Better handling of timeout in rb_io_maybe_wait_*. (#9531)

Merged-By: ioquatix <samuel@codeotaku.com>

include/ruby/io.h

@@ -975,6 +975,7 @@ VALUE rb_io_wait(VALUE io, VALUE events, VALUE timeout);
  * @exception  rb_eRangeError       `timeout` is out of range.
  * @exception  rb_eSystemCallError  `select(2)` failed for some reason.
  * @retval     RUBY_Qfalse          Operation timed out.
+ * @retval     RUBY_Qnil            Operation failed for some other reason (errno).
  * @retval     Otherwise            Actual events reached.
  *
  */
@@ -982,8 +983,11 @@ VALUE rb_io_maybe_wait(int error, VALUE io, VALUE events, VALUE timeout);
 
 /**
  * Blocks until the passed IO is ready for reading, if that makes sense for the
- * passed  errno.  This  is  a  special case  of  rb_io_maybe_wait() that  only
+ * passed  errno.  This  is  a  special case  of  rb_io_maybe_wait() that is
- * concerns for reading.
+ * only concerned with reading and handles the timeout.
+ *
+ * If you do not want the default timeout handling, consider using
+ * ::rb_io_maybe_wait directly.
  *
  * @param[in]  error                System errno.
  * @param[in]  io                   An IO object to wait.
@@ -991,15 +995,18 @@ VALUE rb_io_maybe_wait(int error, VALUE io, VALUE events, VALUE timeout);
  * @exception  rb_eIOError          `io` is not open.
  * @exception  rb_eRangeError       `timeout` is out of range.
  * @exception  rb_eSystemCallError  `select(2)` failed for some reason.
- * @retval     0                    Operation timed out.
+ * @exception  rb_eIOTimeoutError   The wait operation timed out.
  * @retval     Otherwise            Always returns ::RUBY_IO_READABLE.
  */
 int rb_io_maybe_wait_readable(int error, VALUE io, VALUE timeout);
 
 /**
  * Blocks until the passed IO is ready for writing, if that makes sense for the
- * passed  errno.  This  is  a  special case  of  rb_io_maybe_wait() that  only
+ * passed  errno.  This  is  a  special case  of  rb_io_maybe_wait() that is
- * concernsfor writing.
+ * only concerned with writing, and handles the timeout.
+ *
+ * If you do not want the default timeout handling, consider using
+ * ::rb_io_maybe_wait directly.
  *
  * @param[in]  error                System errno.
  * @param[in]  io                   An IO object to wait.
@@ -1007,7 +1014,7 @@ int rb_io_maybe_wait_readable(int error, VALUE io, VALUE timeout);
  * @exception  rb_eIOError          `io` is not open.
  * @exception  rb_eRangeError       `timeout` is out of range.
  * @exception  rb_eSystemCallError  `select(2)` failed for some reason.
- * @retval     0                    Operation timed out.
+ * @exception  rb_eIOTimeoutError   The wait operation timed out.
  * @retval     Otherwise            Always returns ::RUBY_IO_WRITABLE.
  */
 int rb_io_maybe_wait_writable(int error, VALUE io, VALUE timeout);

io.c

@@ -1623,7 +1623,7 @@ rb_io_maybe_wait(int error, VALUE io, VALUE events, VALUE timeout)
 
       default:
         // Non-specific error, no event is ready:
-        return Qfalse;
+        return Qnil;
     }
 }
 
@@ -1635,9 +1635,11 @@ rb_io_maybe_wait_readable(int error, VALUE io, VALUE timeout)
     if (RTEST(result)) {
         return RB_NUM2INT(result);
     }
-    else {
+    else if (result == RUBY_Qfalse) {
-        return 0;
+        rb_raise(rb_eIOTimeoutError, "Timed out waiting for IO to become readable!");
     }
+
+    return 0;
 }
 
 int
@@ -1648,9 +1650,11 @@ rb_io_maybe_wait_writable(int error, VALUE io, VALUE timeout)
     if (RTEST(result)) {
         return RB_NUM2INT(result);
     }
-    else {
+    else if (result == RUBY_Qfalse) {
-        return 0;
+        rb_raise(rb_eIOTimeoutError, "Timed out waiting for IO to become writable!");
     }
+
+    return 0;
 }
 
 static void

spec/ruby/optional/capi/io_spec.rb

@@ -458,10 +458,6 @@ describe "C-API IO function" do
         @o.rb_io_maybe_wait(Errno::EINTR::Errno, @w_io, IO::WRITABLE, nil).should == IO::WRITABLE
       end
 
-      it "returns false if there is no error condition" do
-        @o.rb_io_maybe_wait(0, @w_io, IO::WRITABLE, nil).should == false
-      end
-
       it "raises an IOError if the IO is closed" do
         @w_io.close
         -> { @o.rb_io_maybe_wait(0, @w_io, IO::WRITABLE, nil) }.should raise_error(IOError, "closed stream")
@@ -521,6 +517,14 @@ describe "C-API IO function" do
       end
     end
   end
+
+  ruby_version_is "3.4" do
+    describe "rb_io_maybe_wait" do
+      it "returns nil if there is no error condition" do
+        @o.rb_io_maybe_wait(0, @w_io, IO::WRITABLE, nil).should == nil
+      end
+    end
+  end
 end
 
 describe "rb_fd_fix_cloexec" do