Remove needless weight data from Validator

In randomized leader election environment, CodeChain doesn't need
to manage weight values. Previously, it is utilized to guarantee
stake-proportional leader election but now the property comes from
the nature of the probability model.

Author: HoOngEe

core/src/consensus/stake/action_data.rs

@@ -236,7 +236,6 @@ impl<'a> Delegation<'a> {
 
 #[derive(Clone, Copy, Debug, Eq, Ord, PartialEq, PartialOrd, RlpDecodable, RlpEncodable)]
 pub struct Validator {
-    weight: StakeQuantity,
     delegation: StakeQuantity,
     deposit: Deposit,
     pubkey: Public,
@@ -245,7 +244,6 @@ pub struct Validator {
 impl Validator {
     pub fn new_for_test(delegation: StakeQuantity, deposit: Deposit, pubkey: Public) -> Self {
         Self {
-            weight: delegation,
             delegation,
             deposit,
             pubkey,
@@ -254,17 +252,12 @@ impl Validator {
 
     fn new(delegation: StakeQuantity, deposit: Deposit, pubkey: Public) -> Self {
         Self {
-            weight: delegation,
             delegation,
             deposit,
             pubkey,
         }
     }
 
-    fn reset(&mut self) {
-        self.weight = self.delegation;
-    }
-
     pub fn pubkey(&self) -> &Public {
         &self.pubkey
     }
@@ -345,28 +338,6 @@ impl Validators {
         Ok(())
     }
 
-    pub fn update_weight(&mut self, block_author: &Address) {
-        let min_delegation = self.min_delegation();
-        for Validator {
-            weight,
-            pubkey,
-            ..
-        } in self.0.iter_mut().rev()
-        {
-            if public_to_address(pubkey) == *block_author {
-                // block author
-                *weight = weight.saturating_sub(min_delegation);
-                break
-            }
-            // neglecting validators
-            *weight = weight.saturating_sub(min_delegation * 2);
-        }
-        if self.0.iter().all(|validator| validator.weight == 0) {
-            self.0.iter_mut().for_each(Validator::reset);
-        }
-        self.0.sort_unstable();
-    }
-
     pub fn remove(&mut self, target: &Address) {
         self.0.retain(
             |Validator {
@@ -379,10 +350,6 @@ impl Validators {
     pub fn delegation(&self, pubkey: &Public) -> Option<StakeQuantity> {
         self.0.iter().find(|validator| validator.pubkey == *pubkey).map(|&validator| validator.delegation)
     }
-
-    fn min_delegation(&self) -> StakeQuantity {
-        self.0.iter().map(|&validator| validator.delegation).min().expect("There must be at least one validators")
-    }
 }
 
 impl Deref for Validators {
@@ -1758,7 +1725,6 @@ mod tests {
                     pubkey: *pubkey,
                     deposit: 0,
                     delegation: 0,
-                    weight: 0,
                 })
                 .collect(),
         );

core/src/consensus/stake/mod.rs

@@ -341,12 +341,6 @@ pub fn move_current_to_previous_intermediate_rewards(state: &mut TopLevelState)
     rewards.save_to_state(state)
 }
 
-pub fn update_validator_weights(state: &mut TopLevelState, block_author: &Address) -> StateResult<()> {
-    let mut validators = Validators::load_from_state(state)?;
-    validators.update_weight(block_author);
-    validators.save_to_state(state)
-}
-
 fn change_params(
     state: &mut TopLevelState,
     metadata_seq: u64,

core/src/consensus/tendermint/engine.rs

@@ -184,7 +184,6 @@ impl ConsensusEngine for Tendermint {
                 self.machine.add_balance(block, &author, block_author_reward)?;
             }
             _ => {
-                stake::update_validator_weights(block.state_mut(), &author)?;
                 stake::add_intermediate_rewards(block.state_mut(), author, block_author_reward)?;
             }
         }