isolate root dependencies, avoid TFile

Makefile

@@ -6,24 +6,28 @@ ROOTFLAGS = -std=c++17 -m64 -I$(ROOT)/include
 ROOTLIBS = -L$(ROOT)/lib -lCore -lRIO -lROOTNTuple -lxxhash -Wl,-rpath,$(ROOT)/lib -pthread 
 LIBS = -lglfw
 MOLD = mold -run
+ROOT_IFACE = build/libroot_iface.so
 
 .PHONY: all clean
-all: build/imgui.o build/root_stuff.o noasan
+all: build/imgui.o $(ROOT_IFACE) noasan
 
 clean:
-	rm build/*.o rntviewer
+	rm build/*.o rntviewer $(ROOT_IFACE)
 
 build/imgui.o: src/imgui_inc.cpp third_party/imgui/imgui.h
 	$(CXX) -O3 -fPIC -c -Ithird_party/imgui $< -o $@
 
-build/root_stuff.o: src/PseudoMiniFile.cxx
+# $(ROOT_IFACE): src/root/RMicroFileReader.cxx
-	$(CXX) -O3 -fPIC -c $(ROOTFLAGS) $< -o $@
+# 	$(CXX) -O3 -fPIC -c $(ROOTFLAGS) $< -o $@
+
+$(ROOT_IFACE): src/root/RMicroFileReader.cxx
+	$(CXX) -O3 -fPIC -shared $(ROOTFLAGS) $< -o $@ $(ROOTLIBS)
+
+d: $(ROOT_IFACE) build/imgui.o
+	$(MOLD) $(CXX) -DDEBUG -g -O0 -DENABLE_ASAN $(CFLAGS) -fsanitize=undefined $(INC) -o rntviewer src/rntviewer.cpp build/imgui.o $(ROOT_IFACE) -lasan $(LIBS)
 	
-d: build/root_stuff.o build/imgui.o
+noasan: $(ROOT_IFACE) build/imgui.o
-	$(MOLD) $(CXX) -DDEBUG -g -O0 -DENABLE_ASAN $(CFLAGS) -fsanitize=undefined $(INC) $(ROOTFLAGS) -o rntviewer src/rntviewer.cpp build/imgui.o build/root_stuff.o -lasan $(ROOTLIBS) $(LIBS)
+	$(MOLD) $(CXX) -DDEBUG -g -O0 $(CFLAGS) -fsanitize=undefined $(INC) -o rntviewer src/rntviewer.cpp build/imgui.o $(ROOT_IFACE) $(LIBS)
 
-noasan: build/root_stuff.o build/imgui.o
+r: $(ROOT_IFACE) build/imgui.o
-	$(MOLD) $(CXX) -DDEBUG -g -O0 $(CFLAGS) -fsanitize=undefined $(INC) $(ROOTFLAGS) -o rntviewer src/rntviewer.cpp build/imgui.o build/root_stuff.o $(ROOTLIBS) $(LIBS)
+	$(MOLD) $(CXX) -O2 $(CFLAGS) $(INC) -o rntviewer src/rntviewer.cpp build/imgui.o $(ROOT_IFACE) $(LIBS)
-
-r: build/root_stuff.o build/imgui.o
-	$(MOLD) $(CXX) -O2 $(CFLAGS) $(INC) $(ROOTFLAGS) -o rntviewer src/rntviewer.cpp build/imgui.o build/root_stuff.o $(ROOTLIBS) $(LIBS)

imgui.ini

@@ -8,7 +8,7 @@ Size=1152,1414
 
 [Window][main]
 Pos=0,0
-Size=1777,680
+Size=3440,1440
 
 [Window][Hex View]
 Pos=91,62

src/PseudoMiniFile.hxx

@@ -1,41 +0,0 @@
-#pragma once
-
-#include <ROOT/RError.hxx>
-#include <ROOT/RNTuple.hxx>
-#include <ROOT/RRawFile.hxx>
-#include <string_view>
-
-#include <cstdint>
-#include <cstdio>
-#include <memory>
-#include <string>
-
-struct RNTuple_FileInfo {
-  std::uint64_t anchor_seek;
-  std::uint64_t anchor_nbytes;
-  std::uint64_t anchor_key_seek;
-  std::uint64_t anchor_key_nbytes;
-  std::uint64_t rblob_key_header_nbytes;
-  std::uint64_t tfile_header_nbytes;
-};
-
-class PseudoMiniFileReader final {
-public:
-  explicit PseudoMiniFileReader(ROOT::Internal::RRawFile *rawFile);
-
-  // ROOT::Experimental::RResult<ROOT::Experimental::RNTuple> 
-  ROOT::Experimental::RResult<RNTuple_FileInfo>
-  GetNTupleProper(std::string_view ntupleName);
-
-  void
-  ReadBuffer(void *buffer, size_t nbytes, std::uint64_t offset);
-
-  // ROOT::Experimental::RNTuple
-  // CreateAnchor(
-  //  std::uint16_t versionEpoch, std::uint16_t versionMajor, std::uint16_t versionMinor, std::uint16_t versionPatch,
-  //  std::uint64_t seekHeader, std::uint64_t nbytesHeader, std::uint64_t lenHeader, std::uint64_t seekFooter,
-  //  std::uint64_t nbytesFooter, std::uint64_t lenFooter, std::uint64_t maxKeySize);
-
-  ROOT::Internal::RRawFile *fRawFile;
-  std::uint64_t fMaxBlobSize;
-};

