Fix compatibility with fiber schedulers that don't implement #fiber_interrupt. (ruby#13492)

Author: ioquatix

scheduler.c

@@ -170,6 +170,10 @@ verify_interface(VALUE scheduler)
     if (!rb_respond_to(scheduler, id_io_wait)) {
         rb_raise(rb_eArgError, "Scheduler must implement #io_wait");
     }
+
+    if (!rb_respond_to(scheduler, id_fiber_interrupt)) {
+        rb_warn("Scheduler should implement #fiber_interrupt");
+    }
 }
 
 static VALUE
@@ -458,7 +462,11 @@ rb_fiber_scheduler_io_wait(VALUE scheduler, VALUE io, VALUE events, VALUE timeou
         scheduler, io, events, timeout
     };
 
-    return rb_thread_io_blocking_operation(io, fiber_scheduler_io_wait, (VALUE)&arguments);
+    if (rb_respond_to(scheduler, id_fiber_interrupt)) {
+        return rb_thread_io_blocking_operation(io, fiber_scheduler_io_wait, (VALUE)&arguments);
+    } else {
+        return fiber_scheduler_io_wait((VALUE)&arguments);
+    }
 }
 
 VALUE
@@ -546,7 +554,11 @@ rb_fiber_scheduler_io_read(VALUE scheduler, VALUE io, VALUE buffer, size_t lengt
         scheduler, io, buffer, SIZET2NUM(length), SIZET2NUM(offset)
     };
 
-    return rb_thread_io_blocking_operation(io, fiber_scheduler_io_read, (VALUE)&arguments);
+    if (rb_respond_to(scheduler, id_fiber_interrupt)) {
+        return rb_thread_io_blocking_operation(io, fiber_scheduler_io_read, (VALUE)&arguments);
+    } else {
+        return fiber_scheduler_io_read((VALUE)&arguments);
+    }
 }
 
 /*
@@ -581,7 +593,11 @@ rb_fiber_scheduler_io_pread(VALUE scheduler, VALUE io, rb_off_t from, VALUE buff
         scheduler, io, buffer, OFFT2NUM(from), SIZET2NUM(length), SIZET2NUM(offset)
     };
 
-    return rb_thread_io_blocking_operation(io, fiber_scheduler_io_pread, (VALUE)&arguments);
+    if (rb_respond_to(scheduler, id_fiber_interrupt)) {
+        return rb_thread_io_blocking_operation(io, fiber_scheduler_io_pread, (VALUE)&arguments);
+    } else {
+        return fiber_scheduler_io_pread((VALUE)&arguments);
+    }
 }
 
 /*
@@ -630,7 +646,11 @@ rb_fiber_scheduler_io_write(VALUE scheduler, VALUE io, VALUE buffer, size_t leng
         scheduler, io, buffer, SIZET2NUM(length), SIZET2NUM(offset)
     };
 
-    return rb_thread_io_blocking_operation(io, fiber_scheduler_io_write, (VALUE)&arguments);
+    if (rb_respond_to(scheduler, id_fiber_interrupt)) {
+        return rb_thread_io_blocking_operation(io, fiber_scheduler_io_write, (VALUE)&arguments);
+    } else {
+        return fiber_scheduler_io_write((VALUE)&arguments);
+    }
 }
 
 /*
@@ -666,7 +686,11 @@ rb_fiber_scheduler_io_pwrite(VALUE scheduler, VALUE io, rb_off_t from, VALUE buf
         scheduler, io, buffer, OFFT2NUM(from), SIZET2NUM(length), SIZET2NUM(offset)
     };
 
-    return rb_thread_io_blocking_operation(io, fiber_scheduler_io_pwrite, (VALUE)&arguments);
+    if (rb_respond_to(scheduler, id_fiber_interrupt)) {
+        return rb_thread_io_blocking_operation(io, fiber_scheduler_io_pwrite, (VALUE)&arguments);
+    } else {
+        return fiber_scheduler_io_pwrite((VALUE)&arguments);
+    }
 }
 
