add support for OTLP logging/tracing (#599)

- adds `zentelemetry` project which houses new functionality for serializing logs and traces in OpenTelemetry Protocol format (OTLP)
- moved existing stats functionality from `zencore` to `zentelemetry`
- adds `TRefCounted<T>` for vtable-less refcounting
- adds `MemoryArena` class which allows for linear allocation of memory from chunks
- adds `protozero` which is used to encode OTLP protobuf messages

1 files changed, 126 insertions, 0 deletions

diff --git a/src/zencore/memory/memoryarena.cpp b/src/zencore/memory/memoryarena.cpp
new file mode 100644
index 000000000..9c907a66d
--- /dev/null
+++ b/src/zencore/memory/memoryarena.cpp
@@ -0,0 +1,126 @@
+// Copyright Epic Games, Inc. All Rights Reserved.
+
+#include <zencore/memory/memoryarena.h>
+
+namespace zen {
+
+MemoryArena::~MemoryArena()
+{
+	for (auto Chunk : m_Chunks)
+		delete[] Chunk;
+}
+
+void*
+MemoryArena::AllocateAligned(size_t ByteCount, size_t align)
+{
+	if (ByteCount == 0)
+	{
+		return nullptr;
+	}
+
+	void* Ptr = nullptr;
+
+	m_Lock.WithExclusiveLock([&] {
+		size_t AlignedOffset = (m_CurrentOffset + (align - 1)) & ~(align - 1);
+
+		if (m_CurrentChunk == nullptr || AlignedOffset + ByteCount > ChunkSize)
+		{
+			uint8_t* NewChunk = new uint8_t[ChunkSize];
+			if (!NewChunk)
+			{
+				return;
+			}
+
+			m_Chunks.push_back(NewChunk);
+			m_CurrentChunk = NewChunk;
+			AlignedOffset  = 0;
+		}
+
+		Ptr				= m_CurrentChunk + AlignedOffset;
+		m_CurrentOffset = AlignedOffset + ByteCount;
+	});
+
+	return Ptr;
+}
+
+void*
+MemoryArena::AllocateAlignedWithOffset(size_t ByteCount, size_t align, size_t offset)
+{
+	if (ByteCount == 0)
+	{
+		return nullptr;
+	}
+
+	void* Ptr = nullptr;
+
+	m_Lock.WithExclusiveLock([&] {
+		size_t AlignedOffset = (m_CurrentOffset + (align - 1) + offset) & ~(align - 1);
+
+		if (m_CurrentChunk == nullptr || AlignedOffset + ByteCount > ChunkSize)
+		{
+			uint8_t* NewChunk = new uint8_t[ChunkSize];
+			if (!NewChunk)
+			{
+				return;
+			}
+
+			m_Chunks.push_back(NewChunk);
+			m_CurrentChunk = NewChunk;
+			AlignedOffset  = offset;
+		}
+
+		Ptr				= m_CurrentChunk + AlignedOffset;
+		m_CurrentOffset = AlignedOffset + ByteCount;
+	});
+
+	return Ptr;
+}
+
+void*
+MemoryArena::Allocate(size_t Size)
+{
+	if (Size == 0)
+	{
+		return nullptr;
+	}
+
+	void*			 Ptr	   = nullptr;
+	constexpr size_t Alignment = alignof(std::max_align_t);
+
+	m_Lock.WithExclusiveLock([&] {
+		size_t AlignedOffset = (m_CurrentOffset + Alignment - 1) & ~(Alignment - 1);
+
+		if (m_CurrentChunk == nullptr || AlignedOffset + Size > ChunkSize)
+		{
+			uint8_t* NewChunk = new uint8_t[ChunkSize];
+			if (!NewChunk)
+			{
+				return;
+			}
+
+			m_Chunks.push_back(NewChunk);
+			m_CurrentChunk = NewChunk;
+			AlignedOffset  = 0;
+		}
+
+		Ptr				= m_CurrentChunk + AlignedOffset;
+		m_CurrentOffset = AlignedOffset + Size;
+	});
+
+	return Ptr;
+}
+
+const char*
+MemoryArena::DuplicateString(std::string_view Str)
+{
+	const size_t Len	= Str.size();
+	char*		 NewStr = static_cast<char*>(Allocate(Len + 1));
+	if (NewStr)
+	{
+		memcpy(NewStr, Str.data(), Len);
+		NewStr[Len] = '\0';
+	}
+	return NewStr;
+}
+
+}  // namespace zen