Rename session[:stream] to session[:get_sse_stream]

Follow-up to #294.

The generic `:stream` key does not convey that it refers to the GET SSE stream,
making it harder to distinguish from `session[:post_request_streams]` introduced in #294.

Author: koic

lib/mcp/server/transports/streamable_http_transport.rb

@@ -15,7 +15,7 @@ class StreamableHTTPTransport < Transport
 
         def initialize(server, stateless: false, session_idle_timeout: nil)
           super(server)
-          # Maps `session_id` to `{ stream: stream_object, server_session: ServerSession, last_active_at: float_from_monotonic_clock }`.
+          # Maps `session_id` to `{ get_sse_stream: stream_object, server_session: ServerSession, last_active_at: float_from_monotonic_clock }`.
           @sessions = {}
           @mutex = Mutex.new
 
@@ -61,7 +61,7 @@ def close
           end
 
           removed_sessions.each do |session|
-            close_stream_safely(session[:stream])
+            close_stream_safely(session[:get_sse_stream])
             close_post_request_streams(session)
           end
         end
@@ -113,7 +113,7 @@ def send_notification(method, params = nil, session_id: nil, related_request_id:
               failed_sessions = []
 
               @sessions.each do |sid, session|
-                next unless (stream = session[:stream])
+                next unless (stream = session[:get_sse_stream])
 
                 if session_expired?(session)
                   failed_sessions << sid
@@ -247,7 +247,7 @@ def reap_expired_sessions
           end
 
           removed_sessions.each do |session|
-            close_stream_safely(session[:stream])
+            close_stream_safely(session[:get_sse_stream])
             close_post_request_streams(session)
           end
         end
@@ -334,7 +334,7 @@ def cleanup_session(session_id)
           end
 
           if session
-            close_stream_safely(session[:stream])
+            close_stream_safely(session[:get_sse_stream])
             close_post_request_streams(session)
           end
         end
@@ -358,7 +358,7 @@ def cleanup_session_unsafe(session_id)
         def cleanup_and_collect_stream(session_id, streams_to_close)
           return unless (removed = cleanup_session_unsafe(session_id))
 
-          streams_to_close << removed[:stream]
+          streams_to_close << removed[:get_sse_stream]
           removed[:post_request_streams]&.each_value { |stream| streams_to_close << stream }
         end
 
@@ -449,7 +449,7 @@ def handle_initialization(body_string, body)
 
             @mutex.synchronize do
               @sessions[session_id] = {
-                stream: nil,
+                get_sse_stream: nil,
                 server_session: server_session,
                 last_active_at: Process.clock_gettime(Process::CLOCK_MONOTONIC),
               }
@@ -543,7 +543,7 @@ def active_stream(session, related_request_id: nil)
           if related_request_id
             session.dig(:post_request_streams, related_request_id)
           else
-            session[:stream]
+            session[:get_sse_stream]
           end
         end
 
@@ -572,7 +572,7 @@ def validate_and_touch_session(session_id)
           end
 
           if removed
-            close_stream_safely(removed[:stream])
+            close_stream_safely(removed[:get_sse_stream])
 
             removed[:post_request_streams]&.each_value do |stream|
               close_stream_safely(stream)
@@ -583,7 +583,7 @@ def validate_and_touch_session(session_id)
         end
 
         def get_session_stream(session_id)
-          @mutex.synchronize { @sessions[session_id]&.fetch(:stream, nil) }
+          @mutex.synchronize { @sessions[session_id]&.fetch(:get_sse_stream, nil) }
         end
 
         def session_exists?(session_id)
@@ -626,8 +626,8 @@ def create_sse_body(session_id)
         def store_stream_for_session(session_id, stream)
           @mutex.synchronize do
             session = @sessions[session_id]
-            if session && !session[:stream]
-              session[:stream] = stream
+            if session && !session[:get_sse_stream]
+              session[:get_sse_stream] = stream
             else
               # Either session was removed, or another request already established a stream.
               stream.close
@@ -652,13 +652,13 @@ def start_keepalive_thread(session_id)
         end
 
         def session_active_with_stream?(session_id)
-          @mutex.synchronize { @sessions.key?(session_id) && @sessions[session_id][:stream] }
+          @mutex.synchronize { @sessions.key?(session_id) && @sessions[session_id][:get_sse_stream] }
         end
 
         def send_keepalive_ping(session_id)
           @mutex.synchronize do
-            if @sessions[session_id] && @sessions[session_id][:stream]
-              send_ping_to_stream(@sessions[session_id][:stream])
+            if @sessions[session_id] && @sessions[session_id][:get_sse_stream]
+              send_ping_to_stream(@sessions[session_id][:get_sse_stream])
             end
           end
         rescue *STREAM_WRITE_ERRORS => e

test/mcp/server/transports/streamable_http_transport_test.rb

@@ -346,7 +346,7 @@ def string
 
           # Simulate an active SSE stream by storing a stream object in the session
           mock_stream = StringIO.new
-          @transport.instance_variable_get(:@sessions)[session_id][:stream] = mock_stream
+          @transport.instance_variable_get(:@sessions)[session_id][:get_sse_stream] = mock_stream
 
           # Attempt a second GET request for the same session
           get_request = create_rack_request(
@@ -377,14 +377,14 @@ def string
           # Establish stream A
           stream_a = StringIO.new
           @transport.send(:store_stream_for_session, session_id, stream_a)
-          assert_equal stream_a, @transport.instance_variable_get(:@sessions)[session_id][:stream]
+          assert_equal stream_a, @transport.instance_variable_get(:@sessions)[session_id][:get_sse_stream]
 
           # Attempt to store stream B (simulating a racing request)
           stream_b = StringIO.new
           @transport.send(:store_stream_for_session, session_id, stream_b)
 
           # Stream A should still be the active stream
-          assert_equal stream_a, @transport.instance_variable_get(:@sessions)[session_id][:stream]
+          assert_equal stream_a, @transport.instance_variable_get(:@sessions)[session_id][:get_sse_stream]
 
           # Stream B should have been closed
           assert stream_b.closed?
@@ -928,7 +928,7 @@ def string
             end
           end
 
-          @transport.instance_variable_get(:@sessions)[session_id][:stream] = mock_stream
+          @transport.instance_variable_get(:@sessions)[session_id][:get_sse_stream] = mock_stream
 
           result = @transport.send_notification("test", { message: "test" }, session_id: session_id)
 
@@ -973,7 +973,7 @@ def string
           # The broken request_stream should be removed.
           refute @transport.instance_variable_get(:@sessions)[session_id][:post_request_streams].key?(related_id)
           # GET SSE stream should still be intact.
-          assert @transport.instance_variable_get(:@sessions)[session_id][:stream]
+          assert @transport.instance_variable_get(:@sessions)[session_id][:get_sse_stream]
         end
 
         test "active_stream does not fall back to GET SSE when related_request_id is given but request_stream is missing" do
@@ -2378,7 +2378,7 @@ def string
               mutex.unlock
             end
           end
-          transport.instance_variable_get(:@sessions)[session_id][:stream] = mock_stream
+          transport.instance_variable_get(:@sessions)[session_id][:get_sse_stream] = mock_stream
 
           sleep(0.02) # Wait for session to expire.
 
@@ -2495,7 +2495,7 @@ def string
 
           # Attach a mock stream to the session
           stream = StringIO.new
-          transport.instance_variable_get(:@sessions)[session_id][:stream] = stream
+          transport.instance_variable_get(:@sessions)[session_id][:get_sse_stream] = stream
 
           # Wait for the session to exceed the idle timeout (0.01s)
           sleep(0.02)