValidatorEvent::BeaconNodeUnableToProduceBlock(self.slot))
+        }
+    }
+
+    /// Consumes a block, returning that block signed by the validators private key.
+    ///
+    /// Important: this function will not check to ensure the block is not slashable. This must be
+    /// done upstream.
+    fn sign_block(&mut self, mut block: BeaconBlock, domain: u64) -> Option<BeaconBlock> {
+        self.store_produce(&block);
+
+        match self.signer.sign_message(&block.signed_root()[..], domain) {
+            None => None,
+            Some(signature) => {
+                block.signature = signature;
+                Some(block)
+            }
+        }
+    }
+
+    /// Returns `true` if signing a block is safe (non-slashable).
+    ///
+    /// !!! UNSAFE !!!
+    ///
+    /// Important: this function is presently stubbed-out. It provides ZERO SAFETY.
+    fn safe_to_produce(&self, _block: &BeaconBlock) -> bool {
+        // TODO: ensure the producer doesn't produce slashable blocks.
+        // https://github.com/sigp/lighthouse/issues/160
+        true
+    }
+
+    /// Record that a block was produced so that slashable votes may not be made in the future.
+    ///
+    /// !!! UNSAFE !!!
+    ///
+    /// Important: this function is presently stubbed-out. It provides ZERO SAFETY.
+    fn store_produce(&mut self, _block: &BeaconBlock) {
+        // TODO: record this block production to prevent future slashings.
+        // https://github.com/sigp/lighthouse/issues/160
+    }
+}
+
+impl From<BeaconNodeError> for Error {
+    fn from(e: BeaconNodeError) -> Error {
+        Error::BeaconNodeError(e)
+    }
+}
+
+/* Old tests - Re-work for new logic
+#[cfg(test)]
+mod tests {
+    use super::test_utils::{EpochMap, LocalSigner, SimulatedBeaconNode};
+    use super::*;
+    use slot_clock::TestingSlotClock;
+    use types::{
+        test_utils::{SeedableRng, TestRandom, XorShiftRng},
+        Keypair,
+    };
+
+    // TODO: implement more thorough testing.
+    // https://github.com/sigp/lighthouse/issues/160
+    //
+    // These tests should serve as a good example for future tests.
+
+    #[test]
+    pub fn polling() {
+        let mut rng = XorShiftRng::from_seed([42; 16]);
+
+        let spec = Arc::new(ChainSpec::foundation());
+        let slot_clock = Arc::new(TestingSlotClock::new(0));
+        let beacon_node = Arc::new(SimulatedBeaconNode::default());
+        let signer = Arc::new(LocalSigner::new(Keypair::random()));
+
+        let mut epoch_map = EpochMap::new(spec.slots_per_epoch);
+        let produce_slot = Slot::new(100);
+        let produce_epoch = produce_slot.epoch(spec.slots_per_epoch);
+        epoch_map.map.insert(produce_epoch, produce_slot);
+        let epoch_map = Arc::new(epoch_map);
+
+        let mut block_proposer = BlockProducer::new(
+            spec.clone(),
+            epoch_map.clone(),
+            slot_clock.clone(),
+            beacon_node.clone(),
+            signer.clone(),
+        );
+
+        // Configure responses from the BeaconNode.
+        beacon_node.set_next_produce_result(Ok(Some(BeaconBlock::random_for_test(&mut rng))));
+        beacon_node.set_next_publish_result(Ok(PublishOutcome::ValidBlock));
+
+        // One slot before production slot...
+        slot_clock.set_slot(produce_slot.as_u64() - 1);
+        assert_eq!(
+            block_proposer.poll(),
+            Ok(PollOutcome::BlockProductionNotRequired(produce_slot - 1))
+        );
+
+        // On the produce slot...
+        slot_clock.set_slot(produce_slot.as_u64());
+        assert_eq!(
+            block_proposer.poll(),
+            Ok(PollOutcome::BlockProduced(produce_slot.into()))
+        );
+
+        // Trying the same produce slot again...
+        slot_clock.set_slot(produce_slot.as_u64());
+        assert_eq!(
+            block_proposer.poll(),
+            Ok(PollOutcome::SlotAlreadyProcessed(produce_slot))
+        );
+
+        // One slot after the produce slot...
+        slot_clock.set_slot(produce_slot.as_u64() + 1);
+        assert_eq!(
+            block_proposer.poll(),
+            Ok(PollOutcome::BlockProductionNotRequired(produce_slot + 1))
+        );
+
+        // In an epoch without known duties...
+        let slot = (produce_epoch.as_u64() + 1) * spec.slots_per_epoch;
+        slot_clock.set_slot(slot);
+        assert_eq!(
+            block_proposer.poll(),
+            Ok(PollOutcome::ProducerDutiesUnknown(Slot::new(slot)))
+        );
+    }
+}
+*/

