normal	2018-08-26 21:41:16 +0900 (Sun, 26 Aug 2018)

  New Revision: 64542

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=64542

  Log:
    thread_sync.c: common wakeup_{one,all} implementation
    
    This let us avoid looping in rb_szqueue_max_set, saves us
    some lines of code and reduces binary size slightly
    (numbers from 32-bit x86):
    
             text      data     bss     dec     hex filename
    before: 91272       392     156   91820   166ac thread.o
     after: 91200       392     156   91748   16664 thread.o
    
    Inspiration from this taken from the FUTEX_WAKE op
    of the Linux futex(2) syscall.

  Modified files:
    trunk/thread_sync.c
Index: thread_sync.c
===================================================================
--- thread_sync.c	(revision 64541)
+++ thread_sync.c	(revision 64542)
@@ -12,8 +12,8 @@ struct sync_waiter { https://github.com/ruby/ruby/blob/trunk/thread_sync.c#L12
 
 #define MUTEX_ALLOW_TRAP FL_USER1
 
-static int
-wakeup_one(struct list_head *head)
+static void
+sync_wakeup(struct list_head *head, long max)
 {
     struct sync_waiter *cur = 0, *next;
 
@@ -22,24 +22,21 @@ wakeup_one(struct list_head *head) https://github.com/ruby/ruby/blob/trunk/thread_sync.c#L22
 	if (cur->th->status != THREAD_KILLED) {
 	    rb_threadptr_interrupt(cur->th);
 	    cur->th->status = THREAD_RUNNABLE;
-	    return TRUE;
+	    if (--max == 0) return;
 	}
     }
-    return FALSE;
 }
 
 static void
-wakeup_all(struct list_head *head)
+wakeup_one(struct list_head *head)
 {
-    struct sync_waiter *cur = 0, *next;
+    sync_wakeup(head, 1);
+}
 
-    list_for_each_safe(head, cur, next, node) {
-	list_del_init(&cur->node);
-	if (cur->th->status != THREAD_KILLED) {
-	    rb_threadptr_interrupt(cur->th);
-	    cur->th->status = THREAD_RUNNABLE;
-	}
-    }
+static void
+wakeup_all(struct list_head *head)
+{
+    sync_wakeup(head, LONG_MAX);
 }
 
 /* Mutex */
@@ -1112,9 +1109,7 @@ rb_szqueue_max_set(VALUE self, VALUE vma https://github.com/ruby/ruby/blob/trunk/thread_sync.c#L1109
 	diff = max - sq->max;
     }
     sq->max = max;
-    while (diff-- > 0 && wakeup_one(szqueue_pushq(sq))) {
-	/* keep waking more up */
-    }
+    sync_wakeup(szqueue_pushq(sq), diff);
     return vmax;
 }
 

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