 VALUE

thread.c

@@ -1721,6 +1721,12 @@ rb_io_blocking_operation_enter(struct rb_io *io, struct rb_io_blocking_operation
     ccan_list_add(rb_io_blocking_operations(io), &blocking_operation->list);
 }
 
+static void
+rb_io_blocking_operation_pop(struct rb_io *io, struct rb_io_blocking_operation *blocking_operation)
+{
+    ccan_list_del(&blocking_operation->list);
+}
+
 struct io_blocking_operation_arguments {
     struct rb_io *io;
     struct rb_io_blocking_operation *blocking_operation;
@@ -1732,7 +1738,7 @@ io_blocking_operation_exit(VALUE _arguments)
     struct io_blocking_operation_arguments *arguments = (void*)_arguments;
     struct rb_io_blocking_operation *blocking_operation = arguments->blocking_operation;
 
-    ccan_list_del(&blocking_operation->list);
+    rb_io_blocking_operation_pop(arguments->io, blocking_operation);
 
     rb_io_t *io = arguments->io;
     rb_thread_t *thread = io->closing_ec->thread_ptr;
@@ -1763,6 +1769,9 @@ rb_io_blocking_operation_exit(struct rb_io *io, struct rb_io_blocking_operation
 {
     VALUE wakeup_mutex = io->wakeup_mutex;
 
+    // Indicate that the blocking operation is no longer active:
+    blocking_operation->ec = NULL;
+
     if (RB_TEST(wakeup_mutex)) {
         struct io_blocking_operation_arguments arguments = {
             .io = io,
@@ -1772,7 +1781,8 @@ rb_io_blocking_operation_exit(struct rb_io *io, struct rb_io_blocking_operation
         rb_mutex_synchronize(wakeup_mutex, io_blocking_operation_exit, (VALUE)&arguments);
     }
     else {
-        ccan_list_del(&blocking_operation->list);
+        // If there's no wakeup_mutex, we can safely remove the operation directly:
+        rb_io_blocking_operation_pop(io, blocking_operation);
     }
 }
 
@@ -1809,7 +1819,7 @@ rb_thread_io_blocking_operation(VALUE self, VALUE(*function)(VALUE), VALUE argum
     struct rb_io_blocking_operation blocking_operation = {
         .ec = ec,
     };
-    ccan_list_add(&io->blocking_operations, &blocking_operation.list);
+    rb_io_blocking_operation_enter(io, &blocking_operation);
 
     struct io_blocking_operation_arguments io_blocking_operation_arguments = {
         .io = io,
@@ -2765,13 +2775,20 @@ thread_io_close_notify_all(VALUE _io)
     ccan_list_for_each(rb_io_blocking_operations(io), blocking_operation, list) {
         rb_execution_context_t *ec = blocking_operation->ec;
 
-        rb_thread_t *thread = ec->thread_ptr;
+        // If the operation is in progress, we need to interrupt it:
+        if (ec) {
+            rb_thread_t *thread = ec->thread_ptr;
 
-        if (thread->scheduler != Qnil) {
-            rb_fiber_scheduler_fiber_interrupt(thread->scheduler, rb_fiberptr_self(ec->fiber_ptr), error);
-        } else {
-            rb_threadptr_pending_interrupt_enque(thread, error);
-            rb_threadptr_interrupt(thread);
+            VALUE result = RUBY_Qundef;
+            if (thread->scheduler != Qnil) {
+                result = rb_fiber_scheduler_fiber_interrupt(thread->scheduler, rb_fiberptr_self(ec->fiber_ptr), error);
+            }
+
+            if (result == RUBY_Qundef) {
+                // If the thread is not the current thread, we need to enqueue an error:
+                rb_threadptr_pending_interrupt_enque(thread, error);
+                rb_threadptr_interrupt(thread);
+            }
         }
 
         count += 1;