validator_client/src/block_producer_service/mod.rs

@@ -1,61 +0,0 @@
-mod beacon_block_grpc_client;
-// mod block_producer_service;
-
-use block_proposer::{
-    BeaconNode, BlockProducer, DutiesReader, PollOutcome as BlockProducerPollOutcome, Signer,
-};
-use slog::{error, info, warn, Logger};
-use slot_clock::SlotClock;
-use std::time::Duration;
-
-pub use self::beacon_block_grpc_client::BeaconBlockGrpcClient;
-
-pub struct BlockProducerService<T: SlotClock, U: BeaconNode, V: DutiesReader, W: Signer> {
-    pub block_producer: BlockProducer<T, U, V, W>,
-    pub poll_interval_millis: u64,
-    pub log: Logger,
-}
-
-impl<T: SlotClock, U: BeaconNode, V: DutiesReader, W: Signer> BlockProducerService<T, U, V, W> {
-    /// Run a loop which polls the block producer each `poll_interval_millis` millseconds.
-    ///
-    /// Logs the results of the polls.
-    pub fn run(&mut self) {
-        loop {
-            match self.block_producer.poll() {
-                Err(error) => {
-                    error!(self.log, "Block producer poll error"; "error" => format!("{:?}", error))
-                }
-                Ok(BlockProducerPollOutcome::BlockProduced(slot)) => {
-                    info!(self.log, "Produced block"; "slot" => slot)
-                }
-                Ok(BlockProducerPollOutcome::SlashableBlockNotProduced(slot)) => {
-                    warn!(self.log, "Slashable block was not signed"; "slot" => slot)
-                }
-                Ok(BlockProducerPollOutcome::BlockProductionNotRequired(slot)) => {
-                    info!(self.log, "Block production not required"; "slot" => slot)
-                }
-                Ok(BlockProducerPollOutcome::ProducerDutiesUnknown(slot)) => {
-                    error!(self.log, "Block production duties unknown"; "slot" => slot)
-                }
-                Ok(BlockProducerPollOutcome::SlotAlreadyProcessed(slot)) => {
-                    warn!(self.log, "Attempted to re-process slot"; "slot" => slot)
-                }
-                Ok(BlockProducerPollOutcome::BeaconNodeUnableToProduceBlock(slot)) => {
-                    error!(self.log, "Beacon node unable to produce block"; "slot" => slot)
-                }
-                Ok(BlockProducerPollOutcome::SignerRejection(slot)) => {
-                    error!(self.log, "The cryptographic signer refused to sign the block"; "slot" => slot)
-                }
-                Ok(BlockProducerPollOutcome::ValidatorIsUnknown(slot)) => {
-                    error!(self.log, "The Beacon Node does not recognise the validator"; "slot" => slot)
-                }
-                Ok(BlockProducerPollOutcome::UnableToGetFork(slot)) => {
-                    error!(self.log, "Unable to get a `Fork` struct to generate signature domains"; "slot" => slot)
-                }
-            };
-
-            std::thread::sleep(Duration::from_millis(self.poll_interval_millis));
-        }
-    }
-}

validator_client/src/duties/beacon_node_duties.rs

@@ -2,12 +2,12 @@ use super::EpochDuties;
 use types::{Epoch, PublicKey};
 
 #[derive(Debug, PartialEq, Clone)]
-pub enum BeaconNodeError {
+pub enum BeaconNodeDutiesError {
     RemoteFailure(String),
 }
 
 /// Defines the methods required to obtain a validators shuffling from a Beacon Node.
-pub trait BeaconNode: Send + Sync {
+pub trait BeaconNodeDuties: Send + Sync {
     /// Gets the duties for all validators.
     ///
     /// Returns a vector of EpochDuties for each validator public key. The entry will be None for
@@ -15,6 +15,6 @@ pub trait BeaconNode: Send + Sync {
     fn request_duties(
         &self,
         epoch: Epoch,
-        pubkeys: &[PublicKey],
-    ) -> Result<EpochDuties, BeaconNodeError>;
+        pub_keys: &[PublicKey],
+    ) -> Result<EpochDuties, BeaconNodeDutiesError>;
 }

validator_client/src/duties/epoch_duties.rs

@@ -1,4 +1,5 @@
 use std::collections::HashMap;
+use std::fmt;
 use std::ops::{Deref, DerefMut};
 use types::{AttestationDuty, Epoch, PublicKey, Slot};
 
@@ -22,9 +23,7 @@ pub struct WorkInfo {
 #[derive(Debug, PartialEq, Clone, Copy, Default)]
 pub struct EpochDuty {
     pub block_production_slot: Option<Slot>,
-    pub attestation_slot: Slot,
-    pub attestation_shard: u64,
-    pub committee_index: u64,
+    pub attestation_duty: AttestationDuty,
 }
 
 impl EpochDuty {
@@ -38,12 +37,8 @@ impl EpochDuty {
 
         // if the validator is required to attest to a shard, create the data
         let mut attestation_duty = None;
-        if self.attestation_slot == slot {
-            attestation_duty = Some(AttestationDuty {
-                slot,
-                shard: self.attestation_shard,
-                committee_index: self.committee_index as usize,
-            });
+        if self.attestation_duty.slot == slot {
+            attestation_duty = Some(self.attestation_duty)
         }
 
         if produce_block | attestation_duty.is_some() {
@@ -55,11 +50,25 @@ impl EpochDuty {
         None
     }
 }
-/// Maps a list of public keys (many validators) to an EpochDuty.
+
+impl fmt::Display for EpochDuty {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let mut display_block = String::from("None");
+        if let Some(block_slot) = self.block_production_slot {
+            display_block = block_slot.to_string();
+        }
+        write!(
+            f,
+            "produce block slot: {}, attestation slot: {}, attestation shard: {}",
+            display_block, self.attestation_duty.slot, self.attestation_duty.shard
+        )
+    }
+}
+
+/// Maps a list of keypairs (many validators) to an EpochDuty.
 pub type EpochDuties = HashMap<PublicKey, Option<EpochDuty>>;
 
 pub enum EpochDutiesMapError {
-    Poisoned,
     UnknownEpoch,
     UnknownValidator,
 }
@@ -98,7 +107,7 @@ impl EpochDutiesMap {
     pub fn is_work_slot(
         &self,
         slot: Slot,
-        pubkey: &PublicKey,
+        signer: &PublicKey,
     ) -> Result<Option<WorkInfo>, EpochDutiesMapError> {
         let epoch = slot.epoch(self.slots_per_epoch);
 
