feat(optimistic_block): Introduce the optimistic block struct (#12730)

This PR introduces the shape of the optimistic block described in
#10584.
Along with it I have added the functions to create and sign it. In the
next PR,
I will link this in the path of the block production.

core/primitives/src/lib.rs

@@ -22,6 +22,7 @@ pub mod epoch_sync;
 pub mod errors;
 pub mod merkle;
 pub mod network;
+pub mod optimistic_block;
 pub mod profile_data_v2;
 pub mod profile_data_v3;
 pub mod rand;

core/primitives/src/optimistic_block.rs

@@ -0,0 +1,80 @@
+use borsh::{BorshDeserialize, BorshSerialize};
+use near_crypto::Signature;
+use near_schema_checker_lib::ProtocolSchema;
+
+use crate::block::BlockHeader;
+use crate::hash::{hash, CryptoHash};
+use crate::types::{BlockHeight, SignatureDifferentiator};
+
+#[derive(BorshSerialize, BorshDeserialize, Clone, Debug, Eq, PartialEq, ProtocolSchema)]
+pub struct OptimisticBlockInner {
+    pub prev_block_hash: CryptoHash,
+    pub block_height: BlockHeight,
+    pub block_timestamp: u64,
+    // Data to confirm the correctness of randomness beacon output
+    pub random_value: CryptoHash,
+    pub vrf_value: near_crypto::vrf::Value,
+    pub vrf_proof: near_crypto::vrf::Proof,
+    signature_differentiator: SignatureDifferentiator,
+}
+
+/// An optimistic block is independent of specific chunks and can be generated
+/// and distributed immediately after the previous block is processed.
+/// This block is shared with the validators and used to optimistically process
+/// chunks before they get included in the block.
+#[derive(BorshSerialize, BorshDeserialize, Clone, Debug, Eq, PartialEq, ProtocolSchema)]
+#[borsh(init=init)]
+pub struct OptimisticBlock {
+    pub inner: OptimisticBlockInner,
+    /// Signature of the block producer.
+    pub signature: Signature,
+    #[borsh(skip)]
+    pub hash: CryptoHash,
+}
+
+impl OptimisticBlock {
+    #[cfg(feature = "clock")]
+    pub fn produce(
+        prev_block_header: &BlockHeader,
+        height: BlockHeight,
+        signer: &crate::validator_signer::ValidatorSigner,
+        clock: near_time::Clock,
+        sandbox_delta_time: Option<near_time::Duration>,
+    ) -> Self {
+        let prev_block_hash = *prev_block_header.hash();
+        let (vrf_value, vrf_proof) =
+            signer.compute_vrf_with_proof(prev_block_header.random_value().as_ref());
+        let random_value = hash(vrf_value.0.as_ref());
+
+        let now = clock.now_utc().unix_timestamp_nanos() as u64;
+        #[cfg(feature = "sandbox")]
+        let now = now + sandbox_delta_time.unwrap().whole_nanoseconds() as u64;
+        #[cfg(not(feature = "sandbox"))]
+        debug_assert!(sandbox_delta_time.is_none());
+        let time = if now <= prev_block_header.raw_timestamp() {
+            prev_block_header.raw_timestamp() + 1
+        } else {
+            now
+        };
+
+        let inner = OptimisticBlockInner {
+            prev_block_hash,
+            block_height: height,
+            block_timestamp: time,
+            random_value,
+            vrf_value,
+            vrf_proof,
+            signature_differentiator: "OptimisticBlock".to_owned(),
+        };
+
+        let hash = hash(&borsh::to_vec(&inner).expect("Failed to serialize"));
+        let signature = signer.sign_bytes(hash.as_ref());
+
+        Self { inner, signature, hash }
+    }
+
+    /// Recompute the hash after deserialization.
+    pub fn init(&mut self) {
+        self.hash = hash(&borsh::to_vec(&self.inner).expect("Failed to serialize"));
+    }
+}

core/primitives/src/stateless_validation/chunk_endorsement.rs

@@ -1,14 +1,14 @@
 use std::fmt::Debug;
 
 use crate::sharding::{ChunkHash, ShardChunkHeader};
-use crate::types::EpochId;
+use crate::types::{EpochId, SignatureDifferentiator};
 use crate::validator_signer::ValidatorSigner;
 use borsh::{BorshDeserialize, BorshSerialize};
 use near_crypto::{PublicKey, Signature};
 use near_primitives_core::types::{AccountId, BlockHeight, ShardId};
 use near_schema_checker_lib::ProtocolSchema;
 
-use super::{ChunkProductionKey, SignatureDifferentiator};
+use super::ChunkProductionKey;
 
