From 42c40db7ef341b3dbf2b975e61d87ce8000042a9 Mon Sep 17 00:00:00 2001
From: Arun Banala <arun.banala@10gen.com>
Date: Mon, 21 Oct 2019 10:06:08 +0000
Subject: SERVER-43706 M/R Agg: Support referencing 'scope' variables in
 translated aggregation pipeline for mongos

---
 .../suites/sharding_map_reduce_agg.yaml            |  1 +
 jstests/sharding/map_reduce_scope.js               | 42 ++++++++++++++++++++++
 src/mongo/s/commands/cluster_map_reduce_agg.cpp    | 18 ++++++----
 3 files changed, 55 insertions(+), 6 deletions(-)
 create mode 100644 jstests/sharding/map_reduce_scope.js

diff --git a/buildscripts/resmokeconfig/suites/sharding_map_reduce_agg.yaml b/buildscripts/resmokeconfig/suites/sharding_map_reduce_agg.yaml
index 175efe9f381..1f71cbb0279 100644
--- a/buildscripts/resmokeconfig/suites/sharding_map_reduce_agg.yaml
+++ b/buildscripts/resmokeconfig/suites/sharding_map_reduce_agg.yaml
@@ -11,6 +11,7 @@ selector:
   - jstests/sharding/localhostAuthBypass.js
   - jstests/sharding/map_reduce_invalid_output_collection.js
   - jstests/sharding/map_reduce_invalid_result_set.js
+  - jstests/sharding/map_reduce_scope.js
   - jstests/sharding/max_time_ms_sharded.js
   - jstests/sharding/mr_and_agg_versioning.js
   - jstests/sharding/mr_shard_version.js
diff --git a/jstests/sharding/map_reduce_scope.js b/jstests/sharding/map_reduce_scope.js
new file mode 100644
index 00000000000..8657a99afdb
--- /dev/null
+++ b/jstests/sharding/map_reduce_scope.js
@@ -0,0 +1,42 @@
+/**
+ * Test to verify 'scope' parameter of mapReduce command. This test verfies that 'map', 'reduce' and
+ * 'finalize' functions can use 'scope' variable passed in the input.
+ */
+(function() {
+"use strict";
+
+const st = new ShardingTest({shards: 2});
+const dbName = jsTest.name();
+const coll = st.s.getDB(dbName).coll;
+st.s.adminCommand({enableSharding: dbName});
+st.ensurePrimaryShard(dbName, st.shard0.shardName);
+
+function runTest(coll) {
+    const map = function() {
+        emit(xx.val, this.a);
+    };
+    const reduce = function(key, values) {
+        return {reduce: Array.sum(values) + xx.val};
+    };
+    const finalize = function(key, values) {
+        values.finalize = xx.val + 1;
+        return values;
+    };
+    const res = assert.commandWorked(
+        coll.mapReduce(map, reduce, {finalize: finalize, out: {inline: 1}, scope: {xx: {val: 9}}}));
+    assert.eq(9, res.results[0].value.reduce);
+    assert.eq(10, res.results[0].value.finalize);
+}
+
+assert.commandWorked(coll.insert({a: -4}));
+assert.commandWorked(coll.insert({a: 4}));
+
+// Run test when a single shard is targetted.
+runTest(coll);
+
+// Run test when more than one shard is targetted.
+st.shardColl("coll", {a: 1}, {a: 0});
+runTest(coll);
+
+st.stop();
+})();
diff --git a/src/mongo/s/commands/cluster_map_reduce_agg.cpp b/src/mongo/s/commands/cluster_map_reduce_agg.cpp
index 837de4feda2..6df1e77250c 100644
--- a/src/mongo/s/commands/cluster_map_reduce_agg.cpp
+++ b/src/mongo/s/commands/cluster_map_reduce_agg.cpp
@@ -77,7 +77,10 @@ auto makeExpressionContext(OperationContext* opCtx,
                                       parsedMr.getOutOptions().getCollectionName()};
         resolvedNamespaces.try_emplace(outNss.coll(), outNss, std::vector<BSONObj>{});
     }
-
+    auto runtimeConstants = Variables::generateRuntimeConstants(opCtx);
+    if (parsedMr.getScope()) {
+        runtimeConstants.setJsScope(parsedMr.getScope()->getObj());
+    }
     auto expCtx = make_intrusive<ExpressionContext>(
         opCtx,
         boost::none,  // explain
@@ -87,7 +90,7 @@ auto makeExpressionContext(OperationContext* opCtx,
         parsedMr.getBypassDocumentValidation().get_value_or(false),
         nss,
         collationObj,
-        boost::none,  // runtimeConstants
+        runtimeConstants,
         std::move(resolvedCollator),
         std::make_shared<MongoSInterface>(),
         std::move(resolvedNamespaces),
@@ -100,10 +103,13 @@ Document serializeToCommand(BSONObj originalCmd, const MapReduce& parsedMr, Pipe
     MutableDocument translatedCmd;
 
     translatedCmd["aggregate"] = Value(parsedMr.getNamespace().coll());
-    translatedCmd["pipeline"] = Value(pipeline->serialize());
-    translatedCmd["cursor"] = Value(Document{{"batchSize", std::numeric_limits<long long>::max()}});
-    translatedCmd["allowDiskUse"] = Value(true);
-    translatedCmd["fromMongos"] = Value(true);
+    translatedCmd[AggregationRequest::kPipelineName] = Value(pipeline->serialize());
+    translatedCmd[AggregationRequest::kCursorName] =
+        Value(Document{{"batchSize", std::numeric_limits<long long>::max()}});
+    translatedCmd[AggregationRequest::kAllowDiskUseName] = Value(true);
+    translatedCmd[AggregationRequest::kFromMongosName] = Value(true);
+    translatedCmd[AggregationRequest::kRuntimeConstants] =
+        Value(pipeline->getContext()->getRuntimeConstants().toBSON());
 
     // Append generic command options.
     for (const auto& elem : CommandHelpers::appendPassthroughFields(originalCmd, BSONObj())) {
-- 
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