From d77ca22f5f846d2db5e3d75067e924eefded905e Mon Sep 17 00:00:00 2001
From: Max Regan <mgregan2@gmail.com>
Date: Wed, 30 Nov 2022 00:52:07 -0500
Subject: [PATCH] Add size-1 cache to arenas

---
 src/arena.c | 27 +++++++++++++++++++++++++++
 src/scope.c |  8 ++++----
 src/types.h |  2 ++
 3 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/src/arena.c b/src/arena.c
index a6d0b7d..b9fd61c 100644
--- a/src/arena.c
+++ b/src/arena.c
@@ -20,6 +20,7 @@ struct ucl_arena *ucl_arena_create(size_t object_size, size_t capacity) {
     arena->capacity = capacity;
     arena->objects = malloc(capacity * object_size);
     arena->used_map = malloc(used_map_size);
+    arena->next_free = 0;
     arena->stats.used = 0;
     arena->stats.freed = 0;
 
@@ -50,6 +51,26 @@ void ucl_arena_map(struct ucl_arena *arena, void (*map_function)(struct ucl_aren
 
 void *ucl_arena_get(struct ucl_arena *arena) {
     int used_map_ints = DIV_ROUND_UP(arena->capacity, INT_BITS);
+
+
+    if (arena->next_free != -1) {
+        // Cache hit
+        /* unsigned int int_index = arena->next_free / INT_BITS; */
+        /* unsigned int bit_index = arena->next_free % INT_BITS; */
+
+        unsigned int int_index = arena->next_free >> 5;
+        unsigned int bit_index = arena->next_free & 31;
+
+        arena->used_map[int_index] |= 1 << bit_index;
+
+        void *ret = (char *) arena->objects + (arena->next_free * arena->object_size);
+        arena->next_free = -1;
+
+        arena->stats.used += 1;
+        return ret;
+    }
+
+    // Cache miss
     for (int i = 0; i < used_map_ints; i++ ) {
         // TODO: Maybe keep a cache of available used_map_ints
         int map = arena->used_map[i];
@@ -65,6 +86,7 @@ void *ucl_arena_get(struct ucl_arena *arena) {
         }
         arena->used_map[i] |= 1 << bit_index;
         arena->stats.used += 1;
+
         return (char *) arena->objects + (index * arena->object_size);
     }
 
@@ -90,6 +112,11 @@ void ucl_arena_put(struct ucl_arena *arena, void *object) {
     total_arena_puts++;
 
     arena->used_map[int_index] &= ~(1 << bit_index);
+
+    /* if (arena->next_free == -1) { */
+    arena->next_free = index;
+    /* } */
+
     arena->stats.used -= 1;
     arena->stats.freed += 1;
 }
diff --git a/src/scope.c b/src/scope.c
index 2cbf3b0..f622564 100644
--- a/src/scope.c
+++ b/src/scope.c
@@ -30,15 +30,16 @@ static struct ucl_object *ucl_scope_get_cell(struct ucl_scope *scope, const char
 
 struct ucl_object *ucl_scope_get(struct ucl *state, struct ucl_scope *scope, const char *name) {
     struct ucl_object *cell = ucl_scope_get_cell(scope, name);
-    if (cell == NULL) {
+    while (cell == NULL) {
         if (scope->parent == NULL) {
             // TODO: Include the symbol name
             return ucl_error_create(state, "Unbound symbol");
-        } else {
-            return ucl_scope_get(state, scope->parent, name);
         }
+        scope = scope->parent;
+        cell = ucl_scope_get_cell(scope, name);
     }
     return ucl_list_nth(cell, DATA_POSITION);
+
 }
 
 void ucl_scope_put(struct ucl *state, struct ucl_scope *scope, const char *name, struct ucl_object *obj) {
@@ -51,7 +52,6 @@ void ucl_scope_put(struct ucl *state, struct ucl_scope *scope, const char *name,
                             ucl_string_create(state, name),
                             obj));
     } else {
-        // TODO: Refcounting / cleanup
         cell->cell.cdr->cell.car = obj;
     }
 }
diff --git a/src/types.h b/src/types.h
index a9cce81..631e990 100644
--- a/src/types.h
+++ b/src/types.h
@@ -55,6 +55,8 @@ struct ucl_arena {
     size_t capacity;
     void *objects;
     int *used_map;
+    /** Cache of size 1 **/
+    int next_free;
 
     struct {
         size_t used;