[hadd] Improve verbosity settings

new verbosity works like this:

  v0: only output errors
  v1: only output errors and warnings
  v2: output errors, warnings and TFileMerger messages
  v3: output all messages

This is largely backwards-compatible as the default verbosity was and
still is 99.

Author: silverweed

main/src/hadd.cxx

@@ -63,16 +63,21 @@
                        whitespaces or '/'. You can also pass TDirectory names, which apply to the entire directory
                        content. Lines beginning with '#' are ignored. If this flag is passed, "-Ltype" MUST be
                        passed as well.
-  \param -Ltype <SkipListed|OnlyListed> Sets the type of operation performed on the objects listed in FILE given with the
+  \param -Ltype <SkipListed|OnlyListed> Sets the type of operation performed on the objects listed in FILE given with
+  the
                        "-L" flag. "SkipListed" will skip all the listed objects; "OnlyListed" will only merge those
                        objects. If this flag is passed, "-L" must be passed as well.
   \param -n <N_FILES>  Open at most `N` files at once (use 0 to request to use the system maximum - which is also
                        the default). This number includes both the input reading files as well as the output file.
-                       Thus, if set to 1, it will be automatically replaced to a minimum of 2. If set to a too large value,
-                       it will be clipped to the system maximum.
+                       Thus, if set to 1, it will be automatically replaced to a minimum of 2. If set to a too large
+  value, it will be clipped to the system maximum.
   \param -O            Re-optimize basket size when merging TTree
   \param -T            Do not merge Trees
-  \param -v [LEVEL]    Explicitly set the verbosity level: 0 request no output, 99 is the default
+  \param -v [LEVEL]    Explicitly set the verbosity level:
+                            <= 0 = only output errors;
+                            1 = only output errors and warnings;
+                            2 = output minimal informative messages, errors and warnings;
+                            >= 3 = output all messages (default).
   \return hadd returns a status code: 0 if OK, 1 otherwise
 
   For example assume 3 files f1, f2, f3 containing histograms hn and Trees Tn
@@ -155,29 +160,62 @@
 #include <optional>
 #include <sstream>
 #include <string>
+#include <streambuf>
 
 #ifndef R__WIN32
 #include "ROOT/TProcessExecutor.hxx"
 #endif
 
 ////////////////////////////////////////////////////////////////////////////////
 
-inline std::ostream &Err()
+// NOTE: TFileMerger will use PrintLevel = gVerbosity - 1. If PrintLevel is < 1, it will print nothing, otherwise
+// it will print everything. To give some granularity to hadd, we do the following:
+// gVerbosity = 0: only print hadd errors
+// gVerbosity = 1: only print hadd errors + warnings
+// gVerbosity = 2: print hadd errors + warnings and TFileMerger messages
+// gVerbosity > 2: print all hadd and TFileMerger messages.
+static int gVerbosity = 99;
+
+namespace {
+
+class NullBuf : public std::streambuf {
+public:
+   int overflow(int c) final { return c; }
+};
+
+class NullStream : public std::ostream {
+   NullBuf fBuf;
+
+public:
+   NullStream() : std::ostream(&fBuf) {}
+};
+
+} // namespace
+
+static NullStream &GetNullStream()
+{
+   static NullStream nullStream;
+   return nullStream;
+}
+
+static inline std::ostream &Err()
 {
    std::cerr << "Error in <hadd>: ";
    return std::cerr;
 }
 
-inline std::ostream &Warn()
+static inline std::ostream &Warn()
 {
-   std::cerr << "Warning in <hadd>: ";
-   return std::cerr;
+   std::ostream &s = gVerbosity < 1 ? GetNullStream() : std::cerr;
+   s << "Warning in <hadd>: ";
+   return s;
 }
 
-inline std::ostream &Info()
+static inline std::ostream &Info()
 {
-   std::cerr << "Info in <hadd>: ";
-   return std::cerr;
+   std::ostream &s = gVerbosity < 3 ? GetNullStream() : std::cerr;
+   s << "Info in <hadd>: ";
+   return s;
 }
 
 using IntFlag_t = uint32_t;
@@ -626,7 +664,7 @@ int main(int argc, char **argv)
 
