Remove support for stake redelegation (#7995) (#8024)

automerge

book/src/cluster/stake-delegation-and-rewards.md

@@ -94,12 +94,13 @@ The Stakes and the RewardsPool are accounts that are owned by the same `Stake` p
 
 ### StakeInstruction::DelegateStake
 
-The Stake account is moved from Ininitialized to StakeState::Stake form. This is how stakers choose their initial delegate validator node and activate their stake account lamports. The transaction must be signed by the stake's `authorized_staker`.  If the stake account is already StakeState::Stake \(i.e. already activated\), the stake is re-delegated.  Stakes may be re-delegated at any time, and updated stakes are reflected immediately, but only one re-delegation is permitted per epoch.
+The Stake account is moved from Initialized to StakeState::Stake form, or from a deactivated (i.e. fully cooled-down) StakeState::Stake to activated StakeState::Stake. This is how stakers choose the vote account and validator node to which their stake account lamports are delegated. The transaction must be signed by the stake's `authorized_staker`.
 
 * `account[0]` - RW - The StakeState::Stake instance.  `StakeState::Stake::credits_observed` is initialized to `VoteState::credits`,  `StakeState::Stake::voter_pubkey` is initialized to `account[1]`.  If this is the initial delegation of stake, `StakeState::Stake::stake` is initialized to the account's balance in lamports,  `StakeState::Stake::activated` is initialized to the current Bank epoch, and  `StakeState::Stake::deactivated` is initialized to std::u64::MAX
 * `account[1]` - R - The VoteState instance.
 * `account[2]` - R - sysvar::clock account, carries information about current Bank epoch
-* `account[3]` - R - stake::Config accoount, carries warmup, cooldown, and slashing configuration
+* `account[3]` - R - sysvar::stakehistory account, carries information about stake history
+* `account[4]` - R - stake::Config accoount, carries warmup, cooldown, and slashing configuration
 
 ### StakeInstruction::Authorize\(Pubkey, StakeAuthorize\)
 

programs/stake/src/stake_instruction.rs

@@ -306,6 +306,7 @@ pub fn delegate_stake(
         AccountMeta::new(*stake_pubkey, false),
         AccountMeta::new_readonly(*vote_pubkey, false),
         AccountMeta::new_readonly(sysvar::clock::id(), false),
+        AccountMeta::new_readonly(sysvar::stake_history::id(), false),
         AccountMeta::new_readonly(crate::config::id(), false),
     ]
     .with_signer(authorized_pubkey);
@@ -396,9 +397,10 @@ pub fn process_instruction(
         StakeInstruction::DelegateStake => {
             let vote = next_keyed_account(keyed_accounts)?;
 
-            me.delegate_stake(
+            me.delegate(
                 &vote,
                 &Clock::from_keyed_account(next_keyed_account(keyed_accounts)?)?,
+                &StakeHistory::from_keyed_account(next_keyed_account(keyed_accounts)?)?,
                 &config::from_keyed_account(next_keyed_account(keyed_accounts)?)?,
                 &signers,
             )
@@ -418,7 +420,7 @@ pub fn process_instruction(
                 &signers,
             )
         }
-        StakeInstruction::Deactivate => me.deactivate_stake(
+        StakeInstruction::Deactivate => me.deactivate(
             &Clock::from_keyed_account(next_keyed_account(keyed_accounts)?)?,
             &signers,
         ),
@@ -658,6 +660,13 @@ mod tests {
                         false,
                         &RefCell::new(sysvar::clock::Clock::default().create_account(1))
                     ),
+                    KeyedAccount::new(
+                        &sysvar::stake_history::id(),
+                        false,
+                        &RefCell::new(
+                            sysvar::stake_history::StakeHistory::default().create_account(1)
+                        )
+                    ),
                     KeyedAccount::new(
                         &config::id(),
                         false,