perf(state): Cache the block hash cometbft#2924 (#30) (#34)

* perf(state): Cache the block hash (backport cometbft#2924) (cometbft#2932)

Closes cometbft#2923

Caches the block hash to ensure we only compute it once in consensus
execution.

---

#### PR checklist

- [x] Tests written/updated - not sure what test I should write, any
suggestions?
- [x] Changelog entry added in `.changelog` (we use
[unclog](https://github.com/informalsystems/unclog) to manage our
changelog)
- [ ] Updated relevant documentation (`docs/` or `spec/`) and code
comments
- [x] Title follows the [Conventional
Commits](https://www.conventionalcommits.org/en/v1.0.0/) spec
<hr>This is an automatic backport of pull request cometbft#2924 done by
[Mergify](https://mergify.com).

---------

Co-authored-by: Dev Ojha <[email protected]>
Co-authored-by: Anton Kaliaev <[email protected]>

* delete md

* changelog

* changelog

---------

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
Co-authored-by: Dev Ojha <[email protected]>
Co-authored-by: Anton Kaliaev <[email protected]>
(cherry picked from commit 7cbbf31)

Co-authored-by: Adam Tucker <[email protected]>

CHANGELOG.md

@@ -2,9 +2,12 @@
 
 ## Unreleased
 
+## v0.37.4-v24-osmo-4
+
 * [#27](https://github.com/osmosis-labs/cometbft/pull/27) Lower allocation overhead of txIndex matchRange
 * [#28](https://github.com/osmosis-labs/cometbft/pull/28) Significantly speedup bitArray.PickRandom
 * [#29](https://github.com/osmosis-labs/cometbft/pull/29) Lower heap overhead of JSON encoding
+* [#30](https://github.com/osmosis-labs/cometbft/pull/30) Cache the block hash
 
 ## v0.37.4-v24-osmo-3
 

types/block.go

@@ -43,10 +43,11 @@ const (
 type Block struct {
 	mtx cmtsync.Mutex
 
-	Header     `json:"header"`
-	Data       `json:"data"`
-	Evidence   EvidenceData `json:"evidence"`
-	LastCommit *Commit      `json:"last_commit"`
+	verifiedHash cmtbytes.HexBytes // Verified block hash (not included in the struct hash)
+	Header       `json:"header"`
+	Data         `json:"data"`
+	Evidence     EvidenceData `json:"evidence"`
+	LastCommit   *Commit      `json:"last_commit"`
 }
 
 // ValidateBasic performs basic validation that doesn't involve state data.
@@ -130,8 +131,13 @@ func (b *Block) Hash() cmtbytes.HexBytes {
 	if b.LastCommit == nil {
 		return nil
 	}
+	if b.verifiedHash != nil {
+		return b.verifiedHash
+	}
 	b.fillHeader()
-	return b.Header.Hash()
+	hash := b.Header.Hash()
+	b.verifiedHash = hash
+	return hash
 }
 
 // MakePartSet returns a PartSet containing parts of a serialized block.