From 028aec79f5d3ac5dc5361f643be88d65c7a23a3d Mon Sep 17 00:00:00 2001
From: Matt Broadstone <mbroadst@gmail.com>
Date: Fri, 1 Dec 2017 15:31:30 -0500
Subject: [PATCH] feat(retryable-writes): retry on "not master" stepdown errors

NODE-1105
---
 lib/topologies/mongos.js                      |  2 +-
 lib/topologies/replset.js                     |  2 +-
 .../unit/mongos/retryable_writes_tests.js     | 54 +++++++++++++++++++
 .../unit/replset/retryable_writes_tests.js    | 54 +++++++++++++++++++
 4 files changed, 110 insertions(+), 2 deletions(-)

diff --git a/lib/topologies/mongos.js b/lib/topologies/mongos.js
index 836b69f4c..5f881517e 100644
--- a/lib/topologies/mongos.js
+++ b/lib/topologies/mongos.js
@@ -900,7 +900,7 @@ var executeWriteOperation = function(self, op, ns, ops, options, callback) {
 
   server[op](ns, ops, options, (err, result) => {
     if (!err) return callback(null, result);
-    if (!(err instanceof errors.MongoNetworkError)) {
+    if (!(err instanceof errors.MongoNetworkError) && !err.message.match(/not master/)) {
       return callback(err);
     }
 
diff --git a/lib/topologies/replset.js b/lib/topologies/replset.js
index 3fec27d4a..f6472cda3 100644
--- a/lib/topologies/replset.js
+++ b/lib/topologies/replset.js
@@ -1187,7 +1187,7 @@ var executeWriteOperation = function(self, op, ns, ops, options, callback) {
 
   self.s.replicaSetState.primary[op](ns, ops, options, (err, result) => {
     if (!err) return callback(null, result);
-    if (!(err instanceof errors.MongoNetworkError)) {
+    if (!(err instanceof errors.MongoNetworkError) && !err.message.match(/not master/)) {
       return callback(err);
     }
 
diff --git a/test/tests/unit/mongos/retryable_writes_tests.js b/test/tests/unit/mongos/retryable_writes_tests.js
index 0020be26f..08e7ad326 100644
--- a/test/tests/unit/mongos/retryable_writes_tests.js
+++ b/test/tests/unit/mongos/retryable_writes_tests.js
@@ -113,4 +113,58 @@ describe('Retryable Writes (Mongos)', function() {
       mongos.connect();
     }
   });
+
+  it('should retry write commands where `retryWrites` is true, and there is a "not master" error', {
+    metadata: { requires: { topology: ['single'] } },
+    test: function(done) {
+      const mongos = new Mongos(test.servers.map(server => server.address()), {
+        connectionTimeout: 3000,
+        socketTimeout: 0,
+        haInterval: 10000,
+        localThresholdMS: 500,
+        size: 1
+      });
+
+      const sessionPool = new ServerSessionPool(mongos);
+      const session = new ClientSession(mongos, sessionPool);
+
+      let command = null,
+        insertCount = 0;
+
+      const messageHandler = () => {
+        return request => {
+          const doc = request.document;
+          if (doc.ismaster) {
+            request.reply(test.defaultFields);
+          } else if (doc.insert) {
+            insertCount++;
+            if (insertCount === 1) {
+              request.reply({ ok: 0, errmsg: 'not master' }); // simulate a stepdown
+            } else {
+              command = doc;
+              request.reply({ ok: 1 });
+            }
+          }
+        };
+      };
+
+      test.servers[0].setMessageHandler(messageHandler('MONGOS1'));
+      test.servers[1].setMessageHandler(messageHandler('MONGOS2'));
+      mongos.once('fullsetup', function() {
+        mongos.insert('test.test', [{ a: 1 }], { retryWrites: true, session: session }, function(
+          err
+        ) {
+          expect(err).to.not.exist;
+          expect(command).to.have.property('txnNumber');
+          expect(command.txnNumber).to.eql(1);
+
+          mongos.destroy();
+          done();
+        });
+      });
+
+      mongos.on('error', done);
+      mongos.connect();
+    }
+  });
 });
diff --git a/test/tests/unit/replset/retryable_writes_tests.js b/test/tests/unit/replset/retryable_writes_tests.js
index 8d74c69fc..95872046f 100644
--- a/test/tests/unit/replset/retryable_writes_tests.js
+++ b/test/tests/unit/replset/retryable_writes_tests.js
@@ -111,4 +111,58 @@ describe('Retryable Writes (ReplSet)', function() {
       replset.connect();
     }
   });
+
+  it('should retry write commands where `retryWrites` is true, and there is a "not master" error', {
+    metadata: { requires: { topology: ['single'] } },
+    test: function(done) {
+      var replset = new ReplSet(
+        [test.primaryServer.address(), test.firstSecondaryServer.address()],
+        {
+          setName: 'rs',
+          connectionTimeout: 100,
+          socketTimeout: 0,
+          haInterval: 100,
+          size: 5,
+          minSize: 1
+        }
+      );
+
+      const sessionPool = new ServerSessionPool(replset);
+      const session = new ClientSession(replset, sessionPool);
+
+      let command = null,
+        insertCount = 0;
+
+      test.primaryServer.setMessageHandler(request => {
+        const doc = request.document;
+        if (doc.ismaster) {
+          request.reply(test.primaryStates[0]);
+        } else if (doc.insert) {
+          insertCount++;
+          if (insertCount === 1) {
+            request.reply({ ok: 0, errmsg: 'not master' }); // simulate a stepdown
+          } else {
+            command = doc;
+            request.reply({ ok: 1 });
+          }
+        }
+      });
+
+      replset.on('all', () => {
+        replset.insert('test.test', [{ a: 1 }], { retryWrites: true, session: session }, function(
+          err
+        ) {
+          expect(err).to.not.exist;
+          expect(command).to.have.property('txnNumber');
+          expect(command.txnNumber).to.eql(1);
+
+          replset.destroy();
+          done();
+        });
+      });
+
+      replset.on('error', done);
+      replset.connect();
+    }
+  });
 });