ADIOS2: enable stats by default, starting ADIOS2 v2.12.0

This PR ornladios/ADIOS2#4502 changes things a bit performance-wise.

Author: franzpoeschel

examples/10_streaming_write.cpp

@@ -50,7 +50,7 @@ int main()
     // Iterations can be accessed independently from one another. This more
     // restricted mode enables performance optimizations in the backends, and
     // more importantly is compatible with streaming I/O.
-    Series series = Series("electrons.sst", Access::CREATE_LINEAR, R"(
+    Series series = Series("electrons.bp5", Access::CREATE_LINEAR, R"(
 {
   "adios2": {
     "engine": {

include/openPMD/IO/ADIOS/macros.hpp

@@ -34,6 +34,9 @@
          ADIOS2_VERSION_PATCH >=                                               \
      2101)
 
+#define openPMD_HAS_ADIOS_2_12                                                 \
+    (ADIOS2_VERSION_MAJOR * 100 + ADIOS2_VERSION_MINOR >= 212)
+
 #if defined(ADIOS2_HAVE_BP5) || openPMD_HAS_ADIOS_2_10
 // ADIOS2 v2.10 no longer defines this
 #define openPMD_HAVE_ADIOS2_BP5 1

src/IO/ADIOS/ADIOS2File.cpp

@@ -718,6 +718,7 @@ void ADIOS2File::configure_IO()
                 std::to_string((uint64_t)MaxShmMB * (uint64_t)1048576));
     }
 #endif
+    constexpr int default_stats_level = openPMD_HAS_ADIOS_2_12;
     if (notYetConfigured("StatsLevel"))
     {
         /*
@@ -726,8 +727,8 @@ void ADIOS2File::configure_IO()
          * environment variable "OPENPMD_ADIOS2_STATS_LEVEL" be positive.
          * The ADIOS2 default was "1" (on).
          */
-        auto stats_level =
-            auxiliary::getEnvNum("OPENPMD_ADIOS2_STATS_LEVEL", 0);
+        auto stats_level = auxiliary::getEnvNum(
+            "OPENPMD_ADIOS2_STATS_LEVEL", default_stats_level);
         m_IO.SetParameter("StatsLevel", std::to_string(stats_level));
     }
     if (m_impl->realEngineType() == "sst" && notYetConfigured("QueueLimit"))