Make max Stream Capacity Configurable

src/block_range_scanner.rs

@@ -93,7 +93,7 @@ pub const DEFAULT_MAX_BLOCK_RANGE: u64 = 1000;
 // copied form https://github.com/taikoxyz/taiko-mono/blob/f4b3a0e830e42e2fee54829326389709dd422098/packages/taiko-client/pkg/chain_iterator/block_batch_iterator.go#L19
 pub const DEFAULT_BLOCK_CONFIRMATIONS: u64 = 0;
 
-pub const MAX_BUFFERED_MESSAGES: usize = 50000;
+pub const DEFAULT_STREAM_BUFFER_CAPACITY: usize = 50000;
 
 // Maximum amount of reorged blocks on Ethereum (after this amount of block confirmations, a block
 // is considered final)
@@ -121,10 +121,11 @@ impl IntoScannerResult<RangeInclusive<BlockNumber>> for RangeInclusive<BlockNumb
     }
 }
 
-#[derive(Clone, Debug)]
+#[derive(Clone)]
 pub struct BlockRangeScanner {
     pub max_block_range: u64,
     pub past_blocks_storage_capacity: RingBufferCapacity,
+    pub buffer_capacity: usize,
 }
 
 impl Default for BlockRangeScanner {
@@ -139,6 +140,7 @@ impl BlockRangeScanner {
         Self {
             max_block_range: DEFAULT_MAX_BLOCK_RANGE,
             past_blocks_storage_capacity: RingBufferCapacity::Limited(10),
+            buffer_capacity: DEFAULT_STREAM_BUFFER_CAPACITY,
         }
     }
 
@@ -157,6 +159,12 @@ impl BlockRangeScanner {
         self
     }
 
+    #[must_use]
+    pub fn buffer_capacity(mut self, buffer_capacity: usize) -> Self {
+        self.buffer_capacity = buffer_capacity;
+        self
+    }
+
     /// Connects to an existing provider
     ///
     /// # Errors
@@ -166,20 +174,27 @@ impl BlockRangeScanner {
         self,
         provider: impl IntoRobustProvider<N>,
     ) -> Result<ConnectedBlockRangeScanner<N>, ScannerError> {
+        if self.max_block_range == 0 {
+            return Err(ScannerError::InvalidMaxBlockRange);
+        }
+        if self.buffer_capacity == 0 {
+            return Err(ScannerError::InvalidBufferCapacity);
+        }
         let provider = provider.into_robust_provider().await?;
         Ok(ConnectedBlockRangeScanner {
             provider,
             max_block_range: self.max_block_range,
             past_blocks_storage_capacity: self.past_blocks_storage_capacity,
+            buffer_capacity: self.buffer_capacity,
         })
     }
 }
 
-#[derive(Debug)]
 pub struct ConnectedBlockRangeScanner<N: Network> {
     provider: RobustProvider<N>,
     max_block_range: u64,
     past_blocks_storage_capacity: RingBufferCapacity,
+    buffer_capacity: usize,
 }
 
 impl<N: Network> ConnectedBlockRangeScanner<N> {
@@ -189,6 +204,12 @@ impl<N: Network> ConnectedBlockRangeScanner<N> {
         &self.provider
     }
 
+    /// Returns the stream buffer capacity.
+    #[must_use]
+    pub fn buffer_capacity(&self) -> usize {
+        self.buffer_capacity
+    }
+
     /// Starts the subscription service and returns a client for sending commands.
     ///
     /// # Errors
@@ -203,7 +224,7 @@ impl<N: Network> ConnectedBlockRangeScanner<N> {
         tokio::spawn(async move {
             service.run().await;
         });
-        Ok(BlockRangeScannerClient::new(cmd_tx))
+        Ok(BlockRangeScannerClient::new(cmd_tx, self.buffer_capacity))
     }
 }
 
