[Feature #18364] Add GC.stat_heap to get stats for memory heaps

GC.stat_heap will return stats for memory heaps. This is
used for the Variable Width Allocation feature.

1 files changed, 122 insertions, 0 deletions

diff --git a/gc.c b/gc.c
index 0f44ff5c98..d9ce489724 100644
--- a/gc.c
+++ b/gc.c
@@ -10643,6 +10643,128 @@ rb_gc_stat(VALUE key)
     }
 }
 
+
+enum gc_stat_heap_sym {
+    gc_stat_heap_sym_slot_size,
+    gc_stat_heap_sym_heap_allocatable_pages,
+    gc_stat_heap_sym_heap_eden_pages,
+    gc_stat_heap_sym_heap_eden_slots,
+    gc_stat_heap_sym_heap_tomb_pages,
+    gc_stat_heap_sym_heap_tomb_slots,
+    gc_stat_heap_sym_last
+};
+
+static VALUE gc_stat_heap_symbols[gc_stat_heap_sym_last];
+
+static void
+setup_gc_stat_heap_symbols(void)
+{
+    if (gc_stat_heap_symbols[0] == 0) {
+#define S(s) gc_stat_heap_symbols[gc_stat_heap_sym_##s] = ID2SYM(rb_intern_const(#s))
+        S(slot_size);
+        S(heap_allocatable_pages);
+        S(heap_eden_pages);
+        S(heap_eden_slots);
+        S(heap_tomb_pages);
+        S(heap_tomb_slots);
+#undef S
+    }
+}
+
+static size_t
+gc_stat_heap_internal(int size_pool_idx, VALUE hash_or_sym)
+{
+    rb_objspace_t *objspace = &rb_objspace;
+    VALUE hash = Qnil, key = Qnil;
+
+    setup_gc_stat_heap_symbols();
+
+    if (RB_TYPE_P(hash_or_sym, T_HASH)) {
+        hash = hash_or_sym;
+    }
+    else if (SYMBOL_P(hash_or_sym)) {
+        key = hash_or_sym;
+    }
+    else {
+        rb_raise(rb_eTypeError, "non-hash or symbol argument");
+    }
+
+    if (size_pool_idx < 0 || size_pool_idx >= SIZE_POOL_COUNT) {
+        rb_raise(rb_eArgError, "size pool index out of range");
+    }
+
+    rb_size_pool_t *size_pool = &size_pools[size_pool_idx];
+
+#define SET(name, attr) \
+    if (key == gc_stat_heap_symbols[gc_stat_heap_sym_##name]) \
+        return attr; \
+    else if (hash != Qnil) \
+        rb_hash_aset(hash, gc_stat_heap_symbols[gc_stat_heap_sym_##name], SIZET2NUM(attr));
+
+    SET(slot_size, size_pool->slot_size);
+    SET(heap_allocatable_pages, size_pool->allocatable_pages);
+    SET(heap_eden_pages, SIZE_POOL_EDEN_HEAP(size_pool)->total_pages);
+    SET(heap_eden_slots, SIZE_POOL_EDEN_HEAP(size_pool)->total_slots);
+    SET(heap_tomb_pages, SIZE_POOL_TOMB_HEAP(size_pool)->total_pages);
+    SET(heap_tomb_slots, SIZE_POOL_TOMB_HEAP(size_pool)->total_slots);
+#undef SET
+
+    if (!NIL_P(key)) { /* matched key should return above */
+        rb_raise(rb_eArgError, "unknown key: %"PRIsVALUE, rb_sym2str(key));
+    }
+
+    return 0;
+}
+
+static VALUE
+gc_stat_heap(rb_execution_context_t *ec, VALUE self, VALUE heap_name, VALUE arg)
+{
+    if (NIL_P(heap_name)) {
+        if (NIL_P(arg)) {
+            arg = rb_hash_new();
+        }
+        else if (RB_TYPE_P(arg, T_HASH)) {
+            // ok
+        }
+        else {
+            rb_raise(rb_eTypeError, "non-hash given");
+        }
+
+        for (int i = 0; i < SIZE_POOL_COUNT; i++) {
+            VALUE hash = rb_hash_aref(arg, INT2FIX(i));
+            if (NIL_P(hash)) {
+                hash = rb_hash_new();
+                rb_hash_aset(arg, INT2FIX(i), hash);
+            }
+            gc_stat_heap_internal(i, hash);
+        }
+    }
+    else if (FIXNUM_P(heap_name)) {
+        int size_pool_idx = FIX2INT(heap_name);
+
+        if (NIL_P(arg)) {
+            arg = rb_hash_new();
+        }
+        else if (SYMBOL_P(arg)) {
+            size_t value = gc_stat_heap_internal(size_pool_idx, arg);
+            return SIZET2NUM(value);
+        }
+        else if (RB_TYPE_P(arg, T_HASH)) {
+            // ok
+        }
+        else {
+            rb_raise(rb_eTypeError, "non-hash or symbol given");
+        }
+
+        gc_stat_heap_internal(size_pool_idx, arg);
+    }
+    else {
+        rb_raise(rb_eTypeError, "heap_name must be nil or an Integer");
+    }
+
+    return arg;
+}
+
 static VALUE
 gc_stress_get(rb_execution_context_t *ec, VALUE self)
 {