ruby · ioquatix · Jan 16, 2025
diff --git a/include/ruby/fiber/scheduler.h b/include/ruby/fiber/scheduler.h
@@ -411,6 +411,12 @@ struct rb_fiber_scheduler_blocking_operation_state {
  */
 VALUE rb_fiber_scheduler_blocking_operation_wait(VALUE scheduler, void* (*function)(void *), void *data, rb_unblock_function_t *unblock_function, void *data2, int flags, struct rb_fiber_scheduler_blocking_operation_state *state);
 
+/**
+ * Interrupt a fiber by raising an exception. You can construct an exception using `rb_make_exception`.
+ *
+ */
+VALUE rb_fiber_scheduler_fiber_interrupt(VALUE scheduler, VALUE fiber, VALUE exception);
+
 /**
  * Create and schedule a non-blocking fiber.
  *

diff --git a/include/ruby/io.h b/include/ruby/io.h
@@ -664,6 +664,19 @@ VALUE rb_io_get_io(VALUE io);
  */
 VALUE rb_io_check_io(VALUE io);
 
+/**
+ * Invoke the given function with the given data, which may block the current
+ * execution context.
+ *
+ * During the execution of the function, the current execution context may be
+ * interrupted by an exception raised by another thread if the IO is closed.
+ *
+ * @param[in]  self      An IO.
+ * @param[in]  function  A function to call.
+ * @param[in]  argument  An argument to pass to the function.
+ */
+VALUE rb_io_interruptible_operation(VALUE self, VALUE(*function)(VALUE), VALUE argument);
+
 /**
  * Queries the tied IO  for writing.  An IO can be  duplexed.  Fine.  The thing
  * is,  that characteristics  could  sometimes be  achieved  by the  underlying

diff --git a/internal/thread.h b/internal/thread.h
@@ -76,6 +76,9 @@ void *rb_thread_prevent_fork(void *(*func)(void *), void *data); /* for ext/sock
 VALUE rb_thread_io_blocking_region(rb_blocking_function_t *func, void *data1, int fd);
 VALUE rb_thread_io_blocking_call(rb_blocking_function_t *func, void *data1, int fd, int events);
 
+// Invoke the given function, with the specified argument, in a way that `IO#close` from another execution context can interrupt it.
+VALUE rb_thread_io_interruptible_operation(VALUE self, VALUE(*function)(VALUE), VALUE argument);
+
 /* thread.c (export) */
 int ruby_thread_has_gvl_p(void); /* for ext/fiddle/closure.c */
 

diff --git a/io.c b/io.c
@@ -233,6 +233,32 @@ VALUE rb_io_blocking_region(struct rb_io *io, rb_blocking_function_t *function,
     return rb_io_blocking_region_wait(io, function, argument, 0);
 }
 
+VALUE
+rb_io_interruptible_operation(VALUE self, VALUE(*function)(VALUE), VALUE argument)
+{
+    VALUE scheduler = rb_fiber_scheduler_current();
+
+    if (scheduler == Qnil) {
+        return function(argument);
+    } else {
+        return rb_thread_io_interruptible_operation(self, function, argument);
+    }
+}
+
+static VALUE
+io_interruptible_operation_begin(VALUE block)
+{
+    return rb_proc_call_with_block(block, 0, NULL, Qnil);
+}
+
+static VALUE
+io_interruptible_operation(VALUE self)
+{
+    VALUE block = rb_block_proc();
+
+    return rb_io_interruptible_operation(self, io_interruptible_operation_begin, block);
+}
+
 struct argf {
     VALUE filename, current_file;
     long last_lineno;		/* $. */
@@ -15700,6 +15726,8 @@ Init_IO(void)
 
     rb_define_method(rb_cIO, "initialize", rb_io_initialize, -1);
 