src/defer.hpp

@@ -1,17 +1,12 @@
-#pragma once
+template <typename F>
-
-#include <functional>
-#include <utility>
-
 struct Defer_Guard {
-  template <typename F>
   Defer_Guard(F && f) : _f(f) {}
   ~Defer_Guard() { _f(); }
-  std::function<void()> _f;
+  F _f;
 };
 struct Defer_Guard_Helper {
 	template <typename F>
-	Defer_Guard operator+(F&& f) { return Defer_Guard(std::forward<F>(f)); }
+	Defer_Guard<F> operator+(F&& f) { return Defer_Guard<F>(std::forward<F>(f)); }
 };
 
 #define CONCAT_STR_INTERNAL(A, B) A##B

src/platform_linux.h

@@ -1,5 +1,6 @@
 #include <sys/mman.h>
 #include <sys/inotify.h>
+#include <errno.h>
 #include <unistd.h>
 #include <limits.h> // for NAME_MAX
 

src/rntuple.cpp

@@ -1,11 +1,11 @@
 internal
-String8 rntuple_description(Arena *arena, const RNTuple &anchor)
+String8 rntuple_description(Arena *arena, const RNTuple_Anchor &anchor)
 {
   String8 desc = push_str8f(arena, "version %u.%u.%u.%u", 
-                            anchor.GetVersionEpoch(),
+                            anchor.fVersionEpoch,
-                            anchor.GetVersionMajor(),
+                            anchor.fVersionMajor,
-                            anchor.GetVersionMinor(),
+                            anchor.fVersionMinor,
-                            anchor.GetVersionPatch());
+                            anchor.fVersionPatch);
   return desc;
 }
 
@@ -14,31 +14,14 @@ RNTuple_Info get_rntuple_info(const char *fname, const char *ntpl_name)
 {
   RNTuple_Info info = {};
   
-  // Open the TFile
-  TFile *tfile = TFile::Open(fname, "READ");
-  if (!tfile) {
-    fprintf(stderr, "Failed to open TFile.\n");
-    return info;
-  }
-  defer { delete tfile; };
-
-  // Get the RNTuple information
-  const RNTuple *anchor = tfile->Get<RNTuple>(ntpl_name);
-  if (anchor) {
-    info.anchor = *anchor;
-    info.rng_header.start = anchor->GetSeekHeader();
-    info.rng_header.len = anchor->GetNBytesHeader();
-    info.rng_footer.start = anchor->GetSeekFooter();
-    info.rng_footer.len = anchor->GetNBytesFooter();
-  } else {
-    fprintf(stderr, "RNTuple '%s' not found in %s.\n", ntpl_name, fname);
-  }
-
   // TODO: proper error handling
-  auto raw_file = ROOT::Internal::RRawFile::Create(fname);
+  RMicroFileReader file_reader { fname };
-  if (raw_file) {
+  RNTuple_File_Info file_info = file_reader.GetNTupleProper(ntpl_name);
-    PseudoMiniFileReader file_reader { raw_file.get() };
+  if (!file_info.failed) {
-    auto file_info = file_reader.GetNTupleProper(ntpl_name).Unwrap();
+    info.rng_header.start = file_info.anchor.fSeekHeader;
+    info.rng_header.len = file_info.anchor.fNBytesHeader;
+    info.rng_footer.start = file_info.anchor.fSeekFooter;
+    info.rng_footer.len = file_info.anchor.fNBytesFooter;
     info.rng_anchor.start = file_info.anchor_seek;
     info.rng_anchor.len = file_info.anchor_nbytes;
     info.rng_anchor_key.start = file_info.anchor_key_seek;

src/rntuple.h

@@ -1,4 +1,4 @@
-using RNTuple = ROOT::Experimental::RNTuple;
+// using RNTuple = ROOT::Experimental::RNTuple;
 
