add function to return last data record timestamp

Summary:
analagous to getFirstDataRecordTime()

this is useful for testing purpose when, for example, writing a tool that translates timestamps

Reviewed By: georges-berenger

Differential Revision: D67035162

fbshipit-source-id: 200a678939d0a7a8ef8dec62cbbf06e716c70dc2

tools/vrs/test/VrsAppTest.cpp

@@ -300,6 +300,7 @@ TEST_F(VrsAppTest, ANDROID_DISABLED(mergeTimeFilterTest)) {
   // Data records are constrained by the +0.2 range
   EXPECT_NEAR(reader.getFirstDataRecordTime(), 2.002, 0.0001);
   EXPECT_NEAR(reader.getIndex().back().timestamp, 12.071, 0.0001);
+  EXPECT_NEAR(reader.getLastDataRecordTime(), 12.071, 0.0001);
 
   remove(outputFile.c_str());
 }

vrs/RecordFileReader.cpp

@@ -843,6 +843,15 @@ double RecordFileReader::getFirstDataRecordTime() const {
   return 0; // no data record...
 }
 
+double RecordFileReader::getLastDataRecordTime() const {
+  for (auto iter = recordIndex_.rbegin(); iter != recordIndex_.rend(); ++iter) {
+    if (iter->recordType == Record::Type::DATA) {
+      return iter->timestamp;
+    }
+  }
+  return 0;
+}
+
 bool RecordFileReader::readConfigRecords(
     const set<const IndexRecord::RecordInfo*>& configRecords,
     StreamPlayer* streamPlayer) {

vrs/RecordFileReader.h

@@ -352,6 +352,10 @@ class RecordFileReader {
   /// @return The timestamp for the file data record, or 0, if the file contains no data record.
   double getFirstDataRecordTime() const;
 
+  /// Timestamp for the last data record in the whole file.
+  /// @return The timestamp for the file data record, or 0, if the file contains no data record.
+  double getLastDataRecordTime() const;
+
   /// Helper function: Read a stream's first configuration record.
   /// This might be necessary to properly read records containing image or audio blocks,
   /// if their configuration is defined in a configuration record using datalayout conventions.