gc history log (#519)

- Feature: Writes a `gc.log` with settings and detailed result after each GC execution (version 2 only)
- Break out file name rotate to allow access for gclog
- CompactBinaryToJson(MemoryView Data, StringBuilderBase& InBuilder)

1 files changed, 64 insertions, 0 deletions

diff --git a/src/zencore/filesystem.cpp b/src/zencore/filesystem.cpp
index b64c9973e..06cda7382 100644
--- a/src/zencore/filesystem.cpp
+++ b/src/zencore/filesystem.cpp
@@ -40,6 +40,7 @@ ZEN_THIRD_PARTY_INCLUDES_END
 #	include <unistd.h>
 #endif
 
+#include <fmt/format.h>
 #include <filesystem>
 #include <gsl/gsl-lite.hpp>
 
@@ -1396,6 +1397,69 @@ GetEnvVariable(std::string_view VariableName)
 	return "";
 }
 
+std::error_code
+RotateFiles(const std::filesystem::path& Filename, std::size_t MaxFiles)
+{
+	const std::filesystem::path BasePath(Filename.parent_path());
+	const std::string			Stem(Filename.stem().string());
+	const std::string			Extension(Filename.extension().string());
+
+	std::error_code Result;
+
+	auto GetFileName = [&](size_t Index) -> std::filesystem::path {
+		if (Index == 0)
+		{
+			return BasePath / (Stem + Extension);
+		}
+		return BasePath / fmt::format("{}.{}{}", Stem, Index, Extension);
+	};
+
+	auto IsEmpty = [](const std::filesystem::path& Path, std::error_code& Ec) -> bool {
+		bool Exists = std::filesystem::exists(Path, Ec);
+		if (Ec)
+		{
+			return false;
+		}
+		if (!Exists)
+		{
+			return true;
+		}
+		uintmax_t Size = std::filesystem::file_size(Path, Ec);
+		if (Ec)
+		{
+			return false;
+		}
+		return Size == 0;
+	};
+
+	bool BaseIsEmpty = IsEmpty(GetFileName(0), Result);
+	if (Result)
+	{
+		return Result;
+	}
+	if (!BaseIsEmpty)
+	{
+		// We try our best to rotate the logs, if we fail we fail and will try to open the base log file anyway
+		for (auto i = MaxFiles; i > 0; i--)
+		{
+			std::filesystem::path src = GetFileName(i - 1);
+			if (!std::filesystem::exists(src))
+			{
+				continue;
+			}
+			std::error_code		  DummyEc;
+			std::filesystem::path target = GetFileName(i);
+			if (std::filesystem::exists(target, DummyEc))
+			{
+				std::filesystem::remove(target, DummyEc);
+			}
+			std::filesystem::rename(src, target, DummyEc);
+		}
+	}
+
+	return Result;
+}
+
 //////////////////////////////////////////////////////////////////////////
 //
 // Testing related code follows...