Fix significant drop in match scrutinee

rust-lang/rust#93883
ZcashFoundation · Jun 7, 2022 · 3b895cd · 3b895cd
1 parent 00aa64a
commit 3b895cd
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Showing 4 changed files with 15 additions and 6 deletions.
diff --git a/zebra-chain/src/orchard/tree.rs b/zebra-chain/src/orchard/tree.rs
@@ -335,7 +335,8 @@ impl NoteCommitmentTree {
  .cached_root
  .write()
  .expect("a thread that previously held exclusive lock access panicked");
- match *write_root {
+ let read_root = write_root.as_ref().cloned();
+ match read_root {
  // Another thread got write access first, return cached root.
  Some(root) => root,
  None => {

diff --git a/zebra-chain/src/sapling/tree.rs b/zebra-chain/src/sapling/tree.rs
@@ -340,7 +340,8 @@ impl NoteCommitmentTree {
  .cached_root
  .write()
  .expect("a thread that previously held exclusive lock access panicked");
- match *write_root {
+ let read_root = write_root.as_ref().cloned();
+ match read_root {
  // Another thread got write access first, return cached root.
  Some(root) => root,
  None => {

diff --git a/zebra-chain/src/sprout/tree.rs b/zebra-chain/src/sprout/tree.rs
@@ -274,7 +274,8 @@ impl NoteCommitmentTree {
  .cached_root
  .write()
  .expect("a thread that previously held exclusive lock access panicked");
- match *write_root {
+ let read_root = write_root.as_ref().cloned();
+ match read_root {
  // Another thread got write access first, return cached root.
  Some(root) => root,
  None => {

diff --git a/zebra-state/src/service/chain_tip.rs b/zebra-state/src/service/chain_tip.rs
@@ -195,12 +195,18 @@ impl ChainTipSender {
  // a read-lock being created and living beyond the `self.sender.send(..)` call. If that
  // happens, the `send` method will attempt to obtain a write-lock and will dead-lock.
  // Without the binding, the guard is dropped at the end of the expression.
- let needs_update = match (new_tip.as_ref(), self.sender.borrow().as_ref()) {
+ let active_hash = self
+ .sender
+ .borrow()
+ .as_ref()
+ .map(|active_value| active_value.hash);
+
+ let needs_update = match (new_tip.as_ref(), active_hash) {
  // since the blocks have been contextually validated,
  // we know their hashes cover all the block data
- (Some(new_tip), Some(active_value)) => new_tip.hash != active_value.hash,
+ (Some(new_tip), Some(active_hash)) => new_tip.hash != active_hash,
  (Some(_new_tip), None) => true,
- (None, _active_value) => false,
+ (None, _active_value_hash) => false,
  };
 
  if needs_update {