[main] Extract hadd's logging utils into a header file

Author: silverweed

main/src/hadd.cxx

@@ -151,6 +151,7 @@
 #include <ROOT/TIOFeatures.hxx>
 
 #include "haddCommandLineOptionsHelp.h"
+#include "logging.hxx"
 
 #include <climits>
 #include <cstdlib>
@@ -168,56 +169,13 @@
 
 ////////////////////////////////////////////////////////////////////////////////
 
-// NOTE: TFileMerger will use PrintLevel = gHaddVerbosity - 1. If PrintLevel is < 1, it will print nothing, otherwise
+// NOTE: TFileMerger will use PrintLevel = GetLogVerbosity() - 1. If PrintLevel is < 1, it will print nothing, otherwise
 // it will print everything. To give some granularity to hadd, we do the following:
-// gHaddVerbosity = 0: only print hadd errors
-// gHaddVerbosity = 1: only print hadd errors + warnings
-// gHaddVerbosity = 2: print hadd errors + warnings and TFileMerger messages
-// gHaddVerbosity > 2: print all hadd and TFileMerger messages.
+// LogVerbosity = 0: only print hadd errors
+// LogVerbosity = 1: only print hadd errors + warnings
+// LogVerbosity = 2: print hadd errors + warnings and TFileMerger messages
+// LogVerbosity > 2: print all hadd and TFileMerger messages.
 static constexpr int kDefaultHaddVerbosity = 2;
-static int gHaddVerbosity = kDefaultHaddVerbosity;
-
-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;
-}
-
-static inline std::ostream &Warn()
-{
-   std::ostream &s = gHaddVerbosity < 1 ? GetNullStream() : std::cerr;
-   s << "Warning in <hadd>: ";
-   return s;
-}
-
-static inline std::ostream &Info(int minLevel)
-{
-   std::ostream &s = gHaddVerbosity < minLevel ? GetNullStream() : std::cerr;
-   s << "Info in <hadd>: ";
-   return s;
-}
 
 using IntFlag_t = uint32_t;
 
@@ -658,6 +616,8 @@ static Int_t ParseFilterFile(const std::optional<std::string> &filterFileName,
 
 int main(int argc, char **argv)
 {
+   InitLog("hadd", kDefaultHaddVerbosity);
+
    const auto argsOpt = ParseArgs(argc, argv);
    if (!argsOpt)
       return 1;
@@ -670,7 +630,7 @@ int main(int argc, char **argv)
 
    ROOT::TIOFeatures features = args.fFeatures.value_or(ROOT::TIOFeatures{});
    Int_t maxopenedfiles = args.fMaxOpenedFiles.value_or(0);
-   gHaddVerbosity = args.fVerbosity.value_or(kDefaultHaddVerbosity);
+   SetLogVerbosity(args.fVerbosity.value_or(kDefaultHaddVerbosity));
    Int_t newcomp = args.fCompressionSettings.value_or(-1);
    TString cacheSize = args.fCacheSize.value_or("");
 
@@ -731,7 +691,7 @@ int main(int argc, char **argv)
 
    TFileMerger fileMerger(kFALSE, kFALSE);
    fileMerger.SetMsgPrefix("hadd");
-   fileMerger.SetPrintLevel(gHaddVerbosity - 1);
+   fileMerger.SetPrintLevel(GetLogVerbosity() - 1);
    if (maxopenedfiles > 0) {
       fileMerger.SetMaxOpenedFiles(maxopenedfiles);
    }
@@ -896,7 +856,7 @@ int main(int argc, char **argv)
    auto parallelMerge = [&](int start) {
       TFileMerger mergerP(kFALSE, kFALSE);
       mergerP.SetMsgPrefix("hadd");
-      mergerP.SetPrintLevel(gHaddVerbosity - 1);
+      mergerP.SetPrintLevel(GetLogVerbosity() - 1);
       if (maxopenedfiles > 0) {
          mergerP.SetMaxOpenedFiles(maxopenedfiles / nProcesses);
       }

main/src/logging.hxx

@@ -0,0 +1,75 @@
+///
+/// Basic logging utilities meant to be used by binaries.
+/// Use instead of RLogger for user-facing messages.
+///
+#ifndef ROOT_Main_Logging
+#define ROOT_Main_Logging
+
+#include <iostream>
+
+namespace Detail {
+
+class NullBuf : public std::streambuf {
+public:
+   int overflow(int c) final { return c; }
+};
+
+// A stream that discards all input.
+class NullStream : public std::ostream {
+   NullBuf fBuf;
+
+public:
+   NullStream() : std::ostream(&fBuf) {}
+};
+
+inline const char *gLogName = "";
+/// Log verbosity works this way:
+/// If it's <= 0, all warnings are suppressed.
+/// Additionally, when Info(lv) is called, it is only displayed if lv <= LogVerbosity.
+inline int gLogVerbosity = 1;
+
+inline NullStream &GetNullStream()
+{
+   static NullStream nullStream;
+   return nullStream;
+}
+
+} // namespace Detail
+
+inline void InitLog(const char *name, int defaultVerbosity = 1)
+{
+   Detail::gLogName = name;
+   Detail::gLogVerbosity = defaultVerbosity;
+}
+
+inline void SetLogVerbosity(int verbosity)
+{
+   Detail::gLogVerbosity = verbosity;
+}
+
+inline int GetLogVerbosity()
+{
+   return Detail::gLogVerbosity;
+}
+
+inline std::ostream &Err()
+{
+   std::cerr << "Error in <" << Detail::gLogName << ">: ";
+   return std::cerr;
+}
+
+inline std::ostream &Warn()
+{
+   std::ostream &s = Detail::gLogVerbosity < 1 ? Detail::GetNullStream() : std::cerr;
+   s << "Warning in <" << Detail::gLogName << ">: ";
+   return s;
+}
+
+inline std::ostream &Info(int minLevel)
+{
+   std::ostream &s = Detail::gLogVerbosity < minLevel ? Detail::GetNullStream() : std::cerr;
+   s << "Info in <" << Detail::gLogName << ">: ";
+   return s;
+}
+
+#endif