From 5bf90aa4e7e5b6127352a494782346caf69386b7 Mon Sep 17 00:00:00 2001
From: KunoiSayami <i@leanhe.dev>
Date: Thu, 21 Oct 2021 01:57:05 +0800
Subject: init

Signed-off-by: KunoiSayami <i@leanhe.dev>
---
 arena.cuh | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 arena.cuh

(limited to 'arena.cuh')

diff --git a/arena.cuh b/arena.cuh
new file mode 100644
index 0000000..20da470
--- /dev/null
+++ b/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
-- 
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