feat(retryableWrites): adding more support for retries

- Adds support for retryable commands that route through the topology `.commands` function instead of a designated function like `.insert`. This adds coverage for `findAndModify` commands.

- Adds support for retrying on more types of errors, and retrying on writeConcern errors

Fixes NODE-1456

lib/connection/pool.js

@@ -575,15 +575,19 @@ function messageHandler(self) {
         }
 
         // Establish if we have an error
-        if (
-          workItem.command &&
-          message.documents[0] &&
-          (message.documents[0].ok === 0 ||
-            message.documents[0]['$err'] ||
-            message.documents[0]['errmsg'] ||
-            message.documents[0]['code'])
-        ) {
-          return handleOperationCallback(self, workItem.cb, new MongoError(message.documents[0]));
+        if (workItem.command && message.documents[0]) {
+          const responseDoc = message.documents[0];
+          if (responseDoc.ok === 0 || responseDoc.$err || responseDoc.errmsg || responseDoc.code) {
+            return handleOperationCallback(self, workItem.cb, new MongoError(responseDoc));
+          }
+
+          if (responseDoc.writeConcernError) {
+            return handleOperationCallback(
+              self,
+              workItem.cb,
+              new MongoError(responseDoc.writeConcernError)
+            );
+          }
         }
 
         // Add the connection details

lib/error.js

@@ -94,10 +94,40 @@ const MongoTimeoutError = function(message) {
 };
 util.inherits(MongoTimeoutError, MongoError);
 
+// see: https://github.com/mongodb/specifications/blob/master/source/retryable-writes/retryable-writes.rst#terms
+const RETRYABLE_ERROR_CODES = new Set([
+  6, // HostUnreachable
+  7, // HostNotFound
+  64, // WriteConcernFailed
+  89, // NetworkTimeout
+  91, // ShutdownInProgress
+  189, // PrimarySteppedDown
+  9001, // SocketException
+  11600, // InterruptedAtShutdown
+  11602, // InterruptedDueToReplStateChange
+  10107, // NotMaster
+  13435, // NotMasterNoSlaveOk
+  13436 // NotMasterOrSecondary
+]);
+
+function isRetryableError(error) {
+  if (
+    RETRYABLE_ERROR_CODES.has(error.code) ||
+    error instanceof MongoNetworkError ||
+    error.message.match(/not master/) ||
+    error.message.match(/node is recovering/)
+  ) {
+    return true;
+  }
+
+  return false;
+}
+
 module.exports = {
   MongoError,
   MongoNetworkError,
   MongoParseError,
   MongoTimeoutError,
-  mongoErrorContextSymbol
+  mongoErrorContextSymbol,
+  isRetryableError
 };

lib/sessions.js

@@ -6,7 +6,7 @@ const BSON = retrieveBSON();
 const Binary = BSON.Binary;
 const uuidV4 = require('./utils').uuidV4;
 const MongoError = require('./error').MongoError;
-const MongoNetworkError = require('./error').MongoNetworkError;
+const isRetryableError = require('././error').isRetryableError;
 
 function assertAlive(session, callback) {
   if (session.serverSession == null) {
@@ -219,35 +219,6 @@ class ClientSession extends EventEmitter {
   }
 }
 
-// see: https://github.com/mongodb/specifications/blob/master/source/retryable-writes/retryable-writes.rst#terms
-const RETRYABLE_ERROR_CODES = new Set([
-  6, // HostUnreachable
-  7, // HostNotFound
-  64, // WriteConcernFailed
-  89, // NetworkTimeout
-  91, // ShutdownInProgress
-  189, // PrimarySteppedDown
-  9001, // SocketException
-  11600, // InterruptedAtShutdown
-  11602, // InterruptedDueToReplStateChange
-  10107, // NotMaster
-  13435, // NotMasterNoSlaveOk
-  13436 // NotMasterOrSecondary
-]);
-
-function isRetryableError(error) {
-  if (
-    RETRYABLE_ERROR_CODES.has(error.code) ||
-    error instanceof MongoNetworkError ||
-    error.message.match(/not master/) ||
-    error.message.match(/node is recovering/)
-  ) {
-    return true;
-  }
-
-  return false;
-}
-
 function resetTransactionState(clientSession) {
   clientSession.transactionOptions = null;
 }

lib/topologies/mongos.js

@@ -7,7 +7,6 @@ const BasicCursor = require('../cursor');
 const Logger = require('../connection/logger');
 const retrieveBSON = require('../connection/utils').retrieveBSON;
 const MongoError = require('../error').MongoError;
-const errors = require('../error');
 const Server = require('./server');
 const clone = require('./shared').clone;
 const diff = require('./shared').diff;
@@ -16,6 +15,7 @@ const createClientInfo = require('./shared').createClientInfo;
 const SessionMixins = require('./shared').SessionMixins;
 const isRetryableWritesSupported = require('./shared').isRetryableWritesSupported;
 const relayEvents = require('./shared').relayEvents;
+const isRetryableError = require('../error').isRetryableError;
 const BSON = retrieveBSON();
 
 /**
@@ -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) && !err.message.match(/not master/)) {
+    if (!isRetryableError(err)) {
       return callback(err);
     }
 
