perf(rpc): fetch range of blocks and return empty if unchanged

crates/rpc/rpc/src/eth/filter.rs

@@ -71,13 +71,20 @@ where
         let info = self.inner.provider.chain_info()?;
         let best_number = info.best_number;
 
+        // start_block is the block from which we should start fetching changes, the next block from
+        // the last time changes were polled, in other words the best block at last poll + 1
         let (start_block, kind) = {
             let mut filters = self.inner.active_filters.inner.lock().await;
             let filter = filters.get_mut(&id).ok_or(FilterError::FilterNotFound(id))?;
 
+            if filter.block > best_number {
+                // no new blocks since the last poll
+                return Ok(FilterChanges::Empty)
+            }
+
             // update filter
             // we fetch all changes from [filter.block..best_block], so we advance the filter's
-            // block to `best_block +1`
+            // block to `best_block +1`, the next from which we should start fetching changes again
             let mut block = best_number + 1;
             std::mem::swap(&mut filter.block, &mut block);
             filter.last_poll_timestamp = Instant::now();
@@ -90,15 +97,14 @@ where
                 Err(EthApiError::Unsupported("pending transaction filter not supported").into())
             }
             FilterKind::Block => {
-                let mut block_hashes = Vec::new();
-                for block_num in start_block..best_number {
-                    let block_hash = self
-                        .inner
-                        .provider
-                        .block_hash(block_num)?
-                        .ok_or(EthApiError::UnknownBlockNumber)?;
-                    block_hashes.push(block_hash);
-                }
+                // Note: we need to fetch the block hashes from inclusive range
+                // [start_block..best_block]
+                let end_block = best_number + 1;
+                let block_hashes = self
+                    .inner
+                    .provider
+                    .canonical_hashes_range(start_block, end_block)
+                    .map_err(|_| EthApiError::UnknownBlockNumber)?;
                 Ok(FilterChanges::Hashes(block_hashes))
             }
             FilterKind::Log(filter) => {
@@ -117,6 +123,7 @@ where
                     FilterBlockOption::AtBlockHash(_) => {
                         // blockHash is equivalent to fromBlock = toBlock = the block number with
                         // hash blockHash
+                        // get_logs_in_block_range is inclusive
                         (start_block, best_number)
                     }
                 };

crates/storage/provider/src/traits/block_hash.rs

@@ -19,5 +19,9 @@ pub trait BlockHashReader: Send + Sync {
     }
 
     /// Get headers in range of block hashes or numbers
+    ///
+    /// Returns the available hashes of that range.
+    ///
+    /// Note: The range is `start..end`, so the expected result is `[start..end)`
     fn canonical_hashes_range(&self, start: BlockNumber, end: BlockNumber) -> Result<Vec<H256>>;
 }