    ROOT::TIOFeatures features = args.fFeatures.value_or(ROOT::TIOFeatures{});
    Int_t maxopenedfiles = args.fMaxOpenedFiles.value_or(0);
-   Int_t verbosity = args.fVerbosity.value_or(99);
+   gVerbosity = args.fVerbosity.value_or(99);
    Int_t newcomp = args.fCompressionSettings.value_or(-1);
    TString cacheSize = args.fCacheSize.value_or("");
 
@@ -674,8 +712,7 @@ int main(int argc, char **argv)
    }
    targetname = argv[args.fOutputArgIdx];
 
-   if (verbosity > 1)
-      Info() << "target file: " << targetname << "\n";
+   Info() << "target file: " << targetname << "\n";
 
    if (args.fCacheSize)
       Info() << "Using " << cacheSize << "\n";
@@ -686,7 +723,7 @@ int main(int argc, char **argv)
 
    TFileMerger fileMerger(kFALSE, kFALSE);
    fileMerger.SetMsgPrefix("hadd");
-   fileMerger.SetPrintLevel(verbosity - 1);
+   fileMerger.SetPrintLevel(gVerbosity - 1);
    if (maxopenedfiles > 0) {
       fileMerger.SetMaxOpenedFiles(maxopenedfiles);
    }
@@ -758,21 +795,22 @@ int main(int argc, char **argv)
          fileMerger.SetMergeOptions(TString("DefaultCompression"));
       }
    }
-   if (verbosity > 1) {
-      if (args.fKeepCompressionAsIs && !args.fReoptimize)
-         Info() << "compression setting for meta data: " << newcomp << '\n';
-      else
-         Info() << "compression setting for all output: " << newcomp << '\n';
-   }
+   if (args.fKeepCompressionAsIs && !args.fReoptimize)
+      Info() << "compression setting for meta data: " << newcomp << '\n';
+   else
+      Info() << "compression setting for all output: " << newcomp << '\n';
+
    if (args.fAppend) {
       if (!fileMerger.OutputFile(targetname, "UPDATE", newcomp)) {
          Err() << "error opening target file for update :" << targetname << ".\n";
          return 2;
       }
    } else if (!fileMerger.OutputFile(targetname, args.fForce, newcomp)) {
-      Err() << "error opening target file (does " << targetname << " exist?).\n";
+      std::stringstream ss;
+      ss << "error opening target file (does " << targetname << " exist?).\n";
       if (!args.fForce)
-         Info() << "pass \"-f\" argument to force re-creation of output file.\n";
+         ss << "pass \"-f\" argument to force re-creation of output file.\n";
+      Err() << ss.str();
       return 1;
    }
 
@@ -850,7 +888,7 @@ int main(int argc, char **argv)
    auto parallelMerge = [&](int start) {
       TFileMerger mergerP(kFALSE, kFALSE);
       mergerP.SetMsgPrefix("hadd");
-      mergerP.SetPrintLevel(verbosity - 1);
+      mergerP.SetPrintLevel(gVerbosity - 1);
       if (maxopenedfiles > 0) {
          mergerP.SetMaxOpenedFiles(maxopenedfiles / nProcesses);
       }
@@ -893,16 +931,12 @@ int main(int argc, char **argv)
 #endif
 
    if (status) {
-      if (verbosity == 1) {
-         Info() << "merged " << allSubfiles.size() << " (" << fileMerger.GetMergeList()->GetEntries()
-                << ") input (partial) files into " << targetname << ".\n";
-      }
+      Info() << "merged " << allSubfiles.size() << " (" << fileMerger.GetMergeList()->GetEntries()
+             << ") input (partial) files into " << targetname << "\n";
       return 0;
    } else {
-      if (verbosity == 1) {
-         Err() << "failure during the merge of " << allSubfiles.size() << " ("
-               << fileMerger.GetMergeList()->GetEntries() << ") input (partial) files into " << targetname << ".\n";
-      }
+      Err() << "failure during the merge of " << allSubfiles.size() << " (" << fileMerger.GetMergeList()->GetEntries()
+            << ") input (partial) files into " << targetname << "\n";
       return 1;
    }
 }