@@ -106,7 +115,7 @@ impl EpochDutiesMap {
             .map
             .get(&epoch)
             .ok_or_else(|| EpochDutiesMapError::UnknownEpoch)?;
-        if let Some(epoch_duty) = epoch_duties.get(pubkey) {
+        if let Some(epoch_duty) = epoch_duties.get(signer) {
             if let Some(duty) = epoch_duty {
                 // Retrieves the duty for a validator at a given slot
                 return Ok(duty.is_work_slot(slot));

validator_client/src/duties/grpc.rs

@@ -1,26 +1,27 @@
+use super::beacon_node_duties::{BeaconNodeDuties, BeaconNodeDutiesError};
 use super::epoch_duties::{EpochDuties, EpochDuty};
-use super::traits::{BeaconNode, BeaconNodeError};
-use grpcio::CallOption;
+// to use if we manually specify a timeout
+//use grpcio::CallOption;
 use protos::services::{GetDutiesRequest, Validators};
 use protos::services_grpc::ValidatorServiceClient;
 use ssz::ssz_encode;
 use std::collections::HashMap;
-use std::time::Duration;
-use types::{Epoch, PublicKey, Slot};
+// use std::time::Duration;
+use types::{AttestationDuty, Epoch, PublicKey, Slot};
 
-impl BeaconNode for ValidatorServiceClient {
+impl BeaconNodeDuties for ValidatorServiceClient {
     /// Requests all duties (block signing and committee attesting) from the Beacon Node (BN).
     fn request_duties(
         &self,
         epoch: Epoch,
-        pubkeys: &[PublicKey],
-    ) -> Result<EpochDuties, BeaconNodeError> {
+        pub_keys: &[PublicKey],
+    ) -> Result<EpochDuties, BeaconNodeDutiesError> {
         // Get the required duties from all validators
         // build the request
         let mut req = GetDutiesRequest::new();
         req.set_epoch(epoch.as_u64());
         let mut validators = Validators::new();
-        validators.set_public_keys(pubkeys.iter().map(|v| ssz_encode(v)).collect());
+        validators.set_public_keys(pub_keys.iter().map(|v| ssz_encode(v)).collect());
         req.set_validators(validators);
 
         // set a timeout for requests
@@ -29,13 +30,13 @@ impl BeaconNode for ValidatorServiceClient {
         // send the request, get the duties reply
         let reply = self
             .get_validator_duties(&req)
-            .map_err(|err| BeaconNodeError::RemoteFailure(format!("{:?}", err)))?;
+            .map_err(|err| BeaconNodeDutiesError::RemoteFailure(format!("{:?}", err)))?;
 
         let mut epoch_duties: HashMap<PublicKey, Option<EpochDuty>> = HashMap::new();
         for (index, validator_duty) in reply.get_active_validators().iter().enumerate() {
             if !validator_duty.has_duty() {
                 // validator is inactive
-                epoch_duties.insert(pubkeys[index].clone(), None);
+                epoch_duties.insert(pub_keys[index].clone(), None);
                 continue;
             }
             // active validator
@@ -47,13 +48,19 @@ impl BeaconNode for ValidatorServiceClient {
                     None
                 }
             };
+
+            let attestation_duty = AttestationDuty {
+                slot: Slot::from(active_duty.get_attestation_slot()),
+                shard: active_duty.get_attestation_shard(),
+                committee_index: active_duty.get_committee_index() as usize,
+                committee_len: active_duty.get_committee_len() as usize,
+            };
+
             let epoch_duty = EpochDuty {
                 block_production_slot,
-                attestation_slot: Slot::from(active_duty.get_attestation_slot()),
-                attestation_shard: active_duty.get_attestation_shard(),
-                committee_index: active_duty.get_committee_index(),
+                attestation_duty,
             };
-            epoch_duties.insert(pubkeys[index].clone(), Some(epoch_duty));
+            epoch_duties.insert(pub_keys[index].clone(), Some(epoch_duty));
         }
         Ok(epoch_duties)
     }

validator_client/src/duties/mod.rs

@@ -1,15 +1,17 @@
+mod beacon_node_duties;
 mod epoch_duties;
 mod grpc;
 // TODO: reintroduce tests
 //#[cfg(test)]
 //mod test_node;
-mod traits;
 