@@ -585,6 +606,7 @@ impl<N: Network> Service<N> {
 
 pub struct BlockRangeScannerClient {
     command_sender: mpsc::Sender<Command>,
+    buffer_capacity: usize,
 }
 
 impl BlockRangeScannerClient {
@@ -593,9 +615,10 @@ impl BlockRangeScannerClient {
     /// # Arguments
     ///
     /// * `command_sender` - The sender for sending commands to the subscription service.
+    /// * `buffer_capacity` - The capacity for buffering messages in the stream.
     #[must_use]
-    pub fn new(command_sender: mpsc::Sender<Command>) -> Self {
-        Self { command_sender }
+    pub fn new(command_sender: mpsc::Sender<Command>, buffer_capacity: usize) -> Self {
+        Self { command_sender, buffer_capacity }
     }
 
     /// Streams live blocks starting from the latest block.
@@ -611,7 +634,7 @@ impl BlockRangeScannerClient {
         &self,
         block_confirmations: u64,
     ) -> Result<ReceiverStream<BlockScannerResult>, ScannerError> {
-        let (blocks_sender, blocks_receiver) = mpsc::channel(MAX_BUFFERED_MESSAGES);
+        let (blocks_sender, blocks_receiver) = mpsc::channel(self.buffer_capacity);
         let (response_tx, response_rx) = oneshot::channel();
 
         let command = Command::StreamLive {
@@ -642,7 +665,7 @@ impl BlockRangeScannerClient {
         start_id: impl Into<BlockId>,
         end_id: impl Into<BlockId>,
     ) -> Result<ReceiverStream<BlockScannerResult>, ScannerError> {
-        let (blocks_sender, blocks_receiver) = mpsc::channel(MAX_BUFFERED_MESSAGES);
+        let (blocks_sender, blocks_receiver) = mpsc::channel(self.buffer_capacity);
         let (response_tx, response_rx) = oneshot::channel();
 
         let command = Command::StreamHistorical {
@@ -674,7 +697,7 @@ impl BlockRangeScannerClient {
         start_id: impl Into<BlockId>,
         block_confirmations: u64,
     ) -> Result<ReceiverStream<BlockScannerResult>, ScannerError> {
-        let (blocks_sender, blocks_receiver) = mpsc::channel(MAX_BUFFERED_MESSAGES);
+        let (blocks_sender, blocks_receiver) = mpsc::channel(self.buffer_capacity);
         let (response_tx, response_rx) = oneshot::channel();
 
         let command = Command::StreamFrom {
@@ -733,7 +756,7 @@ impl BlockRangeScannerClient {
         start_id: impl Into<BlockId>,
         end_id: impl Into<BlockId>,
     ) -> Result<ReceiverStream<BlockScannerResult>, ScannerError> {
-        let (blocks_sender, blocks_receiver) = mpsc::channel(MAX_BUFFERED_MESSAGES);
+        let (blocks_sender, blocks_receiver) = mpsc::channel(self.buffer_capacity);
         let (response_tx, response_rx) = oneshot::channel();
 
         let command = Command::Rewind {
@@ -754,23 +777,28 @@ impl BlockRangeScannerClient {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use alloy::eips::{BlockId, BlockNumberOrTag};
+    use alloy::{
+        eips::{BlockId, BlockNumberOrTag},
+        network::Ethereum,
+        providers::{RootProvider, mock::Asserter},
+        rpc::client::RpcClient,
+    };
     use tokio::sync::mpsc;
 
     #[test]
     fn block_range_scanner_defaults_match_constants() {
         let scanner = BlockRangeScanner::new();
 
         assert_eq!(scanner.max_block_range, DEFAULT_MAX_BLOCK_RANGE);
+        assert_eq!(scanner.buffer_capacity, DEFAULT_STREAM_BUFFER_CAPACITY);
     }
 
     #[test]
     fn builder_methods_update_configuration() {
-        let max_block_range = 42;
+        let scanner = BlockRangeScanner::new().max_block_range(42).buffer_capacity(33);
 
-        let scanner = BlockRangeScanner::new().max_block_range(max_block_range);
-
-        assert_eq!(scanner.max_block_range, max_block_range);
+        assert_eq!(scanner.max_block_range, 42);
+        assert_eq!(scanner.buffer_capacity, 33);
     }
 
