Support blocking FFI calls

Author: eregon

lib/truffle/truffle/ffi_backend/function.rb

@@ -65,6 +65,7 @@ def call(*args, &block)
       param_types = @function_info.param_types
       return_type = @function_info.return_type
       enums = @function_info.enums
+      blocking = @function_info.blocking
 
       converted_args = args.dup
       if block
@@ -80,7 +81,18 @@ def call(*args, &block)
         converted_args[i] = convert_ruby_to_native(param_types[i], arg, enums)
       end
 
-      result = @function.call(*converted_args)
+      if blocking
+        result = Truffle.invoke_primitive :thread_run_blocking_nfi_system_call, -> {
+          r = @function.call(*converted_args)
+          if Integer === r and r == -1 and Errno.errno == Errno::EINTR::Errno
+            undefined # retry
+          else
+            r
+          end
+        }
+      else
+        result = @function.call(*converted_args)
+      end
 
       convert_native_to_ruby(return_type, result)
     end

lib/truffle/truffle/ffi_backend/type.rb

@@ -195,7 +195,7 @@ def get_at(pointer, offset)
   FFI::Type::Struct = StructByValue
 
   class FunctionType < Type
-    attr_reader :return_type, :param_types, :enums
+    attr_reader :return_type, :param_types, :enums, :blocking
 
     def initialize(return_type, param_types, options = {})
       super(FFI::Type::POINTER.size, FFI::Type::POINTER.alignment, FFI::Type::POINTER.nfi_type)
@@ -211,6 +211,7 @@ def initialize(return_type, param_types, options = {})
       end
       @param_types = param_types
       @enums = options[:enums]
+      @blocking = options[:blocking]
 
       if varargs
         @signature = nfi_varags_signature(@return_type, varargs, @param_types)

src/main/ruby/truffleruby/core/posix.rb

@@ -134,7 +134,7 @@ def self.attach_function_eagerly(native_name, argument_types, return_type,
           result = Truffle.invoke_primitive :thread_run_blocking_nfi_system_call, -> {
             r = bound_func.call(*args)
             if Integer === r and r == -1 and Errno.errno == EINTR
-              undefined
+              undefined # retry
             else
               r
             end