Rename `rb_current_thread_scheduler` to `rb_thread_scheduler_if_nonblocking`.

Correctly capture thread before releasing GVL and pass as argument to
`rb_thread_scheduler_if_nonblocking`.

include/ruby/internal/intern/thread.h

@@ -73,7 +73,8 @@ VALUE rb_mutex_synchronize(VALUE mutex, VALUE (*func)(VALUE arg), VALUE arg);
 
 VALUE rb_thread_scheduler_get(VALUE);
 VALUE rb_thread_scheduler_set(VALUE, VALUE);
-VALUE rb_current_thread_scheduler(void);
+
+VALUE rb_thread_scheduler_if_nonblocking(VALUE thread);
 
 RBIMPL_SYMBOL_EXPORT_END()
 

io.c

@@ -1044,6 +1044,7 @@ io_alloc(VALUE klass)
 #endif
 
 struct io_internal_read_struct {
+    VALUE th;
     int fd;
     int nonblock;
     void *buf;
@@ -1064,7 +1065,7 @@ struct io_internal_writev_struct {
 };
 #endif
 
-static int nogvl_wait_for_single_fd(int fd, short events);
+static int nogvl_wait_for_single_fd(VALUE th, int fd, short events);
 static VALUE
 internal_read_func(void *ptr)
 {
@@ -1075,7 +1076,7 @@ retry:
     if (r < 0 && !iis->nonblock) {
         int e = errno;
         if (e == EAGAIN || e == EWOULDBLOCK) {
-            if (nogvl_wait_for_single_fd(iis->fd, RB_WAITFD_IN) != -1) {
+            if (nogvl_wait_for_single_fd(iis->th, iis->fd, RB_WAITFD_IN) != -1) {
                 goto retry;
             }
             errno = e;
@@ -1118,12 +1119,13 @@ internal_writev_func(void *ptr)
 static ssize_t
 rb_read_internal(int fd, void *buf, size_t count)
 {
-    struct io_internal_read_struct iis;
-
-    iis.fd = fd;
-    iis.nonblock = 0;
-    iis.buf = buf;
-    iis.capa = count;
+    struct io_internal_read_struct iis = {
+        .th = rb_thread_current(),
+        .fd = fd,
+        .nonblock = 0,
+        .buf = buf,
+        .capa = count
+    };
 
     return (ssize_t)rb_thread_io_blocking_region(internal_read_func, &iis, fd);
 }
@@ -1131,10 +1133,11 @@ rb_read_internal(int fd, void *buf, size_t count)
 static ssize_t
 rb_write_internal(int fd, const void *buf, size_t count)
 {
-    struct io_internal_write_struct iis;
-    iis.fd = fd;
-    iis.buf = buf;
-    iis.capa = count;
+    struct io_internal_write_struct iis = {
+        .fd = fd,
+        .buf = buf,
+        .capa = count
+    };
 
     return (ssize_t)rb_thread_io_blocking_region(internal_write_func, &iis, fd);
 }
@@ -1142,10 +1145,11 @@ rb_write_internal(int fd, const void *buf, size_t count)
 static ssize_t
 rb_write_internal2(int fd, const void *buf, size_t count)
 {
-    struct io_internal_write_struct iis;
-    iis.fd = fd;
-    iis.buf = buf;
-    iis.capa = count;
+    struct io_internal_write_struct iis = {
+        .fd = fd,
+        .buf = buf,
+        .capa = count
+    };
 
     return (ssize_t)rb_thread_call_without_gvl2(internal_write_func2, &iis,
 						RUBY_UBF_IO, NULL);
@@ -1155,10 +1159,11 @@ rb_write_internal2(int fd, const void *buf, size_t count)
 static ssize_t
 rb_writev_internal(int fd, const struct iovec *iov, int iovcnt)
 {
-    struct io_internal_writev_struct iis;
-    iis.fd = fd;
-    iis.iov = iov;
-    iis.iovcnt = iovcnt;
+    struct io_internal_writev_struct iis = {
+        .fd = fd,
+        .iov = iov,
+        .iovcnt = iovcnt,
+    };
 
     return (ssize_t)rb_thread_io_blocking_region(internal_writev_func, &iis, fd);
 }
@@ -1209,8 +1214,7 @@ io_flush_buffer_async2(VALUE arg)
     rb_io_t *fptr = (rb_io_t *)arg;
     VALUE ret;
 
-    ret = (VALUE)rb_thread_call_without_gvl2(io_flush_buffer_sync2, fptr,
-					     RUBY_UBF_IO, NULL);
+    ret = (VALUE)rb_thread_call_without_gvl2(io_flush_buffer_sync2, fptr, RUBY_UBF_IO, NULL);
 
