COB-66: Log which IERS tables we use, and how old they are.

RTCP/Cobalt/InputProc/src/Delays/Delays.cc

@@ -27,11 +27,24 @@
 #include <Common/Thread/Mutex.h>
 #include <Common/Thread/Cancellation.h>
 #include <CoInterface/Exceptions.h>
+#include <CoInterface/TimeFuncs.h>
 
 #ifdef HAVE_CASACORE
 #include <casacore/measures/Measures/MEpoch.h>
 #include <casacore/measures/Measures/MCDirection.h>
 #include <casacore/casa/Exceptions/Error.h>
+#include <casacore/measures/Measures/MeasIERS.h>
+#include <casacore/tables/Tables/Table.h>
+#include <casacore/tables/Tables/TableRecord.h>
+#include <casacore/tables/Tables/ScalarColumn.h>
+#include <casacore/casa/Containers/RecordField.h>
+#include <casacore/casa/OS/Time.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <cstdlib>
+#include <limits.h>
 #endif
 
 
@@ -39,6 +52,10 @@ namespace LOFAR
 {
   namespace Cobalt
   {
+    static std::string time2str(const time_t time)
+    {
+      return TimeDouble::toString(time, false);
+    }
 
     //##----------------  Public methods  ----------------##//
 
@@ -53,6 +70,11 @@ namespace LOFAR
       ASSERTSTR(test(), "Delay compensation engine is broken");
 
       init();
+
+      // Log TAI_UTC table information to inform the user about the age of the delay information we're about to use
+      struct IERS_tablestats stats = get_IERS_tablestats();
+
+      LOG_INFO_STR("Using IERS table " << stats.realpath << ", last entry is " << time2str(stats.last_entry_timestamp) << ", table written on " << time2str(stats.last_fs_modification));
     }
 
 
@@ -91,9 +113,56 @@ namespace LOFAR
       return MVEpoch(day + 40587., frac);
     }
 
+    struct Delays::IERS_tablestats Delays::get_IERS_tablestats()
+    {
+      struct IERS_tablestats result;
+
+      Table table;
+      TableRecord kws;
+      ROTableRow row;
+      RORecordFieldPtr<Double> rfp[1];
+      String vs;
+      Double dt;
+      Int N = 0;
+      String rfn[1];
+
+      // locate TAI_UTC table
+      if (!MeasIERS::getTable(table, kws, row, rfp, vs, dt, N, rfn, "IERSeop97", "measures.ierseop97.directory", ""))
+        THROW(Exception, "Cannot open IERSeop97 table");
+
+      result.path = table.tableName();
+
+      // resolve any symlinks, which typically includes f.e. "current"
+      char resolved_path[PATH_MAX];
+      if (!realpath(table.tableName().c_str(), resolved_path))
+        THROW_SYSCALL("realpath()");
+
+      result.realpath = resolved_path;
+
+      // obtain table last modification on file system
+      struct stat filestats;
+
+      if (stat(resolved_path, &filestats) != 0)
+        THROW_SYSCALL("stat(): Cannot access IERSeop97 table");
+
+      result.last_fs_modification = filestats.st_mtime;
+
+      // read which timestamps the table contains
+      casacore::Vector<Double> mjds;
+      ScalarColumn<Double>(table, "MJD").getColumn(mjds);
+      casacore::Double last_mjd = mjds[mjds.size()-1];
+
+      Time last_time(last_mjd + 2400000);
+
+      // MJD -> seconds since 1970
+      result.last_entry_timestamp = (last_mjd - 40587) * 86400;
+
+      return result;
+    }
 
     bool Delays::test()
     {
+      // Test whether delays can be calculated
       try {
         ScopedLock lock(casacoreMutex);
         ScopedDelayCancellation dc;
@@ -122,6 +191,8 @@ namespace LOFAR
         return false;
       }
 
+      // Print information about age of TAI_UTC table
+
       return true;
     }
 
@@ -234,6 +305,19 @@ namespace LOFAR
     void Delays::init() {
     }
 
+    struct Delays::IERS_tablestats Delays::get_IERS_tablestats() {
+      struct IERS_tablestats result;
+      result.path     = "/dev/null";
+      result.realpath = "/dev/null";
+      result.last_fs_modification = 0;
+      result.last_entry_timestamp = 0;
+      return result;
+    }
+
+    std::time_t Delays::TAI_UTC_tableage() {
+      return 0;
+    }
+
     void Delays::calcDelays( const TimeStamp &timestamp, AllDelays &result ) {
       (void)timestamp;