 /// The endorsement of a chunk by a chunk validator. By providing this, a
 /// chunk validator has verified that the chunk state witness is correct.

core/primitives/src/stateless_validation/contract_distribution.rs

@@ -9,12 +9,12 @@ use near_primitives_core::hash::{hash, CryptoHash};
 use near_primitives_core::types::{AccountId, ShardId};
 use near_schema_checker_lib::ProtocolSchema;
 
+use super::ChunkProductionKey;
 #[cfg(feature = "solomon")]
 use crate::reed_solomon::{ReedSolomonEncoderDeserialize, ReedSolomonEncoderSerialize};
+use crate::types::SignatureDifferentiator;
 use crate::{utils::compression::CompressedData, validator_signer::ValidatorSigner};
 
-use super::{ChunkProductionKey, SignatureDifferentiator};
-
 // Data structures for chunk producers to send accessesed contracts to chunk validators.
 
 /// Contains contracts (as code-hashes) accessed during the application of a chunk.

core/primitives/src/stateless_validation/mod.rs

@@ -12,14 +12,6 @@ pub mod state_witness;
 pub mod stored_chunk_state_transition_data;
 pub mod validator_assignment;
 
-/// An arbitrary static string to make sure that this struct cannot be
-/// serialized to look identical to another serialized struct. For chunk
-/// production we are signing a chunk hash, so we need to make sure that
-/// this signature means something different.
-///
-/// This is a messy workaround until we know what to do with NEP 483.
-type SignatureDifferentiator = String;
-
 /// This struct contains combination of fields that uniquely identify chunk production.
 /// It means that for a given instance only one chunk could be produced.
 #[derive(Debug, Hash, PartialEq, Eq, Clone, BorshSerialize, BorshDeserialize, ProtocolSchema)]

core/primitives/src/stateless_validation/partial_witness.rs

@@ -1,8 +1,8 @@
 use std::fmt::{Debug, Formatter};
 
-use super::{ChunkProductionKey, SignatureDifferentiator};
+use super::ChunkProductionKey;
 use crate::sharding::ShardChunkHeader;
-use crate::types::EpochId;
+use crate::types::{EpochId, SignatureDifferentiator};
 use crate::validator_signer::ValidatorSigner;
 use borsh::{BorshDeserialize, BorshSerialize};
 use bytesize::ByteSize;

core/primitives/src/stateless_validation/state_witness.rs

@@ -1,15 +1,15 @@
 use std::collections::HashMap;
 use std::fmt::Debug;
 
-use super::{ChunkProductionKey, SignatureDifferentiator};
+use super::ChunkProductionKey;
 use crate::bandwidth_scheduler::BandwidthRequests;
 use crate::challenge::PartialState;
 use crate::congestion_info::CongestionInfo;
 #[cfg(feature = "solomon")]
 use crate::reed_solomon::{ReedSolomonEncoderDeserialize, ReedSolomonEncoderSerialize};
 use crate::sharding::{ChunkHash, ReceiptProof, ShardChunkHeader, ShardChunkHeaderV3};
 use crate::transaction::SignedTransaction;
-use crate::types::EpochId;
+use crate::types::{EpochId, SignatureDifferentiator};
 use crate::utils::compression::CompressedData;
 use crate::validator_signer::EmptyValidatorSigner;
 use borsh::{BorshDeserialize, BorshSerialize};

core/primitives/src/types.rs

@@ -22,6 +22,14 @@ pub use chunk_validator_stats::ChunkStats;
 /// Hash used by to store state root.
 pub type StateRoot = CryptoHash;
 
+/// An arbitrary static string to make sure that this struct cannot be
+/// serialized to look identical to another serialized struct. For chunk
+/// production we are signing a chunk hash, so we need to make sure that
+/// this signature means something different.
+///
+/// This is a messy workaround until we know what to do with NEP 483.
+pub(crate) type SignatureDifferentiator = String;
+
 /// Different types of finality.
 #[derive(
     serde::Serialize, serde::Deserialize, Default, Clone, Debug, PartialEq, Eq, arbitrary::Arbitrary,

tools/protocol-schema-check/res/protocol_schema.toml

@@ -167,6 +167,8 @@ MethodResolveError = 1206790835
 MissingTrieValueContext = 2666011379
 NextEpochValidatorInfo = 3660299258
 NonDelegateAction = 2970737551
+OptimisticBlock = 1384126355
+OptimisticBlockInner = 1534008891
 ParentSplitParameters = 2945469052
 PartialEdgeInfo = 1350359189
 PartialEncodedChunk = 2321210648