chore: Refactor struct

Signed-off-by: KunoiSayami <[email protected]>

2 files changed, 137 insertions, 0 deletions

diff --git a/headers/arena.cu b/headers/arena.cu
new file mode 100644
index 0000000..7f5de7a
--- /dev/null
+++ b/headers/arena.cu
@@ -0,0 +1,69 @@
+//
+// Created by user on 20/10/2021.
+//
+
+#include "arena.cuh"
+
+namespace cleveldb {
+
+static const int kBlockSize = 4096;
+
+Arena::Arena()
+	: alloc_ptr_(nullptr), alloc_bytes_remaining_(0), memory_usage_(0) {}
+
+Arena::~Arena() {
+	for (size_t i = 0; i < blocks_.size(); i++) {
+		//delete[] blocks_[i];
+		cudaFree(blocks_[i]);
+	}
+}
+
+char* Arena::AllocateFallback(size_t bytes) {
+	if (bytes > kBlockSize / 4) {
+		// Object is more than a quarter of our block size.  Allocate it separately
+		// to avoid wasting too much space in leftover bytes.
+		char* result = AllocateNewBlock(bytes);
+		return result;
+	}
+
+	// We waste the remaining space in the current block.
+	alloc_ptr_ = AllocateNewBlock(kBlockSize);
+	alloc_bytes_remaining_ = kBlockSize;
+
+	char* result = alloc_ptr_;
+	alloc_ptr_ += bytes;
+	alloc_bytes_remaining_ -= bytes;
+	return result;
+}
+
+char* Arena::AllocateAligned(size_t bytes) {
+	const int align = (sizeof(void*) > 8) ? sizeof(void*) : 8;
+	static_assert((align & (align - 1)) == 0,
+				  "Pointer size should be a power of 2");
+	size_t current_mod = reinterpret_cast<uintptr_t>(alloc_ptr_) & (align - 1);
+	size_t slop = (current_mod == 0 ? 0 : align - current_mod);
+	size_t needed = bytes + slop;
+	char* result;
+	if (needed <= alloc_bytes_remaining_) {
+		result = alloc_ptr_ + slop;
+		alloc_ptr_ += needed;
+		alloc_bytes_remaining_ -= needed;
+	} else {
+		// AllocateFallback always returned aligned memory
+		result = AllocateFallback(bytes);
+	}
+	assert((reinterpret_cast<uintptr_t>(result) & (align - 1)) == 0);
+	return result;
+}
+
+char* Arena::AllocateNewBlock(size_t block_bytes) {
+	//char* result = new char[block_bytes];
+	char* result = nullptr;
+	cudaMallocManaged((void **)&result, sizeof(char) * block_bytes);
+	blocks_.push_back(result);
+	memory_usage_.fetch_add(block_bytes + sizeof(char*),
+							std::memory_order_relaxed);
+	return result;
+}
+
+}  // namespace cleveldb
\ No newline at end of file
diff --git a/headers/arena.cuh b/headers/arena.cuh
new file mode 100644
index 0000000..20da470
--- /dev/null
+++ b/headers/arena.cuh
@@ -0,0 +1,68 @@
+//
+// Created by user on 20/10/2021.
+//
+
+#ifndef CLEVELDB_ARENA_CUH
+#define CLEVELDB_ARENA_CUH
+
+
+#include <atomic>
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <vector>
+
+namespace cleveldb {
+
+
+class Arena {
+public:
+	Arena();
+	Arena(const Arena &) = delete;
+
+	Arena& operator=(const Arena&) = delete;
+
+	~Arena();
+
+	// Return a pointer to a newly allocated memory block of "bytes" bytes.
+	char* Allocate(size_t bytes);
+
+	// Allocate memory with the normal alignment guarantees provided by malloc.
+	char* AllocateAligned(size_t bytes);
+
+	// Returns an estimate of the total memory usage of data allocated
+	// by the arena.
+	size_t MemoryUsage() const {
+		return memory_usage_.load(std::memory_order_relaxed);
+	}
+
+private:
+	char* AllocateFallback(size_t bytes);
+	char* AllocateNewBlock(size_t block_bytes);
+
+	char* alloc_ptr_;
+	size_t alloc_bytes_remaining_;
+
+	std::vector<char*> blocks_;
+
+	std::atomic<size_t> memory_usage_;
+};
+
+inline char* Arena::Allocate(size_t bytes) {
+	// The semantics of what to return are a bit messy if we allow
+	// 0-byte allocations, so we disallow them here (we don't need
+	// them for our internal use).
+	assert(bytes > 0);
+	if (bytes <= alloc_bytes_remaining_) {
+		char* result = alloc_ptr_;
+		alloc_ptr_ += bytes;
+		alloc_bytes_remaining_ -= bytes;
+		return result;
+	}
+	return AllocateFallback(bytes);
+}
+
+
+}  // namespace cleveldb
+
+#endif //CLEVELDB_ARENA_CUH