From 62ae217a27531d9767bcdda0e7ff6c4368ed857e Mon Sep 17 00:00:00 2001
From: steven-na <noreply.github@stvnc.dev>
Date: Wed, 29 Jul 2026 01:53:59 -0700
Subject: Scratch and temp arenas

---
 tests/smrt_arena.c | 133 +++++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 115 insertions(+), 18 deletions(-)

(limited to 'tests')

diff --git a/tests/smrt_arena.c b/tests/smrt_arena.c
index 87230d3..5e3ef5c 100644
--- a/tests/smrt_arena.c
+++ b/tests/smrt_arena.c
@@ -18,7 +18,7 @@ Test(smrt_arena, create_arena) {
 }
 
 Test(smrt_arena, alloc_arena) {
-    smrt_arena_t *arena = smrt_arena_create(sizeof(uint32_t), true, false);
+    smrt_arena_t *arena = smrt_arena_create(sizeof(uint32_t), plat_get_pagesize(), false);
 
     uint32_t *i = smrt_arena_push(arena, sizeof(uint32_t), true);
 
@@ -30,7 +30,7 @@ Test(smrt_arena, alloc_arena) {
 }
 
 Test(smrt_arena, alloc_zero_arena) {
-    smrt_arena_t *arena = smrt_arena_create(sizeof(uint32_t), true, false);
+    smrt_arena_t *arena = smrt_arena_create(sizeof(uint32_t), plat_get_pagesize(), false);
 
     uint32_t *i = smrt_arena_push(arena, sizeof(uint32_t), true);
 
@@ -43,7 +43,7 @@ Test(smrt_arena, alloc_array_arena) {
     const size_t len = 24;
     cr_expect(len != 0);
 
-    smrt_arena_t *arena = smrt_arena_create(sizeof(uint8_t) * len, true, false);
+    smrt_arena_t *arena = smrt_arena_create(sizeof(uint8_t) * len, plat_get_pagesize(), false);
 
     uint8_t *arr = SMRTA_ALLOC_ARRAY(arena, uint8_t, len);
 
@@ -58,7 +58,7 @@ Test(smrt_arena, alloc_array_arena) {
 }
 
 Test(smrt_arena, alloc_clear_arena) {
-    smrt_arena_t *arena = smrt_arena_create(sizeof(uint32_t), true, false);
+    smrt_arena_t *arena = smrt_arena_create(sizeof(uint32_t), plat_get_pagesize(), false);
 
     uint32_t *i = smrt_arena_push(arena, sizeof(uint32_t), true);
 
@@ -72,7 +72,7 @@ Test(smrt_arena, alloc_clear_arena) {
 }
 
 Test(smrt_arena, alloc_clear_zero_arena) {
-    smrt_arena_t *arena = smrt_arena_create(sizeof(uint32_t), true, false);
+    smrt_arena_t *arena = smrt_arena_create(sizeof(uint32_t), plat_get_pagesize(), false);
 
     uint32_t *i = smrt_arena_push(arena, sizeof(uint32_t), true);
 
@@ -95,7 +95,7 @@ Test(smrt_arena, alloc_clear_zero_arena) {
 }
 
 Test(smrt_arena, alloc_clear_dont_zero_arena) {
-    smrt_arena_t *arena = smrt_arena_create(sizeof(uint32_t), true, false);
+    smrt_arena_t *arena = smrt_arena_create(sizeof(uint32_t), plat_get_pagesize(), false);
 
     uint32_t *i = smrt_arena_push(arena, sizeof(uint32_t), true);
 
@@ -109,7 +109,7 @@ Test(smrt_arena, alloc_clear_dont_zero_arena) {
 }
 
 Test(smrt_arena, pop_arena) {
-    smrt_arena_t *arena = smrt_arena_create(KiB(1), true, false);
+    smrt_arena_t *arena = smrt_arena_create(KiB(1), plat_get_pagesize(), false);
 
     uint64_t mark = arena->pos;
     uint32_t *i = smrt_arena_push(arena, sizeof(uint32_t), true);
@@ -124,7 +124,7 @@ Test(smrt_arena, pop_arena) {
 }
 
 Test(smrt_arena, pop_to_arena) {
-    smrt_arena_t *arena = smrt_arena_create(KiB(1), true, false);
+    smrt_arena_t *arena = smrt_arena_create(KiB(1), plat_get_pagesize(), false);
 
     smrt_arena_push(arena, sizeof(uint32_t), true);
     uint64_t mark = arena->pos;
@@ -139,7 +139,7 @@ Test(smrt_arena, pop_to_arena) {
 }
 
