CXX-516 support nolock in eval

Author: amidvidy

src/mongo/client/dbclient.cpp

@@ -1458,11 +1458,15 @@ namespace mongo {
         return result.obj();
     }
 
-    bool DBClientWithCommands::eval(const string &dbname, const string &jscode, BSONObj& info, BSONElement& retValue, BSONObj *args) {
+    bool DBClientWithCommands::eval(const string &dbname, const string &jscode, BSONObj& info, BSONElement& retValue, BSONObj *args, bool nolock) {
         BSONObjBuilder b;
         b.appendCode("$eval", jscode);
-        if ( args )
+        if ( args ) {
             b.appendArray("args", *args);
+        }
+        if ( nolock ) {
+            b.appendBool("nolock", true);
+        }
         bool ok = runCommand(dbname, b.done(), info);
         if ( ok )
             retValue = info.getField("retval");

src/mongo/client/dbclientinterface.h

@@ -1075,12 +1075,13 @@ namespace mongo {
            retValue  return value from the jscode function.
            args      args to pass to the jscode function.  when invoked, the 'args' variable will be defined
                      for use by the jscode.
+           nolock    if true, the server will not take a global write lock when executing the jscode.
 
            returns true if runs ok.
 
            See testDbEval() in dbclient.cpp for an example of usage.
         */
-        bool eval(const std::string &dbname, const std::string &jscode, BSONObj& info, BSONElement& retValue, BSONObj *args = 0);
+        bool eval(const std::string &dbname, const std::string &jscode, BSONObj& info, BSONElement& retValue, BSONObj *args = 0, bool nolock = false);
 
         /** validate a collection, checking for errors and reporting back statistics.
             this operation is slow and blocking.