Merge pull request #5121 from shuujii/reduce-memory-usage-of-Hash-object

Reduce memory usage of Hash object

include/mruby/hash.h

@@ -14,10 +14,22 @@
  */
 MRB_BEGIN_DECL
 
+/* offset of `iv` must be 3 words */
 struct RHash {
   MRB_OBJECT_HEADER;
+#ifdef MRB_64BIT
+  uint32_t size;
   struct iv_tbl *iv;
-  struct htable *ht;
+  uint32_t ea_capa;
+  uint32_t ea_n_used;
+#else
+  struct iv_tbl *iv;
+  uint32_t size;
+#endif
+  union {
+    struct hash_entry *ea;
+    struct hash_table *ht;
+  };
 };
 
 #define mrb_hash_ptr(v)    ((struct RHash*)(mrb_ptr(v)))
@@ -179,8 +191,9 @@ MRB_API mrb_value mrb_hash_clear(mrb_state *mrb, mrb_value hash);
 MRB_API mrb_int mrb_hash_size(mrb_state *mrb, mrb_value hash);
 
 /*
- * Copies the hash.
- *
+ * Copies the hash. This function does NOT copy the instance variables
+ * (except for the default value). Use mrb_obj_dup() to copy the instance
+ * variables as well.
  *
  * @param mrb The mruby state reference.
  * @param hash The target hash.
@@ -198,16 +211,24 @@ MRB_API mrb_value mrb_hash_dup(mrb_state *mrb, mrb_value hash);
  */
 MRB_API void mrb_hash_merge(mrb_state *mrb, mrb_value hash1, mrb_value hash2);
 
-/* RHASH_TBL allocates st_table if not available. */
-#define RHASH(obj)   ((struct RHash*)(mrb_ptr(obj)))
-#define RHASH_TBL(h)          (RHASH(h)->ht)
-#define RHASH_IFNONE(h)       mrb_iv_get(mrb, (h), MRB_SYM(ifnone))
-#define RHASH_PROCDEFAULT(h)  RHASH_IFNONE(h)
+#define RHASH(hash) ((struct RHash*)(mrb_ptr(hash)))
+#define RHASH_IFNONE(hash) mrb_iv_get(mrb, (hash), MRB_SYM(ifnone))
+#define RHASH_PROCDEFAULT(hash) RHASH_IFNONE(hash)
 
-#define MRB_HASH_DEFAULT      1
-#define MRB_HASH_PROC_DEFAULT 2
-#define MRB_RHASH_DEFAULT_P(h) (RHASH(h)->flags & MRB_HASH_DEFAULT)
-#define MRB_RHASH_PROCDEFAULT_P(h) (RHASH(h)->flags & MRB_HASH_PROC_DEFAULT)
+#define MRB_HASH_IB_BIT_BIT         5
+#define MRB_HASH_AR_EA_CAPA_BIT     5
+#define MRB_HASH_IB_BIT_SHIFT       0
+#define MRB_HASH_AR_EA_CAPA_SHIFT   0
+#define MRB_HASH_AR_EA_N_USED_SHIFT MRB_HASH_AR_EA_CAPA_BIT
+#define MRB_HASH_SIZE_FLAGS_SHIFT   (MRB_HASH_AR_EA_CAPA_BIT * 2)
+#define MRB_HASH_IB_BIT_MASK        ((1 << MRB_HASH_IB_BIT_BIT) - 1)
+#define MRB_HASH_AR_EA_CAPA_MASK    ((1 << MRB_HASH_AR_EA_CAPA_BIT) - 1)
+#define MRB_HASH_AR_EA_N_USED_MASK  (MRB_HASH_AR_EA_CAPA_MASK << MRB_HASH_AR_EA_N_USED_SHIFT)
+#define MRB_HASH_DEFAULT            (1 << (MRB_HASH_SIZE_FLAGS_SHIFT + 0))
+#define MRB_HASH_PROC_DEFAULT       (1 << (MRB_HASH_SIZE_FLAGS_SHIFT + 1))
+#define MRB_HASH_HT                 (1 << (MRB_HASH_SIZE_FLAGS_SHIFT + 2))
+#define MRB_RHASH_DEFAULT_P(hash) (RHASH(hash)->flags & MRB_HASH_DEFAULT)
+#define MRB_RHASH_PROCDEFAULT_P(hash) (RHASH(hash)->flags & MRB_HASH_PROC_DEFAULT)
 
 /* GC functions */
 void mrb_gc_mark_hash(mrb_state*, struct RHash*);

mrblib/hash.rb

@@ -144,26 +144,6 @@ class Hash
     self
   end
 
-  ##
-  # Replaces the contents of <i>hsh</i> with the contents of other hash
-  #
-  # ISO 15.2.13.4.23
-  def replace(hash)
-    raise TypeError, "Hash required (#{hash.class} given)" unless Hash === hash
-    self.clear
-    hash.each_key{|k|
-      self[k] = hash[k]
-    }
-    if hash.default_proc
-      self.default_proc = hash.default_proc
-    else
-      self.default = hash.default
-    end
-    self
-  end
-  # ISO 15.2.13.4.17
-  alias initialize_copy replace
-
   ##
   # Return a hash which contains the content of
   # +self+ and +other+. If a block is given