DPL Analysis: standalone AOD reader which by-passes root

This abstract the reading of I/O files from TFile, and introduces a new
plugin which is able to read them without using ROOT at all. The goal of this
is to demonstrate:

- reduced dependency on ROOT for I/O, getting rid of the interpreter overhead
- optimise access patterns based on the known AO2D structure, reducing the number of stats
- reduce memory usage by decompressing stream on the fly, rather than going through multiple tbuffers
- parallel decompression of baskets
- prefetching of dataframes
- support for https without depending of webdav libraries

Author: ktf

Framework/AODNative/CMakeLists.txt

@@ -0,0 +1,93 @@
+# Copyright 2019-2026 CERN and copyright holders of ALICE O2.
+# See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
+# All rights not expressly granted are reserved.
+#
+# This software is distributed under the terms of the GNU General Public
+# License v3 (GPL Version 3), copied verbatim in the file "COPYING".
+#
+# In applying this license CERN does not waive the privileges and immunities
+# granted to it by virtue of its status as an Intergovernmental Organization
+# or submit itself to any jurisdiction.
+
+# ROOT-free reader for AO2D files. Nothing in this directory may depend on
+# ROOT, at build or run time: see the check at the end of this file.
+o2_add_library(AODNative
+               SOURCES src/ByteSource.cxx
+                       src/LocalByteSource.cxx
+                       src/Container.cxx
+                       src/Objects.cxx
+                       src/Codecs.cxx
+                       src/Decoder.cxx
+                       src/ArrowTable.cxx
+                       src/ReadPlan.cxx
+               TARGETVARNAME targetName
+               PRIVATE_INCLUDE_DIRECTORIES ${CMAKE_CURRENT_LIST_DIR}/src
+               PUBLIC_LINK_LIBRARIES Arrow::arrow_shared
+               PRIVATE_LINK_LIBRARIES PkgConfig::zstd PkgConfig::lz4 PkgConfig::lzma ZLIB::ZLIB)
+
+# Reading over root:// needs the XRootD client, which does not depend on ROOT.
+if(XROOTD_FOUND AND XROOTD_CLIENT_FOUND)
+  target_sources(${targetName} PRIVATE src/XRootDByteSource.cxx)
+  target_include_directories(${targetName} SYSTEM PRIVATE ${XROOTD_INCLUDE_DIRS})
+  target_link_libraries(${targetName} PRIVATE ${XROOTD_CLIENT_LIBRARIES})
+  target_compile_definitions(${targetName} PRIVATE AODNATIVE_WITH_XROOTD)
+endif()
+
+# Public HTTP(S) with libcurl.
+if(TARGET CURL::libcurl)
+  target_sources(${targetName} PRIVATE src/HttpByteSource.cxx)
+  target_link_libraries(${targetName} PRIVATE CURL::libcurl)
+  target_compile_definitions(${targetName} PRIVATE AODNATIVE_WITH_CURL)
+endif()
+
+o2_add_executable(inspect
+                  COMPONENT_NAME aod-native
+                  SOURCES tools/inspect.cxx
+                  PUBLIC_LINK_LIBRARIES O2::AODNative)
+
+o2_add_executable(dump
+                  COMPONENT_NAME aod-native
+                  SOURCES tools/dump.cxx
+                  PUBLIC_LINK_LIBRARIES O2::AODNative)
+
+add_executable(o2-test-framework-aod-native
+               test/test_Codecs.cxx
+               test/test_Objects.cxx
+               test/test_Decoder.cxx
+               test/test_ReadPlan.cxx)
+target_include_directories(o2-test-framework-aod-native PRIVATE ${CMAKE_CURRENT_LIST_DIR}/src)
+target_link_libraries(o2-test-framework-aod-native PRIVATE O2::AODNative O2::Catch2 PkgConfig::zstd PkgConfig::lz4 PkgConfig::lzma ZLIB::ZLIB)
+
+get_filename_component(outdir ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/../tests ABSOLUTE)
+set_property(TARGET o2-test-framework-aod-native PROPERTY RUNTIME_OUTPUT_DIRECTORY ${outdir})
+
+add_test(NAME framework:aod-native COMMAND o2-test-framework-aod-native)
+
+# Measures private memory while decoding the files given on the command line.
+# It interposes glibc's malloc, so it is Linux only and cannot be built with sanitizers.
+if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
+  add_executable(o2-test-framework-aod-native-memory test/test_Memory.cxx)
+  target_link_libraries(o2-test-framework-aod-native-memory PRIVATE O2::AODNative)
+  set_property(TARGET o2-test-framework-aod-native-memory PROPERTY RUNTIME_OUTPUT_DIRECTORY ${outdir})
+endif()
+
+# libFuzzer target for the container, object and decoder layers. Needs clang,
+# and the whole library built with -fsanitize=address,undefined to be useful.
+option(AODNATIVE_FUZZ "Build the AODNative libFuzzer target" OFF)
+if(AODNATIVE_FUZZ)
+  add_executable(o2-fuzz-aod-native test/fuzz/fuzz_RootFile.cxx)
+  target_include_directories(o2-fuzz-aod-native PRIVATE ${CMAKE_CURRENT_LIST_DIR}/src)
+  target_compile_options(o2-fuzz-aod-native PRIVATE -fsanitize=fuzzer)
+  target_link_options(o2-fuzz-aod-native PRIVATE -fsanitize=fuzzer)
+  target_link_libraries(o2-fuzz-aod-native PRIVATE O2::AODNative PkgConfig::zstd PkgConfig::lz4 PkgConfig::lzma ZLIB::ZLIB)
+endif()
+
+# The reader core must not link ROOT, directly or through its dependencies.
+foreach(property LINK_LIBRARIES INTERFACE_LINK_LIBRARIES)
+  get_target_property(libs ${targetName} ${property})
+  foreach(lib IN LISTS libs)
+    if(lib MATCHES "ROOT::" OR lib MATCHES "O2::Framework")
+      message(FATAL_ERROR "O2::AODNative must not depend on ROOT, but links ${lib}")
+    endif()
+  endforeach()
+endforeach()