merge revision(s) 31731:31734:

* variable.c (rb_autoload_load):  There is a  race condition while
	  autoloading.  When two or more threads touch a single autoloaded
	  constant at  a time,  one of them  does the require,  but others
	  behave  oddly.   To  fix  this  situation we  now  refrain  from
	  deleting the autoload table while someone is doing the autoload.
	  That  deletion is  deferred to  a  point where  a require  ended
	  successfully.  Doing so make it possible for multiple threads to
	  enter autoloading at the same  time but the require is protected
	  against  multiple simultaneous  entrance anyway  so all  but one
	  thread  gets blocked  at that  point.   So with  it, touching  a
	  constant that gets autoloaded cause those threads to block until
	  there is another one that does the same thing.
	  [ruby-core:36308] (#921)

	* variable.c (rb_const_get_0): ditto.

	* variable.c (autoload_node): ditto.

	* variable.c (autoload_delete): ditto.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8@31732 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Signed-off-by: URABE, Shyouhei <shyouhei@ruby-lang.org>

	* variable.c (rb_const_get_0):  Fix  previous change.   There were
	  possibilities   when   an   autoload-specified   library   lacks
	  definition of  the constant  it was bound  to.  Once  after such
	  library had  already beed loaded, the autoload  engine shall not
	  reload  it.   Instead  the  interpreter have  to  consider  such
	  constant nonexistent.  It results in a const_missing situation.

	* variable.c (rb_autoload_load): ditto.

	* variable.c (autoload_node): ditto.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8@31734 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Signed-off-by: URABE, Shyouhei <shyouhei@ruby-lang.org>

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8_7@31904 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,38 @@
+Thu Jun  2 18:33:51 2011  URABE Shyouhei  <shyouhei@ruby-lang.org>
+
+	* variable.c (rb_const_get_0):  Fix  previous change.   There were
+	  possibilities   when   an   autoload-specified   library   lacks
+	  definition of  the constant  it was bound  to.  Once  after such
+	  library had  already beed loaded, the autoload  engine shall not
+	  reload  it.   Instead  the  interpreter have  to  consider  such
+	  constant nonexistent.  It results in a const_missing situation.
+
+	* variable.c (rb_autoload_load): ditto.
+
+	* variable.c (autoload_node): ditto.
+
+Thu Jun  2 18:28:58 2011  URABE Shyouhei  <shyouhei@ruby-lang.org>
+
+	* variable.c (rb_autoload_load):  There is a  race condition while
+	  autoloading.  When two or more threads touch a single autoloaded
+	  constant at  a time,  one of them  does the require,  but others
+	  behave  oddly.   To  fix  this  situation we  now  refrain  from
+	  deleting the autoload table while someone is doing the autoload.
+	  That  deletion is  deferred to  a  point where  a require  ended
+	  successfully.  Doing so make it possible for multiple threads to
+	  enter autoloading at the same  time but the require is protected
+	  against  multiple simultaneous  entrance anyway  so all  but one
+	  thread  gets blocked  at that  point.   So with  it, touching  a
+	  constant that gets autoloaded cause those threads to block until
+	  there is another one that does the same thing.
+	  [ruby-core:36308] (#921)
+
+	* variable.c (rb_const_get_0): ditto.
+
+	* variable.c (autoload_node): ditto.
+
+	* variable.c (autoload_delete): ditto.
+
 Mon May 30 10:58:17 2011  Hiroshi Nakamura  <nahi@ruby-lang.org>
 
 	* lib/logger.rb (Logger::ProgName): do not depend on subversion

variable.c

@@ -1331,7 +1331,6 @@ autoload_delete(mod, id)
     VALUE val;
     st_data_t load = 0;
 
-    st_delete(RCLASS(mod)->iv_tbl, (st_data_t*)&id, 0);
     if (st_lookup(RCLASS(mod)->iv_tbl, autoload, &val)) {
 	struct st_table *tbl = check_autoload_table(val);
 
@@ -1346,18 +1345,55 @@ autoload_delete(mod, id)
     return (NODE *)load;
 }
 
+static NODE *
+autoload_node(mod, id)
+    VALUE mod;
+    ID id;
+{
+    st_data_t val, load, n = id;
+    struct st_table *p, *q;
+
+    if ((p = RCLASS(mod)->iv_tbl) == 0) {
+        return 0;
+    }
+    else if (!st_lookup(p, n, &val)) {
+        return 0;
+    }
+    else if (val != Qundef) {
+        return 0;
+    }
+    else if (!st_lookup(p, autoload, &val)) {
+        return 0;
+    }
+    else if ((q = check_autoload_table((VALUE)val)) == 0) {
+        return 0;
+    }
+    else if (!st_lookup(q, n, &load)) {
+        return 0;
+    }
+    else {
+        return (NODE *)load;
+    }
+}
+
 VALUE
 rb_autoload_load(klass, id)
     VALUE klass;
     ID id;
 {
-    VALUE file;
+    NODE *load = 0;
-    NODE *load = autoload_delete(klass, id);
+    VALUE ret = 0;
 
-    if (!load || !(file = load->nd_lit) || rb_provided(RSTRING(file)->ptr)) {
+    if ((load = autoload_node(klass, id)) == 0) {
-	return Qfalse;
+        return 0;
+    }
+    else if ((ret = rb_require_safe(load->nd_lit, load->nd_nth)) == Qfalse) {
+        return 0;
+    }
+    else {
+        (void) autoload_delete(klass, id);
+        return ret;
     }
-    return rb_require_safe(file, load->nd_nth);
 }
 
 static VALUE
@@ -1419,8 +1455,15 @@ rb_const_get_0(klass, id, exclude, recurse)
     while (tmp) {
 	while (RCLASS(tmp)->iv_tbl && st_lookup(RCLASS(tmp)->iv_tbl,id,&value)) {
 	    if (value == Qundef) {
-		if (!RTEST(rb_autoload_load(tmp, id))) break;
+		rb_autoload_load(tmp, id);
-		continue;
+                st_lookup(RCLASS(tmp)->iv_tbl, id, &value);
+                if (value == Qundef) {
+                    /* the autoload above did not assign a constant */
+                    break;
+                }
+                else {
+                    continue;
+                }
 	    }
 	    if (exclude && tmp == rb_cObject && klass != rb_cObject) {
 		rb_warn("toplevel constant %s referenced by %s::%s",

version.h

@@ -2,7 +2,7 @@
 #define RUBY_RELEASE_DATE "2011-06-02"
 #define RUBY_VERSION_CODE 187
 #define RUBY_RELEASE_CODE 20110602
-#define RUBY_PATCHLEVEL 347
+#define RUBY_PATCHLEVEL 348
 
 #define RUBY_VERSION_MAJOR 1
 #define RUBY_VERSION_MINOR 8