@@ -1019,6 +1019,12 @@ Mongos.prototype.remove = function(ns, ops, options, callback) {
   executeWriteOperation(this, 'remove', ns, ops, options, callback);
 };
 
+const RETRYABLE_WRITE_OPERATIONS = ['findAndModify', 'insert', 'update', 'delete'];
+
+function isWriteCommand(command) {
+  return RETRYABLE_WRITE_OPERATIONS.some(op => command[op]);
+}
+
 /**
  * Execute a command
  * @method
@@ -1057,8 +1063,36 @@ Mongos.prototype.command = function(ns, cmd, options, callback) {
   var clonedOptions = cloneOptions(options);
   clonedOptions.topology = self;
 
+  const willRetryWrite =
+    !options.retrying &&
+    options.retryWrites &&
+    options.session &&
+    isRetryableWritesSupported(self) &&
+    !options.session.inTransaction() &&
+    isWriteCommand(cmd);
+
+  const cb = (err, result) => {
+    if (!err) return callback(null, result);
+    if (!isRetryableError(err)) {
+      return callback(err);
+    }
+
+    if (willRetryWrite) {
+      const newOptions = Object.assign({}, clonedOptions, { retrying: true });
+      return this.command(ns, cmd, newOptions, callback);
+    }
+
+    return callback(err);
+  };
+
+  // increment and assign txnNumber
+  if (willRetryWrite) {
+    options.session.incrementTransactionNumber();
+    options.willRetryWrite = willRetryWrite;
+  }
+
   // Execute the command
-  server.command(ns, cmd, clonedOptions, callback);
+  server.command(ns, cmd, clonedOptions, cb);
 };
 
 /**

lib/topologies/replset.js

@@ -8,7 +8,6 @@ const BasicCursor = require('../cursor');
 const retrieveBSON = require('../connection/utils').retrieveBSON;
 const Logger = require('../connection/logger');
 const MongoError = require('../error').MongoError;
-const errors = require('../error');
 const Server = require('./server');
 const ReplSetState = require('./replset_state');
 const clone = require('./shared').clone;
@@ -18,6 +17,7 @@ const createClientInfo = require('./shared').createClientInfo;
 const SessionMixins = require('./shared').SessionMixins;
 const isRetryableWritesSupported = require('./shared').isRetryableWritesSupported;
 const relayEvents = require('./shared').relayEvents;
+const isRetryableError = require('../error').isRetryableError;
 
 const defaultAuthProviders = require('../auth/defaultAuthProviders').defaultAuthProviders;
 
@@ -1206,7 +1206,7 @@ function executeWriteOperation(args, options, callback) {
 
   const handler = (err, result) => {
     if (!err) return callback(null, result);
-    if (!(err instanceof errors.MongoNetworkError) && !err.message.match(/not master/)) {
+    if (!isRetryableError(err)) {
       return callback(err);
     }
 
@@ -1298,6 +1298,12 @@ ReplSet.prototype.remove = function(ns, ops, options, callback) {
   executeWriteOperation({ self: this, op: 'remove', ns, ops }, options, callback);
 };
 
+const RETRYABLE_WRITE_OPERATIONS = ['findAndModify', 'insert', 'update', 'delete'];
+
+function isWriteCommand(command) {
+  return RETRYABLE_WRITE_OPERATIONS.some(op => command[op]);
+}
+
 /**
  * Execute a command
  * @method
@@ -1370,8 +1376,41 @@ ReplSet.prototype.command = function(ns, cmd, options, callback) {
     );
   }
 
+  const willRetryWrite =
+    !options.retrying &&
+    options.retryWrites &&
+    options.session &&
+    isRetryableWritesSupported(self) &&
+    !options.session.inTransaction() &&
+    isWriteCommand(cmd);
+
+  const cb = (err, result) => {
+    if (!err) return callback(null, result);
+    if (!isRetryableError(err)) {
+      return callback(err);
+    }
+
+    if (willRetryWrite) {
+      const newOptions = Object.assign({}, options, { retrying: true });
+      return this.command(ns, cmd, newOptions, callback);
+    }
+
+    // Per SDAM, remove primary from replicaset
+    if (this.s.replicaSetState.primary) {
+      this.s.replicaSetState.remove(this.s.replicaSetState.primary, { force: true });
+    }
+
+    return callback(err);
+  };
+
+  // increment and assign txnNumber
+  if (willRetryWrite) {
+    options.session.incrementTransactionNumber();
+    options.willRetryWrite = willRetryWrite;
+  }
+
   // Execute the command
-  server.command(ns, cmd, options, callback);
+  server.command(ns, cmd, options, cb);
 };
 
 /**

lib/wireprotocol/3_2_support.js

@@ -350,7 +350,7 @@ WireProtocol.prototype.command = function(bson, ns, cmd, cursorState, topology,
   }
 
   // optionally decorate query with transaction data
-  decorateWithTransactionsData(query.query, options.session);
+  decorateWithTransactionsData(query.query, options.session, options.willRetryWrite);
 
   // We need to increment the statement id if we're in a transaction
   if (options.session && options.session.inTransaction()) {