     #[tokio::test]
@@ -784,4 +812,20 @@ mod tests {
             Some(Err(ScannerError::BlockNotFound(BlockId::Number(BlockNumberOrTag::Number(4)))))
         ));
     }
+
+    #[tokio::test]
+    async fn returns_error_with_zero_buffer_capacity() {
+        let provider = RootProvider::<Ethereum>::new(RpcClient::mocked(Asserter::new()));
+        let result = BlockRangeScanner::new().buffer_capacity(0).connect(provider).await;
+
+        assert!(matches!(result, Err(ScannerError::InvalidBufferCapacity)));
+    }
+
+    #[tokio::test]
+    async fn returns_error_with_zero_max_block_range() {
+        let provider = RootProvider::<Ethereum>::new(RpcClient::mocked(Asserter::new()));
+        let result = BlockRangeScanner::new().max_block_range(0).connect(provider).await;
+
+        assert!(matches!(result, Err(ScannerError::InvalidMaxBlockRange)));
+    }
 }

src/block_range_scanner/reorg_handler.rs

@@ -14,7 +14,7 @@ use crate::{
 
 use super::ring_buffer::RingBuffer;
 
-#[derive(Clone, Debug)]
+#[derive(Clone)]
 pub(crate) struct ReorgHandler<N: Network = Ethereum> {
     provider: RobustProvider<N>,
     buffer: RingBuffer<BlockHash>,

src/block_range_scanner/ring_buffer.rs

@@ -20,7 +20,7 @@ macro_rules! impl_from_unsigned {
 
 impl_from_unsigned!(RingBufferCapacity; u8, u16, u32, usize);
 
-#[derive(Clone, Debug)]
+#[derive(Clone)]
 pub(crate) struct RingBuffer<T> {
     inner: VecDeque<T>,
     capacity: RingBufferCapacity,

src/block_range_scanner/sync_handler.rs

@@ -12,15 +12,13 @@ use crate::{
 };
 
 /// Represents the initial state when starting a sync operation
-#[derive(Debug)]
 enum SyncState {
     /// Start block is already at or beyond the confirmed tip - go straight to live
     AlreadyLive { start_block: BlockNumber },
     /// Start block is behind - need to catch up first, then go live
     NeedsCatchup { start_block: BlockNumber, confirmed_tip: BlockNumber },
 }
 
-#[derive(Debug)]
 pub(crate) struct SyncHandler<N: Network> {
     provider: RobustProvider<N>,
     max_block_range: u64,

src/error.rs

@@ -31,6 +31,9 @@ pub enum ScannerError {
     #[error("Max block range must be greater than 0")]
     InvalidMaxBlockRange,
 
+    #[error("Stream buffer capacity must be greater than 0")]
+    InvalidBufferCapacity,
+
     #[error("Max concurrent fetches must be greater than 0")]
     InvalidMaxConcurrentFetches,
 

src/event_scanner/listener.rs

@@ -1,7 +1,7 @@
 use crate::event_scanner::{EventScannerResult, filter::EventFilter};
 use tokio::sync::mpsc::Sender;
 
-#[derive(Clone, Debug)]
+#[derive(Clone)]
 pub(crate) struct EventListener {
     pub filter: EventFilter,
     pub sender: Sender<EventScannerResult>,

src/event_scanner/scanner/common.rs

@@ -2,7 +2,7 @@ use std::ops::RangeInclusive;
 
 use crate::{
     Message, Notification, ScannerError, ScannerMessage,
-    block_range_scanner::{BlockScannerResult, MAX_BUFFERED_MESSAGES},
+    block_range_scanner::BlockScannerResult,
     event_scanner::{filter::EventFilter, listener::EventListener},
     robust_provider::{RobustProvider, provider::Error as RobustProviderError},
     types::TryStream,
@@ -56,8 +56,9 @@ pub(crate) async fn handle_stream<N: Network, S: Stream<Item = BlockScannerResul
     listeners: &[EventListener],
     mode: ConsumerMode,
     max_concurrent_fetches: usize,
+    buffer_capacity: usize,
 ) {
-    let (range_tx, _) = broadcast::channel::<BlockScannerResult>(MAX_BUFFERED_MESSAGES);
+    let (range_tx, _) = broadcast::channel::<BlockScannerResult>(buffer_capacity);
 