 struct Byte_Range {
   u64 start, len;
@@ -6,7 +6,7 @@ struct Byte_Range {
 };
 
 struct RNTuple_Info {
-  RNTuple anchor;  
+  RNTuple_Anchor anchor;  
 
   u64 root_file_header_size;
   u64 rblob_header_size;

src/rntviewer.cpp

@@ -1,9 +1,19 @@
-#include <ROOT/RNTupleReader.hxx>
+// ************************************
-#include <ROOT/RNTuple.hxx>
+// *
-#include <TFile.h>
+// * rntviewer
+// *
+// * A graphical RNTuple visualizer 
+// *
+// * @author silverweed, 2024
+// *
+// ***********************************
+// #include <ROOT/RNTupleReader.hxx>
+// #include <ROOT/RNTuple.hxx>
+// #include <TFile.h>
 
 #include <cstdio>
 #include <cstdint>
+#include <utility>    // for std::forward
 #include <chrono>
 
 #ifdef DEBUG
@@ -18,7 +28,7 @@
 #define GLFW_INCLUDE_NONE
 #include <GLFW/glfw3.h>
 
-#include "PseudoMiniFile.hxx"
+#include "root/RMicroFileReader.hxx"
 
 #include "types.h"
 #include "defer.hpp"
@@ -40,8 +50,6 @@ namespace chr = std::chrono;
 #include "render.cpp"
 #include "mainloop.cpp"
 
-using namespace ROOT::Experimental;
-
 internal 
 b8 init_imgui(GLFWwindow* window) {
 	IMGUI_CHECKVERSION();

src/root/RMicroFileReader.cxx

@@ -1,11 +1,11 @@
 /// Stripped-down version of RMiniFile.cxx, only used to read RNTuples from TFiles.
 
-#include "PseudoMiniFile.hxx"
+#include "RMicroFileReader.hxx"
 
 #include "Rtypes.h"
 #include <ROOT/RConfig.hxx>
 #include <ROOT/RError.hxx>
-
+#include <ROOT/RNTuple.hxx>
 #include <ROOT/RRawFile.hxx>
 #include <ROOT/RNTupleZip.hxx>
 #include <ROOT/RNTupleSerialize.hxx>
@@ -1064,9 +1064,21 @@ static size_t ComputeNumChunks(size_t nbytes, size_t maxChunkSize)
    return nChunks;
 }
 
-PseudoMiniFileReader::PseudoMiniFileReader(ROOT::Internal::RRawFile *rawFile) : fRawFile(rawFile) {}
+struct RMicroFileReader::Impl {
+  std::unique_ptr<ROOT::Internal::RRawFile> fRawFile;
+  std::uint64_t fMaxBlobSize;
+};
 
-// ROOT::Experimental::RNTuple PseudoMiniFileReader::CreateAnchor(
+RMicroFileReader::RMicroFileReader(const char *fname) {
+   impl = new Impl;
+   impl->fRawFile = ROOT::Internal::RRawFile::Create(fname);
+}
+
+RMicroFileReader::~RMicroFileReader() {
+   delete impl;
+}
+
+// ROOT::Experimental::RNTuple RMicroFileReader::CreateAnchor(
 //    std::uint16_t versionEpoch, std::uint16_t versionMajor, std::uint16_t versionMinor, std::uint16_t versionPatch,
 //    std::uint64_t seekHeader, std::uint64_t nbytesHeader, std::uint64_t lenHeader, std::uint64_t seekFooter,
 //    std::uint64_t nbytesFooter, std::uint64_t lenFooter, std::uint64_t maxKeySize)
@@ -1087,10 +1099,15 @@ PseudoMiniFileReader::PseudoMiniFileReader(ROOT::Internal::RRawFile *rawFile) :
 // }
 
 // ROOT::Experimental::RResult<ROOT::Experimental::RNTuple>
-ROOT::Experimental::RResult<RNTuple_FileInfo>
+RNTuple_File_Info
-PseudoMiniFileReader::GetNTupleProper(std::string_view ntupleName)
+RMicroFileReader::GetNTupleProper(const char *ntupleName)
 {
-   RNTuple_FileInfo fileInfo {};
+   RNTuple_File_Info fileInfo {};
+
+#define FAIL(msg) \
+   fprintf(stderr, "%s", std::string(msg).c_str()); \
+   fileInfo.failed = true; \
+   return fileInfo
    
