Move block_proposer into separate crate

Cargo.toml

@@ -19,4 +19,5 @@ members = [
 	"beacon_node/beacon_chain",
 	"protos",
 	"validator_client",
+	"validator_client/block_proposer",
 ]

validator_client/block_proposer/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "block_proposer"
+version = "0.1.0"
+authors = ["Paul Hauner <paul@paulhauner.com>"]
+edition = "2018"
+
+[dependencies]
+slot_clock = { path = "../../eth2/utils/slot_clock" }
+spec = { path = "../../eth2/spec" }
+types = { path = "../../eth2/types" }

validator_client/block_proposer/src/lib.rs

@@ -0,0 +1,263 @@
+#[cfg(test)]
+mod test_node;
+mod traits;
+
+use slot_clock::SlotClock;
+use spec::ChainSpec;
+use std::sync::{Arc, RwLock};
+use types::BeaconBlock;
+
+pub use self::traits::{BeaconNode, BeaconNodeError, DutiesReader, DutiesReaderError};
+
+#[derive(Debug, PartialEq)]
+pub enum PollOutcome {
+    /// A new block was produced.
+    BlockProduced(u64),
+    /// A block was not produced as it would have been slashable.
+    SlashableBlockNotProduced(u64),
+    /// The validator duties did not require a block to be produced.
+    BlockProductionNotRequired(u64),
+    /// The duties for the present epoch were not found.
+    ProducerDutiesUnknown(u64),
+    /// The slot has already been processed, execution was skipped.
+    SlotAlreadyProcessed(u64),
+    /// The Beacon Node was unable to produce a block at that slot.
+    BeaconNodeUnableToProduceBlock(u64),
+}
+
+#[derive(Debug, PartialEq)]
+pub enum Error {
+    SlotClockError,
+    SlotUnknowable,
+    EpochMapPoisoned,
+    SlotClockPoisoned,
+    EpochLengthIsZero,
+    BeaconNodeError(BeaconNodeError),
+}
+
+/// A polling state machine which performs block production duties, based upon some epoch duties
+/// (`EpochDutiesMap`) and a concept of time (`SlotClock`).
+///
+/// Ensures that messages are not slashable.
+///
+/// Relies upon an external service to keep the `EpochDutiesMap` updated.
+pub struct BlockProducer<T: SlotClock, U: BeaconNode, V: DutiesReader> {
+    pub last_processed_slot: u64,
+    spec: Arc<ChainSpec>,
+    epoch_map: Arc<V>,
+    slot_clock: Arc<RwLock<T>>,
+    beacon_node: Arc<U>,
+}
+
+impl<T: SlotClock, U: BeaconNode, V: DutiesReader> BlockProducer<T, U, V> {
+    /// Returns a new instance where `last_processed_slot == 0`.
+    pub fn new(
+        spec: Arc<ChainSpec>,
+        epoch_map: Arc<V>,
+        slot_clock: Arc<RwLock<T>>,
+        beacon_node: Arc<U>,
+    ) -> Self {
+        Self {
+            last_processed_slot: 0,
+            spec,
+            epoch_map,
+            slot_clock,
+            beacon_node,
+        }
+    }
+}
+
+impl<T: SlotClock, U: BeaconNode, V: DutiesReader> BlockProducer<T, U, V> {
+    /// "Poll" to see if the validator is required to take any action.
+    ///
+    /// The slot clock will be read and any new actions undertaken.
+    pub fn poll(&mut self) -> Result<PollOutcome, Error> {
+        let slot = self
+            .slot_clock
+            .read()
+            .map_err(|_| Error::SlotClockPoisoned)?
+            .present_slot()
+            .map_err(|_| Error::SlotClockError)?
+            .ok_or(Error::SlotUnknowable)?;
+
+        let epoch = slot
+            .checked_div(self.spec.epoch_length)
+            .ok_or(Error::EpochLengthIsZero)?;
+
+        // If this is a new slot.
+        if slot > self.last_processed_slot {
+            let is_block_production_slot =
+                match self.epoch_map.is_block_production_slot(epoch, slot) {
+                    Ok(result) => result,
+                    Err(DutiesReaderError::UnknownEpoch) => {
+                        return Ok(PollOutcome::ProducerDutiesUnknown(slot))
+                    }
+                    Err(DutiesReaderError::Poisoned) => return Err(Error::EpochMapPoisoned),
+                };
+
+            if is_block_production_slot {
+                self.last_processed_slot = slot;
+
+                self.produce_block(slot)
+            } else {
+                Ok(PollOutcome::BlockProductionNotRequired(slot))
+            }
+        } else {
+            Ok(PollOutcome::SlotAlreadyProcessed(slot))
+        }
+    }
+
+    /// 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.
+    fn produce_block(&mut self, slot: u64) -> Result<PollOutcome, Error> {
+        if let Some(block) = self.beacon_node.produce_beacon_block(slot)? {
+            if self.safe_to_produce(&block) {
+                let block = self.sign_block(block);
+                self.beacon_node.publish_beacon_block(block)?;
+                Ok(PollOutcome::BlockProduced(slot))
+            } else {
+                Ok(PollOutcome::SlashableBlockNotProduced(slot))
+            }
+        } else {
+            Ok(PollOutcome::BeaconNodeUnableToProduceBlock(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, block: BeaconBlock) -> BeaconBlock {
+        // TODO: sign the block
+        // https://github.com/sigp/lighthouse/issues/160
+        self.store_produce(&block);
+        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)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::test_node::TestBeaconNode;
+    use super::*;
+    use slot_clock::TestingSlotClock;
+    use std::collections::HashMap;
+    use types::test_utils::{SeedableRng, TestRandom, XorShiftRng};
+
+    // TODO: implement more thorough testing.
+    // https://github.com/sigp/lighthouse/issues/160
+    //
+    // These tests should serve as a good example for future tests.
+
+    type EpochMap = HashMap<u64, u64>;
+
+    impl DutiesReader for EpochMap {
+        fn is_block_production_slot(
+            &self,
+            epoch: u64,
+            slot: u64,
+        ) -> Result<bool, DutiesReaderError> {
+            match self.get(&epoch) {
+                Some(s) if *s == slot => Ok(true),
+                Some(s) if *s != slot => Ok(false),
+                _ => Err(DutiesReaderError::UnknownEpoch),
+            }
+        }
+    }
+
+    #[test]
+    pub fn polling() {
+        let mut rng = XorShiftRng::from_seed([42; 16]);
+
+        let spec = Arc::new(ChainSpec::foundation());
+        let slot_clock = Arc::new(RwLock::new(TestingSlotClock::new(0)));
+        let beacon_node = Arc::new(TestBeaconNode::default());
+
+        let mut epoch_map = EpochMap::new();
+        let produce_slot = 100;
+        let produce_epoch = produce_slot / spec.epoch_length;
+        epoch_map.insert(produce_epoch, produce_slot);
+        let epoch_map = Arc::new(epoch_map);
+
+        let mut block_producer = BlockProducer::new(
+            spec.clone(),
+            epoch_map.clone(),
+            slot_clock.clone(),
+            beacon_node.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(true));
+
+        // One slot before production slot...
+        slot_clock.write().unwrap().set_slot(produce_slot - 1);
+        assert_eq!(
+            block_producer.poll(),
+            Ok(PollOutcome::BlockProductionNotRequired(produce_slot - 1))
+        );
+
+        // On the produce slot...
+        slot_clock.write().unwrap().set_slot(produce_slot);
+        assert_eq!(
+            block_producer.poll(),
+            Ok(PollOutcome::BlockProduced(produce_slot))
+        );
+
+        // Trying the same produce slot again...
+        slot_clock.write().unwrap().set_slot(produce_slot);
+        assert_eq!(
+            block_producer.poll(),
+            Ok(PollOutcome::SlotAlreadyProcessed(produce_slot))
+        );
+
+        // One slot after the produce slot...
+        slot_clock.write().unwrap().set_slot(produce_slot + 1);
+        assert_eq!(
+            block_producer.poll(),
+            Ok(PollOutcome::BlockProductionNotRequired(produce_slot + 1))
+        );
+
+        // In an epoch without known duties...
+        let slot = (produce_epoch + 1) * spec.epoch_length;
+        slot_clock.write().unwrap().set_slot(slot);
+        assert_eq!(
+            block_producer.poll(),
+            Ok(PollOutcome::ProducerDutiesUnknown(slot))
+        );
+    }
+}

