[ntuple] remove "cluster bunch size" from public read options

This option has been useful for performance studies. It specifies the
number of clusters to be preloaded in the cluster cache. Since the size
of clusters is a priori unknown, this option is not well suited as a
general interface. Eventually, the option will be replaced by a prefetch
setting based on available memory ("prefill at max x MB").

tree/dataframe/src/RNTupleDS.cxx

@@ -395,7 +395,7 @@ const ROOT::Experimental::RNTupleReadOptions &GetOpts()
          std::string envStr{env};
          auto envNum{std::stoul(envStr)};
          envNum = envNum == 0 ? 1 : envNum;
-         opts.SetClusterBunchSize(envNum);
+         Internal::RNTupleReadOptionsManip::SetClusterBunchSize(opts, envNum);
       }
    });
    return opts;

tree/ntuple/v7/inc/ROOT/RNTupleReadOptions.hxx

@@ -19,6 +19,18 @@
 namespace ROOT {
 namespace Experimental {
 
+class RNTupleReadOptions;
+
+namespace Internal {
+
+class RNTupleReadOptionsManip final {
+public:
+   static unsigned int GetClusterBunchSize(const RNTupleReadOptions &options);
+   static void SetClusterBunchSize(RNTupleReadOptions &options, unsigned int val);
+};
+
+} // namespace Internal
+
 // clang-format off
 /**
 \class ROOT::Experimental::RNTupleReadOptions
@@ -29,6 +41,8 @@ All page source classes need to support the common options.
 */
 // clang-format on
 class RNTupleReadOptions {
+   friend class Internal::RNTupleReadOptionsManip;
+
 public:
    enum class EClusterCache {
       kOff,
@@ -52,16 +66,27 @@ public:
    EClusterCache GetClusterCache() const { return fClusterCache; }
    void SetClusterCache(EClusterCache val) { fClusterCache = val; }
 
-   unsigned int GetClusterBunchSize() const { return fClusterBunchSize; }
-   void SetClusterBunchSize(unsigned int val) { fClusterBunchSize = val; }
-
    EImplicitMT GetUseImplicitMT() const { return fUseImplicitMT; }
    void SetUseImplicitMT(EImplicitMT val) { fUseImplicitMT = val; }
 
    bool HasMetricsEnabled() const { return fEnableMetrics; }
    void SetMetricsEnabled(bool enable) { fEnableMetrics = enable; }
 };
 
+namespace Internal {
+
+inline unsigned int RNTupleReadOptionsManip::GetClusterBunchSize(const RNTupleReadOptions &options)
+{
+   return options.fClusterBunchSize;
+}
+
+inline void RNTupleReadOptionsManip::SetClusterBunchSize(RNTupleReadOptions &options, unsigned int val)
+{
+   options.fClusterBunchSize = val;
+}
+
+} // namespace Internal
+
 } // namespace Experimental
 } // namespace ROOT
 

tree/ntuple/v7/src/RPageStorage.cxx

@@ -344,7 +344,8 @@ void ROOT::Experimental::Internal::RPageSource::UpdateLastUsedCluster(Descriptor
       itr = fPreloadedClusters.erase(itr);
    }
    std::size_t poolWindow = 0;
-   while ((itr != fPreloadedClusters.end()) && (poolWindow < 2 * fOptions.GetClusterBunchSize())) {
+   while ((itr != fPreloadedClusters.end()) &&
+          (poolWindow < 2 * RNTupleReadOptionsManip::GetClusterBunchSize(fOptions))) {
       ++itr;
       ++poolWindow;
    }

tree/ntuple/v7/src/RPageStorageDaos.cxx

@@ -492,7 +492,7 @@ ROOT::Experimental::Internal::RPageSourceDaos::RPageSourceDaos(std::string_view
                                                                const RNTupleReadOptions &options)
    : RPageSource(ntupleName, options),
      fURI(uri),
-     fClusterPool(std::make_unique<RClusterPool>(*this, options.GetClusterBunchSize()))
+     fClusterPool(std::make_unique<RClusterPool>(*this, RNTupleReadOptionsManip::GetClusterBunchSize(options)))
 {
    EnableDefaultMetrics("RPageSourceDaos");
 

tree/ntuple/v7/src/RPageStorageFile.cxx

@@ -251,9 +251,9 @@ void ROOT::Experimental::Internal::RPageSinkFile::CommitDatasetImpl(unsigned cha
 ////////////////////////////////////////////////////////////////////////////////
 
 ROOT::Experimental::Internal::RPageSourceFile::RPageSourceFile(std::string_view ntupleName,
-                                                               const RNTupleReadOptions &options)
-   : RPageSource(ntupleName, options),
-     fClusterPool(std::make_unique<RClusterPool>(*this, options.GetClusterBunchSize()))
+                                                               const RNTupleReadOptions &opts)
+   : RPageSource(ntupleName, opts),
+     fClusterPool(std::make_unique<RClusterPool>(*this, Internal::RNTupleReadOptionsManip::GetClusterBunchSize(opts)))
 {
    EnableDefaultMetrics("RPageSourceFile");
 }

tree/ntuple/v7/test/ntuple_storage_daos.cxx

@@ -112,7 +112,7 @@ TEST_F(RPageStorageDaos, Extended)
    }
 
    RNTupleReadOptions options;
-   options.SetClusterBunchSize(5);
+   ROOT::Experimental::Internal::RNTupleReadOptionsManip::SetClusterBunchSize(options, 5);
    auto ntuple = RNTupleReader::Open(ntupleName, daosUri, options);
    auto rdVector = ntuple->GetModel().GetDefaultEntry().GetPtr<std::vector<double>>("vector");
 
@@ -155,11 +155,11 @@ TEST_F(RPageStorageDaos, Options)
    }
 
    auto readOptions = RNTupleReadOptions();
-   readOptions.SetClusterBunchSize(3);
+   ROOT::Experimental::Internal::RNTupleReadOptionsManip::SetClusterBunchSize(readOptions, 3);
    ROOT::Experimental::Internal::RPageSourceDaos source(ntupleName, daosUri, readOptions);
    source.Attach();
    EXPECT_STREQ("RP_XSF", source.GetObjectClass().c_str());
-   EXPECT_EQ(3U, source.GetReadOptions().GetClusterBunchSize());
+   EXPECT_EQ(3U, ROOT::Experimental::Internal::RNTupleReadOptionsManip::GetClusterBunchSize(source.GetReadOptions()));
    EXPECT_EQ(1U, source.GetNEntries());
 }
 
@@ -286,7 +286,7 @@ TEST_F(RPageStorageDaos, CagedPages)
    {
       RNTupleReadOptions options;
       options.SetClusterCache(RNTupleReadOptions::EClusterCache::kOn);
-      options.SetClusterBunchSize(5);
+      ROOT::Experimental::Internal::RNTupleReadOptionsManip::SetClusterBunchSize(options, 5);
       auto ntuple = RNTupleReader::Open(ntupleName, daosUri, options);
       auto rdVector = ntuple->GetModel().GetDefaultEntry().GetPtr<std::vector<double>>("vector");