    RTFHeader fileHeader;
    ReadBuffer(&fileHeader, sizeof(fileHeader), 0);
@@ -1129,21 +1146,21 @@ PseudoMiniFileReader::GetNTupleProper(std::string_view ntupleName)
       offset += name.GetSize();
       ReadBuffer(&name, 1, offset);
       ReadBuffer(&name, name.GetSize(), offset);
-      if (std::string_view(name.fData, name.fLName) == ntupleName) {
+      if (std::string_view(name.fData, name.fLName) == std::string_view(ntupleName)) {
          found = true;
          break;
       }
       offset = offsetNextKey;
    }
    if (!found) {
-      return R__FAIL("no RNTuple named '" + std::string(ntupleName) + "' in file '" + fRawFile->GetUrl() + "'");
+      FAIL("no RNTuple named '" + std::string(ntupleName) + "' in file '" + impl->fRawFile->GetUrl() + "'");
    }
 
    offset = key.GetSeekKey() + key.fKeyLen;
 
    constexpr size_t kMinNTupleSize = 70; // size of a RTFNTuple version 4 (min supported version)
    if (key.fObjLen < kMinNTupleSize) {
-      return R__FAIL("invalid anchor size: " + std::to_string(key.fObjLen) + " < " + std::to_string(sizeof(RTFNTuple)));
+      FAIL("invalid anchor size: " + std::to_string(key.fObjLen) + " < " + std::to_string(sizeof(RTFNTuple)));
    }
    // The object length can be smaller than the size of RTFNTuple if it comes from a past RNTuple class version,
    // or larger than it if it comes from a future RNTuple class version.
@@ -1166,7 +1183,7 @@ PseudoMiniFileReader::GetNTupleProper(std::string_view ntupleName)
    }
 
    if (ntuple->fVersionClass < 4) {
-      return R__FAIL("invalid anchor, unsupported pre-release of RNTuple");
+      FAIL("invalid anchor, unsupported pre-release of RNTuple");
    }
 
    // We require that future class versions only append members and store the checksum in the last 8 bytes
@@ -1184,34 +1201,35 @@ PseudoMiniFileReader::GetNTupleProper(std::string_view ntupleName)
       ckOnDisk = static_cast<uint64_t>(*ckOnDiskPtr);
    }
    if (ckCalc != ckOnDisk) {
-      return R__FAIL("RNTuple anchor checksum mismatch");
+      FAIL("RNTuple anchor checksum mismatch");
    }
 
-   fMaxBlobSize = ntuple->fMaxKeySize;
+   impl->fMaxBlobSize = ntuple->fMaxKeySize;
 
-   // return CreateAnchor(ntuple->fVersionEpoch, ntuple->fVersionMajor, ntuple->fVersionMinor, ntuple->fVersionPatch,
+   fileInfo.anchor = {ntuple->fVersionEpoch, ntuple->fVersionMajor, ntuple->fVersionMinor, ntuple->fVersionPatch,
-   //                     ntuple->fSeekHeader, ntuple->fNBytesHeader, ntuple->fLenHeader, ntuple->fSeekFooter,
+                       ntuple->fSeekHeader, ntuple->fNBytesHeader, ntuple->fLenHeader, ntuple->fSeekFooter,
-   //                     ntuple->fNBytesFooter, ntuple->fLenFooter, ntuple->fMaxKeySize);
+                       ntuple->fNBytesFooter, ntuple->fLenFooter, ntuple->fMaxKeySize};
 
    return fileInfo;
 }
 
-void PseudoMiniFileReader::ReadBuffer(void *buffer, size_t nbytes, std::uint64_t offset)
+void RMicroFileReader::ReadBuffer(void *buffer, size_t nbytes, std::uint64_t offset)
 {
    size_t nread;
-   if (fMaxBlobSize == 0 || nbytes <= fMaxBlobSize) {
+   uint64_t maxBlobSize = impl->fMaxBlobSize;
+   if (maxBlobSize == 0 || nbytes <= maxBlobSize) {
       // Fast path: read single blob
-      nread = fRawFile->ReadAt(buffer, nbytes, offset);
+      nread = impl->fRawFile->ReadAt(buffer, nbytes, offset);
    } else {
       // Read chunked blob. See RNTupleFileWriter::WriteBlob() for details.
-      const size_t nChunks = ComputeNumChunks(nbytes, fMaxBlobSize);
+      const size_t nChunks = ComputeNumChunks(nbytes, maxBlobSize);
       const size_t nbytesChunkOffsets = (nChunks - 1) * sizeof(std::uint64_t);
-      const size_t nbytesFirstChunk = fMaxBlobSize - nbytesChunkOffsets;
+      const size_t nbytesFirstChunk = maxBlobSize - nbytesChunkOffsets;
       uint8_t *bufCur = reinterpret_cast<uint8_t *>(buffer);
 
