From 392f5a692b96e6a328b22dee11d8ca2057589bf1 Mon Sep 17 00:00:00 2001
From: Katherine Walker <kvwalker@users.noreply.github.com>
Date: Mon, 12 Aug 2019 13:24:50 -0400
Subject: [PATCH] fix(topology): add new error for retryWrites on MMAPv1

Fixes NODE-2098
---
 lib/core/sdam/topology.js      |  2 ++
 lib/core/topologies/mongos.js  |  2 ++
 lib/core/topologies/replset.js |  2 ++
 lib/core/topologies/shared.js  | 22 ++++++++++++++++++++++
 4 files changed, 28 insertions(+)

diff --git a/lib/core/sdam/topology.js b/lib/core/sdam/topology.js
index 0372dea895..3b046f2dda 100644
--- a/lib/core/sdam/topology.js
+++ b/lib/core/sdam/topology.js
@@ -25,6 +25,7 @@ const createClientInfo = require('../topologies/shared').createClientInfo;
 const MongoError = require('../error').MongoError;
 const resolveClusterTime = require('../topologies/shared').resolveClusterTime;
 const SrvPoller = require('./srv_polling').SrvPoller;
+const getMMAPError = require('../topologies/shared').getMMAPError;
 
 // Global state
 let globalTopologyCounter = 0;
@@ -972,6 +973,7 @@ function executeWriteOperation(args, options, callback) {
     const handler = (err, result) => {
       if (!err) return callback(null, result);
       if (!isRetryableError(err)) {
+        err = getMMAPError(err);
         return callback(err);
       }
 
diff --git a/lib/core/topologies/mongos.js b/lib/core/topologies/mongos.js
index 9dcf5f77c6..5164e07897 100644
--- a/lib/core/topologies/mongos.js
+++ b/lib/core/topologies/mongos.js
@@ -17,6 +17,7 @@ const isRetryableWritesSupported = require('./shared').isRetryableWritesSupporte
 const relayEvents = require('../utils').relayEvents;
 const isRetryableError = require('../error').isRetryableError;
 const BSON = retrieveBSON();
+const getMMAPError = require('./shared').getMMAPError;
 
 /**
  * @fileOverview The **Mongos** class is a class that represents a Mongos Proxy topology and is
@@ -880,6 +881,7 @@ function executeWriteOperation(args, options, callback) {
   const handler = (err, result) => {
     if (!err) return callback(null, result);
     if (!isRetryableError(err) || !willRetryWrite) {
+      err = getMMAPError(err);
       return callback(err);
     }
 
diff --git a/lib/core/topologies/replset.js b/lib/core/topologies/replset.js
index 3bf6b6ec43..141d937c20 100644
--- a/lib/core/topologies/replset.js
+++ b/lib/core/topologies/replset.js
@@ -20,6 +20,7 @@ const relayEvents = require('../utils').relayEvents;
 const isRetryableError = require('../error').isRetryableError;
 const BSON = retrieveBSON();
 const calculateDurationInMs = require('../utils').calculateDurationInMs;
+const getMMAPError = require('./shared').getMMAPError;
 
 //
 // States
@@ -1190,6 +1191,7 @@ function executeWriteOperation(args, options, callback) {
   const handler = (err, result) => {
     if (!err) return callback(null, result);
     if (!isRetryableError(err)) {
+      err = getMMAPError(err);
       return callback(err);
     }
 
diff --git a/lib/core/topologies/shared.js b/lib/core/topologies/shared.js
index 5f39130d23..dbcebcd64e 100644
--- a/lib/core/topologies/shared.js
+++ b/lib/core/topologies/shared.js
@@ -5,6 +5,9 @@ const f = require('util').format;
 const ReadPreference = require('./read_preference');
 const Buffer = require('safe-buffer').Buffer;
 const TopologyType = require('../sdam/topology_description').TopologyType;
+const MongoError = require('../error').MongoError;
+
+const MMAPv1_RETRY_WRITES_ERROR_CODE = 20;
 
 /**
  * Emit event if it exists
@@ -437,6 +440,24 @@ const isRetryableWritesSupported = function(topology) {
   return true;
 };
 
+const MMAPv1_RETRY_WRITES_ERROR_MESSAGE =
+  'This MongoDB deployment does not support retryable writes. Please add retryWrites=false to your connection string.';
+
+function getMMAPError(err) {
+  if (err.code !== MMAPv1_RETRY_WRITES_ERROR_CODE || !err.errmsg.includes('Transaction numbers')) {
+    return err;
+  }
+
+  // According to the retryable writes spec, we must replace the error message in this case.
+  // We need to replace err.message so the thrown message is correct and we need to replace err.errmsg to meet the spec requirement.
+  const newErr = new MongoError({
+    message: MMAPv1_RETRY_WRITES_ERROR_MESSAGE,
+    errmsg: MMAPv1_RETRY_WRITES_ERROR_MESSAGE,
+    originalError: err
+  });
+  return newErr;
+}
+
 module.exports.SessionMixins = SessionMixins;
 module.exports.resolveClusterTime = resolveClusterTime;
 module.exports.inquireServerState = inquireServerState;
@@ -451,3 +472,4 @@ module.exports.diff = diff;
 module.exports.Interval = Interval;
 module.exports.Timeout = Timeout;
 module.exports.isRetryableWritesSupported = isRetryableWritesSupported;
+module.exports.getMMAPError = getMMAPError;