fix(sessions): move active session tracking to topology base (#1665)

Moves the tracking of active sessions to the topology base.
Doing this allows us to ensure that all active and pooled
sessions are ended when the topology closes, and that implicit
sessions are tracked. Also adds a test case to make sure none of
our unit tests are leaking sessions, and corrects many leaky tests.
Also bumps version of mongodb-core

Part of HELP-5384

Author: daprahamian

.eslintrc

@@ -7,7 +7,8 @@
     "mocha": true
   },
   "globals": {
-    "Promise": true
+    "Promise": true,
+    "Set": true
   },
   "parserOptions": {
     "ecmaVersion": 2017

lib/mongo_client.js

@@ -327,14 +327,6 @@ MongoClient.prototype.close = function(force, callback) {
   // Remove listeners after emit
   self.removeAllListeners('close');
 
-  // If we have sessions, we want to send a single `endSessions` command for them,
-  // and then individually clean them up.  They will be removed from the internal state
-  // when they emit their `ended` events.
-  if (this.s.sessions.length) {
-    this.topology.endSessions(this.s.sessions);
-    this.s.sessions.forEach(session => session.endSession({ skipCommand: true }));
-  }
-
   // Callback after next event loop tick
   if (typeof callback === 'function')
     return process.nextTick(function() {
@@ -507,13 +499,7 @@ MongoClient.prototype.startSession = function(options) {
     throw new MongoError('Current topology does not support sessions');
   }
 
-  const session = this.topology.startSession(options);
-  session.once('ended', () => {
-    this.s.sessions = this.s.sessions.filter(s => s.equals(session));
-  });
-
-  this.s.sessions.push(session);
-  return session;
+  return this.topology.startSession(options);
 };
 
 var mergeOptions = function(target, source, flatten) {

lib/topologies/mongos.js

@@ -190,6 +190,8 @@ class Mongos extends TopologyBase {
       options: options,
       // Server Session Pool
       sessionPool: null,
+      // Active client sessions
+      sessions: [],
       // Promise library
       promiseLibrary: options.promiseLibrary || Promise
     };

lib/topologies/replset.js

@@ -206,6 +206,8 @@ class ReplSet extends TopologyBase {
       options: options,
       // Server Session Pool
       sessionPool: null,
+      // Active client sessions
+      sessions: [],
       // Promise library
       promiseLibrary: options.promiseLibrary || Promise
     };
@@ -371,22 +373,9 @@ class ReplSet extends TopologyBase {
   }
 
   close(forceClosed) {
-    var self = this;
-    // Call destroy on the topology
-    this.s.coreTopology.destroy({
-      force: typeof forceClosed === 'boolean' ? forceClosed : false
-    });
-
-    // We need to wash out all stored processes
-    if (forceClosed === true) {
-      this.s.storeOptions.force = forceClosed;
-      this.s.store.flush();
-    }
+    super.close(forceClosed);
 
-    var events = ['timeout', 'error', 'close', 'joined', 'left'];
-    events.forEach(function(e) {
-      self.removeAllListeners(e);
-    });
+    ['timeout', 'error', 'close', 'joined', 'left'].forEach(e => this.removeAllListeners(e));
   }
 }
 

lib/topologies/server.js

@@ -198,6 +198,8 @@ class Server extends TopologyBase {
       options: options,
       // Server Session Pool
       sessionPool: null,
+      // Active client sessions
+      sessions: [],
       // Promise library
       promiseLibrary: promiseLibrary || Promise
     };

lib/topologies/topology_base.js

@@ -290,7 +290,13 @@ class TopologyBase extends EventEmitter {
   }
 
   startSession(options) {
-    return new ClientSession(this, this.s.sessionPool, options);
+    const session = new ClientSession(this, this.s.sessionPool, options);
+    session.once('ended', () => {
+      this.s.sessions = this.s.sessions.filter(s => !s.equals(session));
+    });
+
+    this.s.sessions.push(session);
+    return session;
   }
 
   endSessions(sessions, callback) {
@@ -388,6 +394,18 @@ class TopologyBase extends EventEmitter {
   }
 
   close(forceClosed) {
+    // If we have sessions, we want to send a single `endSessions` command for them,
+    // and then individually clean them up.  They will be removed from the internal state
+    // when they emit their `ended` events.
+    if (this.s.sessions.length) {
+      this.endSessions(this.s.sessions.map(session => session.id));
+      this.s.sessions.forEach(session => session.endSession({ skipCommand: true }));
+    }
+
+    if (this.s.sessionPool) {
+      this.s.sessionPool.endAllPooledSessions();
+    }
+
     this.s.coreTopology.destroy({
       force: typeof forceClosed === 'boolean' ? forceClosed : false
     });

package.json

@@ -13,7 +13,7 @@
     "official"
   ],
   "dependencies": {
-    "mongodb-core": "3.0.2"
+    "mongodb-core": "3.0.3"
   },
   "devDependencies": {
     "betterbenchmarks": "^0.1.0",
@@ -32,6 +32,7 @@
     "mongodb-test-runner": "^1.1.18",
     "prettier": "^1.5.3",
     "semver": "5.4.1",
+    "sinon": "^4.3.0",
     "worker-farm": "^1.5.0"
   },
   "author": "Christian Kvalheim",

test/functional/apm_tests.js

@@ -1036,6 +1036,10 @@ describe('APM', function() {
         // Get the result
         result = results.successes.shift();
 
+        if (result.commandName === 'endSessions') {
+          result = results.successes.shift();
+        }
+
         // Validate the test
         expect(commandName).to.equal(result.commandName);
         // Do we have a getMore command
@@ -1054,6 +1058,10 @@ describe('APM', function() {
         results.failures = filterSessionsCommands(results.failures);
         result = results.failures.shift();
 
+        if (result.commandName === 'endSessions') {
+          result = results.failures.shift();
+        }
+
         // Validate the test
         expect(commandName).to.equal(result.commandName);
       }

test/functional/crud_api_tests.js

@@ -830,7 +830,7 @@ describe('CRUD API', function() {
         test.equal(null, err);
 
         // Delete all items with no selector
-        db.collection('t6_1').deleteMany(function(err) {
+        db.collection('t6_1').deleteMany({}, function(err) {
           test.equal(null, err);
 
           client.close();

test/functional/crud_spec_tests.js

@@ -39,6 +39,12 @@ describe('CRUD spec', function() {
       });
   });
 
+  afterEach(() => {
+    if (testContext.client) {
+      testContext.client.close();
+    }
+  });
+
   describe('read', function() {
     readScenarios.forEach(function(scenarioData) {
       var scenarioName = scenarioData[0];