perf: use Vec::with_capacity and reserve_exact (#11904)

crates/evm/execution-types/src/chain.rs

@@ -228,11 +228,11 @@ impl Chain {
     ///
     /// Attachment includes block number, block hash, transaction hash and transaction index.
     pub fn receipts_with_attachment(&self) -> Vec<BlockReceipts> {
-        let mut receipt_attach = Vec::new();
+        let mut receipt_attach = Vec::with_capacity(self.blocks().len());
         for ((block_num, block), receipts) in
             self.blocks().iter().zip(self.execution_outcome.receipts().iter())
         {
-            let mut tx_receipts = Vec::new();
+            let mut tx_receipts = Vec::with_capacity(receipts.len());
             for (tx, receipt) in block.body.transactions().zip(receipts.iter()) {
                 tx_receipts.push((
                     tx.hash(),

crates/net/discv4/src/lib.rs

@@ -2324,9 +2324,9 @@ mod tests {
         let original = EnrForkIdEntry {
             fork_id: ForkId { hash: ForkHash([0xdc, 0xe9, 0x6c, 0x2d]), next: 0 },
         };
-        let mut encoded = Vec::new();
-        original.encode(&mut encoded);
         let expected: [u8; 8] = [0xc7, 0xc6, 0x84, 0xdc, 0xe9, 0x6c, 0x2d, 0x80];
+        let mut encoded = Vec::with_capacity(expected.len());
+        original.encode(&mut encoded);
         assert_eq!(&expected[..], encoded.as_slice());
     }
 

crates/rpc/rpc-eth-types/src/fee_history.rs

@@ -305,7 +305,7 @@ pub fn calculate_reward_percentiles_for_block(
     // the percentiles are monotonically increasing.
     let mut tx_index = 0;
     let mut cumulative_gas_used = transactions.first().map(|tx| tx.gas_used).unwrap_or_default();
-    let mut rewards_in_block = Vec::new();
+    let mut rewards_in_block = Vec::with_capacity(percentiles.len());
     for percentile in percentiles {
         // Empty blocks should return in a zero row
         if transactions.is_empty() {

crates/rpc/rpc-eth-types/src/simulate.rs

@@ -183,7 +183,7 @@ pub fn build_block<T: TransactionCompat>(
 ) -> Result<SimulatedBlock<Block<T::Transaction>>, EthApiError> {
     let mut calls: Vec<SimCallResult> = Vec::with_capacity(results.len());
     let mut senders = Vec::with_capacity(results.len());
-    let mut receipts = Vec::new();
+    let mut receipts = Vec::with_capacity(results.len());
 
     let mut log_index = 0;
     for (transaction_index, ((sender, result), tx)) in

crates/rpc/rpc/src/eth/core.rs

@@ -421,8 +421,8 @@ mod tests {
         let mut rng = generators::rng();
 
         // Build mock data
-        let mut gas_used_ratios = Vec::new();
-        let mut base_fees_per_gas = Vec::new();
+        let mut gas_used_ratios = Vec::with_capacity(block_count as usize);
+        let mut base_fees_per_gas = Vec::with_capacity(block_count as usize);
         let mut last_header = None;
         let mut parent_hash = B256::default();
 
@@ -444,8 +444,9 @@ mod tests {
             last_header = Some(header.clone());
             parent_hash = hash;
 
-            let mut transactions = vec![];
-            for _ in 0..100 {
+            const TOTAL_TRANSACTIONS: usize = 100;
+            let mut transactions = Vec::with_capacity(TOTAL_TRANSACTIONS);
+            for _ in 0..TOTAL_TRANSACTIONS {
                 let random_fee: u128 = rng.gen();
 
                 if let Some(base_fee_per_gas) = header.base_fee_per_gas {

crates/rpc/rpc/src/eth/helpers/signer.rs

@@ -40,7 +40,7 @@ impl DevSigner {
     /// Generates provided number of random dev signers
     /// which satisfy [`EthSigner`] trait
     pub fn random_signers(num: u32) -> Vec<Box<dyn EthSigner + 'static>> {
-        let mut signers = Vec::new();
+        let mut signers = Vec::with_capacity(num as usize);
         for _ in 0..num {
             let sk = PrivateKeySigner::random_with(&mut rand::thread_rng());
 

