Revert "Introduce Fiber Scheduler `blocking_region` hook. (#11963)" (#12013)

This reverts some of commit 87fb44dff6.

We will rename and propose a slightly different interface.

NEWS.md

@@ -57,11 +57,6 @@ Note: We're only listing outstanding class updates.
       associated with the AST node. [[Feature #20624]]
     * Add RubyVM::AbstractSyntaxTree::Location class which holds location information. [[Feature #20624]]
 
-* Fiber::Scheduler
-
-    * An optional `Fiber::Scheduler#blocking_region` hook allows blocking operations to be moved out of the event loop
-      in order to reduce latency and improve multi-core processor utilization. [[Feature #20855]]
-
 ## Stdlib updates
 
 * Tempfile
@@ -228,4 +223,3 @@ details of the default gems or bundled gems.
 [Feature #20497]: https://bugs.ruby-lang.org/issues/20497
 [Feature #20624]: https://bugs.ruby-lang.org/issues/20624
 [Feature #20775]: https://bugs.ruby-lang.org/issues/20775
-[Feature #20855]: https://bugs.ruby-lang.org/issues/20855

common.mk

@@ -16683,7 +16683,6 @@ scheduler.$(OBJEXT): {$(VPATH)}scheduler.c
 scheduler.$(OBJEXT): {$(VPATH)}shape.h
 scheduler.$(OBJEXT): {$(VPATH)}st.h
 scheduler.$(OBJEXT): {$(VPATH)}subst.h
-scheduler.$(OBJEXT): {$(VPATH)}thread.h
 scheduler.$(OBJEXT): {$(VPATH)}thread_$(THREAD_MODEL).h
 scheduler.$(OBJEXT): {$(VPATH)}thread_native.h
 scheduler.$(OBJEXT): {$(VPATH)}vm_core.h

include/ruby/fiber/scheduler.h

@@ -391,26 +391,6 @@ VALUE rb_fiber_scheduler_io_close(VALUE scheduler, VALUE io);
  */
 VALUE rb_fiber_scheduler_address_resolve(VALUE scheduler, VALUE hostname);
 
-struct rb_fiber_scheduler_blocking_region_state {
-    void *result;
-    int saved_errno;
-};
-
-/**
- * Defer the execution of the passed function to the scheduler.
- *
- * @param[in]  scheduler         Target scheduler.
- * @param[in]  function          The function to run.
- * @param[in]  data              The data to pass to the function.
- * @param[in]  unblock_function  The unblock function to use to interrupt the operation.
- * @param[in]  data2             The data to pass to the unblock function.
- * @param[in]  flags             Flags passed to `rb_nogvl`.
- * @param[out] state             The result and errno of the operation.
- * @retval     RUBY_Qundef       `scheduler` doesn't have `#blocking_region`.
- * @return     otherwise         What `scheduler.blocking_region` returns.
- */
-VALUE rb_fiber_scheduler_blocking_region(VALUE scheduler, void* (*function)(void *), void *data, rb_unblock_function_t *unblock_function, void *data2, int flags, struct rb_fiber_scheduler_blocking_region_state *state);
-
 /**
  * Create and schedule a non-blocking fiber.
  *

scheduler.c

@@ -13,9 +13,6 @@
 #include "ruby/io.h"
 #include "ruby/io/buffer.h"
 
-#include "ruby/thread.h"
-
-// For `ruby_thread_has_gvl_p`.
 #include "internal/thread.h"
 
 static ID id_close;
@@ -36,8 +33,6 @@ static ID id_io_close;
 
 static ID id_address_resolve;
 
-static ID id_blocking_region;
-
 static ID id_fiber_schedule;
 
 /*
@@ -114,8 +109,6 @@ Init_Fiber_Scheduler(void)
 
     id_address_resolve = rb_intern_const("address_resolve");
 
-    id_blocking_region = rb_intern_const("blocking_region");
-
     id_fiber_schedule = rb_intern_const("fiber");
 
 #if 0 /* for RDoc */
@@ -700,62 +693,6 @@ rb_fiber_scheduler_address_resolve(VALUE scheduler, VALUE hostname)
     return rb_check_funcall(scheduler, id_address_resolve, 1, arguments);
 }
 
-struct rb_blocking_region_arguments {
-    void *(*function)(void *);
-    void *data;
-    rb_unblock_function_t *unblock_function;
-    void *data2;
-    int flags;
-
-    struct rb_fiber_scheduler_blocking_region_state *state;
-};
-
-static VALUE
-rb_fiber_scheduler_blocking_region_proc(RB_BLOCK_CALL_FUNC_ARGLIST(value, _arguments))
-{
-    struct rb_blocking_region_arguments *arguments = (struct rb_blocking_region_arguments*)_arguments;
-
-    if (arguments->state == NULL) {
-        rb_raise(rb_eRuntimeError, "Blocking function was already invoked!");
-    }
-
-    arguments->state->result = rb_nogvl(arguments->function, arguments->data, arguments->unblock_function, arguments->data2, arguments->flags);
-    arguments->state->saved_errno = rb_errno();
-
-    // Make sure it's only invoked once.
-    arguments->state = NULL;
-
-    return Qnil;
-}
-
-/*
- *  Document-method: Fiber::Scheduler#blocking_region
- *  call-seq: blocking_region(work)
- *
- *  Invoked by Ruby's core methods to run a blocking operation in a non-blocking way.
- *
- *  Minimal suggested implementation is:
- *
- *     def blocking_region(work)
- *       Thread.new(&work).join
- *     end
- */
-VALUE rb_fiber_scheduler_blocking_region(VALUE scheduler, void* (*function)(void *), void *data, rb_unblock_function_t *unblock_function, void *data2, int flags, struct rb_fiber_scheduler_blocking_region_state *state)
-{
-    struct rb_blocking_region_arguments arguments = {
-        .function = function,
-        .data = data,
-        .unblock_function = unblock_function,
-        .data2 = data2,
-        .flags = flags,
-        .state = state
-    };
-
-    VALUE proc = rb_proc_new(rb_fiber_scheduler_blocking_region_proc, (VALUE)&arguments);
-
-    return rb_check_funcall(scheduler, id_blocking_region, 1, &proc);
-}
-
 /*
  *  Document-method: Fiber::Scheduler#fiber
  *  call-seq: fiber(&block)

test/fiber/scheduler.rb

@@ -309,10 +309,6 @@ class Scheduler
       Addrinfo.getaddrinfo(hostname, nil).map(&:ip_address).uniq
     end.value
   end
-
-  def blocking_region(work)
-    Thread.new(&work).join
-  end
 end
 
 # This scheduler class implements `io_read` and `io_write` hooks which require

thread.c

@@ -1523,18 +1523,6 @@ rb_nogvl(void *(*func)(void *), void *data1,
          rb_unblock_function_t *ubf, void *data2,
          int flags)
 {
-    VALUE scheduler = rb_fiber_scheduler_current();
-    if (scheduler != Qnil) {
-        struct rb_fiber_scheduler_blocking_region_state state;
-
-        VALUE result = rb_fiber_scheduler_blocking_region(scheduler, func, data1, ubf, data2, flags, &state);
-
-        if (!UNDEF_P(result)) {
-            rb_errno_set(state.saved_errno);
-            return state.result;
-        }
-    }
-
     void *val = 0;
     rb_execution_context_t *ec = GET_EC();
     rb_thread_t *th = rb_ec_thread_ptr(ec);