4 files changed, 112 insertions, 7 deletions
diff --git a/headers/arena.cu b/headers/arena.cu
index 7f5de7a..fe316f2 100644
--- a/headers/arena.cu
+++ b/headers/arena.cu
@@ -1,7 +1,3 @@
-//
-// Created by user on 20/10/2021.
-//
-
 #include "arena.cuh"
 
 namespace cleveldb {
diff --git a/headers/arena.cuh b/headers/arena.cuh
index 20da470..5f8d1c7 100644
--- a/headers/arena.cuh
+++ b/headers/arena.cuh
@@ -2,8 +2,8 @@
 // Created by user on 20/10/2021.
 //
 
-#ifndef CLEVELDB_ARENA_CUH
-#define CLEVELDB_ARENA_CUH
+#ifndef CLEVELDB_ARENA_TEST_CUH
+#define CLEVELDB_ARENA_TEST_CUH
 
 
 #include <atomic>
@@ -65,4 +65,4 @@ inline char* Arena::Allocate(size_t bytes) {
 
 }  // namespace cleveldb
 
-#endif //CLEVELDB_ARENA_CUH
+#endif //CLEVELDB_ARENA_TEST_CUH
diff --git a/headers/arena_test.cu b/headers/arena_test.cu
new file mode 100644
index 0000000..68fc8ff
--- /dev/null
+++ b/headers/arena_test.cu
@@ -0,0 +1,52 @@
+#include "arena.cuh"
+#include "random.h"
+
+using namespace cleveldb;
+
+int main() {
+	std::vector<std::pair<size_t, char*>> allocated;
+	Arena arena;
+	const int N = 100000;
+	size_t bytes = 0;
+	Random rnd(301);
+	for (int i = 0; i < N; i++) {
+		size_t s;
+		if (i % (N / 10) == 0) {
+			s = i;
+		} else {
+			s = rnd.OneIn(4000)
+				? rnd.Uniform(6000)
+				: (rnd.OneIn(10) ? rnd.Uniform(100) : rnd.Uniform(20));
+		}
+		if (s == 0) {
+			// Our arena disallows size 0 allocations.
+			s = 1;
+		}
+		char* r;
+		if (rnd.OneIn(10)) {
+			r = arena.AllocateAligned(s);
+		} else {
+			r = arena.Allocate(s);
+		}
+
+		for (size_t b = 0; b < s; b++) {
+			// Fill the "i"th allocation with a known bit pattern
+			r[b] = i % 256;
+		}
+		bytes += s;
+		allocated.push_back(std::make_pair(s, r));
+		assert(arena.MemoryUsage() >= bytes);
+		if (i > N / 10) {
+			assert(arena.MemoryUsage() <= bytes * 1.10);
+		}
+	}
+	for (size_t i = 0; i < allocated.size(); i++) {
+		size_t num_bytes = allocated[i].first;
+		const char* p = allocated[i].second;
+		for (size_t b = 0; b < num_bytes; b++) {
+			// Check the "i"th allocation for the known bit pattern
+			assert((int(p[b]) & 0xff) == (i % 256));
+		}
+	}
+	return 0;
+}
diff --git a/headers/random.h b/headers/random.h
new file mode 100644
index 0000000..2b04757
--- /dev/null
+++ b/headers/random.h
@@ -0,0 +1,57 @@
+#ifndef CLEVELDB_RANDOM_H
+#define CLEVELDB_RANDOM_H
+#include <cstdint>
+
+namespace cleveldb {
+
+// A very simple random number generator.  Not especially good at
+// generating truly random bits, but good enough for our needs in this
+// package.
+	class Random {
+	private:
+		uint32_t seed_;
+
+	public:
+		explicit Random(uint32_t s) : seed_(s & 0x7fffffffu) {
+			// Avoid bad seeds.
+			if (seed_ == 0 || seed_ == 2147483647L) {
+				seed_ = 1;
+			}
+		}
+		uint32_t Next() {
+			static const uint32_t M = 2147483647L;  // 2^31-1
+			static const uint64_t A = 16807;        // bits 14, 8, 7, 5, 2, 1, 0
+			// We are computing
+			//       seed_ = (seed_ * A) % M,    where M = 2^31-1
+			//
+			// seed_ must not be zero or M, or else all subsequent computed values
+			// will be zero or M respectively.  For all other values, seed_ will end
+			// up cycling through every number in [1,M-1]
+			uint64_t product = seed_ * A;
+
+			// Compute (product % M) using the fact that ((x << 31) % M) == x.
+			seed_ = static_cast<uint32_t>((product >> 31) + (product & M));
+			// The first reduction may overflow by 1 bit, so we may need to
+			// repeat.  mod == M is not possible; using > allows the faster
+			// sign-bit-based test.
+			if (seed_ > M) {
+				seed_ -= M;
+			}
+			return seed_;
+		}
+		// Returns a uniformly distributed value in the range [0..n-1]
+		// REQUIRES: n > 0
+		uint32_t Uniform(int n) { return Next() % n; }
+
+		// Randomly returns true ~"1/n" of the time, and false otherwise.
+		// REQUIRES: n > 0
+		bool OneIn(int n) { return (Next() % n) == 0; }
+
+		// Skewed: pick "base" uniformly from range [0,max_log] and then
+		// return "base" random bits.  The effect is to pick a number in the
+		// range [0,2^max_log-1] with exponential bias towards smaller numbers.
+		uint32_t Skewed(int max_log) { return Uniform(1 << Uniform(max_log + 1)); }
+	};
+
+}  // namespace cleveldb
+#endif //CLEVELDB_RANDOM_H