Batch requests over WebSocketService are overwritten by simple requests if send at about the same time

[Shohou]

Request ids generated for batch requests clash with request ids of normal standalone requests

WebSocketService in sendBatchAsync method overwrites id of first request in batch and puts it int requestForId map. Problem is the new id is generated using AtomicInteger called nextBatchId which is different than AtomicInteger used for id generation in Request. So what happens:

1. User sends simple standalone request by creating it with one of Web3j methods, Web3j.ethBlockNumber() for example. It generates id using AtomicInteger nextId field in Request which starts with 0. WebSocketService.sendAsync saves this id in requestForId map for further mapping of arriving response.
2. User without waiting for response asynchronously creates batch with Web3j.newBatch adds some requests in it and sends it. WebSocketService.sendBatchAsync generates substitute id using AtomicInteger nextBatchId which also starts with 0 and puts it in the same requestForId map overwriting first request which was there.
3. Response for first request arrives in onWebSocketMessage method and fails with ClassCastException because it expects to find there WebSocketRequest by id 0, but instead gets WebSocketRequests.
4. Response for batch request arrives and WebSocketService.getAndRemoveRequest throws IOException with message "Received reply for unexpected request id: 0"

Steps To Reproduce

Steps described in description.

Expected behavior

I expect it not to fail with exceptions and responses mapped correctly with corresponding requests

Actual behavior

Two exceptions are thrown, and both requests are never completed, not even by timeout

Environment

• Web3j version - 4.12.2

Additional context

Exceptions:

2024-12-16 02:29:40,407 ERROR [org.web3j.protocol.websocket.WebSocketClient] (WebSocketConnectReadThread-75) Failed to process message '[{"jsonrpc":"2.0","id":0,"result":{long body of batch request}}]' from server wss://holesky.infura.io/ws/v3/xxxxxx: java.lang.ClassCastException: class org.web3j.protocol.websocket.WebSocketRequest cannot be cast to class org.web3j.protocol.websocket.WebSocketRequests (org.web3j.protocol.websocket.WebSocketRequest and org.web3j.protocol.websocket.WebSocketRequests are in unnamed module of loader io.quarkus.bootstrap.runner.RunnerClassLoader @6193b845)
        at org.web3j.protocol.websocket.WebSocketService.processBatchRequestReply(WebSocketService.java:309)
        at org.web3j.protocol.websocket.WebSocketService.onWebSocketMessage(WebSocketService.java:281)
        at org.web3j.protocol.websocket.WebSocketService$1.onMessage(WebSocketService.java:155)
        at org.web3j.protocol.websocket.WebSocketClient.lambda$onMessage$0(WebSocketClient.java:52)
        at java.base/java.util.Optional.ifPresent(Optional.java:178)
        at org.web3j.protocol.websocket.WebSocketClient.onMessage(WebSocketClient.java:49)
        at org.java_websocket.client.WebSocketClient.onWebsocketMessage(WebSocketClient.java:644)
        at org.java_websocket.drafts.Draft_6455.processFrameText(Draft_6455.java:986)
        at org.java_websocket.drafts.Draft_6455.processFrame(Draft_6455.java:910)
        at org.java_websocket.WebSocketImpl.decodeFrames(WebSocketImpl.java:402)
        at org.java_websocket.WebSocketImpl.decode(WebSocketImpl.java:234)
        at org.java_websocket.client.WebSocketClient.run(WebSocketClient.java:527)
        at java.base/java.lang.Thread.run(Thread.java:1583)

2024-12-16 02:29:40,422 ERROR [org.web3j.protocol.websocket.WebSocketClient] (WebSocketConnectReadThread-75) Failed to process message '{"jsonrpc":"2.0","id":0,"result":"0x2cf161"}' from server wss://holesky.infura.io/ws/v3/xxxxx: java.io.IOException: Received reply for unexpected request id: 0
        at org.web3j.protocol.websocket.WebSocketService.getAndRemoveRequest(WebSocketService.java:433)
        at org.web3j.protocol.websocket.WebSocketService.processRequestReply(WebSocketService.java:292)
        at org.web3j.protocol.websocket.WebSocketService.onWebSocketMessage(WebSocketService.java:279)
        at org.web3j.protocol.websocket.WebSocketService$1.onMessage(WebSocketService.java:155)
        at org.web3j.protocol.websocket.WebSocketClient.lambda$onMessage$0(WebSocketClient.java:52)
        at java.base/java.util.Optional.ifPresent(Optional.java:178)
        at org.web3j.protocol.websocket.WebSocketClient.onMessage(WebSocketClient.java:49)
        at org.java_websocket.client.WebSocketClient.onWebsocketMessage(WebSocketClient.java:644)
        at org.java_websocket.drafts.Draft_6455.processFrameText(Draft_6455.java:986)
        at org.java_websocket.drafts.Draft_6455.processFrame(Draft_6455.java:910)
        at org.java_websocket.WebSocketImpl.decodeFrames(WebSocketImpl.java:402)
        at org.java_websocket.WebSocketImpl.decode(WebSocketImpl.java:234)
        at org.java_websocket.client.WebSocketClient.run(WebSocketClient.java:527)
        at java.base/java.lang.Thread.run(Thread.java:1583)