Remove look ahead (#442)

* remove look ahead in query topdown

* use three pointers

* up crate

* fix error

* Update fendermint/vm/topdown/src/sync/syncer.rs

Co-authored-by: Akosh Farkash <[email protected]>

* fix from integration testing

* remove to_confirm pointer

* restrict memory size

* dont propose until interval reached

* update latest height

* split tendermint query to separete file

* Update fendermint/vm/topdown/src/sync/syncer.rs

Co-authored-by: adlrocha <[email protected]>

* fix test linting

* fix tests

* more tests

* check hash when executing

* sync

* sort by nonce

* fmt

* more unit tests

* New proposal logic (#447)

* new proposal logic

* fmt

* fix typo

* minor changes

* adding check

* ignore proposal height

* Fix type

* expose config params

---------

Co-authored-by: Alfonso de la Rocha <[email protected]>

---------

Signed-off-by: Alfonso de la Rocha <[email protected]>
Co-authored-by: Akosh Farkash <[email protected]>
Co-authored-by: adlrocha <[email protected]>
Co-authored-by: Alfonso de la Rocha <[email protected]>

fendermint/app/settings/src/lib.rs

@@ -112,6 +112,12 @@ pub struct TopDownConfig {
     /// conservative and avoid other from rejecting the proposal because they don't see the
     /// height as final yet.
     pub chain_head_delay: BlockHeight,
+    /// The number of blocks on top of `chain_head_delay` to wait before proposing a height
+    /// as final on the parent chain, to avoid slight disagreements between validators whether
+    /// a block is final, or not just yet.
+    pub proposal_delay: BlockHeight,
+    /// The max number of blocks one should make the topdown proposal
+    pub max_proposal_range: BlockHeight,
     /// Parent syncing cron period, in seconds
     #[serde_as(as = "DurationSeconds<u64>")]
     pub polling_interval: Duration,

fendermint/app/src/cmd/run.rs

@@ -162,12 +162,14 @@ async fn run(settings: Settings) -> anyhow::Result<()> {
     let (parent_finality_provider, ipc_tuple) = if settings.ipc.is_topdown_enabled() {
         info!("topdown finality enabled");
         let topdown_config = settings.ipc.topdown_config()?;
-        let config = fendermint_vm_topdown::Config {
-            chain_head_delay: topdown_config.chain_head_delay,
-            polling_interval: topdown_config.polling_interval,
-            exponential_back_off: topdown_config.exponential_back_off,
-            exponential_retry_limit: topdown_config.exponential_retry_limit,
-        };
+        let config = fendermint_vm_topdown::Config::new(
+            topdown_config.chain_head_delay,
+            topdown_config.polling_interval,
+            topdown_config.exponential_back_off,
+            topdown_config.exponential_retry_limit,
+        )
+        .with_proposal_delay(topdown_config.proposal_delay)
+        .with_max_proposal_range(topdown_config.max_proposal_range);
         let ipc_provider = Arc::new(create_ipc_provider_proxy(&settings)?);
         let finality_provider =
             CachedFinalityProvider::uninitialized(config.clone(), ipc_provider.clone()).await?;

fendermint/vm/interpreter/src/chain.rs

@@ -264,14 +264,21 @@ where
                         "chain interpreter committed topdown finality",
                     );
 
+                    // The commitment of the finality for block `N` triggers
+                    // the execution of all side-effects up till `N-1`, as for
+                    // deferred execution chains, this is the latest state that
+                    // we know for sure that we have available.
+                    let execution_fr = prev_height;
+                    let execution_to = finality.height - 1;
+
                     // error happens if we cannot get the validator set from ipc agent after retries
                     let validator_changes = provider
-                        .validator_changes_from(prev_height + 1, finality.height)
+                        .validator_changes_from(execution_fr, execution_to)
                         .await
                         .context("failed to fetch validator changes")?;
                     tracing::debug!(
-                        from = prev_height + 1,
-                        to = finality.height,
+                        from = execution_fr,
+                        to = execution_to,
                         msgs = validator_changes.len(),
                         "chain interpreter received total validator changes"
                     );
@@ -282,13 +289,13 @@ where
 
                     // error happens if we cannot get the cross messages from ipc agent after retries
                     let msgs = provider
-                        .top_down_msgs_from(prev_height + 1, p.height as u64, &finality.block_hash)
+                        .top_down_msgs_from(execution_fr, execution_to)
                         .await
                         .context("failed to fetch top down messages")?;
                     tracing::debug!(
                         number_of_messages = msgs.len(),
-                        start = prev_height + 1,
-                        end = p.height,
+                        start = execution_fr,
+                        end = execution_to,
                         "chain interpreter received topdown msgs",
                     );
 

fendermint/vm/topdown/src/cache.rs

@@ -50,6 +50,10 @@ impl<K: PrimInt + Debug, V> SequentialKeyCache<K, V> {
         self.increment
     }
 
+    pub fn size(&self) -> usize {
+        self.data.len()
+    }
+
     pub fn is_empty(&self) -> bool {
         self.data.is_empty()
     }

fendermint/vm/topdown/src/error.rs

@@ -15,8 +15,4 @@ pub enum Error {
     ParentChainReorgDetected,
     #[error("Cannot query parent at height {1}: {0}")]
     CannotQueryParent(String, BlockHeight),
-    /// This error happens when querying top down messages, the block ahead are all null rounds.
-    /// See `parent_views_at_height` for detailed explanation
-    #[error("Look ahead limit reached from {0}: {1}")]
-    LookAheadLimitReached(BlockHeight, BlockHeight),
 }