use OnceLock for BlockExtra::block

Author: RCasatta

cli/examples/signatures_in_witness.rs

@@ -33,7 +33,7 @@ fn main() -> Result<(), Box<dyn Error>> {
             );
         }
 
-        for tx in &block_extra.block().expect("block is not loaded").txdata {
+        for tx in &block_extra.block().txdata {
             for input in &tx.input {
                 for witness in input.witness.iter() {
                     if let Ok(_sig) = deserialize::<ParsedSignature>(witness) {

cli/examples/with_pipe.rs

@@ -20,7 +20,7 @@ fn main() -> Result<(), Box<dyn Error>> {
 
     for block_extra in iter {
         let txs_fee = block_extra.fee().expect("launch without `--skip-prevout`");
-        let block = block_extra.block().expect("block is not loaded");
+        let block = block_extra.block();
         let coinbase = &block.txdata[0];
         let coinbase_sum_outputs: u64 = coinbase
             .output

lib/src/block_extra.rs

@@ -9,6 +9,7 @@ use std::collections::HashMap;
 use std::convert::TryFrom;
 use std::io::{Read, Seek, SeekFrom};
 use std::ops::DerefMut;
+use std::sync::OnceLock;
 
 /// The bitcoin block and additional metadata returned by the [crate::iter()] method
 #[derive(Debug, Eq, PartialEq)]
@@ -22,7 +23,7 @@ pub struct BlockExtra {
     /// avoiding the performance costs and use visitor directly on the bytes with [`bitcoin_slices`]
     block_bytes: Vec<u8>,
 
-    block: Option<Block>,
+    block: OnceLock<Block>,
 
     /// The bitcoin block hash, same as `block.block_hash()` but result from hashing is cached
     pub(crate) block_hash: BlockHash,
@@ -77,7 +78,7 @@ impl TryFrom<FsBlock> for BlockExtra {
         Ok(BlockExtra {
             version: fs_block.serialization_version,
             block_bytes,
-            block: None,
+            block: OnceLock::new(),
             block_hash: fs_block.hash,
             size: (fs_block.end - fs_block.start) as u32,
             next: fs_block.next,
@@ -98,13 +99,10 @@ impl BlockExtra {
 
     /// Returns the block from the bytes
     ///
-    /// This is an expensive operations, re-use the results instead of calling it multiple times
-    pub fn block(&self) -> Option<&Block> {
-        self.block.as_ref()
-    }
-
-    pub fn init_block(&mut self) {
-        self.block = Some(Block::consensus_decode(&mut &self.block_bytes[..]).unwrap());
+    /// This is an expensive operation, re-use the results instead of calling it multiple times
+    pub fn block(&self) -> &Block {
+        self.block
+            .get_or_init(|| Block::consensus_decode(&mut &self.block_bytes[..]).unwrap())
     }
 
     pub fn block_bytes(&self) -> &[u8] {
@@ -180,9 +178,7 @@ impl BlockExtra {
     ///
     /// requires serializing the block bytes, consider using a visitor on the bytes for performance
     pub fn iter_tx(&self) -> impl Iterator<Item = (&Txid, &Transaction)> {
-        self.txids
-            .iter()
-            .zip(self.block().expect("block not loaded").txdata.iter())
+        self.txids.iter().zip(self.block().txdata.iter())
     }
 }
 
@@ -246,7 +242,7 @@ impl Decodable for BlockExtra {
         let mut b = BlockExtra {
             version,
             block_bytes,
-            block: None,
+            block: OnceLock::new(),
             block_hash,
             size,
             next: Decodable::consensus_decode(d)?,
@@ -325,6 +321,7 @@ pub mod test {
     use bitcoin::hashes::Hash;
     use bitcoin::{BlockHash, CompactTarget};
     use std::collections::HashMap;
+    use std::sync::OnceLock;
 
     #[test]
     fn block_extra_round_trip() {
@@ -358,7 +355,7 @@ pub mod test {
         BlockExtra {
             version: 0,
             block_bytes,
-            block: None,
+            block: OnceLock::new(),
             block_hash: BlockHash::all_zeros(),
             size,
             next: vec![BlockHash::all_zeros()],

lib/src/iter.rs

@@ -59,7 +59,7 @@ mod inner_test {
         let genesis = genesis_block(Network::Testnet);
         let mut current = genesis.clone();
         for b in iter(test_conf()).skip(1) {
-            let block = b.block().unwrap();
+            let block = b.block();
             assert_eq!(current.block_hash(), block.header.prev_blockhash);
             current = block.clone();
         }

lib/src/stages/fee.rs

@@ -55,7 +55,7 @@ impl Fee {
 
                                 let mut outpoint_values =
                                     HashMap::with_capacity(block_extra.block_total_inputs());
-                                let block = block_extra.block().expect("block is not loaded");
+                                let block = block_extra.block();
 
                                 for tx in block.txdata.iter().skip(1) {
                                     for input in tx.input.iter() {

lib/src/stages/reorder.rs

@@ -147,12 +147,11 @@ impl Reorder {
                                 while let Some(block_to_send) = blocks.remove(&next) {
                                     let mut block_extra: BlockExtra =
                                         block_to_send.try_into().unwrap();
-                                    block_extra.init_block();
                                     busy_time += now.elapsed().as_nanos();
                                     next = block_extra.next[0];
                                     block_extra.height = height;
                                     blocks.follows.remove(&block_extra.block_hash);
-                                    let block = block_extra.block().expect("block is not loaded");
+                                    let block = block_extra.block();
 
                                     blocks.blocks.remove(&block.header.prev_blockhash);
 

lib/src/utxo/db.rs

@@ -73,7 +73,7 @@ impl UtxoStore for DbUtxo {
             height, self.updated_up_to_height
         );
         if height > self.updated_up_to_height {
-            let block = block_extra.block().expect("block is not loaded");
+            let block = block_extra.block();
 
             // since we can spend outputs created in this same block, we first put outputs in memory...
             let total_outputs = block_extra.block_total_outputs();

lib/src/utxo/mem.rs

@@ -35,7 +35,7 @@ impl MemUtxo {
 
 impl UtxoStore for MemUtxo {
     fn add_outputs_get_inputs(&mut self, block_extra: &BlockExtra, _height: u32) -> Vec<TxOut> {
-        let block = block_extra.block().expect("block is not loaded");
+        let block = block_extra.block();
         for (txid, tx) in block_extra.iter_tx() {
             self.add_tx_outputs(txid, &tx);
         }

lib/src/utxo/redb.rs

@@ -58,7 +58,7 @@ impl RedbUtxo {
 
 impl UtxoStore for RedbUtxo {
     fn add_outputs_get_inputs(&mut self, block_extra: &BlockExtra, height: u32) -> Vec<TxOut> {
-        let block = block_extra.block().expect("block is not loaded");
+        let block = block_extra.block();
         // let mut outpoint_buffer = [0u8; 36]; // txid (32) + vout (4)
 
         // max script size for spendable output is 10k https://bitcoin.stackexchange.com/a/35881/6693 ...