From 905b48745e6fc03a4cd071f6c50d01ba211da746 Mon Sep 17 00:00:00 2001
From: Prottay Das <prottay@alipap1.cern.ch>
Date: Wed, 6 May 2026 19:43:45 +0200
Subject: [PATCH] added a linked table for time

---
 PWGLF/DataModel/ZDCCalTables.h           | 16 +++++++++++++++
 PWGLF/TableProducer/Common/zdcvector.cxx | 25 +++++++++++++++++++++++-
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/PWGLF/DataModel/ZDCCalTables.h b/PWGLF/DataModel/ZDCCalTables.h
index 40b5fbdd575..097fb57e16c 100644
--- a/PWGLF/DataModel/ZDCCalTables.h
+++ b/PWGLF/DataModel/ZDCCalTables.h
@@ -85,5 +85,21 @@ DECLARE_SOA_TABLE(ZDCEnergyTables, "AOD", "ZDCENERGY",
 
 using ZDCEnergyTable = ZDCEnergyTables::iterator;
 
+// Extra optional linked table for time information.
+// It only stores timestamp and relative time, linked back to ZDCCalTables.
+namespace zdctimetable
+{
+DECLARE_SOA_INDEX_COLUMN(ZDCCalTable, zdcCalTable);
+
+DECLARE_SOA_COLUMN(Timestamp, timestamp, uint64_t); // bc.timestamp(), in ms
+DECLARE_SOA_COLUMN(TimeMin, timeMin, float);        // time from first event seen in this run, in minutes
+} // namespace zdctimetable
+
+DECLARE_SOA_TABLE(ZDCTimeTables, "AOD", "ZDCTIME",
+                  zdctimetable::ZDCCalTableId,
+                  zdctimetable::Timestamp,
+                  zdctimetable::TimeMin);
+
+using ZDCTimeTable = ZDCTimeTables::iterator;
 } // namespace o2::aod
 #endif // PWGLF_DATAMODEL_ZDCCALTABLES_H_
diff --git a/PWGLF/TableProducer/Common/zdcvector.cxx b/PWGLF/TableProducer/Common/zdcvector.cxx
index dd1b9860d05..b6b5407156f 100644
--- a/PWGLF/TableProducer/Common/zdcvector.cxx
+++ b/PWGLF/TableProducer/Common/zdcvector.cxx
@@ -44,7 +44,9 @@
 #include <chrono>
 #include <cmath>
 #include <cstddef>
+#include <cstdint>
 #include <string>
+#include <unordered_map>
 #include <vector>
 
 using namespace o2;
@@ -59,6 +61,7 @@ struct zdcvector {
 
   Produces<aod::ZDCCalTables> zdccaltable;
   Produces<aod::ZDCEnergyTables> zdcenergytable;
+  Produces<aod::ZDCTimeTables> zdctimetable;
 
   // Configurables.
   struct : ConfigurableGroup {
@@ -100,8 +103,10 @@ struct zdcvector {
   } rctCut;
 
   Configurable<bool> storeZdcEnergy{"storeZdcEnergy", true, "Store ZDC tower/common energies in a linked extra table"};
+  Configurable<bool> storeZdcTime{"storeZdcTime", true, "Store timestamp and time from first event of run"};
 
   RCTFlagsChecker rctChecker;
+  std::unordered_map<int, uint64_t> runStartTime;
 
   void init(o2::framework::InitContext&)
   {
@@ -194,6 +199,17 @@ struct zdcvector {
     float znc3 = 0.f;
 
     auto bc = collision.foundBC_as<BCsRun3>();
+    const uint64_t timestampzdc = bc.timestamp(); // in milliseconds
+
+    float timeInMinutes = 0.f;
+
+    auto itStart = runStartTime.find(currentRunNumber);
+    if (itStart == runStartTime.end()) {
+      runStartTime[currentRunNumber] = timestampzdc;
+      timeInMinutes = 0.f;
+    } else {
+      timeInMinutes = static_cast<float>(timestampzdc - itStart->second) / 60000.f;
+    }
 
     // Helper to keep your early-return structure unchanged.
     // Every time ZDCCalTables is filled, the optional linked energy table is also filled.
@@ -213,8 +229,10 @@ struct zdcvector {
                   qyA,
                   qyC);
 
+      auto zdcCalIndex = zdccaltable.lastIndex();
+
       if (storeZdcEnergy) {
-        zdcenergytable(zdccaltable.lastIndex(),
+        zdcenergytable(zdcCalIndex,
                        znaEnergycommon,
                        zncEnergycommon,
                        zna0,
@@ -226,6 +244,11 @@ struct zdcvector {
                        znc2,
                        znc3);
       }
+      if (storeZdcTime) {
+        zdctimetable(zdcCalIndex,
+                     timestampzdc,
+                     timeInMinutes);
+      }
     };
 
     if (!bc.has_zdc()) {