+pub use self::beacon_node_duties::{BeaconNodeDuties, BeaconNodeDutiesError};
 use self::epoch_duties::{EpochDuties, EpochDutiesMapError};
 pub use self::epoch_duties::{EpochDutiesMap, WorkInfo};
-use self::traits::{BeaconNode, BeaconNodeError};
+use super::signer::Signer;
 use futures::Async;
 use slog::{debug, error, info};
+use std::fmt::Display;
 use std::sync::Arc;
 use std::sync::RwLock;
 use types::{Epoch, PublicKey, Slot};
@@ -28,8 +30,7 @@ pub enum UpdateOutcome {
 #[derive(Debug, PartialEq)]
 pub enum Error {
     DutiesMapPoisoned,
-    EpochMapPoisoned,
-    BeaconNodeError(BeaconNodeError),
+    BeaconNodeDutiesError(BeaconNodeDutiesError),
     UnknownEpoch,
     UnknownValidator,
 }
@@ -38,19 +39,20 @@ pub enum Error {
 /// Node.
 ///
 /// This keeps track of all validator keys and required voting slots.
-pub struct DutiesManager<U: BeaconNode> {
+pub struct DutiesManager<U: BeaconNodeDuties, S: Signer> {
     pub duties_map: RwLock<EpochDutiesMap>,
-    /// A list of all public keys known to the validator service.
-    pub pubkeys: Vec<PublicKey>,
+    /// A list of all signer objects known to the validator service.
+    pub signers: Arc<Vec<S>>,
     pub beacon_node: Arc<U>,
 }
 
-impl<U: BeaconNode> DutiesManager<U> {
+impl<U: BeaconNodeDuties, S: Signer + Display> DutiesManager<U, S> {
     /// Check the Beacon Node for `EpochDuties`.
     ///
     /// be a wall-clock (e.g., system time, remote server time, etc.).
     fn update(&self, epoch: Epoch) -> Result<UpdateOutcome, Error> {
-        let duties = self.beacon_node.request_duties(epoch, &self.pubkeys)?;
+        let public_keys: Vec<PublicKey> = self.signers.iter().map(|s| s.to_public()).collect();
+        let duties = self.beacon_node.request_duties(epoch, &public_keys)?;
         {
             // If these duties were known, check to see if they're updates or identical.
             if let Some(known_duties) = self.duties_map.read()?.get(&epoch) {
@@ -67,7 +69,7 @@ impl<U: BeaconNode> DutiesManager<U> {
         // duties have changed
         //TODO: Duties could be large here. Remove from display and avoid the clone.
         self.duties_map.write()?.insert(epoch, duties.clone());
-        return Ok(UpdateOutcome::DutiesChanged(epoch, duties));
+        Ok(UpdateOutcome::DutiesChanged(epoch, duties))
     }
 
     /// A future wrapping around `update()`. This will perform logic based upon the update
@@ -82,25 +84,27 @@ impl<U: BeaconNode> DutiesManager<U> {
                 info!(log, "Duties changed (potential re-org)"; "epoch" => epoch, "duties" => format!("{:?}", duties))
             }
             Ok(UpdateOutcome::NewDuties(epoch, duties)) => {
-                info!(log, "New duties obtained"; "epoch" => epoch, "duties" => format!("{:?}", duties))
+                info!(log, "New duties obtained"; "epoch" => epoch);
+                print_duties(&log, duties);
             }
         };
         Ok(Async::Ready(()))
     }
 
-    /// Returns a list of (Public, WorkInfo) indicating all the validators that have work to perform
+    /// Returns a list of (index, WorkInfo) indicating all the validators that have work to perform
     /// this slot.
-    pub fn get_current_work(&self, slot: Slot) -> Option<Vec<(PublicKey, WorkInfo)>> {
-        let mut current_work: Vec<(PublicKey, WorkInfo)> = Vec::new();
+    pub fn get_current_work(&self, slot: Slot) -> Option<Vec<(usize, WorkInfo)>> {
+        let mut current_work: Vec<(usize, WorkInfo)> = Vec::new();
 
         // if the map is poisoned, return None
         let duties = self.duties_map.read().ok()?;
 
-        for validator_pk in &self.pubkeys {
-            match duties.is_work_slot(slot, &validator_pk) {
-                Ok(Some(work_type)) => current_work.push((validator_pk.clone(), work_type)),
+        for (index, validator_signer) in self.signers.iter().enumerate() {
+            match duties.is_work_slot(slot, &validator_signer.to_public()) {
+                Ok(Some(work_type)) => current_work.push((index, work_type)),
                 Ok(None) => {} // No work for this validator
-                Err(_) => {}   // Unknown epoch or validator, no work
+                //TODO: This should really log an error, as we shouldn't end up with an err here.
+                Err(_) => {} // Unknown epoch or validator, no work
             }
         }
         if current_work.is_empty() {
@@ -111,9 +115,9 @@ impl<U: BeaconNode> DutiesManager<U> {
 }
 
 //TODO: Use error_chain to handle errors
-impl From<BeaconNodeError> for Error {
-    fn from(e: BeaconNodeError) -> Error {
-        Error::BeaconNodeError(e)
+impl From<BeaconNodeDutiesError> for Error {
+    fn from(e: BeaconNodeDutiesError) -> Error {
+        Error::BeaconNodeDutiesError(e)
     }
 }
 
