fix(server-session-pool): don't add expired sessions to the pool

NODE-1088

Author: mbroadst

lib/sessions.js

@@ -88,7 +88,7 @@ class ServerSession {
       (((Date.now() - this.lastUse) % 86400000) % 3600000) / 60000
     );
 
-    return idleTimeMinutes > sessionTimeoutMinutes;
+    return idleTimeMinutes > sessionTimeoutMinutes - 1;
   }
 }
 
@@ -135,7 +135,9 @@ class ServerSessionPool {
       }
     }
 
-    this.sessions.push(session);
+    if (!session.hasTimedOut(sessionTimeoutMinutes)) {
+      this.sessions.push(session);
+    }
   }
 }
 

test/tests/unit/sessions_tests.js

@@ -155,5 +155,19 @@ describe('Sessions', function() {
         done();
       }
     });
+
+    it('should not reintroduce a soon-to-expire session to the pool on release', {
+      metadata: { requires: { topology: 'single' } },
+
+      test: function(done) {
+        const session = new ServerSession();
+        session.lastUse = new Date(Date.now() - 9.5 * 60 * 1000).getTime(); // add 9.5min
+
+        const pool = new ServerSessionPool(test.client);
+        pool.release(session);
+        expect(pool.sessions).to.have.length(0);
+        done();
+      }
+    });
   });
 });

test/tests/unit/single/sessions_tests.js

@@ -230,7 +230,8 @@ describe('Sessions (Single)', function() {
         sentIsMaster = true;
         request.reply(
           assign({}, mock.DEFAULT_ISMASTER, {
-            maxWireVersion: 6
+            maxWireVersion: 6,
+            logicalSessionTimeoutMinutes: 10
           })
         );
       });