validator_client/block_proposer/src/test_node.rs

@@ -0,0 +1,47 @@
+use super::traits::{BeaconNode, BeaconNodeError};
+use std::sync::RwLock;
+use types::BeaconBlock;
+
+type ProduceResult = Result<Option<BeaconBlock>, BeaconNodeError>;
+type PublishResult = Result<bool, BeaconNodeError>;
+
+/// A test-only struct used to simulate a Beacon Node.
+#[derive(Default)]
+pub struct TestBeaconNode {
+    pub produce_input: RwLock<Option<u64>>,
+    pub produce_result: RwLock<Option<ProduceResult>>,
+    pub publish_input: RwLock<Option<BeaconBlock>>,
+    pub publish_result: RwLock<Option<PublishResult>>,
+}
+
+impl TestBeaconNode {
+    /// Set the result to be returned when `produce_beacon_block` is called.
+    pub fn set_next_produce_result(&self, result: ProduceResult) {
+        *self.produce_result.write().unwrap() = Some(result);
+    }
+
+    /// Set the result to be returned when `publish_beacon_block` is called.
+    pub fn set_next_publish_result(&self, result: PublishResult) {
+        *self.publish_result.write().unwrap() = Some(result);
+    }
+}
+
+impl BeaconNode for TestBeaconNode {
+    /// Returns the value specified by the `set_next_produce_result`.
+    fn produce_beacon_block(&self, slot: u64) -> ProduceResult {
+        *self.produce_input.write().unwrap() = Some(slot);
+        match *self.produce_result.read().unwrap() {
+            Some(ref r) => r.clone(),
+            None => panic!("TestBeaconNode: produce_result == None"),
+        }
+    }
+
+    /// Returns the value specified by the `set_next_publish_result`.
+    fn publish_beacon_block(&self, block: BeaconBlock) -> PublishResult {
+        *self.publish_input.write().unwrap() = Some(block);
+        match *self.publish_result.read().unwrap() {
+            Some(ref r) => r.clone(),
+            None => panic!("TestBeaconNode: publish_result == None"),
+        }
+    }
+}

validator_client/block_proposer/src/traits.rs

@@ -0,0 +1,28 @@
+use types::BeaconBlock;
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum BeaconNodeError {
+    RemoteFailure(String),
+    DecodeFailure,
+}
+
+/// Defines the methods required to produce and publish blocks on a Beacon Node.
+pub trait BeaconNode: 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: u64) -> Result<Option<BeaconBlock>, BeaconNodeError>;
+    /// Request that the node publishes a block.
+    ///
+    /// Returns `true` if the publish was sucessful.
+    fn publish_beacon_block(&self, block: BeaconBlock) -> Result<bool, BeaconNodeError>;
+}
+
+pub enum DutiesReaderError {
+    UnknownEpoch,
+    Poisoned,
+}
+
+pub trait DutiesReader: Send + Sync {
+    fn is_block_production_slot(&self, epoch: u64, slot: u64) -> Result<bool, DutiesReaderError>;
+}