@@ -126,13 +130,22 @@ impl<T> From<std::sync::PoisonError<T>> for Error {
 impl From<EpochDutiesMapError> for Error {
     fn from(e: EpochDutiesMapError) -> Error {
         match e {
-            EpochDutiesMapError::Poisoned => Error::EpochMapPoisoned,
             EpochDutiesMapError::UnknownEpoch => Error::UnknownEpoch,
             EpochDutiesMapError::UnknownValidator => Error::UnknownValidator,
         }
     }
 }
 
+fn print_duties(log: &slog::Logger, duties: EpochDuties) {
+    for (pk, duty) in duties.iter() {
+        if let Some(display_duty) = duty {
+            info!(log, "Validator: {}",pk; "Duty" => format!("{}",display_duty));
+        } else {
+            info!(log, "Validator: {}",pk; "Duty" => "None");
+        }
+    }
+}
+
 /* TODO: Modify tests for new Duties Manager form
 #[cfg(test)]
 mod tests {

validator_client/src/main.rs

@@ -1,14 +1,17 @@
-mod attester_service;
-mod block_producer_service;
+mod attestation_producer;
+mod block_producer;
 mod config;
 mod duties;
 pub mod error;
 mod service;
+mod signer;
 
 use crate::config::Config as ValidatorClientConfig;
 use clap::{App, Arg};
+use protos::services_grpc::ValidatorServiceClient;
 use service::Service as ValidatorService;
 use slog::{error, info, o, Drain};
+use types::Keypair;
 
 fn main() {
     // Logging
@@ -52,7 +55,8 @@ fn main() {
         .expect("Unable to build a configuration for the validator client.");
 
     // start the validator service.
-    match ValidatorService::start(config, log.clone()) {
+    // this specifies the GRPC and signer type to use as the duty manager beacon node.
+    match ValidatorService::<ValidatorServiceClient, Keypair>::start(config, log.clone()) {
         Ok(_) => info!(log, "Validator client shutdown successfully."),
         Err(e) => error!(log, "Validator exited due to: {}", e.to_string()),
     }

validator_client/src/service.rs

@@ -1,14 +1,20 @@
-/// The validator service. Connects to a beacon node and signs blocks when required.
-use crate::attester_service::{AttestationGrpcClient, AttesterService};
-use crate::block_producer_service::{BeaconBlockGrpcClient, BlockProducerService};
+/// The Validator Client service.
+///
+/// Connects to a beacon node and negotiates the correct chain id.
+///
+/// Once connected, the service loads known validators keypairs from disk. Every slot,
+/// the service pings the beacon node, asking for new duties for each of the validators.
+///
+/// When a validator needs to either produce a block or sign an attestation, it requests the
+/// data from the beacon node and performs the signing before publishing the block to the beacon
+/// node.
+use crate::attestation_producer::AttestationProducer;
+use crate::block_producer::{BeaconBlockGrpcClient, BlockProducer};
 use crate::config::Config as ValidatorConfig;
-use crate::duties::UpdateOutcome;
-use crate::duties::{DutiesManager, EpochDutiesMap};
+use crate::duties::{BeaconNodeDuties, DutiesManager, EpochDutiesMap};
 use crate::error as error_chain;
 use crate::error::ErrorKind;
-use attester::test_utils::EpochMap;
-use attester::{test_utils::LocalSigner as AttesterLocalSigner, Attester};
-use block_proposer::{test_utils::LocalSigner as BlockProposerLocalSigner, BlockProducer};
+use crate::signer::Signer;
 use bls::Keypair;
 use grpcio::{ChannelBuilder, EnvBuilder};
 use protos::services::Empty;
@@ -16,65 +22,64 @@ use protos::services_grpc::{
     AttestationServiceClient, BeaconBlockServiceClient, BeaconNodeServiceClient,
     ValidatorServiceClient,
 };
-use slog::{debug, error, info, warn};
+use slog::{error, info, warn};
 use slot_clock::{SlotClock, SystemTimeSlotClock};
 use std::sync::Arc;
 use std::sync::RwLock;
 use std::time::{Duration, Instant, SystemTime};
 use tokio::prelude::*;
 use tokio::runtime::Builder;
-use tokio::timer::Interval;
+use tokio::timer::{Delay, Interval};
 use tokio_timer::clock::Clock;
 use types::test_utils::generate_deterministic_keypairs;
-use types::{Epoch, Fork, Slot};
+use types::{ChainSpec, Epoch, Fork, Slot};
 
-//TODO: This service should be simplified in the future. Can be made more steamlined.
+/// A fixed amount of time after a slot to perform operations. This gives the node time to complete
+/// per-slot processes.
+const TIME_DELAY_FROM_SLOT: Duration = Duration::from_millis(200);
 
 /// The validator service. This is the main thread that executes and maintains validator
 /// duties.
-pub struct Service {
-    /// The node we currently connected to.
-    connected_node_version: String,
-    /// The chain id we are processing on.
-    chain_id: u16,
-    /// The fork state we processing on.
+//TODO: Generalize the BeaconNode types to use testing
+pub struct Service<B: BeaconNodeDuties + 'static, S: Signer + 'static> {
+    /// The node's current fork version we are processing on.
     fork: Fork,
     /// The slot clock for this service.
     slot_clock: SystemTimeSlotClock,
     /// The current slot we are processing.
     current_slot: Slot,
-    /// The number of slots per epoch to allow for converting slots to epochs.
-    slots_per_epoch: u64,
+    /// The chain specification for this clients instance.
+    spec: Arc<ChainSpec>,
+    /// The duties manager which maintains the state of when to perform actions.
+    duties_manager: Arc<DutiesManager<B, S>>,
     // GRPC Clients
     /// The beacon block GRPC client.
-    beacon_block_client: Arc<BeaconBlockServiceClient>,
-    /// The validator GRPC client.
-    validator_client: Arc<ValidatorServiceClient>,
+    beacon_block_client: Arc<BeaconBlockGrpcClient>,
     /// The attester GRPC client.
-    attester_client: Arc<AttestationServiceClient>,
+    attestation_client: Arc<AttestationServiceClient>,
     /// The validator client logger.
     log: slog::Logger,
 }
 
