From 48d18f24c99ee1b8f1828db1e681cbe03b110db9 Mon Sep 17 00:00:00 2001
From: Sebastien Ponce <sebastien.ponce@cern.ch>
Date: Mon, 5 Dec 2022 11:29:14 +0100
Subject: [PATCH] Allow Root Sinks to write to a common file
This is done by only updating the potentially existing file when writing and droping the file at initialization to not mix data from 2 rounds.
There is no thread safety issue for now as we write in the stop method
---
.../RootHistogramSinkBase.h | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/GaudiCommonSvc/include/HistogramPersistencySvc/RootHistogramSinkBase.h b/GaudiCommonSvc/include/HistogramPersistencySvc/RootHistogramSinkBase.h
index a72f847cc8..c1529b7dd1 100644
--- a/GaudiCommonSvc/include/HistogramPersistencySvc/RootHistogramSinkBase.h
+++ b/GaudiCommonSvc/include/HistogramPersistencySvc/RootHistogramSinkBase.h
@@ -16,6 +16,7 @@
#include <nlohmann/json.hpp>
+#include <filesystem>
#include <map>
#include <string>
#include <vector>
@@ -39,9 +40,21 @@ namespace Gaudi::Histograming::Sink {
.orThrow( "Unable to set typesToSaveProperty", "Histograming::Sink::Base" );
}
+ StatusCode initialize() override {
+ return BaseSink::initialize().andThen( [&] {
+ // empty output file if it exists, as we will update it at the end
+ // This allows multiple Sinks to write to the same ROOT file
+ std::filesystem::remove( m_fileName.value() );
+ } );
+ }
+
StatusCode stop() override {
return Service::stop().andThen( [&] {
- TFile histoFile( m_fileName.value().c_str(), "RECREATE" );
+ // File is updated so that multiple sinks can write to the same file
+ // As we are in stop, there is no multithreading so it is safe
+ // As we dropped the file at initialization, no old data from a previous
+ // run may be mixed with new one
+ TFile histoFile( m_fileName.value().c_str(), "UPDATE" );
applytoAllEntities(
[&histoFile, this]( auto& ent ) {
auto j = ent.toJSON();
--
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