GC: Run it automatically

Finally running it automatically :). Method for when to run it was copied
from Crafting Interpreters by Robert Nystrom. Should have bought that book
earlier :D

examples/mandelbrot.apfl

@@ -36,6 +36,6 @@ iterdim height { b ->
     iterdim width { a ->
         line = & line (if (mandel maxiter a::b 0::0) {"#"} {" "})
     }
-    gc 'collect
+
     print line
 }

src/gc.c

@@ -11,6 +11,9 @@
 #include "scope.h"
 #include "value.h"
 
+#define GC_INITIAL_NEXT_GC 1024 * 1024
+#define GC_GROWTH_FACTOR 2
+
 // #define GC_DEBUG_COLLECT_EVERY_ALLOCATION 1
 // #define GC_DEBUG_STATS 1
 // #define GC_DEBUG_WIPE_RECLAIMED_OBJECTS 1
@@ -55,12 +58,19 @@ gc_allocator(void *opaque, void *oldptr, size_t oldsize, size_t newsize)
     apfl_ctx ctx = opaque;
     struct gc *gc = &ctx->gc;
 
+    gc->bytes_allocated += newsize;
+    gc->bytes_allocated -= oldsize;
+
     #ifdef GC_DEBUG_COLLECT_EVERY_ALLOCATION
         if (newsize != 0 && !gc->is_collecting) {
-            apfl_gc_full(gc);
+            apfl_gc_full(ctx);
         }
     #endif
 
+    if (gc->bytes_allocated > gc->next_gc && !gc->is_collecting) {
+        apfl_gc_full(ctx);
+    }
+
     void *out = ALLOCATOR_CALL(gc->base_allocator, oldptr, oldsize, newsize);
     if (newsize != 0 && out == NULL && !gc->is_collecting) {
         // We're out of memory! Try to get out of this situation by doing a full
@@ -106,6 +116,10 @@ apfl_gc_init(apfl_ctx ctx, struct apfl_allocator allocator)
         .cap = 0,
     };
     gc->tmproot_for_adding = NULL;
+
+    gc->bytes_allocated = 0;
+    gc->next_gc = GC_INITIAL_NEXT_GC;
+
     gc->is_collecting = false;
 }
 
@@ -433,7 +447,7 @@ sweep(apfl_ctx ctx)
                 deinit_object(ctx, object);
 
                 #ifdef GC_DEBUG_WIPE_RECLAIMED_OBJECTS
-                    memset(object, 0, sizeof(struct gc_object));
+                    memset(object, 0x77, sizeof(struct gc_object));
                     object->type = 0xFF; // Some intentionally undefined type
                 #endif
 
@@ -496,6 +510,8 @@ apfl_gc_full(apfl_ctx ctx)
     sweep(ctx);
     DUMP_ON_COLLECT();
 
+    gc->next_gc = gc->bytes_allocated * GC_GROWTH_FACTOR;
+
     gc->is_collecting = false;
 }
 

src/gc.h

@@ -54,6 +54,9 @@ struct gc {
     struct gc_tmproots tmproots;
     struct gc_object *tmproot_for_adding;
 
+    size_t bytes_allocated;
+    size_t next_gc;
+
     bool is_collecting;
 };