-impl Service {
+impl<B: BeaconNodeDuties + 'static, S: Signer + 'static> Service<B, S> {
     ///  Initial connection to the beacon node to determine its properties.
     ///
     ///  This tries to connect to a beacon node. Once connected, it initialised the gRPC clients
     ///  and returns an instance of the service.
     fn initialize_service(
-        config: &ValidatorConfig,
+        config: ValidatorConfig,
         log: slog::Logger,
-    ) -> error_chain::Result<Self> {
+    ) -> error_chain::Result<Service<ValidatorServiceClient, Keypair>> {
         // initialise the beacon node client to check for a connection
 
         let env = Arc::new(EnvBuilder::new().build());
         // Beacon node gRPC beacon node endpoints.
         let beacon_node_client = {
             let ch = ChannelBuilder::new(env.clone()).connect(&config.server);
-            Arc::new(BeaconNodeServiceClient::new(ch))
+            BeaconNodeServiceClient::new(ch)
         };
 
-        // retrieve node information
+        // retrieve node information and validate the beacon node
         let node_info = loop {
             match beacon_node_client.info(&Empty::new()) {
                 Err(e) => {
@@ -84,18 +89,27 @@ impl Service {
                     continue;
                 }
                 Ok(info) => {
+                    // verify the node's genesis time
                     if SystemTime::now()
                         .duration_since(SystemTime::UNIX_EPOCH)
                         .unwrap()
                         .as_secs()
                         < info.genesis_time
                     {
-                        warn!(
+                        error!(
                             log,
                             "Beacon Node's genesis time is in the future. No work to do.\n Exiting"
                         );
                         return Err("Genesis time in the future".into());
                     }
+                    // verify the node's chain id
+                    if config.spec.chain_id != info.chain_id as u8 {
+                        error!(
+                            log,
+                            "Beacon Node's genesis time is in the future. No work to do.\n Exiting"
+                        );
+                        return Err(format!("Beacon node has the wrong chain id. Expected chain id: {}, node's chain id: {}", config.spec.chain_id, info.chain_id).into());
+                    }
                     break info;
                 }
             };
@@ -123,7 +137,9 @@ impl Service {
         // Beacon node gRPC beacon block endpoints.
         let beacon_block_client = {
             let ch = ChannelBuilder::new(env.clone()).connect(&config.server);
-            Arc::new(BeaconBlockServiceClient::new(ch))
+            let beacon_block_service_client = Arc::new(BeaconBlockServiceClient::new(ch));
+            // a wrapper around the service client to implement the beacon block node trait
+            Arc::new(BeaconBlockGrpcClient::new(beacon_block_service_client))
         };
 
         // Beacon node gRPC validator endpoints.
@@ -133,7 +149,7 @@ impl Service {
         };
 
         //Beacon node gRPC attester endpoints.
-        let attester_client = {
+        let attestation_client = {
             let ch = ChannelBuilder::new(env.clone()).connect(&config.server);
             Arc::new(AttestationServiceClient::new(ch))
         };
@@ -145,27 +161,51 @@ impl Service {
 
         let current_slot = slot_clock
             .present_slot()
-            .map_err(|e| ErrorKind::SlotClockError(e))?
+            .map_err(ErrorKind::SlotClockError)?
             .expect("Genesis must be in the future");
 
-        Ok(Self {
-            connected_node_version: node_info.version,
-            chain_id: node_info.chain_id as u16,
+        /* Generate the duties manager */
+
+        // generate keypairs
+
+        // TODO: keypairs are randomly generated; they should be loaded from a file or generated.
+        // https://github.com/sigp/lighthouse/issues/160
+        let keypairs = Arc::new(generate_deterministic_keypairs(8));
+
+        // Builds a mapping of Epoch -> Map(PublicKey, EpochDuty)
+        // where EpochDuty contains slot numbers and attestation data that each validator needs to
+        // produce work on.
+        let duties_map = RwLock::new(EpochDutiesMap::new(config.spec.slots_per_epoch));
+
+        // builds a manager which maintains the list of current duties for all known validators
+        // and can check when a validator needs to perform a task.
+        let duties_manager = Arc::new(DutiesManager {
+            duties_map,
+            // these are abstract objects capable of signing
+            signers: keypairs,
+            beacon_node: validator_client,
+        });
+
+        let spec = Arc::new(config.spec);
+
+        Ok(Service {
             fork,
             slot_clock,
             current_slot,
-            slots_per_epoch: config.spec.slots_per_epoch,
+            spec,
+            duties_manager,
             beacon_block_client,
-            validator_client,
-            attester_client,
+            attestation_client,
             log,
         })
     }
 
