[Backport #8328] [ruby-core:55250] Patch by funny-falcon

* benchmark/bm_hash_shift.rb: add benchmark for Hash#shift

* hash.c (rb_hash_shift): use st_shift if hash is not being iterated to
  delete element without iterating the whole hash.

* hash.c (shift_i): remove function

* include/ruby/st.h (st_shift): add st_shift function

* st.c (st_shift): ditto


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_3@41652 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,18 @@
+Wed Jun 26 17:01:22 2013  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* benchmark/bm_hash_shift.rb: add benchmark for Hash#shift
+
+	* hash.c (rb_hash_shift): use st_shift if hash is not being iterated to
+	  delete element without iterating the whole hash.
+
+	* hash.c (shift_i): remove function
+
+	* include/ruby/st.h (st_shift): add st_shift function
+
+	* st.c (st_shift): ditto
+
+	[Backport #8328] [ruby-core:55250] Patch by funny-falcon
+
 Wed Jun 26 16:52:57 2013  Kazuki Tsujimoto  <kazuki@callcc.net>
 
 	* test/ruby/test_proc.rb (TestProc#test_block_given_method_to_proc):

hash.c

@@ -823,18 +823,6 @@ struct shift_var {
     VALUE val;
 };
 
-static int
-shift_i(VALUE key, VALUE value, VALUE arg)
-{
-    struct shift_var *var = (struct shift_var *)arg;
-
-    if (key == Qundef) return ST_CONTINUE;
-    if (var->key != Qundef) return ST_STOP;
-    var->key = key;
-    var->val = value;
-    return ST_DELETE;
-}
-
 static int
 shift_i_safe(VALUE key, VALUE value, VALUE arg)
 {
@@ -866,16 +854,20 @@ rb_hash_shift(VALUE hash)
 
     rb_hash_modify(hash);
     var.key = Qundef;
-    rb_hash_foreach(hash, RHASH(hash)->iter_lev > 0 ? shift_i_safe : shift_i,
-		    (VALUE)&var);
-
-    if (var.key != Qundef) {
-	if (RHASH(hash)->iter_lev > 0) {
-	    rb_hash_delete_key(hash, var.key);
+    if (RHASH(hash)->iter_lev == 0) {
+	if (st_shift(RHASH(hash)->ntbl, &var.key, &var.val)) {
+	    return rb_assoc_new(var.key, var.val);
 	}
-	return rb_assoc_new(var.key, var.val);
     }
-    else if (FL_TEST(hash, HASH_PROC_DEFAULT)) {
+    else {
+	rb_hash_foreach(hash, shift_i_safe, (VALUE)&var);
+
+	if (var.key != Qundef) {
+	    rb_hash_delete_key(hash, var.key);
+	    return rb_assoc_new(var.key, var.val);
+	}
+    }
+    if (FL_TEST(hash, HASH_PROC_DEFAULT)) {
 	return rb_funcall(RHASH_IFNONE(hash), id_yield, 2, hash, Qnil);
     }
     else {

include/ruby/st.h

@@ -109,6 +109,7 @@ st_table *st_init_strcasetable(void);
 st_table *st_init_strcasetable_with_size(st_index_t);
 int st_delete(st_table *, st_data_t *, st_data_t *); /* returns 0:notfound 1:deleted */
 int st_delete_safe(st_table *, st_data_t *, st_data_t *, st_data_t);
+int st_shift(st_table *, st_data_t *, st_data_t *); /* returns 0:notfound 1:deleted */
 int st_insert(st_table *, st_data_t, st_data_t);
 int st_insert2(st_table *, st_data_t, st_data_t, st_data_t (*)(st_data_t));
 int st_lookup(st_table *, st_data_t, st_data_t *);

st.c

@@ -695,6 +695,45 @@ st_delete_safe(register st_table *table, register st_data_t *key, st_data_t *val
     return 0;
 }
 
+int
+st_shift(register st_table *table, register st_data_t *key, st_data_t *value)
+{
+    st_index_t hash_val;
+    st_table_entry **prev;
+    register st_table_entry *ptr;
+
+    if (table->num_entries == 0) {
+        if (value != 0) *value = 0;
+        return 0;
+    }
+
+    if (table->entries_packed) {
+        if (value != 0) *value = (st_data_t)table->bins[1];
+        *key = (st_data_t)table->bins[0];
+        table->num_entries--;
+        memmove(&table->bins[0], &table->bins[2],
+                sizeof(struct st_table_entry*) * 2*table->num_entries);
+        return 1;
+    }
+
+    hash_val = do_hash_bin(table->head->key, table);
+    prev = &table->bins[hash_val];
+    for (;(ptr = *prev) != 0; prev = &ptr->next) {
+	if (ptr == table->head) {
+	    *prev = ptr->next;
+            REMOVE_ENTRY(table, ptr);
+            if (value != 0) *value = ptr->record;
+            *key = ptr->key;
+            free(ptr);
+            return 1;
+	}
+    }
+
+    /* if hash is not consistent and need to be rehashed */
+    if (value != 0) *value = 0;
+    return 0;
+}
+
 void
 st_cleanup_safe(st_table *table, st_data_t never)
 {

version.h

@@ -1,5 +1,5 @@
 #define RUBY_VERSION "1.9.3"
-#define RUBY_PATCHLEVEL 443
+#define RUBY_PATCHLEVEL 444
 
 #define RUBY_RELEASE_DATE "2013-06-26"
 #define RUBY_RELEASE_YEAR 2013