Limit number of pgf stewards

.changelog/unreleased/improvements/3442-limit-pgf-stewards.md

@@ -0,0 +1,2 @@
+- Enforce an upper limit on the number of PGF stewards allowed to exist at a
+  given time. ([\#3442](https://github.com/anoma/namada/pull/3442))

crates/apps_lib/src/config/genesis/chain.rs

@@ -759,6 +759,7 @@ impl FinalizedParameters {
             stewards: pgf_params.stewards,
             pgf_inflation_rate: pgf_params.pgf_inflation_rate,
             stewards_inflation_rate: pgf_params.stewards_inflation_rate,
+            maximum_number_of_stewards: pgf_params.maximum_number_of_stewards,
         };
         Self {
             parameters,

crates/apps_lib/src/config/genesis/templates.rs

@@ -474,6 +474,8 @@ pub struct PgfParams<T: TemplateValidation> {
     pub pgf_inflation_rate: Dec,
     /// The pgf stewards inflation rate
     pub stewards_inflation_rate: Dec,
+    /// The maximum allowed number of PGF stewards at any time
+    pub maximum_number_of_stewards: u64,
     #[serde(default)]
     #[serde(skip_serializing)]
     #[cfg(test)]
@@ -913,6 +915,8 @@ pub fn validate_parameters(
                 stewards: pgf_params.stewards,
                 pgf_inflation_rate: pgf_params.pgf_inflation_rate,
                 stewards_inflation_rate: pgf_params.stewards_inflation_rate,
+                maximum_number_of_stewards: pgf_params
+                    .maximum_number_of_stewards,
                 valid: Default::default(),
             },
             eth_bridge_params,

crates/governance/src/pgf/parameters.rs

@@ -34,6 +34,8 @@ pub struct PgfParameters {
     pub pgf_inflation_rate: Dec,
     /// The pgf stewards inflation rate
     pub stewards_inflation_rate: Dec,
+    /// The maximum number of pgf stewards at once
+    pub maximum_number_of_stewards: u64,
 }
 
 impl Default for PgfParameters {
@@ -42,6 +44,7 @@ impl Default for PgfParameters {
             stewards: BTreeSet::default(),
             pgf_inflation_rate: Dec::new(10, 2).unwrap(),
             stewards_inflation_rate: Dec::new(1, 2).unwrap(),
+            maximum_number_of_stewards: 5,
         }
     }
 }
@@ -56,6 +59,7 @@ impl PgfParameters {
             stewards,
             pgf_inflation_rate,
             stewards_inflation_rate,
+            maximum_number_of_stewards,
         } = self;
 
         for steward in stewards {
@@ -71,6 +75,11 @@ impl PgfParameters {
 
         let steward_inflation_rate_key =
             pgf_storage::get_steward_inflation_rate_key();
-        storage.write(&steward_inflation_rate_key, stewards_inflation_rate)
+        storage.write(&steward_inflation_rate_key, stewards_inflation_rate)?;
+
+        let maximum_number_of_stewards_key =
+            pgf_storage::get_maximum_number_of_pgf_steward_key();
+        storage
+            .write(&maximum_number_of_stewards_key, maximum_number_of_stewards)
     }
 }

crates/governance/src/pgf/storage/keys.rs

@@ -14,6 +14,7 @@ struct Keys {
     fundings: &'static str,
     pgf_inflation_rate: &'static str,
     steward_inflation_rate: &'static str,
+    maximum_number_of_stewards: &'static str,
 }
 
 /// Obtain a storage key for stewards key
@@ -94,6 +95,13 @@ pub fn get_pgf_inflation_rate_key() -> Key {
         .expect("Cannot obtain a storage key")
 }
 
+/// Get key for maximum number of pgf stewards
+pub fn get_maximum_number_of_pgf_steward_key() -> Key {
+    Key::from(ADDRESS.to_db_key())
+        .push(&Keys::VALUES.maximum_number_of_stewards.to_owned())
+        .expect("Cannot obtain a storage key")
+}
+
 /// Get key for inflation rate key
 pub fn get_steward_inflation_rate_key() -> Key {
     Key::from(ADDRESS.to_db_key())

crates/node/src/shell/governance.rs

@@ -158,14 +158,20 @@ where
                         GovernanceEvent::passed_proposal(id, true, result)
                     }
                     ProposalType::PGFSteward(stewards) => {
-                        let _result = execute_pgf_steward_proposal(
+                        let result = execute_pgf_steward_proposal(
                             &mut shell.state,
                             stewards,
                         )?;
                         tracing::info!(
-                            "Governance proposal (pgf stewards){} has been \
-                             executed and passed.",
-                            id
+                            "Governance proposal #{} for PGF stewards has \
+                             been executed. {}.",
+                            id,
+                            if result {
+                                "State changes have been applied successfully"
+                            } else {
+                                "FAILURE trying to apply the state changes - \
+                                 no state change occurred"
+                            }
                         );
 
                         GovernanceEvent::passed_proposal(id, false, false)
@@ -461,18 +467,41 @@ fn execute_pgf_steward_proposal<S>(
 where
     S: StorageRead + StorageWrite,
 {
-    for action in stewards {
-        match action {
-            AddRemove::Add(address) => {
-                pgf_storage::stewards_handle().insert(
-                    storage,
-                    address.to_owned(),
-                    StewardDetail::base(address),
-                )?;
-            }
-            AddRemove::Remove(address) => {
-                pgf_storage::stewards_handle().remove(storage, &address)?;
-            }
+    let maximum_number_of_pgf_steward_key =
+        pgf_storage::get_maximum_number_of_pgf_steward_key();
+    let maximum_number_of_pgf_steward = storage
+        .read::<u64>(&maximum_number_of_pgf_steward_key)?
+        .expect(
+            "Pgf parameter maximum_number_of_pgf_steward must be in storage",
+        );
+
+    // First, remove the appropriate addresses
+    for address in stewards.iter().filter_map(|action| match action {
+        AddRemove::Add(_) => None,
+        AddRemove::Remove(address) => Some(address),
+    }) {
+        pgf_storage::stewards_handle().remove(storage, address)?;
+    }
+
+    // Then add new addresses
+    let mut steward_count = pgf_storage::stewards_handle().len(storage)?;
+    for address in stewards.iter().filter_map(|action| match action {
+        AddRemove::Add(address) => Some(address),
+        AddRemove::Remove(_) => None,
+    }) {
+        #[allow(clippy::arithmetic_side_effects)]
+        if steward_count + 1 > maximum_number_of_pgf_steward {
+            return Ok(false);
+        }
+        pgf_storage::stewards_handle().insert(
+            storage,
+            address.to_owned(),
+            StewardDetail::base(address.to_owned()),
+        )?;
+
+        #[allow(clippy::arithmetic_side_effects)]
+        {
+            steward_count += 1;
         }
     }
 

genesis/localnet/parameters.toml

@@ -104,6 +104,8 @@ stewards = [
 pgf_inflation_rate = "0.1"
 # The pgf stewards inflation rate
 stewards_inflation_rate = "0.01"
+# The maximum number of pgf stewards
+maximum_number_of_stewards = 5
 
 # IBC parameters
 [ibc_params]

genesis/starter/parameters.toml

@@ -99,6 +99,8 @@ stewards = []
 pgf_inflation_rate = "0.1"
 # The pgf stewards inflation rate
 stewards_inflation_rate = "0.01"
+# The maximum number of pgf stewards
+maximum_number_of_stewards = 5
 
 # IBC parameters
 [ibc_params]