+    rb_define_method(rb_cIO, "interruptible_operation", io_interruptible_operation, 0);
+
     rb_output_fs = Qnil;
     rb_define_hooked_variable("$,", &rb_output_fs, 0, deprecated_str_setter);
 

diff --git a/scheduler.c b/scheduler.c
@@ -37,6 +37,7 @@ static ID id_io_close;
 static ID id_address_resolve;
 
 static ID id_blocking_operation_wait;
+static ID id_fiber_interrupt;
 
 static ID id_fiber_schedule;
 
@@ -108,14 +109,14 @@ Init_Fiber_Scheduler(void)
     id_io_pread = rb_intern_const("io_pread");
     id_io_write = rb_intern_const("io_write");
     id_io_pwrite = rb_intern_const("io_pwrite");
-
     id_io_wait = rb_intern_const("io_wait");
     id_io_select = rb_intern_const("io_select");
     id_io_close = rb_intern_const("io_close");
 
     id_address_resolve = rb_intern_const("address_resolve");
 
     id_blocking_operation_wait = rb_intern_const("blocking_operation_wait");
+    id_fiber_interrupt = rb_intern_const("fiber_interrupt");
 
     id_fiber_schedule = rb_intern_const("fiber");
 
@@ -766,6 +767,15 @@ VALUE rb_fiber_scheduler_blocking_operation_wait(VALUE scheduler, void* (*functi
     return rb_check_funcall(scheduler, id_blocking_operation_wait, 1, &proc);
 }
 
+VALUE rb_fiber_scheduler_fiber_interrupt(VALUE scheduler, VALUE fiber, VALUE exception)
+{
+    VALUE arguments[] = {
+        fiber, exception
+    };
+
+    return rb_check_funcall(scheduler, id_fiber_interrupt, 2, arguments);
+}
+
 /*
  *  Document-method: Fiber::Scheduler#fiber
  *  call-seq: fiber(&block)

diff --git a/test/fiber/scheduler.rb b/test/fiber/scheduler.rb
@@ -68,9 +68,15 @@ def next_timeout
   def run
     # $stderr.puts [__method__, Fiber.current].inspect
 
+    readable = writable = nil
+
     while @readable.any? or @writable.any? or @waiting.any? or @blocking.any?
       # May only handle file descriptors up to 1024...
-      readable, writable = IO.select(@readable.keys + [@urgent.first], @writable.keys, [], next_timeout)
+      begin
+        readable, writable = IO.select(@readable.keys + [@urgent.first], @writable.keys, [], next_timeout)
+      rescue IOError
+        # Ignore - this can happen if the IO is closed while we are waiting.
+      end
 
       # puts "readable: #{readable}" if readable&.any?
       # puts "writable: #{writable}" if writable&.any?
@@ -290,6 +296,30 @@ def unblock(blocker, fiber)
     io.write_nonblock('.')
   end
 
+  class FiberInterrupt
+    def initialize(fiber, exception)
+      @fiber = fiber
+      @exception = exception
+    end
+
+    def alive?
+      @fiber.alive?
+    end
+
+    def transfer
+      @fiber.raise(@exception)
+    end
+  end
+
+  def fiber_interrupt(fiber, exception)
+    @lock.synchronize do
+      @ready << FiberInterrupt.new(fiber, exception)
+    end
+
+    io = @urgent.last
+    io.write_nonblock('.')
+  end
+
   # This hook is invoked by `Fiber.schedule`. Strictly speaking, you should use
   # it to create scheduled fibers, but it is not required in practice;
   # `Fiber.new` is usually sufficient.

