[perf]: backport changes from thunder perf hackathon (#68)

* [perf]: backport changes from thunder perf hackathon

* [misc] Fix std dep order, add comments

* [cli] remove mimalloc from cli

* [fix] smallvec usage

* [misc] Add comments for LMDB flags

* [fix] Switch to Borsh and add small test for OutpointKey

* [fix] make in/out tracking explicit as per suggestion

* [fix] Adjust import ordering

* [fix] clarify counts() use, rm into_parts() and explicit deconstruct

* [fix] explicit From

Author: giaki3003

lib/state/block.rs

@@ -563,14 +563,13 @@ pub fn disconnect_tip(
             .try_for_each(|(outpoint, utxo_hash)| {
                 let key = OutPointKey::from(outpoint);
                 if let Some(spent_output) =
-                    state.stxos.try_get(rwtxn, &key).map_err(DbError::from)?
+                    state.stxos.try_get(rwtxn, &key)?
                 {
                     accumulator_diff.insert(utxo_hash.into());
-                    state.stxos.delete(rwtxn, &key).map_err(DbError::from)?;
+                    state.stxos.delete(rwtxn, &key)?;
                     state
                         .utxos
-                        .put(rwtxn, &key, &spent_output.output)
-                        .map_err(DbError::from)?;
+                        .put(rwtxn, &key, &spent_output.output)?;
                     Ok(())
                 } else {
                     Err(Error::NoStxo {

lib/state/mod.rs

@@ -43,7 +43,8 @@ pub struct PrevalidatedBlock {
     pub computed_merkle_root: MerkleRoot,
     pub total_fees: bitcoin::Amount,
     pub coinbase_value: bitcoin::Amount,
-    pub next_height: u32, // Precomputed next height to avoid DB read in write txn
+    /// Precomputed next height to avoid DB read in write txn
+    pub next_height: u32,
     pub accumulator_diff: crate::types::AccumulatorDiff,
 }