[client] Thrown exception if Server type mismatch.

[loserwang1024]

Purpose

Linked issue: close #2604

Brief change log

Tests

API and Format

Documentation

[Copilot]

Pull request overview

This PR addresses client-side “stuck” behavior when requests are routed to the wrong server type (e.g., coordinator vs tablet server after restarts/IP swaps) by adding a server-type check during API version negotiation and surfacing the mismatch as a metadata-related exception so clients can recover.

Changes:

• Add server_type to ApiVersionsResponse and populate it on the server/test gateways.
• Validate server type on the client during API_VERSIONS handshake and close the connection with an InvalidServerTypeException on mismatch.
• Refresh physical-table metadata during writer-id initialization retries when the failure is an InvalidMetadataException.

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
fluss-server/src/main/java/org/apache/fluss/server/RpcServiceBase.java	Sets server_type in API_VERSIONS responses emitted by servers.
fluss-rpc/src/main/proto/FlussApi.proto	Extends ApiVersionsResponse with optional int32 server_type.
fluss-rpc/src/main/java/org/apache/fluss/rpc/netty/client/ServerConnection.java	Adds server-type validation on API_VERSIONS response and closes with InvalidServerTypeException on mismatch.
fluss-common/src/main/java/org/apache/fluss/exception/InvalidServerTypeException.java	Introduces a new exception type (extends InvalidMetadataException) to trigger metadata refresh/retry behavior.
fluss-common/src/main/java/org/apache/fluss/cluster/ServerType.java	Adds ServerType.forId(int) to decode server_type.
fluss-rpc/src/test/java/org/apache/fluss/rpc/netty/client/ServerConnectionTest.java	Adds coverage for wrong-server-type connection behavior.
fluss-rpc/src/test/java/org/apache/fluss/rpc/netty/authenticate/AuthenticationTest.java	Updates test ServerNode types to match new server-type handshake behavior.
fluss-rpc/src/test/java/org/apache/fluss/rpc/TestingTabletGatewayService.java	Makes test tablet gateway report TABLET_SERVER provider type.
fluss-rpc/src/test/java/org/apache/fluss/rpc/TestingGatewayService.java	Adds server_type to API_VERSIONS responses for test gateway service.
fluss-client/src/main/java/org/apache/fluss/client/write/WriterClient.java	Wires MetadataUpdater into IdempotenceManager construction.
fluss-client/src/main/java/org/apache/fluss/client/write/IdempotenceManager.java	Refreshes metadata on InvalidMetadataException during writer-id init retries.
fluss-client/src/test/java/org/apache/fluss/client/write/SenderTest.java	Updates IdempotenceManager construction to include MetadataUpdater.
fluss-client/src/test/java/org/apache/fluss/client/write/RecordAccumulatorTest.java	Updates IdempotenceManager construction for new signature (passes null updater).

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[loserwang1024]

@wuchong @swuferhong , CC