Add a Strong Type for Memory Sizes (ad-freiburg#1032)

Add a class `ad_utility::MemorySize` that stores an amount of memory in bytes in a strongly typed manner. It can be parsed from strings (e.g. "4 kB" or "8.3 GB") and set from user defined literals (`4.34_GB` etc.). This commit does not yet use the `MemorySize`, but this is left for following PRs.

sonar-project.properties

@@ -8,7 +8,7 @@ sonar.projectVersion=1.0
 # Path is relative to the sonar-project.properties file. Replace "\" by "/" on Windows.
 sonar.sources=./src,./benchmark
 sonar.tests=./test
-sonar.exclusions=src/parser/sparqlParser/generated/*,src/util/http/HttpParser/generated/*, src/util/ConfigManager/generated/*
+sonar.exclusions=src/parser/sparqlParser/generated/*,src/util/http/HttpParser/generated/*, src/util/ConfigManager/generated/*, src/util/MemorySize/generated/*
 
 # Encoding of the source code. Default is default system encoding
 sonar.sourceEncoding=UTF-8

src/util/CMakeLists.txt

@@ -1,4 +1,5 @@
 add_subdirectory(ConfigManager)
+add_subdirectory(MemorySize)
 add_subdirectory(http)
 add_library(util GeoSparqlHelpers.cpp
         antlr/ANTLRErrorHandling.cpp ParseException.cpp Conversions.cpp Date.cpp)

src/util/MemorySize/CMakeLists.txt

@@ -0,0 +1,4 @@
+add_library(memorySize MemorySize.cpp
+    generated/MemorySizeLanguageLexer.cpp
+    generated/MemorySizeLanguageParser.cpp MemorySizeParser.cpp)
+qlever_target_link_libraries(memorySize antlr4_static util)

src/util/MemorySize/MemorySize.cpp

@@ -0,0 +1,75 @@
+// Copyright 2022, University of Freiburg,
+// Chair of Algorithms and Data Structures.
+// Author: Andre Schlegel (July of 2023,
+// [email protected])
+
+#include "util/MemorySize/MemorySize.h"
+
+#include <absl/strings/str_cat.h>
+
+#include <cinttypes>
+#include <ranges>
+#include <string_view>
+
+#include "util/Cache.h"
+#include "util/ConstexprMap.h"
+#include "util/ConstexprUtils.h"
+#include "util/Exception.h"
+#include "util/HashMap.h"
+#include "util/MemorySize/MemorySizeParser.h"
+#include "util/MemorySize/generated/MemorySizeLanguageLexer.h"
+#include "util/MemorySize/generated/MemorySizeLanguageParser.h"
+
+namespace ad_utility {
+// _____________________________________________________________________________
+std::string MemorySize::asString() const {
+  // Convert number and memory unit name to the string, we want to return.
+  auto toString = [](const auto number, std::string_view unitName) {
+    return absl::StrCat(number, " ", unitName);
+  };
+
+  /*
+  Choosing the memory unit type is done by choosing the unit type, in which
+  range `memoryInBytes_` is contained.
+  A memory unit type normally has the range `[hisSize,
+  sizeOfTheNextBiggerUnit)`.
+  Only exceptions are:
+  - `TB`, which has no upper bound, because it's our biggest unit.
+  - `kB`, which has the lower bound `100'000` instead of `1'000`. Typically, for
+  such small sizes you still want the exact value because they mean something
+  ,e.g. a block size or a page size etc..
+  */
+  constexpr ad_utility::ConstexprMap<char, size_t, 4> memoryUnitLowerBound(
+      {std::pair<char, size_t>{'k', ad_utility::pow(10, 5)},
+       std::pair<char, size_t>{'M', detail::numBytesPerUnit.at("MB")},
+       std::pair<char, size_t>{'G', detail::numBytesPerUnit.at("GB")},
+       std::pair<char, size_t>{'T', detail::numBytesPerUnit.at("TB")}});
+
+  // Go through the units from top to bottom, in terms of size, and choose the
+  // first one, that is smaller/equal to `memoryInBytes_`.
+  if (memoryInBytes_ >= memoryUnitLowerBound.at('T')) {
+    return toString(getTerabytes(), "TB");
+  } else if (memoryInBytes_ >= memoryUnitLowerBound.at('G')) {
+    return toString(getGigabytes(), "GB");
+  } else if (memoryInBytes_ >= memoryUnitLowerBound.at('M')) {
+    return toString(getMegabytes(), "MB");
+  } else if (memoryInBytes_ >= memoryUnitLowerBound.at('k')) {
+    return toString(getKilobytes(), "kB");
+  } else {
+    // Just return the amount of bytes.
+    return toString(memoryInBytes_, "B");
+  }
+}
+
+// _____________________________________________________________________________
+MemorySize MemorySize::parse(std::string_view str) {
+  return MemorySizeParser::parseMemorySize(str);
+}
+
+// _____________________________________________________________________________
+std::ostream& operator<<(std::ostream& os, const ad_utility::MemorySize& mem) {
+  os << mem.asString();
+  return os;
+}
+
+}  // namespace ad_utility