Make StakeDelegations clone-on-write #21542
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brooksprumo
commented
Dec 1, 2021
Comment on lines
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| /// current stake delegations for this bank | ||
| pub fn cloned_stake_delegations(&self) -> HashMap<Pubkey, Delegation> { | ||
| self.stakes.read().unwrap().stake_delegations().clone() | ||
| } | ||
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This function was only called by the bank tests, so I've moved it into the test module. Originally I only needed to change the return type (to StakeDelegations), but saw I could also move the fn.
runtime/src/stake_delegations.rs
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| /// A map of pubkey-to-stake-delegation with clone-on-write semantics | ||
| #[derive(Default, Clone, PartialEq, Debug, Deserialize, Serialize)] | ||
| pub struct StakeDelegations(Arc<StakeDelegationsInner>); |
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The inner map needs to be wrapped in an Arc due to it being passed between threads. Found this out from the compiler while building an earlier version with Rc.
@jstarry Using Rc (or Arc) answers the questions we were having yesterday about Rust and lifetimes, vs just using Cow.
| @@ -27,7 +30,7 @@ pub struct Stakes { | |||
| vote_accounts: VoteAccounts, | |||
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| /// stake_delegations | |||
| stake_delegations: HashMap<Pubkey, Delegation>, | |||
| stake_delegations: StakeDelegations, | |||
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Pretty nice! Basically no other changes needed.
Codecov Report
@@ Coverage Diff @@
## master #21542 +/- ##
=======================================
Coverage 81.5% 81.5%
=======================================
Files 506 507 +1
Lines 142216 142251 +35
=======================================
+ Hits 116024 116071 +47
+ Misses 26192 26180 -12 |
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Problem
Stake delegations are cloned into every bank, regardless if they are changed or not.
Summary of Changes
Implement clone-on-write semantics for stake delegations.