Optimization: reduce BLS decompression (#766)

* Add RwLock-style caching for BLS pubkeys

* Tidy docker ignore

* Remove RwLocks

* Merge in master

eth2/types/src/beacon_state.rs

@@ -62,6 +62,7 @@ pub enum Error {
     CommitteeCacheUninitialized(Option<RelativeEpoch>),
     SszTypesError(ssz_types::Error),
     CachedTreeHashError(cached_tree_hash::Error),
+    InvalidValidatorPubkey(ssz::DecodeError),
 }
 
 /// Control whether an epoch-indexed field can be indexed at the next epoch or not.
@@ -784,6 +785,7 @@ impl<T: EthSpec> BeaconState<T> {
         self.update_pubkey_cache()?;
         self.build_tree_hash_cache()?;
         self.exit_cache.build(&self.validators, spec)?;
+        self.decompress_validator_pubkeys()?;
 
         Ok(())
     }
@@ -945,6 +947,23 @@ impl<T: EthSpec> BeaconState<T> {
         self.tree_hash_cache = BeaconTreeHashCache::default();
     }
 
+    /// Iterate through all validators and decompress their public key, unless it has already been
+    /// decompressed.
+    ///
+    /// Does not check the validity of already decompressed keys.
+    pub fn decompress_validator_pubkeys(&mut self) -> Result<(), Error> {
+        self.validators.iter_mut().try_for_each(|validator| {
+            if validator.pubkey.decompressed().is_none() {
+                validator
+                    .pubkey
+                    .decompress()
+                    .map_err(|e| Error::InvalidValidatorPubkey(e))
+            } else {
+                Ok(())
+            }
+        })
+    }
+
     pub fn clone_without_caches(&self) -> Self {
         BeaconState {
             genesis_time: self.genesis_time,

eth2/types/src/validator.rs

@@ -1,5 +1,4 @@
 use crate::{test_utils::TestRandom, Epoch, Hash256, PublicKeyBytes};
-
 use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;