     /// Initialise the service then run the core thread.
+    // TODO: Improve handling of generic BeaconNode types, to stub grpcClient
     pub fn start(config: ValidatorConfig, log: slog::Logger) -> error_chain::Result<()> {
         // connect to the node and retrieve its properties and initialize the gRPC clients
-        let service = Service::initialize_service(&config, log)?;
+        let mut service =
+            Service::<ValidatorServiceClient, Keypair>::initialize_service(config, log)?;
 
         // we have connected to a node and established its parameters. Spin up the core service
 
@@ -185,144 +225,130 @@ impl Service {
         // set up the validator work interval - start at next slot and proceed every slot
         let interval = {
             // Set the interval to start at the next slot, and every slot after
-            let slot_duration = Duration::from_secs(config.spec.seconds_per_slot);
+            let slot_duration = Duration::from_secs(service.spec.seconds_per_slot);
             //TODO: Handle checked add correctly
             Interval::new(Instant::now() + duration_to_next_slot, slot_duration)
         };
 
-        /* kick off core service */
-
-        // generate keypairs
-
-        // TODO: keypairs are randomly generated; they should be loaded from a file or generated.
-        // https://github.com/sigp/lighthouse/issues/160
-        let keypairs = Arc::new(generate_deterministic_keypairs(8));
-
-        /* build requisite objects to pass to core thread */
-
-        // Builds a mapping of Epoch -> Map(PublicKey, EpochDuty)
-        // where EpochDuty contains slot numbers and attestation data that each validator needs to
-        // produce work on.
-        let duties_map = RwLock::new(EpochDutiesMap::new(config.spec.slots_per_epoch));
-
-        // builds a manager which maintains the list of current duties for all known validators
-        // and can check when a validator needs to perform a task.
-        let manager = Arc::new(DutiesManager {
-            duties_map,
-            pubkeys: keypairs.iter().map(|keypair| keypair.pk.clone()).collect(),
-            beacon_node: service.validator_client.clone(),
-        });
-
-        // run the core thread
+        /* kick off the core service */
         runtime.block_on(
             interval
                 .for_each(move |_| {
-                    let log = service.log.clone();
-
-                    /* get the current slot and epoch */
-                    let current_slot = match service.slot_clock.present_slot() {
-                        Err(e) => {
-                            error!(log, "SystemTimeError {:?}", e);
-                            return Ok(());
-                        }
-                        Ok(slot) => slot.expect("Genesis is in the future"),
-                    };
-
-                    let current_epoch = current_slot.epoch(service.slots_per_epoch);
-
-                    debug_assert!(
-                        current_slot > service.current_slot,
-                        "The Timer should poll a new slot"
-                    );
-
-                    info!(log, "Processing slot: {}", current_slot.as_u64());
-
-                    /* check for new duties */
-
-                    let cloned_manager = manager.clone();
-                    let cloned_log = log.clone();
-                    // spawn a new thread separate to the runtime
-                    std::thread::spawn(move || {
-                        cloned_manager.run_update(current_epoch.clone(), cloned_log.clone());
-                        dbg!("Finished thread");
-                    });
-
-                    /* execute any specified duties */
-
-                    if let Some(work) = manager.get_current_work(current_slot) {
-                        for (_public_key, work_type) in work {
-                            if work_type.produce_block {
-                                // TODO: Produce a beacon block in a new thread
-                            }
-                            if work_type.attestation_duty.is_some() {
-                                // available AttestationDuty info
-                                let attestation_duty =
-                                    work_type.attestation_duty.expect("Cannot be None");
-                                //TODO: Produce an attestation in a new thread
-                            }
-                        }
-                    }
-
+                    // wait for node to process
+                    std::thread::sleep(TIME_DELAY_FROM_SLOT);
+                    // if a non-fatal error occurs, proceed to the next slot.
+                    let _ignore_error = service.per_slot_execution();
+                    // completed a slot process
                     Ok(())
                 })
                 .map_err(|e| format!("Service thread failed: {:?}", e)),
-        );
-
-        // completed a slot process
+        )?;
+        // validator client exited
         Ok(())
     }
 
-    /*
+    /// The execution logic that runs every slot.
+    // Errors are logged to output, and core execution continues unless fatal errors occur.
+    fn per_slot_execution(&mut self) -> error_chain::Result<()> {
+        /* get the new current slot and epoch */
+        self.update_current_slot()?;
 
-        // Spawn a new thread to perform block production for the validator.
-        let producer_thread = {
-            let spec = spec.clone();
-            let signer = Arc::new(BlockProposerLocalSigner::new(keypair.clone()));
-            let duties_map = duties_map.clone();
-            let slot_clock = slot_clock.clone();
-            let log = log.clone();
-            let client = Arc::new(BeaconBlockGrpcClient::new(beacon_block_grpc_client.clone()));
-            thread::spawn(move || {
-                let block_producer =
-                    BlockProducer::new(spec, duties_map, slot_clock, client, signer);
-                let mut block_producer_service = BlockProducerService {
-                    block_producer,
-                    poll_interval_millis,
-                    log,
-                };
+        /* check for new duties */
+        self.check_for_duties();
 
-                block_producer_service.run();
-            })
-        };
+        /* process any required duties for validators */
+        self.process_duties();
 
