Bugfixes for ExpandableArena

lib/Base/Array.h

@@ -78,6 +78,11 @@ bool is_valid(Array<T> src) {
   return true;
 }
 
+template <typename T>
+void array_zero (const Array<T>& src) {
+  memset(src.data, 0, src.count * sizeof(T));
+}
+
 template <typename T>
 Array<T> array_copy_zero(const Array<T>& src) {
   if (!src.data || src.count == 0) {
@@ -244,8 +249,8 @@ s64 array_unordered_remove_by_value(Array<T>& src, T item, s64 max_count_to_remo
     if (src[i] == item) {
       removed_count += 1;
       array_unordered_remove_by_index(src, i);
-      debug_break(); // haven't quite figured this one out yet.
-      i -= 1; // check this element again??
+
+      i -= 1; // check this element index again
       if (max_count_to_remove == removed_count) { break; }
     }
   }

lib/Base/Expandable_Arena.cpp

@@ -5,7 +5,9 @@ ExpandableArena* expandable_arena_new (Arena_Reserve starting_reserve, s32 commi
   
   new_arena->current_point = expandable_arena_start(new_arena);
   new_arena->next_arenas = Array<Arena*>(); // next_arenas will be uninitialized, so we have to do this
-  new_arena->next_arenas.allocator = get_allocator(new_arena);
+  // We have to use malloc because if we reset this new arena, all the data will be lost
+  // We don't want to tie the lifetime of next_arenas to this expandable arena.
+  new_arena->next_arenas.allocator = GPAllocator();
   
   array_reserve(new_arena->next_arenas, 8);
 
@@ -66,7 +68,7 @@ void* expandable_arena_alloc (ExpandableArena* arena_ex, s64 byte_count) {
       arena_ex->current     = new_arena;
       array_add(arena_ex->next_arenas, new_arena);
       
-      // Get to actual allocation:
+      // Allocate from new arena, committing pages as required
       result     = Align<u8*>(new_arena->current_point, new_arena->alignment);
       result_end = result + byte_count;
       
@@ -100,8 +102,12 @@ void arena_reset (ExpandableArena* arena_ex, bool free_extra_pages) {
   }
   
   // Reset next_arenas
+#if BUILD_DEBUG 
+  array_zero(arena_ex->next_arenas);
+#endif
   array_reset_keeping_memory(arena_ex->next_arenas);
   
+  arena_ex->current = (Arena*)arena_ex;
   arena_ex->current_point = expandable_arena_start(arena_ex);
   
   if (free_extra_pages) {
@@ -110,6 +116,7 @@ void arena_reset (ExpandableArena* arena_ex, bool free_extra_pages) {
 }
 
 force_inline void arena_delete (ExpandableArena* arena_ex) {
+  array_free(arena_ex->next_arenas);
   arena_reset(arena_ex, true);
   arena_delete((Arena*)arena_ex);
 }

lib/Base/Expandable_Arena.h

@@ -1,8 +1,10 @@
 // Just an idea I had so that we can start with a small arena and increase on an as-needed basis, 
 // this way allocations are always extremely fast.
+// The full structure is 80B, and because we use bootstrapping, we only need a little extra memory for storing 
+// the `next_arenas` pointers
 
-// Note that this downcasts to Arena, so can be initialized in the same way.
-// DO NOT USE push_arena WITH THIS! IT WILL CALL THE WRONG PROC!
+// DO NOT MERGE WITH `Arena`, we need fixed size arenas so that we can back
+// `ArenaArray`s. 
 struct ExpandableArena {
   u8* current_point               = nullptr;
   u8* memory_base                 = nullptr;
@@ -11,9 +13,9 @@ struct ExpandableArena {
   Arena_Reserve reserve_size      = Arena_Reserve::Size_64K;
   Arena_Flags flags               = Arena_Flags::None;
   u32 initial_commit_page_count   = ARENA_DEFAULT_COMMIT_PAGE_COUNT;
-  // 32 bytes up to here
+  // Note that this downcasts to Arena, so can be initialized in the same way.
   Arena* current;
-  Array<Arena*> next_arenas; // 40 B
+  Array<Arena*> next_arenas;
 };
 