     let consumers = match mode {
         ConsumerMode::Stream => spawn_log_consumers_in_stream_mode(

src/event_scanner/scanner/historic.rs

@@ -144,6 +144,7 @@ impl<N: Network> EventScanner<Historic, N> {
         let max_concurrent_fetches = self.config.max_concurrent_fetches;
         let provider = self.block_range_scanner.provider().clone();
         let listeners = self.listeners.clone();
+        let buffer_capacity = self.buffer_capacity();
 
         tokio::spawn(async move {
             handle_stream(
@@ -152,6 +153,7 @@ impl<N: Network> EventScanner<Historic, N> {
                 &listeners,
                 ConsumerMode::Stream,
                 max_concurrent_fetches,
+                buffer_capacity,
             )
             .await;
         });
@@ -162,7 +164,10 @@ impl<N: Network> EventScanner<Historic, N> {
 
 #[cfg(test)]
 mod tests {
-    use crate::event_scanner::scanner::DEFAULT_MAX_CONCURRENT_FETCHES;
+    use crate::{
+        DEFAULT_STREAM_BUFFER_CAPACITY, block_range_scanner::DEFAULT_MAX_BLOCK_RANGE,
+        event_scanner::scanner::DEFAULT_MAX_CONCURRENT_FETCHES,
+    };
 
     use super::*;
     use alloy::{
@@ -180,12 +185,14 @@ mod tests {
             .to_block(200)
             .max_block_range(50)
             .max_concurrent_fetches(10)
+            .buffer_capacity(33)
             .from_block(100);
 
         assert_eq!(builder.config.from_block, BlockNumberOrTag::Number(100).into());
         assert_eq!(builder.config.to_block, BlockNumberOrTag::Number(200).into());
         assert_eq!(builder.config.max_concurrent_fetches, 10);
         assert_eq!(builder.block_range_scanner.max_block_range, 50);
+        assert_eq!(builder.block_range_scanner.buffer_capacity, 33);
     }
 
     #[test]
@@ -195,6 +202,8 @@ mod tests {
         assert_eq!(builder.config.from_block, BlockNumberOrTag::Earliest.into());
         assert_eq!(builder.config.to_block, BlockNumberOrTag::Latest.into());
         assert_eq!(builder.config.max_concurrent_fetches, DEFAULT_MAX_CONCURRENT_FETCHES);
+        assert_eq!(builder.block_range_scanner.max_block_range, DEFAULT_MAX_BLOCK_RANGE);
+        assert_eq!(builder.block_range_scanner.buffer_capacity, DEFAULT_STREAM_BUFFER_CAPACITY);
     }
 
     #[test]
@@ -208,12 +217,15 @@ mod tests {
             .to_block(100)
             .to_block(200)
             .max_concurrent_fetches(10)
-            .max_concurrent_fetches(20);
+            .max_concurrent_fetches(20)
+            .buffer_capacity(20)
+            .buffer_capacity(40);
 
         assert_eq!(builder.block_range_scanner.max_block_range, 105);
         assert_eq!(builder.config.from_block, BlockNumberOrTag::Number(2).into());
         assert_eq!(builder.config.to_block, BlockNumberOrTag::Number(200).into());
         assert_eq!(builder.config.max_concurrent_fetches, 20);
+        assert_eq!(builder.block_range_scanner.buffer_capacity, 40);
     }
 
     #[tokio::test]
@@ -293,6 +305,14 @@ mod tests {
         }
     }
 
+    #[tokio::test]
+    async fn returns_error_with_zero_buffer_capacity() {
+        let provider = RootProvider::<Ethereum>::new(RpcClient::mocked(Asserter::new()));
+        let result = EventScannerBuilder::historic().buffer_capacity(0).connect(provider).await;
+
+        assert!(matches!(result, Err(ScannerError::InvalidBufferCapacity)));
+    }
+
     #[tokio::test]
     async fn returns_error_with_zero_max_concurrent_fetches() {
         let provider = RootProvider::<Ethereum>::new(RpcClient::mocked(Asserter::new()));