perf: skip next block headers if they are already inserted.

benchmarks/benches.rs

@@ -146,6 +146,7 @@ fn bench_function(c: &mut Criterion<Instructions>, method: &str) {
 
 pub fn criterion_benchmark(c: &mut Criterion<Instructions>) {
     bench_function(c, "insert_block_headers");
+    bench_function(c, "insert_block_headers_multiple_times");
     bench_function(c, "insert_300_blocks");
     bench_function(c, "get_metrics");
 }

benchmarks/src/main.rs

@@ -117,6 +117,38 @@ fn insert_block_headers() -> u64 {
     })
 }
 
+// Inserts the same block headers multiple times.
+#[query]
+fn insert_block_headers_multiple_times() -> u64 {
+    ic_btc_canister::init(Config {
+        network: Network::Testnet,
+        ..Config::default()
+    });
+
+    // Compute the next block headers.
+    let next_block_headers = TESTNET_BLOCKS.with(|b| {
+        let blocks = b.borrow();
+        let mut next_block_headers = vec![];
+        for i in 0..1000 {
+            let mut block_header_blob = vec![];
+            BlockHeader::consensus_encode(blocks[i as usize].header(), &mut block_header_blob)
+                .unwrap();
+            next_block_headers.push(BlockHeaderBlob::try_from(block_header_blob).unwrap());
+        }
+
+        next_block_headers
+    });
+
+    // Benchmark inserting the block headers.
+    count_instructions(|| {
+        with_state_mut(|s| {
+            for _ in 0..10 {
+                ic_btc_canister::state::insert_next_block_headers(s, next_block_headers.as_slice());
+            }
+        });
+    })
+}
+
 // Returns the number of instructions consumed by the given function.
 fn count_instructions<R>(f: impl FnOnce() -> R) -> u64 {
     let start = ic_cdk::api::performance_counter(0);

canister/src/state.rs

@@ -198,6 +198,11 @@ pub fn insert_next_block_headers(state: &mut State, next_block_headers: &[BlockH
             }
         };
 
+        if state.unstable_blocks.has_next_block_header(&block_header) {
+            // Already processed this block header. Skip...
+            continue;
+        }
+
         let validation_result =
             match ValidationContext::new_with_next_block_headers(state, &block_header)
                 .map_err(|_| InsertBlockError::PrevHeaderNotFound)

canister/src/unstable_blocks.rs

@@ -112,6 +112,13 @@ impl UnstableBlocks {
         Ok(())
     }
 
+    /// Returns true if the given block header is already stored as one of the next block headers.
+    pub fn has_next_block_header(&self, block_header: &BlockHeader) -> bool {
+        self.next_block_headers
+            .get_header(&BlockHash::from(block_header.block_hash()))
+            .is_some()
+    }
+
     // Public only for testing purpose.
     pub(crate) fn next_block_headers_max_height(&self) -> Option<Height> {
         self.next_block_headers.get_max_height()