add MySQLMetaImpl::UpdateTableFilesToIndex and set maximum_memory to default if config value = 0

Former-commit-id: f8943149b9737b2f0107308aa96a7f77acdf9ce4

cpp/src/db/Options.h

@@ -63,7 +63,7 @@ struct Options {
     size_t  index_trigger_size = ONE_GB;            //unit: byte
     DBMetaOptions meta;
     int mode = MODE::SINGLE;
-    float maximum_memory = 4 * ONE_GB;
+    size_t maximum_memory = 4 * ONE_GB;
 }; // Options
 
 

cpp/src/server/DBWrapper.cpp

@@ -28,11 +28,11 @@ DBWrapper::DBWrapper() {
     if(index_size > 0) {//ensure larger than zero, unit is MB
         opt.index_trigger_size = (size_t)index_size * engine::ONE_MB;
     }
-    float maximum_memory = config.GetFloatValue(CONFIG_MAXMIMUM_MEMORY);
+    int64_t maximum_memory = config.GetInt64Value(CONFIG_MAXMIMUM_MEMORY);
     if (maximum_memory > 1.0) {
         opt.maximum_memory = maximum_memory * engine::ONE_GB;
     }
-    else {
+    else if (maximum_memory != 0) { //if maximum_memory = 0, set it to default
         std::cout << "ERROR: maximum_memory should be at least 1 GB" << std::endl;
         kill(0, SIGUSR1);
     }