crates/stages/api/src/pipeline/builder.rs

@@ -34,7 +34,9 @@ impl<Provider> PipelineBuilder<Provider> {
     /// [`builder`][StageSet::builder] on the set which will convert it to a
     /// [`StageSetBuilder`][crate::StageSetBuilder].
     pub fn add_stages<Set: StageSet<Provider>>(mut self, set: Set) -> Self {
-        for stage in set.builder().build() {
+        let states = set.builder().build();
+        self.stages.reserve_exact(states.len());
+        for stage in states {
             self.stages.push(stage);
         }
         self

crates/stages/stages/src/stages/bodies.rs

@@ -917,7 +917,8 @@ mod tests {
                     return Poll::Ready(None)
                 }
 
-                let mut response = Vec::default();
+                let mut response =
+                    Vec::with_capacity(std::cmp::min(this.headers.len(), this.batch_size as usize));
                 while let Some(header) = this.headers.pop_front() {
                     if header.is_empty() {
                         response.push(BlockResponse::Empty(header))

crates/storage/codecs/src/lib.rs

@@ -505,7 +505,7 @@ mod tests {
 
     #[test]
     fn compact_address() {
-        let mut buf = vec![];
+        let mut buf = Vec::with_capacity(21);
         assert_eq!(Address::ZERO.to_compact(&mut buf), 20);
         assert_eq!(buf, vec![0; 20]);
 

crates/storage/nippy-jar/src/compression/zstd.rs

@@ -213,7 +213,7 @@ impl Compression for Zstd {
             return Err(NippyJarError::ColumnLenMismatch(self.columns, columns.len()))
         }
 
-        let mut dictionaries = vec![];
+        let mut dictionaries = Vec::with_capacity(columns.len());
         for column in columns {
             // ZSTD requires all training data to be continuous in memory, alongside the size of
             // each entry

crates/storage/provider/src/providers/static_file/manager.rs

@@ -1364,13 +1364,13 @@ impl TransactionsProviderExt for StaticFileProvider {
         // chunks are too big, there will be idle threads waiting for work. Choosing an
         // arbitrary smaller value to make sure it doesn't happen.
         let chunk_size = 100;
-        let mut channels = Vec::new();
 
         // iterator over the chunks
         let chunks = tx_range
             .clone()
             .step_by(chunk_size)
             .map(|start| start..std::cmp::min(start + chunk_size as u64, tx_range.end));
+        let mut channels = Vec::with_capacity(tx_range_size.div_ceil(chunk_size));
 
         for chunk_range in chunks {
             let (channel_tx, channel_rx) = mpsc::channel();

crates/transaction-pool/benches/truncate.rs

@@ -66,7 +66,7 @@ fn generate_many_transactions(senders: usize, max_depth: usize) -> Vec<MockTrans
     let rng = TestRng::from_seed(RngAlgorithm::ChaCha, &SEED);
     let mut runner = TestRunner::new_with_rng(config, rng);
 
-    let mut txs = Vec::new();
+    let mut txs = Vec::with_capacity(senders);
     for idx in 0..senders {
         // modulo max_depth so we know it is bounded, plus one so the minimum is always 1
         let depth = any::<usize>().new_tree(&mut runner).unwrap().current() % max_depth + 1;

examples/beacon-api-sidecar-fetcher/src/mined_sidecar.rs

@@ -109,6 +109,7 @@ where
 
         match self.pool.get_all_blobs_exact(txs.iter().map(|(tx, _)| tx.hash()).collect()) {
             Ok(blobs) => {
+                actions_to_queue.reserve_exact(txs.len());
                 for ((tx, _), sidecar) in txs.iter().zip(blobs.iter()) {
                     let transaction = BlobTransaction::try_from_signed(tx.clone(), sidecar.clone())
                         .expect("should not fail to convert blob tx if it is already eip4844");