Initial implementation of a rootbench memory tracing library.

It implements a C library which records information about the memory allocations.
The library is loaded using the LD_PRELOAD mechanism (and DYLD_INSERT_LIBRARIES
for osx).

GoogleBenchmark displays the memory allocation results are only in the json
format. For instance:

DYLD_FORCE_FLAT_NAMESPACE=1 DYLD_INSERT_LIBRARIES=./lib/Instrumentation/libRBInstrumentation.dylib ./root/interpreter/InterpreterLookupHelperBenchmarks --benchma
rk_format=json:

...
{
      "name": "BM_LookupHelper_Leak",
      "run_name": "BM_LookupHelper_Leak",
      "run_type": "iteration",
      "repetitions": 0,
      "repetition_index": 0,
      "threads": 1,
      "iterations": 1,
      "real_time": 1.3199219449888916e+09,
      "cpu_time": 8.0450300000000000e+08,
      "time_unit": "ns",
      "allocs_per_iter": 6.0000000000000000e+00,
      "max_bytes_used": 3368
}

Author: vgvassilev

cmake/modules/AddRootBench.cmake

@@ -43,7 +43,7 @@ function(RB_ADD_GBENCHMARK benchmark)
   # FIXME: For better coherence we could restrict the libraries the test suite could link
   # against. For example, tests in Core should link only against libCore. This could be tricky
   # to implement because some ROOT components create more than one library.
-  target_link_libraries(${benchmark} ${ARG_LIBRARIES} gbenchmark RBSupport)
+  target_link_libraries(${benchmark} PUBLIC  ${ARG_LIBRARIES} gbenchmark RBSupport)
   #ROOT_PATH_TO_STRING(mangled_name ${benchmark} PATH_SEPARATOR_REPLACEMENT "-")
   #ROOT_ADD_TEST(gbench${mangled_name}
   #  COMMAND ${benchmark}
@@ -76,6 +76,29 @@ function(RB_ADD_GBENCHMARK benchmark)
                        FIXTURES_REQUIRED "setup-${benchmark};download-${benchmark}-datafiles")
 endfunction(RB_ADD_GBENCHMARK)
 
+#----------------------------------------------------------------------------
+# function RB_ADD_GBENCHMARK(<benchmark> source1 source2... LIBRARIES libs)
+#----------------------------------------------------------------------------
+function(RB_ADD_MEM_GBENCHMARK benchmark)
+  RB_ADD_GBENCHMARK(${benchmark} ${ARGN})
+
+  set (benchmark_env)
+  if(APPLE)
+    target_link_libraries(${benchmark} PUBLIC
+      -Wl,-bind_at_load -Wl,-undefined -Wl,dynamic_lookup
+      )
+    set (benchmark_env "DYLD_FORCE_FLAT_NAMESPACE=1" "DYLD_INSERT_LIBRARIES=$<TARGET_FILE:RBInstrumentation>")
+  elseif(NOT MSVC)
+    target_link_libraries(${benchmark} PUBLIC
+      -Wl,--unresolved-symbols=ignore-in-object-files
+      )
+    set (benchmark_env "LD_PRELOAD=$<TARGET_FILE:RBInstrumentation>")
+  endif()
+  if (benchmark_env)
+    set_property(TEST rootbench-${benchmark} APPEND PROPERTY ENVIRONMENT ${benchmark_env})
+  endif(benchmark_env)
+
+endfunction(RB_ADD_MEM_GBENCHMARK)
 
 #----------------------------------------------------------------------------
 # function RB_ADD_PYTESTBENCHMARK(<benchmark> filename)
@@ -126,13 +149,19 @@ endfunction()
 function(RB_ADD_LIBRARY library)
   cmake_parse_arguments(ARG "" "" "LIBRARIES;DEPENDENCIES" ${ARGN})
   set(sources ${ARG_UNPARSED_ARGUMENTS})
-  include_directories(BEFORE ${ROOTBENCH_SOURCE_DIR}/include)
   add_library(${library} STATIC ${sources})
-  if (ARG_LIBRARIES OR ARG_DEPENDENCIES)
-    target_link_libraries(${library} ${ARG_LIBRARIES} ${ARG_DEPENDENCIES})
-  endif()
+  target_include_directories(${library} BEFORE PUBLIC ${ROOTBENCH_SOURCE_DIR}/include)
+  target_link_libraries(${library} PUBLIC ${ARG_LIBRARIES} ${ARG_DEPENDENCIES} gbenchmark)
 endfunction(RB_ADD_LIBRARY)
 
