Fix caching of requested session in SessionRepositoryFilter

Closes gh-1076

Author: vpavic

spring-session-core/src/main/java/org/springframework/session/web/http/SessionRepositoryFilter.java

@@ -230,7 +230,8 @@ private void commitSession() {
 			}
 			else {
 				S session = wrappedSession.getSession();
-				saveSession(session);
+				clearRequestedSessionCache();
+				SessionRepositoryFilter.this.sessionRepository.save(session);
 				String sessionId = session.getId();
 				if (!isRequestedSessionIdValid()
 						|| !sessionId.equals(getRequestedSessionId())) {
@@ -371,10 +372,9 @@ private S getRequestedSession() {
 			return this.requestedSession;
 		}
 
-		private void saveSession(S session) {
+		private void clearRequestedSessionCache() {
 			this.requestedSessionCached = false;
 			this.requestedSession = null;
-			SessionRepositoryFilter.this.sessionRepository.save(session);
 		}
 
 		/**
@@ -394,6 +394,7 @@ public void invalidate() {
 				super.invalidate();
 				SessionRepositoryRequestWrapper.this.requestedSessionInvalidated = true;
 				setCurrentSession(null);
+				clearRequestedSessionCache();
 				SessionRepositoryFilter.this.sessionRepository.deleteById(getId());
 			}
 		}

spring-session-core/src/test/java/org/springframework/session/web/http/SessionRepositoryFilterTests.java

@@ -67,6 +67,7 @@
 import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.reset;
 import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.verifyZeroInteractions;
 
@@ -1335,6 +1336,32 @@ public void doFilter(HttpServletRequest wrappedRequest,
 		verifyZeroInteractions(sessionRepository);
 	}
 
+	@Test
+	public void doFilterSessionRetrievalIsCached() throws Exception {
+		MapSession session = this.sessionRepository.createSession();
+		this.sessionRepository.save(session);
+		SessionRepository<MapSession> sessionRepository = spy(this.sessionRepository);
+		setSessionCookie(session.getId());
+
+		this.filter = new SessionRepositoryFilter<>(sessionRepository);
+
+		doFilter(new DoInFilter() {
+			@Override
+			public void doFilter(HttpServletRequest wrappedRequest,
+					HttpServletResponse wrappedResponse) {
+				wrappedRequest.getSession().invalidate();
+				wrappedRequest.getSession();
+			}
+		});
+
+		// 3 invocations expected: initial resolution, after invalidation, after commit
+		verify(sessionRepository, times(3)).findById(eq(session.getId()));
+		verify(sessionRepository).deleteById(eq(session.getId()));
+		verify(sessionRepository).createSession();
+		verify(sessionRepository).save(any());
+		verifyZeroInteractions(sessionRepository);
+	}
+
 	// --- order
 
 	@Test