diff --git a/thread.c b/thread.c
@@ -150,7 +150,7 @@ static rb_internal_thread_specific_key_t specific_key_count;
 
 struct waiting_fd {
     struct ccan_list_node wfd_node; /* <=> vm.waiting_fds */
-    rb_thread_t *th;
+    rb_execution_context_t *ec;
     int fd;
     struct rb_io_close_wait_list *busy;
 };
@@ -1691,12 +1691,14 @@ waitfd_to_waiting_flag(int wfd_event)
 }
 
 static void
-thread_io_setup_wfd(rb_thread_t *th, int fd, struct waiting_fd *wfd)
+thread_io_setup_wfd(rb_execution_context_t *ec, int fd, struct waiting_fd *wfd)
 {
     wfd->fd = fd;
-    wfd->th = th;
+    wfd->ec = ec;
     wfd->busy = NULL;
 
+    rb_thread_t *th = rb_ec_thread_ptr(ec);
+
     RB_VM_LOCK_ENTER();
     {
         ccan_list_add(&th->vm->waiting_fds, &wfd->wfd_node);
@@ -1730,6 +1732,29 @@ thread_io_wake_pending_closer(struct waiting_fd *wfd)
     }
 }
 
+
+static VALUE
+rb_thread_io_interruptible_operation_ensure(VALUE _argument)
+{
+    struct waiting_fd *wfd = (struct waiting_fd *)_argument;
+    thread_io_wake_pending_closer(wfd);
+    return Qnil;
+}
+
+VALUE
+rb_thread_io_interruptible_operation(VALUE self, VALUE(*function)(VALUE), VALUE argument)
+{
+    struct rb_io *io;
+    RB_IO_POINTER(self, io);
+
+    rb_execution_context_t *ec = GET_EC();
+
+    struct waiting_fd waiting_fd;
+    thread_io_setup_wfd(ec, io->fd, &waiting_fd);
+
+    return rb_ensure(function, argument, rb_thread_io_interruptible_operation_ensure, (VALUE)&waiting_fd);
+}
+
 static bool
 thread_io_mn_schedulable(rb_thread_t *th, int events, const struct timeval *timeout)
 {
@@ -1815,18 +1840,18 @@ rb_thread_io_blocking_call(rb_blocking_function_t *func, void *data1, int fd, in
     // `func` or not (as opposed to some previously set value).
     errno = 0;
 
-    thread_io_setup_wfd(th, fd, &waiting_fd);
+    thread_io_setup_wfd(ec, fd, &waiting_fd);
     {
         EC_PUSH_TAG(ec);
         if ((state = EC_EXEC_TAG()) == TAG_NONE) {
             volatile enum ruby_tag_type saved_state = state; /* for BLOCKING_REGION */
           retry:
-            BLOCKING_REGION(waiting_fd.th, {
+            BLOCKING_REGION(th, {
                 val = func(data1);
                 saved_errno = errno;
-            }, ubf_select, waiting_fd.th, FALSE);
+            }, ubf_select, th, FALSE);
 
-            th = rb_ec_thread_ptr(ec);
+            RUBY_ASSERT(th == rb_ec_thread_ptr(ec));
             if (events &&
                 blocking_call_retryable_p((int)val, saved_errno) &&
                 thread_io_wait_events(th, fd, events, NULL)) {
@@ -2640,6 +2665,7 @@ rb_ec_reset_raised(rb_execution_context_t *ec)
 int
 rb_notify_fd_close(int fd, struct rb_io_close_wait_list *busy)
 {
+    // fprintf(stderr, "rb_notify_fd_close(%d) pid=%d\n", fd, getpid());
     rb_vm_t *vm = GET_THREAD()->vm;
     struct waiting_fd *wfd = 0, *next;
     ccan_list_head_init(&busy->pending_fd_users);
@@ -2650,16 +2676,23 @@ rb_notify_fd_close(int fd, struct rb_io_close_wait_list *busy)
     {
         ccan_list_for_each_safe(&vm->waiting_fds, wfd, next, wfd_node) {
             if (wfd->fd == fd) {
-                rb_thread_t *th = wfd->th;
-                VALUE err;
+                rb_execution_context_t *ec = wfd->ec;
+                rb_thread_t *th = rb_ec_thread_ptr(ec);
 