+#----------------------------------------------------------------------------
+# function RB_ADD_C_LIBRARY(<library> source1 source2... LIBRARIES libs)
+#----------------------------------------------------------------------------
+function(RB_ADD_C_LIBRARY library)
+  RB_ADD_LIBRARY(${library} ${ARGN})
+  set_target_properties(${library} PROPERTIES LINKER_LANGUAGE C)
+endfunction(RB_ADD_C_LIBRARY)
+
 #----------------------------------------------------------------------------
 # function RB_ADD_TOOL(<binary> source1 source2... LIBRARIES libs)
 #----------------------------------------------------------------------------

include/rootbench/Instrumentation/Memory.h

@@ -0,0 +1,24 @@
+/// \file Memory.h
+///
+/// The file contains interfaces of the C memory instrumentation library.
+///
+/// \author Vassil Vassilev <[email protected]>
+///
+/// \date Oct, 2020
+///
+
+#ifndef RB_MEMORY_H
+#define RB_MEMORY_H
+
+#include <stddef.h>
+
+struct malloc_stats {
+  size_t num_malloc_calls;
+  size_t max_bytes_used;
+};
+
+void reset_malloc_stats();
+const struct malloc_stats get_current_malloc_stats();
+
+
+#endif // RB_MEMORY_H

include/rootbench/RBConfig.h

@@ -2,9 +2,10 @@
 #ifndef RB_CONFIG_H
 #define RB_CONFIG_H
 
-#include "rootbench/Support/ErrorHandling.h"
 #include <rootbench/Constants.h> // RB::kDatasetDirectory
 
+#include "rootbench/Support/ErrorHandling.h"
+
 #include <string>
 
 #include <stdlib.h>
@@ -29,16 +30,37 @@ namespace RB {
     rb_abort("Please set the ROOTSYS env variable!");
   }
 
+  constexpr const char* GetPreloadEnvVar() {
+#ifdef __APPLE__
+    // FIXME: Remove the need of DYLD_FORCE_FLAT_NAMESPACE by using interposing.
+    return "DYLD_INSERT_LIBRARIES";
+#elif defined(UNIX)
+    return "LD_PRELOAD";
+#else
+# error Unsupported Platform;
+#endif
+  }
+
+  /// Checks if we have set up the LD_PRELOAD mechanism for binary
+  /// instrumentation
+  inline bool IsLdPreloadEnabled() {
+    if (char* rootsys = std::getenv(GetPreloadEnvVar()))
+      return true;
+    return false;
+  }
+
   /// Return the absolute path to the directory where data will be downloaded
   inline std::string GetDataDir() {
-      return RB::kDatasetDirectory;
+    return RB::kDatasetDirectory;
   }
 
   /// Like assert, but it does not disappear if -DNDEBUG
-  inline void Ensure(bool b)
+  inline void Ensure(bool b, const std::string& reason = "")
   {
-     if (!b)
-        std::abort();
+    if (!b) {
+      printf("Aborting with reason: '%s'\n", reason.c_str());
+      std::abort();
+    }
   }
 }
 

include/rootbench/Support/MemoryManager.h

@@ -0,0 +1,40 @@
+/// \file MemoryManager.h
+///
+/// The file contains the implementation of benchmark memory tracking.
+///
+/// \author Vassil Vassilev <[email protected]>
+///
+/// \date Oct, 2020
+///
+
+#ifndef RB_MEMORY_MANAGER_H
+#define RB_MEMORY_MANAGER_H
+
+#include "benchmark/benchmark.h"
+
+
+namespace RB {
+  /// Records number of allocations per iteration and the maximum bites used
+  /// for a benchmark.
+  struct MemoryManager : public benchmark::MemoryManager {
+    size_t cur_num_allocs = 0;
+    size_t cur_max_bytes_used = 0;
+    void Start() override;
+    void Stop(Result* result) override;
+  };
+} // end RB
+
+namespace {
+  static auto mm = std::unique_ptr<RB::MemoryManager>(new RB::MemoryManager());
+  static struct InstrumentationRegistrer {
+    InstrumentationRegistrer() {
+      benchmark::RegisterMemoryManager(mm.get());
+    }
+    ~InstrumentationRegistrer() {
+      benchmark::RegisterMemoryManager(nullptr);
+    }
+  } __mem_mgr_register;
+}
+
+
+#endif // RB_MEMORY_MANAGER_H

