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fix:avoid streamable listening sse duplicate creation #524

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fix:avoid streamable listening sse duplicate creation #524

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3dac307
avoid streamable listening sse duplicate creation
taobaorun Aug 28, 2025
c7cbe98
Listening stream already exists for this session and will be closed t…
taobaorun Aug 31, 2025
e87387b
Atomically close the existing listening stream and switch to the new …
taobaorun Sep 1, 2025
4b30e0a
fix listening sse stream close blocking
taobaorun Sep 3, 2025
90ecbb4
resolve conflicts
taobaorun Sep 3, 2025
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2 changes: 1 addition & 1 deletion ...va/io/modelcontextprotocol/server/transport/WebFluxStreamableServerTransportProvider.java
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Original file line number Diff line number Diff line change
Expand Up @@ -484,4 +484,4 @@ public WebFluxStreamableServerTransportProvider build() {

}

}
}
30 changes: 17 additions & 13 deletions mcp/src/main/java/io/modelcontextprotocol/spec/McpStreamableServerSession.java
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Expand Up @@ -4,28 +4,26 @@

package io.modelcontextprotocol.spec;

import java.time.Duration;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Supplier;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.fasterxml.jackson.core.type.TypeReference;

import io.modelcontextprotocol.server.McpAsyncServerExchange;
import io.modelcontextprotocol.server.McpNotificationHandler;
import io.modelcontextprotocol.server.McpRequestHandler;
import io.modelcontextprotocol.server.McpTransportContext;
import io.modelcontextprotocol.util.Assert;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;
import reactor.core.publisher.MonoSink;

import java.time.Duration;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Supplier;

/**
* Representation of a Streamable HTTP server session that keeps track of mapping
* server-initiated requests to the client and mapping arriving responses. It also allows
Expand Down Expand Up @@ -138,7 +136,13 @@ public Mono<Void> delete() {
*/
public McpStreamableServerSessionStream listeningStream(McpStreamableServerTransport transport) {
McpStreamableServerSessionStream listeningStream = new McpStreamableServerSessionStream(transport);
this.listeningStreamRef.set(listeningStream);
McpLoggableSession listenedStream = this.listeningStreamRef.getAndSet(listeningStream);
if (listenedStream != null) {
logger.debug(
"Listening stream already exists for this session:{} and will be closed to make way for the new listening SSE stream",
this.id);
listenedStream.closeGracefully().block();
}
return listeningStream;
}

Expand Down