roottest/root/io/evolution/versions/attmarker.ref

@@ -5,3 +5,4 @@ hadd Source file 2: hsimple20.root
 Warning in <hadd>: Sources and Target have different compression settings
 hadd merging will be slower
 hadd Target path: result.root:/
+Info in <hadd>: merged 2 (2) input (partial) files into result.root

roottest/root/io/hadd/CMakeLists.txt

@@ -202,3 +202,17 @@ ROOTTEST_ADD_TEST(test_hadd_args_missing_l
                   COMMAND ${ROOT_hadd_CMD} hadd_args_missing_l.root hadd_args_in.root -Ltype SkipListed
                   PASSREGEX "Error in <hadd>: -L must always be passed along with -Ltype"
 )
+
+ROOTTEST_ADD_TEST(test_hadd_args_quiet
+                  FIXTURES_REQUIRED root-io-hadd-test_hadd_args_gen_input-fixture
+                  PRECMD ${CMAKE_COMMAND} -E rm -f hadd_args_quiet.root
+                  COMMAND ${ROOT_hadd_CMD} hadd_args_quiet.root hadd_args_in.root -v2
+                  OUTREF hadd_args_quiet.ref
+)
+
+ROOTTEST_ADD_TEST(test_hadd_args_quieter
+                  FIXTURES_REQUIRED root-io-hadd-test_hadd_args_gen_input-fixture
+                  PRECMD ${CMAKE_COMMAND} -E rm -f hadd_args_quieter.root
+                  COMMAND ${ROOT_hadd_CMD} hadd_args_quieter.root hadd_args_in.root -v1
+                  OUTREF hadd_args_quieter.ref
+)

roottest/root/io/hadd/hadd_args_cachesize.ref

@@ -3,3 +3,4 @@ Info in <hadd>: Using cachesize=100M
 Info in <hadd>: compression setting for all output: 101
 hadd Source file 1: hadd_args_in.root
 hadd Target path: hadd_args_cachesize_out.root:/
+Info in <hadd>: merged 1 (1) input (partial) files into hadd_args_cachesize_out.root

roottest/root/io/hadd/hadd_args_ff_dbg_j_2.ref

@@ -5,3 +5,4 @@ Info in <hadd>: each process should handle at least 3 files for efficiency. Sett
 hadd Source file 1: hadd_args_in.root
 hadd Source file 2: hadd_args_in.root
 hadd Target path: hadd_args_ff_dbg_j_2_out.root:/
+Info in <hadd>: merged 2 (2) input (partial) files into hadd_args_ff_dbg_j_2_out.root

roottest/root/io/hadd/hadd_args_minusminus.ref

@@ -4,3 +4,4 @@ hadd Source file 1: hadd_args_in.root
 Warning in <hadd>: Sources and Target have different compression settings
 hadd merging will be slower
 hadd Target path: --hadd_args_out.root:/
+Info in <hadd>: merged 1 (1) input (partial) files into --hadd_args_out.root

roottest/root/io/hadd/hadd_args_n0.ref

@@ -2,3 +2,4 @@ Info in <hadd>: target file: hadd_args_n0_out.root
 Info in <hadd>: compression setting for all output: 101
 hadd Source file 1: hadd_args_in.root
 hadd Target path: hadd_args_n0_out.root:/
+Info in <hadd>: merged 1 (1) input (partial) files into hadd_args_n0_out.root

roottest/root/io/hadd/hadd_args_n_1.ref

@@ -2,3 +2,4 @@ Info in <hadd>: target file: hadd_args_n_1_out.root
 Info in <hadd>: compression setting for all output: 101
 hadd Source file 1: hadd_args_in.root
 hadd Target path: hadd_args_n_1_out.root:/
+Info in <hadd>: merged 1 (1) input (partial) files into hadd_args_n_1_out.root

roottest/root/io/hadd/hadd_args_quiet.ref

@@ -0,0 +1,2 @@
+hadd Source file 1: hadd_args_in.root
+hadd Target path: hadd_args_quiet.root:/