SERVER-9448: make map and reduce argument and receiver objects mutable

2 files changed, 65 insertions, 3 deletions

diff --git a/jstests/mr_mutable_properties.js b/jstests/mr_mutable_properties.js
new file mode 100644
index 00000000000..7c4442aab9e
--- /dev/null
+++ b/jstests/mr_mutable_properties.js
@@ -0,0 +1,62 @@
+// See SERVER-9448
+// Test argument and receiver (aka 'this') objects and their children can be mutated
+// in Map, Reduce and Finalize functions
+
+var collection = db.mrMutableReceiver;
+collection.drop();
+collection.insert({a:1});
+
+var map = function() {
+    // set property on receiver
+    this.feed = {beef:1};
+
+    // modify property on receiever
+    this.a = {cake:1};
+    emit(this._id, this.feed);
+    emit(this._id, this.a);
+}
+
+var reduce = function(key, values) {
+    // set property on receiver
+    this.feed = {beat:1};
+
+    // set property on key arg
+    key.fed = {mochi:1};
+
+    // push properties onto values array arg
+    values.push(this.feed);
+    values.push(key.fed);
+
+    // modify each value in the (modified) array arg
+    values.forEach(function(val) { val.mod = 1; });
+    return {food:values};
+}
+
+var finalize = function(key, values) {
+    // set property on receiver
+    this.feed = {ice:1};
+
+    // set property on key arg
+    key.fed = {cream:1};
+
+    // push properties onto values array arg
+    printjson(values);
+    values.food.push(this.feed);
+    values.food.push(key.fed);
+
+    // modify each value in the (modified) array arg
+    values.food.forEach(function(val) { val.mod = 1; });
+    return values;
+}
+
+var mr = collection.mapReduce(map, reduce, {finalize: finalize, out: {inline: 1}});
+printjson(mr);
+
+// verify mutated properties exist (order dictated by emit sequence and properties added)
+assert.eq(mr.results[0].value.food[0].beef, 1);
+assert.eq(mr.results[0].value.food[1].cake, 1);
+assert.eq(mr.results[0].value.food[2].beat, 1);
+assert.eq(mr.results[0].value.food[3].mochi, 1);
+assert.eq(mr.results[0].value.food[4].ice, 1);
+assert.eq(mr.results[0].value.food[5].cream, 1);
+mr.results[0].value.food.forEach(function(val) { assert.eq(val.mod, 1); });
diff --git a/src/mongo/db/commands/mr.cpp b/src/mongo/db/commands/mr.cpp
index 742392f04ee..8224783f8b6 100644
--- a/src/mongo/db/commands/mr.cpp
+++ b/src/mongo/db/commands/mr.cpp
@@ -73,8 +73,8 @@ namespace mongo {
         void JSMapper::map( const BSONObj& o ) {
             Scope * s = _func.scope();
             verify( s );
-            if ( s->invoke( _func.func() , &_params, &o , 0 , true, false, true ) )
-                throw UserException( 9014, str::stream() << "map invoke failed: " + s->getError() );
+            if (s->invoke(_func.func(), &_params, &o, 0, true))
+                uasserted(9014, str::stream() << "map invoke failed: " << s->getError());
         }
 
         /**
@@ -193,7 +193,7 @@ namespace mongo {
 
             Scope * s = _func.scope();
 
-            s->invokeSafe( _func.func() , &args, 0, 0, false, false, true );
+            s->invokeSafe(_func.func(), &args, 0);
             ++numReduces;
 
             if ( s->type( "__returnValue" ) == Array ) {