 Test(smrt_arena, pop_clamped_arena) {
-    smrt_arena_t *arena = smrt_arena_create(KiB(1), true, false);
+    smrt_arena_t *arena = smrt_arena_create(KiB(1), plat_get_pagesize(), false);
 
     smrt_arena_push(arena, sizeof(uint32_t), true);
     smrt_arena_pop(arena, KiB(1));
@@ -164,7 +164,7 @@ Test(smrt_arena, push_grows_commit_arena) {
 }
 
 Test(smrt_arena, push_exceeds_reserve_arena) {
-    smrt_arena_t *arena = smrt_arena_create(KiB(1), true, false);
+    smrt_arena_t *arena = smrt_arena_create(KiB(1), plat_get_pagesize(), false);
 
     void *p = smrt_arena_push(arena, KiB(64), true);
 
@@ -174,7 +174,7 @@ Test(smrt_arena, push_exceeds_reserve_arena) {
 }
 
 Test(smrt_arena, push_alignment_arena) {
-    smrt_arena_t *arena = smrt_arena_create(KiB(1), true, false);
+    smrt_arena_t *arena = smrt_arena_create(KiB(1), plat_get_pagesize(), false);
 
     smrt_arena_push(arena, sizeof(uint8_t), true);
     void *p = smrt_arena_push(arena, sizeof(uint64_t), true);
@@ -185,13 +185,13 @@ Test(smrt_arena, push_alignment_arena) {
 }
 
 Test(smrt_arena, create_fails_when_reserve_exceeds_address_space) {
-    smrt_arena_t *arena = smrt_arena_create((u64)1 << 48, true, false);
+    smrt_arena_t *arena = smrt_arena_create((u64)1 << 48, plat_get_pagesize(), false);
 
     cr_expect_eq(arena, NULL);
 }
 
 Test(smrt_arena, mark_push_sets_mark) {
-    smrt_arena_t *arena = smrt_arena_create(KiB(1), true, false);
+    smrt_arena_t *arena = smrt_arena_create(KiB(1), plat_get_pagesize(), false);
 
     uint64_t pre_mark_pos = arena->pos;
     smrt_arena_mark_push(arena, sizeof(uint32_t), true);
@@ -202,7 +202,7 @@ Test(smrt_arena, mark_push_sets_mark) {
 }
 
 Test(smrt_arena, mark_push_failure_leaves_mark_unset) {
-    smrt_arena_t *arena = smrt_arena_create(KiB(1), true, false);
+    smrt_arena_t *arena = smrt_arena_create(KiB(1), plat_get_pagesize(), false);
 
     void *p = smrt_arena_mark_push(arena, KiB(64), true);
 
@@ -213,7 +213,7 @@ Test(smrt_arena, mark_push_failure_leaves_mark_unset) {
 }
 
 Test(smrt_arena, pop_to_mark_restores_position) {
-    smrt_arena_t *arena = smrt_arena_create(KiB(1), true, false);
+    smrt_arena_t *arena = smrt_arena_create(KiB(1), plat_get_pagesize(), false);
 
     uint32_t *i = smrt_arena_mark_push(arena, sizeof(uint32_t), true);
     smrt_arena_push(arena, sizeof(uint32_t), true);
@@ -229,7 +229,7 @@ Test(smrt_arena, pop_to_mark_restores_position) {
 }
 
 Test(smrt_arena, mark_at_base_position_is_valid) {
-    smrt_arena_t *arena = smrt_arena_create(KiB(1), true, false);
+    smrt_arena_t *arena = smrt_arena_create(KiB(1), plat_get_pagesize(), false);
 
     cr_assert_eq(arena->pos, SMRT_ARENA_BASE_POS);
 
@@ -246,7 +246,7 @@ Test(smrt_arena, mark_at_base_position_is_valid) {
 }
 
 Test(smrt_arena, pop_to_mark_without_mark_fails) {
-    smrt_arena_t *arena = smrt_arena_create(KiB(1), true, false);
+    smrt_arena_t *arena = smrt_arena_create(KiB(1), plat_get_pagesize(), false);
 
     smrt_arena_push(arena, sizeof(uint32_t), true);
 