                 ccan_list_del(&wfd->wfd_node);
                 ccan_list_add(&busy->pending_fd_users, &wfd->wfd_node);
 
                 wfd->busy = busy;
-                err = th->vm->special_exceptions[ruby_error_stream_closed];
-                rb_threadptr_pending_interrupt_enque(th, err);
-                rb_threadptr_interrupt(th);
+
+                VALUE error = th->vm->special_exceptions[ruby_error_stream_closed];
+
+                if (th->scheduler != Qnil) {
+                    rb_fiber_scheduler_fiber_interrupt(th->scheduler, rb_fiberptr_self(ec->fiber_ptr), error);
+                } else {
+                    // fprintf(stderr, "rb_notify_fd_close: Interrupting thread %p\n", (void *)th);
+                    rb_threadptr_pending_interrupt_enque(th, error);
+                    rb_threadptr_interrupt(th);
+                }
             }
         }
     }
@@ -4417,7 +4450,7 @@ rb_thread_wait_for_single_fd(int fd, int events, struct timeval *timeout)
     rb_execution_context_t *ec = GET_EC();
     rb_thread_t *th = rb_ec_thread_ptr(ec);
 
-    thread_io_setup_wfd(th, fd, &wfd);
+    thread_io_setup_wfd(ec, fd, &wfd);
 
     if (timeout == NULL && thread_io_wait_events(th, fd, events, NULL)) {
         // fd is readable
@@ -4426,16 +4459,16 @@ rb_thread_wait_for_single_fd(int fd, int events, struct timeval *timeout)
         errno = 0;
     }
     else {
-        EC_PUSH_TAG(wfd.th->ec);
+        EC_PUSH_TAG(ec);
         if ((state = EC_EXEC_TAG()) == TAG_NONE) {
             rb_hrtime_t *to, rel, end = 0;
-            RUBY_VM_CHECK_INTS_BLOCKING(wfd.th->ec);
+            RUBY_VM_CHECK_INTS_BLOCKING(ec);
             timeout_prepare(&to, &rel, &end, timeout);
             do {
                 nfds = numberof(fds);
-                result = wait_for_single_fd_blocking_region(wfd.th, fds, nfds, to, &lerrno);
+                result = wait_for_single_fd_blocking_region(th, fds, nfds, to, &lerrno);
 
-                RUBY_VM_CHECK_INTS_BLOCKING(wfd.th->ec);
+                RUBY_VM_CHECK_INTS_BLOCKING(ec);
             } while (wait_retryable(&result, lerrno, to, end));
         }
         EC_POP_TAG();
@@ -4444,7 +4477,7 @@ rb_thread_wait_for_single_fd(int fd, int events, struct timeval *timeout)
     thread_io_wake_pending_closer(&wfd);
 
     if (state) {
-        EC_JUMP_TAG(wfd.th->ec, state);
+        EC_JUMP_TAG(ec, state);
     }
 
     if (result < 0) {
@@ -4543,14 +4576,13 @@ rb_thread_wait_for_single_fd(int fd, int events, struct timeval *timeout)
     int r;
     VALUE ptr = (VALUE)&args;
     rb_execution_context_t *ec = GET_EC();
-    rb_thread_t *th = rb_ec_thread_ptr(ec);
 
     args.as.fd = fd;
     args.read = (events & RB_WAITFD_IN) ? init_set_fd(fd, &rfds) : NULL;
     args.write = (events & RB_WAITFD_OUT) ? init_set_fd(fd, &wfds) : NULL;
     args.except = (events & RB_WAITFD_PRI) ? init_set_fd(fd, &efds) : NULL;
     args.tv = timeout;
-    thread_io_setup_wfd(th, fd, &args.wfd);
+    thread_io_setup_wfd(ec, fd, &args.wfd);
 
     r = (int)rb_ensure(select_single, ptr, select_single_cleanup, ptr);
     if (r == -1)