       // Read first chunk
-      nread = fRawFile->ReadAt(bufCur, fMaxBlobSize, offset);
+      nread = impl->fRawFile->ReadAt(bufCur, maxBlobSize, offset);
-      R__ASSERT(nread == fMaxBlobSize);
+      R__ASSERT(nread == maxBlobSize);
       // NOTE: we read the entire chunk in `bufCur`, but we only advance the pointer by `nbytesFirstChunk`,
       // since the last part of `bufCur` will later be overwritten by the next chunk's payload.
       // We do this to avoid a second ReadAt to read in the chunk offsets.
@@ -1229,11 +1247,11 @@ void PseudoMiniFileReader::ReadBuffer(void *buffer, size_t nbytes, std::uint64_t
          ROOT::Experimental::Internal::RNTupleSerializer::DeserializeUInt64(curChunkOffset, chunkOffset);
          ++curChunkOffset;
 
-         const size_t bytesToRead = std::min<size_t>(fMaxBlobSize, remainingBytes);
+         const size_t bytesToRead = std::min<size_t>(maxBlobSize, remainingBytes);
          // Ensure we don't read outside of the buffer
          R__ASSERT(static_cast<size_t>(bufCur - reinterpret_cast<uint8_t *>(buffer)) <= nbytes - bytesToRead);
 
-         auto nbytesRead = fRawFile->ReadAt(bufCur, bytesToRead, chunkOffset);
+         auto nbytesRead = impl->fRawFile->ReadAt(bufCur, bytesToRead, chunkOffset);
          R__ASSERT(nbytesRead == bytesToRead);
 
          nread += bytesToRead;

src/root/RMicroFileReader.hxx

@@ -0,0 +1,63 @@
+#pragma once
+
+#include <cstdint>
+
+struct RNTuple_Anchor {
+   /// Version of the RNTuple binary format that the writer supports (see specification).
+   /// Changing the epoch indicates backward-incompatible changes
+   std::uint16_t fVersionEpoch;
+   /// Changing the major version indicates forward incompatible changes; such changes should correspond to a new
+   /// bit in the feature flag of the RNTuple header.
+   /// For the pre-release epoch 0, indicates the release candidate number
+   std::uint16_t fVersionMajor;
+   /// Changing the minor version indicates new optional fields added to the RNTuple meta-data
+   std::uint16_t fVersionMinor;
+   /// Changing the patch version indicates new backported features from newer binary format versions
+   std::uint16_t fVersionPatch;
+   /// The file offset of the header excluding the TKey part
+   std::uint64_t fSeekHeader;
+   /// The size of the compressed ntuple header
+   std::uint64_t fNBytesHeader;
+   /// The size of the uncompressed ntuple header
+   std::uint64_t fLenHeader;
+   /// The file offset of the footer excluding the TKey part
+   std::uint64_t fSeekFooter;
+   /// The size of the compressed ntuple footer
+   std::uint64_t fNBytesFooter;
+   /// The size of the uncompressed ntuple footer
+   std::uint64_t fLenFooter;
+   /// The maximum size for a TKey payload. Payloads bigger than this size will be written as multiple blobs.
+   std::uint64_t fMaxKeySize;
+};
+
+struct RNTuple_File_Info {
+  bool failed;
+  RNTuple_Anchor anchor;
+  std::uint64_t anchor_seek;
+  std::uint64_t anchor_nbytes;
+  std::uint64_t anchor_key_seek;
+  std::uint64_t anchor_key_nbytes;
+  std::uint64_t rblob_key_header_nbytes;
+  std::uint64_t tfile_header_nbytes;
+};
+
+class RMicroFileReader final {
+public:
+  explicit RMicroFileReader(const char *fname);
+  ~RMicroFileReader();
+
+  RNTuple_File_Info
+  GetNTupleProper(const char *ntupleName);
+
+  void
+  ReadBuffer(void *buffer, std::size_t nbytes, std::uint64_t offset);
+
+  // ROOT::Experimental::RNTuple
+  // CreateAnchor(
+  //  std::uint16_t versionEpoch, std::uint16_t versionMajor, std::uint16_t versionMinor, std::uint16_t versionPatch,
+  //  std::uint64_t seekHeader, std::uint64_t nbytesHeader, std::uint64_t lenHeader, std::uint64_t seekFooter,
+  //  std::uint64_t nbytesFooter, std::uint64_t lenFooter, std::uint64_t maxKeySize);
+
+  struct Impl;
+  Impl *impl;
+};