-        // Spawn a new thread for attestation for the validator.
-        let attester_thread = {
-            let signer = Arc::new(AttesterLocalSigner::new(keypair.clone()));
-            let epoch_map = epoch_map_for_attester.clone();
-            let slot_clock = slot_clock.clone();
-            let log = log.clone();
-            let client = Arc::new(AttestationGrpcClient::new(attester_grpc_client.clone()));
-            thread::spawn(move || {
-                let attester = Attester::new(epoch_map, slot_clock, client, signer);
-                let mut attester_service = AttesterService {
-                    attester,
-                    poll_interval_millis,
-                    log,
-                };
-
-                attester_service.run();
-            })
-        };
-
-        threads.push((duties_manager_thread, producer_thread, attester_thread));
+        Ok(())
     }
 
-    // Naively wait for all the threads to complete.
-    for tuple in threads {
-        let (manager, producer, attester) = tuple;
-        let _ = producer.join();
-        let _ = manager.join();
-        let _ = attester.join();
+    /// Updates the known current slot and epoch.
+    fn update_current_slot(&mut self) -> error_chain::Result<()> {
+        let current_slot = match self.slot_clock.present_slot() {
+            Err(e) => {
+                error!(self.log, "SystemTimeError {:?}", e);
+                return Err("Could not read system time".into());
+            }
+            Ok(slot) => slot.expect("Genesis is in the future"),
+        };
+
+        let current_epoch = current_slot.epoch(self.spec.slots_per_epoch);
+
+        // this is a fatal error. If the slot clock repeats, there is something wrong with
+        // the timer, terminate immediately.
+        assert!(
+            current_slot > self.current_slot,
+            "The Timer should poll a new slot"
+        );
+        self.current_slot = current_slot;
+        info!(self.log, "Processing"; "slot" => current_slot.as_u64(), "epoch" => current_epoch.as_u64());
+        Ok(())
+    }
+
+    /// For all known validator keypairs, update any known duties from the beacon node.
+    fn check_for_duties(&mut self) {
+        let cloned_manager = self.duties_manager.clone();
+        let cloned_log = self.log.clone();
+        let current_epoch = self.current_slot.epoch(self.spec.slots_per_epoch);
+        // spawn a new thread separate to the runtime
+        // TODO: Handle thread termination/timeout
+        // TODO: Add duties thread back in, with channel to process duties in duty change.
+        // leave sequential for now.
+        //std::thread::spawn(move || {
+        // the return value is a future which returns ready.
+        // built to be compatible with the tokio runtime.
+        let _empty = cloned_manager.run_update(current_epoch, cloned_log.clone());
+        //});
+    }
+
+    /// If there are any duties to process, spawn a separate thread and perform required actions.
+    fn process_duties(&mut self) {
+        if let Some(work) = self.duties_manager.get_current_work(self.current_slot) {
+            for (signer_index, work_type) in work {
+                if work_type.produce_block {
+                    // we need to produce a block
+                    // spawns a thread to produce a beacon block
+                    let signers = self.duties_manager.signers.clone(); // this is an arc
+                    let fork = self.fork.clone();
+                    let slot = self.current_slot;
+                    let spec = self.spec.clone();
+                    let beacon_node = self.beacon_block_client.clone();
+                    let log = self.log.clone();
+                    std::thread::spawn(move || {
+                        info!(log, "Producing a block"; "Validator"=> format!("{}", signers[signer_index]));
+                        let signer = &signers[signer_index];
+                        let mut block_producer = BlockProducer {
+                            fork,
+                            slot,
+                            spec,
+                            beacon_node,
+                            signer,
+                        };
+                        block_producer.handle_produce_block(log);
+                    });
+                }
+                if work_type.attestation_duty.is_some() {
+                    // we need to produce an attestation
+                    // spawns a thread to produce and sign an attestation
+                    let signers = self.duties_manager.signers.clone(); // this is an arc
+                    let fork = self.fork.clone();
+                    let spec = self.spec.clone();
+                    let beacon_node = self.attestation_client.clone();
+                    let log = self.log.clone();
+                    std::thread::spawn(move || {
+                        info!(log, "Producing an attestation"; "Validator"=> format!("{}", signers[signer_index]));
+                        let signer = &signers[signer_index];
+                        let mut attestation_producer = AttestationProducer {
+                            fork,
+                            duty: work_type.attestation_duty.expect("Should never be none"),
+                            spec,
+                            beacon_node,
+                            signer,
+                        };
+                        attestation_producer.handle_produce_attestation(log);
+                    });
+                }
+            }
+        }
     }
-    */
 }

validator_client/src/signer.rs

@@ -0,0 +1,21 @@
+use std::fmt::Display;
+use types::{Keypair, PublicKey, Signature};
+
+/// Signs message using an internally-maintained private key.
+pub trait Signer: Display + Send + Sync + Clone {
+    fn sign_message(&self, message: &[u8], domain: u64) -> Option<Signature>;
+    /// Returns a public key for the signer object.
+    fn to_public(&self) -> PublicKey;
+}
+
+/* Implements Display and Signer for Keypair */
+
+impl Signer for Keypair {
+    fn to_public(&self) -> PublicKey {
+        self.pk.clone()
+    }
+
+    fn sign_message(&self, message: &[u8], domain: u64) -> Option<Signature> {
+        Some(Signature::new(message, domain, &self.sk))
+    }
+}