1 files changed, 31 insertions, 5 deletions

diff --git a/src/gc/sms.c b/src/gc/sms.c
index a2ab18e..eb76dab 100644
--- a/src/gc/sms.c
+++ b/src/gc/sms.c
@@ -50,6 +50,9 @@ static const struct object_header *hdrc(const void *ptr) {
   return &((const struct object_header *)ptr)[-1];
 }
 
+static size_t collect_amount[5] = {0};
+static size_t collect_amount_i = 0;
+
 void gc_init(void) {}
 
 static void gc_mark(const struct value initial_value) {
@@ -213,15 +216,38 @@ static void gc_sweep(void) {
   }
 }
 
-void gc_collect(void) {
-  fprintf(stderr, "gc_collect()... ");
+static const char *string_of_gc_collect_reason(enum gc_collect_reason reason) {
+  switch (reason) {
+  case GC_COLLECT_MANUAL:
+    return "GC_COLLECT_MANUAL";
+  case GC_COLLECT_LIMIT:
+    return "GC_COLLECT_LIMIT";
+  case GC_COLLECT_OOM:
+    return "GC_COLLECT_OOM";
+  default:
+    return "???";
+  }
+}
+
+void gc_collect(enum gc_collect_reason reason) {
+  debugf("gc_collect(%s)... ", string_of_gc_collect_reason(reason));
   for (size_t i = 0; i < root_stack_depth; i++)
     gc_mark(*root_stack[i]);
   const size_t before = live_bytes;
   gc_sweep();
   const size_t after = live_bytes;
   fprintf(stderr, "collected %zu bytes\n", before - after);
-  assume(live_bytes < limit_bytes);
+
+  collect_amount[collect_amount_i++] = before - after;
+  const size_t collect_amount_count =
+      sizeof(collect_amount) / sizeof(collect_amount[0]);
+  collect_amount_i %= collect_amount_count;
+  size_t i;
+  for (i = 0; i < collect_amount_count; i++)
+    if (collect_amount[i] > before / 50)
+      break;
+  if (i == collect_amount_count)
+    todo("OOM: GC was not productive");
 }
 
 struct object *gc_alloc(size_t value_slot_count, size_t untraced_slot_count) {
@@ -232,10 +258,10 @@ struct object *gc_alloc(size_t value_slot_count, size_t untraced_slot_count) {
       sizeof(struct object_header) +
       (value_slot_count + untraced_slot_count) * sizeof(uintptr_t);
   if ((live_bytes += total_bytes) >= limit_bytes)
-    gc_collect();
+    gc_collect(GC_COLLECT_LIMIT);
   struct object_header *header = malloc(total_bytes);
   if (!header) {
-    gc_collect();
+    gc_collect(GC_COLLECT_OOM);
     header = malloc(total_bytes);
     if (!header)
       todo("OOM");