From de57beccc979fcb98fa632ba37845086a51a8b65 Mon Sep 17 00:00:00 2001
From: Federico Franzoni <8609060+fed-franz@users.noreply.github.com>
Date: Mon, 2 Sep 2024 15:48:13 +0200
Subject: [PATCH] node: store and load last_iteration

---
 node/src/chain/consensus.rs  | 40 ++++++++++++++++++++++++++++++++++--
 node/src/database/rocksdb.rs |  1 +
 2 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/node/src/chain/consensus.rs b/node/src/chain/consensus.rs
index d851447a4f..176a5570a1 100644
--- a/node/src/chain/consensus.rs
+++ b/node/src/chain/consensus.rs
@@ -14,7 +14,7 @@ use dusk_consensus::operations::{
 };
 use dusk_consensus::queue::MsgRegistry;
 use dusk_consensus::user::provisioners::ContextProvisioners;
-use node_data::ledger::{Block, Fault, Header};
+use node_data::ledger::{Block, Fault, Hash, Header};
 use node_data::message::AsyncQueue;
 
 use tokio::sync::{oneshot, Mutex, RwLock};
@@ -24,7 +24,7 @@ use tracing::{debug, info, trace, warn};
 use crate::chain::header_validation::Validator;
 use crate::chain::metrics::AverageElapsedTime;
 use crate::database::rocksdb::{
-    MD_AVG_PROPOSAL, MD_AVG_RATIFICATION, MD_AVG_VALIDATION,
+    MD_AVG_PROPOSAL, MD_AVG_RATIFICATION, MD_AVG_VALIDATION, MD_LAST_ITER,
 };
 use metrics::gauge;
 use node_data::{ledger, Serializable, StepName};
@@ -211,6 +211,42 @@ impl<DB: database::DB> dusk_consensus::commons::Database for CandidateDB<DB> {
             }
         }
     }
+    async fn get_last_iter(&self) -> (Hash, u8) {
+        let data = self
+            .db
+            .read()
+            .await
+            .view(|t| t.op_read(MD_LAST_ITER))
+            .unwrap_or_else(|e| {
+                warn!("Cannot read last_iter from database {e:?}");
+                None
+            })
+            .filter(|v| v.len() == 33)
+            .unwrap_or_else(|| {
+                warn!("No last_iter saved, falling back to default");
+                [0u8; 33].to_vec()
+            });
+
+        let mut hash = [0u8; 32];
+        hash.copy_from_slice(&data[0..32]);
+
+        let iter = data[32];
+
+        (hash, iter)
+    }
+    async fn store_last_iter(&mut self, (hash, iter): (Hash, u8)) {
+        let mut to_store = hash.to_vec();
+        to_store.push(iter);
+
+        if let Err(e) = self
+            .db
+            .read()
+            .await
+            .update(|t| t.op_write(MD_LAST_ITER, to_store))
+        {
+            warn!("Cannot write last_iter to database {e:?}");
+        }
+    }
 }
 
 /// Implements Executor trait to mock Contract Storage calls.
diff --git a/node/src/database/rocksdb.rs b/node/src/database/rocksdb.rs
index 08c7723444..e3b8b83e9d 100644
--- a/node/src/database/rocksdb.rs
+++ b/node/src/database/rocksdb.rs
@@ -53,6 +53,7 @@ pub const MD_STATE_ROOT_KEY: &[u8] = b"state_hash_key";
 pub const MD_AVG_VALIDATION: &[u8] = b"avg_validation_time";
 pub const MD_AVG_RATIFICATION: &[u8] = b"avg_ratification_time";
 pub const MD_AVG_PROPOSAL: &[u8] = b"avg_proposal_time";
+pub const MD_LAST_ITER: &[u8] = b"consensus_last_iter";
 
 #[derive(Clone)]
 pub struct Backend {