@@ -258,7 +258,7 @@ Test(smrt_arena, pop_to_mark_without_mark_fails) {
 }
 
 Test(smrt_arena, pop_to_ahead_of_pos_is_noop) {
-    smrt_arena_t *arena = smrt_arena_create(KiB(1), true, false);
+    smrt_arena_t *arena = smrt_arena_create(KiB(1), plat_get_pagesize(), false);
 
     smrt_arena_push(arena, sizeof(uint32_t), true);
     uint64_t pos = arena->pos;
@@ -348,6 +348,103 @@ Test(smrt_arena, auto_decommit_pop_past_mark_resets_mark) {
     smrt_arena_destroy(arena);
 }
 
+Test(smrt_arena, mark_sets_current_pos) {
+    smrt_arena_t *arena = smrt_arena_create(KiB(1), plat_get_pagesize(), false);
+
+    smrt_arena_push(arena, sizeof(uint32_t), true);
+    uint64_t pos = arena->pos;
+
+    smrt_arena_mark(arena);
+
+    cr_expect_eq(arena->mark_pos, pos);
+
+    smrt_arena_destroy(arena);
+}
+
+Test(smrt_arena, temp_start_captures_arena_and_pos) {
+    smrt_arena_t *arena = smrt_arena_create(KiB(1), plat_get_pagesize(), false);
+    smrt_arena_push(arena, sizeof(uint32_t), true);
+
+    smrta_temp_t temp = smrta_temp_start(arena);
+
+    cr_expect_eq(temp.arena, arena);
+    cr_expect_eq(temp.start_pos, arena->pos);
+
+    smrt_arena_destroy(arena);
+}
+
+Test(smrt_arena, temp_start_end_restores_position) {
+    smrt_arena_t *arena = smrt_arena_create(KiB(1), plat_get_pagesize(), false);
+
+    smrt_arena_push(arena, sizeof(uint32_t), true);
+    uint64_t pos_before = arena->pos;
+
+    smrta_temp_t temp = smrta_temp_start(arena);
+    smrt_arena_push(arena, sizeof(uint32_t), true);
+    smrt_arena_push(arena, sizeof(uint32_t), true);
+
+    smrta_temp_end(temp);
+
+    cr_expect_eq(arena->pos, pos_before);
+
+    smrt_arena_destroy(arena);
+}
+
+Test(smrt_arena, scratch_start_end_provides_usable_arena) {
+    smrta_temp_t scratch = smrta_scratch_start(NULL, 0);
+
+    cr_assert_neq(scratch.arena, NULL);
+
+    uint32_t *i = TEMP_ARENA_PUSH(scratch, uint32_t);
+    *i = UINT32_MAX;
+
+    cr_expect_eq(*i, UINT32_MAX);
+
+    smrta_scratch_end(scratch);
+}
+
+Test(smrt_arena, scratch_end_pops_arena_to_start) {
+    smrta_temp_t scratch = smrta_scratch_start(NULL, 0);
+    uint64_t pos_before = scratch.arena->pos;
+
+    TEMP_ARENA_PUSH(scratch, uint32_t);
+    cr_assert_gt(scratch.arena->pos, pos_before);
+
+    smrta_scratch_end(scratch);
+
+    cr_expect_eq(scratch.arena->pos, pos_before);
+}
+
+Test(smrt_arena, scratch_start_avoids_conflicts) {
+    smrta_temp_t first = smrta_scratch_start(NULL, 0);
+    cr_assert_neq(first.arena, NULL);
+
+    smrt_arena_t *conflicts[] = { first.arena };
+    smrta_temp_t second = smrta_scratch_start(conflicts, 1);
+
+    cr_assert_neq(second.arena, NULL);
+    cr_expect_neq(second.arena, first.arena);
+
+    smrta_scratch_end(second);
+    smrta_scratch_end(first);
+}
+
+Test(smrt_arena, scratch_start_returns_zeroed_when_pool_exhausted) {
+    smrta_temp_t a = smrta_scratch_start(NULL, 0);
+
+    smrt_arena_t *a_conflict[] = { a.arena };
+    smrta_temp_t b = smrta_scratch_start(a_conflict, 1);
+    cr_assert_neq(b.arena, a.arena);
+
+    smrt_arena_t *conflicts[] = { a.arena, b.arena };
+    smrta_temp_t c = smrta_scratch_start(conflicts, 2);
+
+    cr_expect_eq(c.arena, NULL);
+
+    smrta_scratch_end(b);
+    smrta_scratch_end(a);
+}
+
 Test(smrt_arena, decommit_then_recommit_pages) {
     u32 pagesize = plat_get_pagesize();
     void *mem = plat_mem_reserve(pagesize);
-- 
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