From 033bf5d6ef7d189eb899a4ea6046fa6a0a29f968 Mon Sep 17 00:00:00 2001
From: Kearwood Gilbert <kearwood@kearwood.com>
Date: Tue, 15 Sep 2026 22:48:03 -0700
Subject: [PATCH] Add tests for Heap allocator Add Heap::getMaxSize() Add
 Heap::getUsed() Add minSize argument to Heap::init()

---
 include/block.h      |  1 +
 include/heap.h       | 12 +++++++++++-
 src/heap.cpp         | 28 ++++++++++++++++++++++++++--
 src/mimir_impl.h     |  1 +
 tests/CMakeLists.txt |  3 ++-
 tests/arena_test.cpp |  8 ++++++++
 6 files changed, 49 insertions(+), 4 deletions(-)

diff --git a/include/block.h b/include/block.h
index 0865b6e..3c1e817 100644
--- a/include/block.h
+++ b/include/block.h
@@ -35,6 +35,7 @@
 #include <stdint.h>
 
 #if defined(_WIN32) || defined(_WIN64)
+#define NOMINMAX
 #include <Windows.h>
 #endif
 
diff --git a/include/heap.h b/include/heap.h
index 0a001c7..15af098 100644
--- a/include/heap.h
+++ b/include/heap.h
@@ -46,7 +46,7 @@ public:
   Heap();
   ~Heap();
 
-  bool init(size_t maxSize = 1ULL << 32);
+  bool init(size_t minSize = 1ULL << 24, size_t maxSize = 1ULL << 32);
 
   // Allocate `size` bytes
   std::byte* alloc(size_t size);
@@ -60,8 +60,18 @@ public:
   // Free the allocation at `address`
   void free(std::byte* address);
 
+  // Get the actual used size.
+  // This may differ from the sum of allocations due to alignment requirements.
+  size_t getUsed() const;
+
+  // Get the actual maximum size.
+  // This may be greater than the maxSize passed into init, due to page size alignment.
+  size_t getMaxSize() const;
+
 private:
   Region m_region;
+  size_t m_minSize;
+  size_t m_usedSize;
 
   // Add a free block to the index
   void insertFreeBlock(TLSFBlock* block);
diff --git a/src/heap.cpp b/src/heap.cpp
index 0fdd5b1..fa4db50 100644
--- a/src/heap.cpp
+++ b/src/heap.cpp
@@ -32,6 +32,7 @@
 #include "../include/mimir.h"
 #include "mimir_impl.h"
 
+#include <algorithm>
 #include <cassert>
 #include <cstring>
 #include <bit>
@@ -94,6 +95,8 @@ uint64_t blockSizeToIndex(uint64_t size)
 */
 
 Heap::Heap()
+  : m_minSize(0)
+  , m_usedSize(0)
 {
 }
 
@@ -101,12 +104,18 @@ Heap::~Heap()
 {
 }
 
-bool Heap::init(size_t maxSize)
+bool Heap::init(size_t minSize, size_t maxSize)
 {
+  assert(maxSize >= minSize);
+  assert(m_usedSize == 0);
+
+  m_minSize = sizeof(TLSFIndex) + 16;
+  m_minSize = std::max(m_minSize, minSize);
+  m_minSize = KRAKEN_MEM_ROUND_UP_PAGE(m_minSize);
   if (!m_region.init(maxSize)) {
     return false;
   }
-  if (!m_region.resize(sizeof(TLSFIndex) + 16)) {
+  if (!m_region.resize(m_minSize)) {
     return false;
   }
   TLSFIndex* index = (TLSFIndex*)m_region.getAddress();
@@ -124,6 +133,20 @@ bool Heap::init(size_t maxSize)
   return true;
 }
 
+// Get the actual maximum size.
+// This may be greater than the maxSize passed into init, due to page size alignment.
+size_t Heap::getMaxSize() const
+{
+  return m_region.getSize();
+}
+
+// Get the actual used size.
+// This may differ from the sum of allocations due to alignment requirements.
+size_t Heap::getUsed() const
+{
+  return m_usedSize;
+}
+
 void Heap::insertFreeBlock(TLSFBlock* block)
 {
   // Add the block to the index
@@ -281,6 +304,7 @@ std::byte* Heap::alloc(size_t size)
   }
 
   block->size = size;
+  m_usedSize += size;
   return (std::byte*)block + 16;
 }
 
diff --git a/src/mimir_impl.h b/src/mimir_impl.h
index 1882f81..ec6bb04 100644
--- a/src/mimir_impl.h
+++ b/src/mimir_impl.h
@@ -39,6 +39,7 @@
 #endif
 
 #if defined(_WIN32) || defined(_WIN64)
+#define NOMINMAX
 #include <Windows.h>
 #include <memoryapi.h>
 #endif
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 68887b9..6146a9e 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -14,8 +14,9 @@ enable_testing()
 
 add_executable(
   mimir_test
-  "region_test.cpp"
   "arena_test.cpp"
+  "heap_test.cpp"
+  "region_test.cpp"
   "test_util.cpp")
 target_link_libraries(
   mimir_test
diff --git a/tests/arena_test.cpp b/tests/arena_test.cpp
index 2743a7a..9f80569 100644
--- a/tests/arena_test.cpp
+++ b/tests/arena_test.cpp
@@ -6,6 +6,14 @@
 
 namespace mimir_tests {
 
+TEST(Arena, InitialState)
+{
+  mimir::init();
+  mimir::Arena arena;
+  EXPECT_TRUE(arena.init());
+  EXPECT_EQ(arena.getUsed(), 0);
+}
+
 TEST(Arena, OutOfMemory)
 {
   mimir::init();