Add option to drop constant values in import

tools/dcdbcsvimport/dcdbcsvimport.cpp

@@ -57,6 +57,7 @@ typedef struct {
   std::string topic;
   std::string publicName;
   uint64_t count;
+  uint64_t prev;
 } sensor_t;
 
 void usage(int argc, char* argv[])
@@ -66,6 +67,7 @@ void usage(int argc, char* argv[])
   std::cout << "    -t <col>            - Column in the CSV that contains the timestamp [default: 0]" << std::endl;
   std::cout << "    -n <col>            - Sensor name column" << std::endl;
   std::cout << "    -c <col[,col,col]>  - Column in the CSV to use [default: all]" << std::endl;
+  std::cout << "    -d                  - Drop constant values" << std::endl;
   std::cout << "    -s <offset>         - MQTT suffix start value [default: 0]" << std::endl;
   std::cout << "    -p                  - Publish sensors" << std::endl;
 
@@ -129,9 +131,10 @@ int main(int argc, char** argv)
   int suffixStart = 0;
   int tsColumn = 0;
   std::set<int> columns;
+  bool dropConstantValues = false;
   bool publish = false;
   int sensorNameColumn = -1;
-  while ((ret=getopt(argc, argv, "+h:t:n:c:s:pv:"))!=-1) {
+  while ((ret=getopt(argc, argv, "+h:t:n:c:ds:pv:"))!=-1) {
     switch(ret) {
       case 'h':
 	host = optarg;
@@ -148,6 +151,9 @@ int main(int argc, char** argv)
 	for (boost::tokenizer<boost::escaped_list_separator<char> >::iterator i=tk.begin(); i!=tk.end();++i)
 	  columns.insert(std::stoi(*i));
       } break;
+      case 'd':
+	dropConstantValues = true;
+	break;
       case 's':
 	suffixStart = atoi(optarg);
 	std::cout << ret << ": " << optarg << std::endl;
@@ -294,8 +300,13 @@ int main(int argc, char** argv)
 	}
 	try {
 	  DCDB::SensorId sid(sensor->topic);
-	  sensorDataStore.insert(&sid, ts.getRaw(), std::stoll(*i));
-	  sensor->count++;
+	  uint64_t val = std::stoll(*i);
+	  if (!dropConstantValues || val != sensor->prev) {
+	    sensorDataStore.insert(&sid, ts.getRaw(), val);
+	    sensor->count++;
+	    sensor->prev = val;
+	    count++;
+	  }
 	}
 	catch (std::exception &e) {
 	  if (verbose > 1) {
@@ -303,7 +314,6 @@ int main(int argc, char** argv)
 	  }
 	}
 	total++;
-	count++;
 	if (total % 1000 == 0) {
 	  time_t t1 = time(NULL);
 	  if (t1 != t0) {