make bvar_max_dump_multi_dimension_metric_number modifiable (apache#2322

)

* make bvar_max_dump_multi_dimension_metric_number modifiable

* fix comments

---------

Co-authored-by: lhsoft <liuhuwork@gmail.com>

src/bvar/mvariable.cpp

@@ -36,7 +36,7 @@ DECLARE_bool(bvar_abort_on_same_name);
 extern bool s_bvar_may_abort;
 
 DEFINE_int32(bvar_max_multi_dimension_metric_number, 1024, "Max number of multi dimension");
-DEFINE_int32(bvar_max_dump_multi_dimension_metric_number, 0,
+DEFINE_int32(bvar_max_dump_multi_dimension_metric_number, 1024,
     "Max number of multi dimension metric number to dump by prometheus rpc service");
 
 static bool validator_bvar_max_multi_dimension_metric_number(const char*, int32_t v) {
@@ -47,9 +47,21 @@ static bool validator_bvar_max_multi_dimension_metric_number(const char*, int32_
     return true;
 }
 
+static bool validator_bvar_max_dump_multi_dimension_metric_number(const char*, int32_t v) {
+    if (v < 0) {
+        LOG(ERROR) << "Invalid bvar_max_dump_multi_dimension_metric_number=" << v;
+        return false;
+    }
+    return true;
+}
+
+
 const bool ALLOW_UNUSED dummp_bvar_max_multi_dimension_metric_number = ::GFLAGS_NS::RegisterFlagValidator(
     &FLAGS_bvar_max_multi_dimension_metric_number, validator_bvar_max_multi_dimension_metric_number);
 
+const bool ALLOW_UNUSED dummp_bvar_max_dump_multi_dimension_metric_number = ::GFLAGS_NS::RegisterFlagValidator(
+  &FLAGS_bvar_max_dump_multi_dimension_metric_number, validator_bvar_max_dump_multi_dimension_metric_number);
+
 class MVarEntry {
 public:
     MVarEntry() : var(NULL) {}