 ExpandableArena* expandable_arena_new (Arena_Reserve starting_reserve=Arena_Reserve::Size_64K, s32 commit_page_count=8);

lib/Base/General_Purpose_Allocator.cpp

@@ -35,11 +35,11 @@ General_Allocator* get_general_allocator_data() {
 
 constexpr s64 Allocation_Tracking_Is_Enabled = GP_ALLOCATOR_TRACK_ALLOCATIONS;
 
-bool GPAllocator_Tracking_Enabled() {
+bool GPAllocator_Tracking_Enabled () {
     return Allocation_Tracking_Is_Enabled != 0;
 }
 
-void GPAllocator_Initialize_Allocation_Tracker() {
+void GPAllocator_Initialize_Allocation_Tracker () {
 #if GP_ALLOCATOR_TRACK_ALLOCATIONS
     constexpr s64 alignment = 64;
     s64 item_count_max = 64 * 4096;
@@ -50,7 +50,7 @@ void GPAllocator_Initialize_Allocation_Tracker() {
 #endif
 }
 
-bool GPAllocator_Is_This_Yours(void* old_memory) {
+bool GPAllocator_Is_This_Yours (void* old_memory) {
 #if GP_ALLOCATOR_TRACK_ALLOCATIONS
     std::lock_guard<std::mutex> lock(allocator_mutex);
 
@@ -130,7 +130,7 @@ void GPAllocator_Delete (void* memory) {
     Remove_Allocation(memory);
 }
 
-Allocator GPAllocator() {
+Allocator GPAllocator () {
     return { GPAllocator_Proc, nullptr };
 }
 

lib/Base/General_Purpose_Allocator.h

@@ -40,7 +40,7 @@ General_Allocator* get_general_allocator_data();
 
 constexpr u16 GPAllocator_Default_Alignment = 16;
 
-Allocator GPAllocator();
+Allocator GPAllocator ();
 
 void* GPAllocator_Proc (Allocator_Mode mode, s64 requested_size, s64 old_size, void* old_memory, void* allocator_data);
 
@@ -48,7 +48,7 @@ void* GPAllocator_New (s64 new_size, s64 alignment=16, bool initialize=true);
 void* GPAllocator_Resize (s64 old_size, void* old_memory, s64 new_size, s64 alignment=16, bool initialize=true);
 void  GPAllocator_Delete (void* memory);
 
-bool GPAllocator_Is_This_Yours(void* old_memory);
-void GPAllocator_Initialize_Allocation_Tracker();
-bool GPAllocator_Tracking_Enabled();
+bool GPAllocator_Is_This_Yours (void* old_memory);
+void GPAllocator_Initialize_Allocation_Tracker ();
+bool GPAllocator_Tracking_Enabled ();
 

lib/OS/Base_Entry_Point.cpp

@@ -1,5 +1,5 @@
 internal void Bootstrap_Main_Thread_Context () {
-  // 0. Setup general purpose allocator
+  // 0. Setup general MB(70) allocator
   GPAllocator_Initialize_Allocation_Tracker();
   // 1. Setup arena table
   initialize_arena_table();
@@ -23,7 +23,7 @@ void run_arena_array_tests () {
     auto_reset(thread_local_context->temp);
     auto something = New<Thread_Context>();
     auto something2 = New<Array<s64>>();
-    auto something3 = internal_alloc(5000);
+    auto something3 = internal_alloc(MB(70));
   }
   
   { push_allocator(GPAllocator());
@@ -40,7 +40,7 @@ internal void Main_Entry_Point (int argc, WCHAR **argv) {
   run_arena_array_tests();
 
   // Worker_Info* info = (Worker_Info*)GPAllocator_New(sizeof(Worker_Info), 64);
-  
+  temp_reset();
   debug_break();
   printf("sizeof(Array): %zd\n", sizeof(Array<f32>));
   printf("sizeof(Arena): %zd\n", sizeof(Arena));