SERVER-46903 Ensure mongo shell respects readPreference for $out and $merge when 'Mongo.setReadPref' is called

4 files changed, 11 insertions, 91 deletions

diff --git a/jstests/aggregation/bugs/server18198.js b/jstests/aggregation/bugs/server18198.js
deleted file mode 100644
index 9aa26451161..00000000000
--- a/jstests/aggregation/bugs/server18198.js
+++ /dev/null
@@ -1,67 +0,0 @@
-// SERVER-18198 check read pref is only applied when there is no $out stage
-// in aggregate shell helper
-(function() {
-"use strict";
-var t = db.server18198;
-t.drop();
-
-var mongo = db.getMongo();
-
-try {
-    var commandsRan = [];
-    // hook in our patched mongo
-    var mockMongo = {
-        getSlaveOk: function() {
-            return true;
-        },
-        runCommand: function(db, cmd, opts) {
-            commandsRan.push({db: db, cmd: cmd, opts: opts});
-            return {ok: 1.0};
-        },
-        getReadPref: function() {
-            return {mode: "secondaryPreferred"};
-        },
-        getReadPrefMode: function() {
-            return "secondaryPreferred";
-        },
-        getMinWireVersion: function() {
-            return mongo.getMinWireVersion();
-        },
-        getMaxWireVersion: function() {
-            return mongo.getMaxWireVersion();
-        },
-        isReplicaSetMember: function() {
-            return mongo.isReplicaSetMember();
-        },
-        isMongos: function() {
-            return mongo.isMongos();
-        },
-        isCausalConsistency: function() {
-            return false;
-        },
-        getClusterTime: function() {
-            return mongo.getClusterTime();
-        },
-    };
-
-    db._mongo = mockMongo;
-    db._session = new _DummyDriverSession(mockMongo);
-
-    // this query should not get a read pref
-    t.aggregate([{$sort: {"x": 1}}, {$out: "foo"}]);
-    assert.eq(commandsRan.length, 1);
-    // check that it doesn't have a read preference
-    assert(!commandsRan[0].cmd.hasOwnProperty("$readPreference"));
-
-    commandsRan = [];
-
-    t.aggregate([{$sort: {"x": 1}}]);
-    // check another command was run
-    assert.eq(commandsRan.length, 1);
-    // check that it has a read preference
-    assert(commandsRan[0].cmd.hasOwnProperty("$readPreference"));
-} finally {
-    db._mongo = mongo;
-    db._session = new _DummyDriverSession(mongo);
-}
-})();
diff --git a/jstests/noPassthrough/aggregation_out_on_secondary.js b/jstests/noPassthrough/aggregation_out_on_secondary.js
index ef9c7894c2b..32a5f5668e9 100644
--- a/jstests/noPassthrough/aggregation_out_on_secondary.js
+++ b/jstests/noPassthrough/aggregation_out_on_secondary.js
@@ -26,6 +26,9 @@ const readColl = primaryDB[readCollName];
 
 const secondary = rs.getSecondary();
 const secondaryDB = secondary.getDB(dbName);
+const replSetConn = new Mongo(rs.getURL());
+replSetConn.setReadPref("secondary");
+const db = replSetConn.getDB(dbName);
 // Keeps track of values which we expect the aggregate command to return.
 let expectedResults = [];
 // Insert some documents which our pipeline will eventually read from.
@@ -44,10 +47,7 @@ assert.commandWorked(secondaryDB.setProfilingLevel(2));
 
 const pipeline = [{$group: {_id: "$groupKey", sum: {$sum: "$num"}}}, {$out: outCollName}];
 const comment = "$out issued to secondary";
-assert.eq(secondaryDB[readCollName]
-              .aggregate(pipeline, {$readPreference: {mode: "secondary"}, comment: comment})
-              .itcount(),
-          0);
+assert.eq(db[readCollName].aggregate(pipeline, {comment: comment}).itcount(), 0);
 
 // Verify that $out wrote to the primary and that query is correct.
 assert(anyEq(primaryDB[outCollName].find().toArray(), expectedResults));
diff --git a/jstests/noPassthrough/merge_on_secondary.js b/jstests/noPassthrough/merge_on_secondary.js
index 1c91a04ef34..8db2685cb26 100644
--- a/jstests/noPassthrough/merge_on_secondary.js
+++ b/jstests/noPassthrough/merge_on_secondary.js
@@ -16,12 +16,15 @@ replTest.awaitReplication();
 const primary = replTest.getPrimary().getDB("test");
 const secondary = replTest.getSecondary().getDB("test");
 assert.commandWorked(primary.setProfilingLevel(2));
-secondary.getMongo().setReadPref("secondary");
 
 const inputCollPrimary = primary.getCollection("inputColl");
-const inputCollSecondary = secondary.getCollection("inputColl");
 const outColl = primary.getCollection("outColl");
 
+const replSetConn = new Mongo(replTest.getURL());
+replSetConn.setReadPref("secondary");
+const db = replSetConn.getDB("test");
+const inputColl = db["inputColl"];
+
 assert.commandWorked(inputCollPrimary.insert({_id: 0, a: 1}, {writeConcern: {w: 2}}));
 assert.commandWorked(inputCollPrimary.insert({_id: 1, a: 2}, {writeConcern: {w: 2}}));
 
@@ -35,7 +38,7 @@ withEachMergeMode(({whenMatchedMode, whenNotMatchedMode}) => {
 
     const commentStr = "whenMatched_" + whenMatchedMode + "_whenNotMatched_" + whenNotMatchedMode;
     assert.eq(0,
-              inputCollSecondary
+              inputColl
                   .aggregate([{
                                  $merge: {
                                      into: outColl.getName(),
diff --git a/src/mongo/shell/db.js b/src/mongo/shell/db.js
index 5a10d55ff5f..62bd56bf8c5 100644
--- a/src/mongo/shell/db.js
+++ b/src/mongo/shell/db.js
@@ -229,23 +229,7 @@ DB.prototype._runAggregate = function(cmdObj, aggregateOptions) {
         cmdObj.cursor = {};
     }
 
-    const pipeline = cmdObj.pipeline;
-
-    // Check whether the pipeline has a stage which performs writes like $out. If not, we may
-    // run on a Secondary and should attach a readPreference.
-    const hasWritingStage = (function() {
-        if (pipeline.length == 0) {
-            return false;
-        }
-        const lastStage = pipeline[pipeline.length - 1];
-        return lastStage.hasOwnProperty("$out") || lastStage.hasOwnProperty("$merge");
-    }());
-
-    const doAgg = function(cmdObj) {
-        return hasWritingStage ? this.runCommand(cmdObj) : this.runReadCommand(cmdObj);
-    }.bind(this);
-
-    const res = doAgg(cmdObj);
+    const res = this.runReadCommand(cmdObj);
 
     if (!res.ok && (res.code == 17020 || res.errmsg == "unrecognized field \"cursor") &&
         !("cursor" in aggregateOptions)) {