     if (!ret) {
 	/* pending async interrupt is there. */
@@ -1254,7 +1258,7 @@ io_fflush(rb_io_t *fptr)
 int
 rb_io_wait_readable(int f)
 {
-    VALUE scheduler = rb_current_thread_scheduler();
+    VALUE scheduler = rb_thread_scheduler_if_nonblocking(rb_thread_current());
     if (scheduler != Qnil) {
         VALUE result = rb_funcall(scheduler, rb_intern("wait_readable_fd"), 1, INT2NUM(f));
         return RTEST(result);
@@ -1284,7 +1288,7 @@ rb_io_wait_readable(int f)
 int
 rb_io_wait_writable(int f)
 {
-    VALUE scheduler = rb_current_thread_scheduler();
+    VALUE scheduler = rb_thread_scheduler_if_nonblocking(rb_thread_current());
     if (scheduler != Qnil) {
         VALUE result = rb_funcall(scheduler, rb_intern("wait_writable_fd"), 1, INT2NUM(f));
         return RTEST(result);
@@ -2897,6 +2901,7 @@ io_getpartial(int argc, VALUE *argv, VALUE io, int no_exception, int nonblock)
             rb_io_set_nonblock(fptr);
         }
 	io_setstrbuf(&str, len);
+        iis.th = rb_thread_current();
         iis.fd = fptr->fd;
         iis.nonblock = nonblock;
         iis.buf = RSTRING_PTR(str);
@@ -10921,9 +10926,9 @@ void * rb_thread_scheduler_wait_for_single_fd(void * _args) {
 STATIC_ASSERT(pollin_expected, POLLIN == RB_WAITFD_IN);
 STATIC_ASSERT(pollout_expected, POLLOUT == RB_WAITFD_OUT);
 static int
-nogvl_wait_for_single_fd(int fd, short events)
+nogvl_wait_for_single_fd(VALUE th, int fd, short events)
 {
-    VALUE scheduler = rb_current_thread_scheduler();
+    VALUE scheduler = rb_thread_scheduler_if_nonblocking(th);
     if (scheduler != Qnil) {
         struct wait_for_single_fd args = {.scheduler = scheduler, .fd = fd, .events = events};
         rb_thread_call_with_gvl(rb_thread_scheduler_wait_for_single_fd, &args);
@@ -10940,9 +10945,9 @@ nogvl_wait_for_single_fd(int fd, short events)
 #else /* !USE_POLL */
 #  define IOWAIT_SYSCALL "select"
 static int
-nogvl_wait_for_single_fd(int fd, short events)
+nogvl_wait_for_single_fd(VALUE th, int fd, short events)
 {
-    VALUE scheduler = rb_current_thread_scheduler();
+    VALUE scheduler = rb_thread_scheduler_if_nonblocking(th);
     if (scheduler != Qnil) {
         struct wait_for_single_fd args = {.scheduler = scheduler, .fd = fd, .events = events};
         rb_thread_call_with_gvl(rb_thread_scheduler_wait_for_single_fd, &args);
@@ -10981,7 +10986,7 @@ maygvl_copy_stream_wait_read(int has_gvl, struct copy_stream_struct *stp)
 	    ret = rb_wait_for_single_fd(stp->src_fd, RB_WAITFD_IN, NULL);
 	}
 	else {
-	    ret = nogvl_wait_for_single_fd(stp->src_fd, RB_WAITFD_IN);
+	    ret = nogvl_wait_for_single_fd(stp->th, stp->src_fd, RB_WAITFD_IN);
 	}
     } while (ret < 0 && maygvl_copy_stream_continue_p(has_gvl, stp));
 
@@ -10999,7 +11004,7 @@ nogvl_copy_stream_wait_write(struct copy_stream_struct *stp)
     int ret;
 
     do {
-	ret = nogvl_wait_for_single_fd(stp->dst_fd, RB_WAITFD_OUT);
+	ret = nogvl_wait_for_single_fd(stp->th, stp->dst_fd, RB_WAITFD_OUT);
     } while (ret < 0 && maygvl_copy_stream_continue_p(0, stp));
 
     if (ret < 0) {

process.c

@@ -4923,7 +4923,7 @@ static VALUE
 rb_f_sleep(int argc, VALUE *argv, VALUE _)
 {
     time_t beg = time(0);
-    VALUE scheduler = rb_current_thread_scheduler();
+    VALUE scheduler = rb_thread_scheduler_if_nonblocking(rb_thread_current());
 
     if (scheduler != Qnil) {
         rb_funcallv(scheduler, rb_intern("wait_sleep"), argc, argv);

thread.c

@@ -3621,19 +3621,20 @@ VALUE rb_thread_scheduler_set(VALUE thread, VALUE scheduler)
 static VALUE
 rb_thread_scheduler(VALUE klass)
 {
-    return rb_current_thread_scheduler();
+    return rb_thread_scheduler_if_nonblocking(rb_thread_current());
 }
 
-VALUE rb_current_thread_scheduler(void)
+VALUE rb_thread_scheduler_if_nonblocking(VALUE thread)
 {
-    rb_thread_t * th = GET_THREAD();
+    rb_thread_t * th = rb_thread_ptr(thread);
 
     VM_ASSERT(th);
 
-    if (th->blocking == 0)
+    if (th->blocking == 0) {
         return th->scheduler;
-    else
+    } else {
         return Qnil;
+    }
 }
 
 static VALUE
@@ -4234,7 +4235,7 @@ rb_wait_for_single_fd(int fd, int events, struct timeval *timeout)
     struct waiting_fd wfd;
     int state;
 
-    VALUE scheduler = rb_current_thread_scheduler();
+    VALUE scheduler = rb_thread_scheduler_if_nonblocking(rb_thread_current());
     if (scheduler != Qnil) {
         VALUE result = rb_funcall(scheduler, id_wait_for_single_fd, 3, INT2NUM(fd), INT2NUM(events),
             rb_thread_timeout(timeout)
@@ -4376,7 +4377,7 @@ select_single_cleanup(VALUE ptr)
 int
 rb_wait_for_single_fd(int fd, int events, struct timeval *timeout)
 {
-    VALUE scheduler = rb_current_thread_scheduler();
+    VALUE scheduler = rb_thread_scheduler_if_nonblocking(rb_thread_current());
     if (scheduler != Qnil) {
         VALUE result = rb_funcall(scheduler, id_wait_for_single_fd, 3, INT2NUM(fd), INT2NUM(events),
             rb_thread_timeout(timeout)