Caliper patch: record timestamps with µs precision

dcdbpusher/Caliper/patch

@@ -8,3 +8,16 @@
  add_subdirectory(debug)
  add_subdirectory(env)
  add_subdirectory(event)
+
+--- a/src/services/timestamp/Timestamp.cpp
++++ b/src/services/timestamp/Timestamp.cpp
+@@ -208,7 +208,8 @@ class Timestamp
+ 
+         if (record_timestamp && (scope & CALI_SCOPE_PROCESS))
+             sbuf->append(timestamp_attr.id(),
+-                         Variant(cali_make_variant_from_uint(chrono::system_clock::to_time_t(chrono::system_clock::now()))));
++                         Variant(cali_make_variant_from_uint(
++                                 chrono::duration_cast<chrono::microseconds>(chrono::system_clock::now().time_since_epoch()).count())));
+     }
+ 
+     void post_init_cb(Caliper* c, Channel* chn) {

dcdbpusher/sensors/caliper/CaliperSensorGroup.cpp

@@ -166,11 +166,7 @@ void CaliperSensorGroup::read() {
 
         reading_t reading;
         reading.value     = 1;
-        reading.timestamp = S_TO_NS(std::stoull(timestamp)); //Caliper timestamps are seconds since UNIX epoch
-
-        //a timestamp with a precision of seconds is not unique enough --> append current nanoseconds
-        uint64_t now_ns = getTimestamp() % 1000000000;
-        reading.timestamp += now_ns;
+        reading.timestamp = US_TO_NS(std::stoull(timestamp)); //Caliper timestamps are microseconds since UNIX epoch
 
         S_Ptr s;
         auto it = _sensorIndex.find(feName);