merge revision(s) 58284,58812,59028: [Backport #13632]

	vm_core.h: ruby_error_stream_closed

	* vm_core.h (ruby_special_exceptions): renamed
	  ruby_error_closed_stream as ruby_error_stream_closed, like the
	  message.
	speed up IO#close with many threads

	Today, it increases IO#close performance with many threads:

	  Execution time (sec)
	  name            trunk   after
	  vm_thread_close 4.276   3.018

	  Speedup ratio: compare with the result of `trunk' (greater is better)
	  name            after
	  vm_thread_close 1.417

	This speedup comes because rb_notify_fd_close only scans threads
	inside rb_thread_io_blocking_region, not all threads in the VM.

	In the future, this type data structure may allow us to notify
	waiters of multiple FDs on a single thread (when using
	Fibers).

	* thread.c (struct waiting_fd): declare
	  (rb_thread_io_blocking_region): use on-stack list waiter
	  (rb_notify_fd_close): walk vm->waiting_fds instead
	  (call_without_gvl): remove old field setting
	  (th_init): ditto
	* vm_core.h (typedef struct rb_vm_struct): add waiting_fds list
	* (typedef struct rb_thread_struct): remove waiting_fd field
	  (rb_vm_living_threads_init): initialize waiting_fds list

	I am now kicking myself for not thinking about this 3 years ago
	when I introduced ccan/list in [Feature #9632] to optimize this
	same function :<
	IO#close: do not enqueue redundant interrupts (take #2)

	Enqueuing multiple errors for one event causes spurious errors
	down the line, as reported by Nikolay Vashchenko in
	https://bugs.ruby-lang.org/issues/13632

	This should fix bad interactions with test_race_gets_and_close
	in test/ruby/test_io.rb since we ensure rb_notify_fd_close
	continues returning the busy flag after enqueuing the interrupt.

	Backporting changes to 2.4 and earlier releases will be more
	challenging...

	* thread.c (rb_notify_fd_close): do not enqueue multiple interrupts
	  [ruby-core:81581] [Bug #13632]
	* test/ruby/test_io.rb (test_single_exception_on_close):
	  new test based on script from Nikolay

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_4@59286 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 25 insertions, 11 deletions

diff --git a/thread.c b/thread.c
index 7391cf96d2..2691fd835d 100644
--- a/thread.c
+++ b/thread.c
@@ -95,7 +95,11 @@ static int rb_threadptr_pending_interrupt_empty_p(rb_thread_t *th);
 #define eTerminateSignal INT2FIX(1)
 static volatile int system_working = 1;
 
-#define closed_stream_error GET_VM()->special_exceptions[ruby_error_closed_stream]
+struct waiting_fd {
+    struct list_node wfd_node; /* <=> vm.waiting_fds */
+    rb_thread_t *th;
+    int fd;
+};
 
 inline static void
 st_delete_wrap(st_table *table, st_data_t key)
@@ -1310,7 +1314,6 @@ call_without_gvl(void *(*func)(void *), void *data1,
     rb_thread_t *th = GET_THREAD();
     int saved_errno = 0;
 
-    th->waiting_fd = -1;
     if (ubf == RUBY_UBF_IO || ubf == RUBY_UBF_PROCESS) {
 	ubf = ubf_select;
 	data2 = th;
@@ -1433,11 +1436,15 @@ VALUE
 rb_thread_io_blocking_region(rb_blocking_function_t *func, void *data1, int fd)
 {
     volatile VALUE val = Qundef; /* shouldn't be used */
+    rb_vm_t *vm = GET_VM();
     rb_thread_t *th = GET_THREAD();
     volatile int saved_errno = 0;
     int state;
+    struct waiting_fd wfd;
 
-    th->waiting_fd = fd;
+    wfd.fd = fd;
+    wfd.th = th;
+    list_add(&vm->waiting_fds, &wfd.wfd_node);
 
     TH_PUSH_TAG(th);
     if ((state = EXEC_TAG()) == 0) {
@@ -1448,8 +1455,8 @@ rb_thread_io_blocking_region(rb_blocking_function_t *func, void *data1, int fd)
     }
     TH_POP_TAG();
 
-    /* clear waiting_fd anytime */
-    th->waiting_fd = -1;
+    /* must be deleted before jump */
+    list_del(&wfd.wfd_node);
 
     if (state) {
 	TH_JUMP_TAG(th, state);
@@ -2195,16 +2202,23 @@ int
 rb_notify_fd_close(int fd)
 {
     rb_vm_t *vm = GET_THREAD()->vm;
-    rb_thread_t *th = 0;
+    struct waiting_fd *wfd = 0;
     int busy;
 
     busy = 0;
-    list_for_each(&vm->living_threads, th, vmlt_node) {
-	if (th->waiting_fd == fd) {
-	    VALUE err = th->vm->special_exceptions[ruby_error_closed_stream];
+    list_for_each(&vm->waiting_fds, wfd, wfd_node) {
+	if (wfd->fd == fd) {
+	    rb_thread_t *th = wfd->th;
+	    VALUE err;
+
+	    busy = 1;
+	    if (!th) {
+		continue;
+	    }
+	    wfd->th = 0;
+	    err = th->vm->special_exceptions[ruby_error_stream_closed];
 	    rb_threadptr_pending_interrupt_enque(th, err);
 	    rb_threadptr_interrupt(th);
-	    busy = 1;
 	}
     }
     return busy;
@@ -4839,7 +4853,7 @@ Init_Thread(void)
     rb_define_method(rb_cThread, "name=", rb_thread_setname, 1);
     rb_define_method(rb_cThread, "inspect", rb_thread_inspect, 0);
 
-    rb_vm_register_special_exception(ruby_error_closed_stream, rb_eIOError, "stream closed");
+    rb_vm_register_special_exception(ruby_error_stream_closed, rb_eIOError, "stream closed");
 
     cThGroup = rb_define_class("ThreadGroup", rb_cObject);
     rb_define_alloc_func(cThGroup, thgroup_s_alloc);