JSON Configuration from command line

Summary: Treadmill currently supports a configuration file.  But specifying the configuration blob directly from a flag would be more convenient, otherwise we would have to add new logic to write a file just to be read back in.

Reviewed By: mackorone

Differential Revision: D4335439

fbshipit-source-id: b679e3db69879cf59d69dc59475990aedf01ae27

Treadmill.cpp

@@ -76,6 +76,12 @@ DEFINE_string(config_in_file,
               "",
               "Config filename to pass into the workload in JSON format.");
 
+DEFINE_string(config_in_json,
+              "",
+              "Configuration string to be parsed as JSON for the workload. "
+              "If --config_in_file is also specified, "
+              "the configs are merged.");
+
 // Config filename to export from the workload in JSON format
 DEFINE_string(config_out_file,
               "",

Treadmill.h

@@ -15,6 +15,7 @@
 #include <vector>
 
 #include <folly/futures/helpers.h>
+#include <folly/json.h>
 #include <folly/String.h>
 #include <gflags/gflags.h>
 #include <glog/logging.h>
@@ -59,6 +60,9 @@ DECLARE_int32(max_outstanding_requests);
 // Config filename to pass into the workload in JSON format
 DECLARE_string(config_in_file);
 
+// Config string to pass into the workload in JSON format
+DECLARE_string(config_in_json);
+
 // Config filename to export from the workload in JSON format
 DECLARE_string(config_out_file);
 
@@ -103,6 +107,10 @@ int run(int argc, char* argv[]) {
   if (FLAGS_config_in_file != "") {
     config = readDynamicFromFile(FLAGS_config_in_file);
   }
+  if (FLAGS_config_in_json != "") {
+    folly::dynamic config2 = folly::parseJson(FLAGS_config_in_json);
+    config.update(config2);
+  }
   int cpu_affinity_list[FLAGS_number_of_workers];
   std::fill_n(cpu_affinity_list, FLAGS_number_of_workers, -1);