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307388ea19
* Add a "pinning" reference A `Fiddle::Pinned` objects will prevent the objects they point to from moving. This is useful in the case where you need to pass a reference to a C extension that keeps the address in a global and needs the address to be stable. For example: ```ruby class Foo A = "hi" # this is an embedded string some_c_function A # A might move! end ``` If `A` moves, then the underlying string buffer may also move. `Fiddle::Pinned` will prevent the object from moving: ```ruby class Foo A = "hi" # this is an embedded string A_pinner = Fiddle::Pinned.new(A) # :nodoc: some_c_function A # A can't move because of `Fiddle::Pinned` end ``` This is a similar strategy to what Graal uses: https://www.graalvm.org/sdk/javadoc/org/graalvm/nativeimage/PinnedObject.html#getObject-- * rename global to match exception name * Introduce generic Fiddle::Error and rearrange error classes Fiddle::Error is the generic exception base class for Fiddle exceptions. This commit introduces the class and rearranges Fiddle exceptions to inherit from it. https://github.com/ruby/fiddle/commit/ac52d00223
123 lines
2.7 KiB
C
123 lines
2.7 KiB
C
#include <fiddle.h>
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VALUE rb_cPinned;
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VALUE rb_eFiddleClearedReferenceError;
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struct pinned_data {
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VALUE ptr;
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};
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static void
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pinned_mark(void *ptr)
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{
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struct pinned_data *data = (struct pinned_data*)ptr;
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/* Ensure reference is pinned */
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if (data->ptr) {
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rb_gc_mark(data->ptr);
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}
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}
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static size_t
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pinned_memsize(const void *ptr)
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{
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return sizeof(struct pinned_data);
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}
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static const rb_data_type_t pinned_data_type = {
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"fiddle/pinned",
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{pinned_mark, xfree, pinned_memsize, },
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0, 0, RUBY_TYPED_FREE_IMMEDIATELY | RUBY_TYPED_WB_PROTECTED
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};
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static VALUE
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allocate(VALUE klass)
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{
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struct pinned_data *data;
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VALUE obj = TypedData_Make_Struct(klass, struct pinned_data, &pinned_data_type, data);
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data->ptr = 0;
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return obj;
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}
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/*
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* call-seq:
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* Fiddle::Pinned.new(object) => pinned_object
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*
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* Create a new pinned object reference. The Fiddle::Pinned instance will
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* prevent the GC from moving +object+.
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*/
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static VALUE
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initialize(VALUE self, VALUE ref)
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{
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struct pinned_data *data;
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TypedData_Get_Struct(self, struct pinned_data, &pinned_data_type, data);
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RB_OBJ_WRITE(self, &data->ptr, ref);
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return self;
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}
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/*
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* call-seq: ref
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*
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* Return the object that this pinned instance references.
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*/
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static VALUE
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ref(VALUE self)
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{
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struct pinned_data *data;
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TypedData_Get_Struct(self, struct pinned_data, &pinned_data_type, data);
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if (data->ptr) {
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return data->ptr;
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} else {
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rb_raise(rb_eFiddleClearedReferenceError, "`ref` called on a cleared object");
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}
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}
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/*
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* call-seq: clear
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*
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* Clear the reference to the object this is pinning.
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*/
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static VALUE
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clear(VALUE self)
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{
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struct pinned_data *data;
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TypedData_Get_Struct(self, struct pinned_data, &pinned_data_type, data);
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data->ptr = 0;
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return self;
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}
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/*
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* call-seq: cleared?
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*
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* Returns true if the reference has been cleared, otherwise returns false.
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*/
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static VALUE
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cleared_p(VALUE self)
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{
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struct pinned_data *data;
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TypedData_Get_Struct(self, struct pinned_data, &pinned_data_type, data);
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if (data->ptr) {
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return Qfalse;
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} else {
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return Qtrue;
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}
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}
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extern VALUE rb_eFiddleError;
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void
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Init_fiddle_pinned(void)
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{
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rb_cPinned = rb_define_class_under(mFiddle, "Pinned", rb_cObject);
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rb_define_alloc_func(rb_cPinned, allocate);
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rb_define_method(rb_cPinned, "initialize", initialize, 1);
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rb_define_method(rb_cPinned, "ref", ref, 0);
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rb_define_method(rb_cPinned, "clear", clear, 0);
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rb_define_method(rb_cPinned, "cleared?", cleared_p, 0);
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/*
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* Document-class: Fiddle::ClearedReferenceError
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*
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* Cleared reference exception
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*/
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rb_eFiddleClearedReferenceError = rb_define_class_under(mFiddle, "ClearedReferenceError", rb_eFiddleError);
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}
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