lib/CMakeLists.txt

@@ -1,2 +1,3 @@
 #---Add the support libraries.
+add_subdirectory(Instrumentation)
 add_subdirectory(Support)

lib/Instrumentation/CMakeLists.txt

@@ -0,0 +1,3 @@
+RB_ADD_C_LIBRARY(RBInstrumentation SHARED
+  Memory.c
+  )

lib/Instrumentation/Memory.c

@@ -0,0 +1,47 @@
+/// \file Memory.c
+///
+/// The file contains code of the C memory instrumentation library.
+///
+/// \author Vassil Vassilev <[email protected]>
+///
+/// \date Oct, 2020
+///
+
+
+#include "rootbench/Instrumentation/Memory.h"
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <dlfcn.h>
+#undef _GNU_SOURCE
+
+static void* (*real_malloc)(size_t) = NULL;
+
+static void mtrace_init(void) {
+  real_malloc = dlsym(RTLD_NEXT, "malloc");
+  if (!real_malloc) {
+    fprintf(stderr, "Error in `dlsym`: %s\n", dlerror());
+  }
+}
+
+static struct malloc_stats cur_malloc_stats;
+void reset_malloc_stats() {
+  cur_malloc_stats.num_malloc_calls = 0;
+  cur_malloc_stats.max_bytes_used = 0;
+}
+
+const struct malloc_stats get_current_malloc_stats() {
+  return cur_malloc_stats;
+}
+
+void *malloc(size_t size) {
+  if(!real_malloc)
+    mtrace_init();
+
+  void *p = NULL;
+  p = real_malloc(size);
+  cur_malloc_stats.num_malloc_calls++;
+  cur_malloc_stats.max_bytes_used += size;
+
+  return p;
+}

lib/Support/CMakeLists.txt

@@ -1,3 +1,8 @@
 RB_ADD_LIBRARY(RBSupport
   ErrorHandling.cxx
-  )
+  MemoryManager.cxx
+)
+target_include_directories(RBSupport PUBLIC
+  ${PROJECT_BINARY_DIR}/include
+  ${PROJECT_SOURCE_DIR}/include
+  ${GBENCHMARK_INCLUDE_DIR})

lib/Support/MemoryManager.cxx

@@ -0,0 +1,44 @@
+/// \file MemoryManager.h
+///
+/// The file contains interfaces for benchmark memory tracking.
+///
+/// \author Vassil Vassilev <[email protected]>
+///
+/// \date Oct, 2020
+///
+
+#include <rootbench/Support/MemoryManager.h>
+
+#include <rootbench/RBConfig.h>
+
+extern "C" {
+  #include <rootbench/Instrumentation/Memory.h>
+}
+
+#include <benchmark/benchmark.h>
+
+// FIXME: Remove the need of DYLD_FORCE_FLAT_NAMESPACE by using interposing.
+static void EnsureFlatNamespaceOSX() {
+#ifdef __APPLE__
+  RB::Ensure(std::getenv("DYLD_FORCE_FLAT_NAMESPACE"),
+             "DYLD_FORCE_FLAT_NAMESPACE not set.");
+#endif // __APPLE__
+}
+
+namespace RB {
+  void MemoryManager::Start() {
+    Ensure(IsLdPreloadEnabled(), std::string(GetPreloadEnvVar()) + " not set.");
+    EnsureFlatNamespaceOSX();
+    cur_num_allocs = 0;
+    cur_max_bytes_used = 0;
+    reset_malloc_stats();
+  }
+
+  void MemoryManager::Stop(Result* result) {
+    Ensure(IsLdPreloadEnabled(), std::string(GetPreloadEnvVar()) + " not set.");
+    EnsureFlatNamespaceOSX();
+    const malloc_stats& stats = get_current_malloc_stats();
+    result->num_allocs = stats.num_malloc_calls;
+    result->max_bytes_used = stats.max_bytes_used;
+  }
+} // end RB

root/interpreter/CMakeLists.txt

@@ -4,4 +4,8 @@ RB_ADD_GBENCHMARK(InterpreterBenchmarks
 
 RB_ADD_GBENCHMARK(InterpreterBenchmarksNoPCH
   RunInterpreterNoPCH.cxx
-  LABEL short)
+  LABEL short)
+
+RB_ADD_MEM_GBENCHMARK(InterpreterLookupHelperBenchmarks
+  LookupHelper.cxx LIBRARIES Core
+  LABEL short)