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per-method serial number

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Methods and their definitions can be allocated/deallocated on-the-fly.
One pathological situation is when a method is deallocated then another
one is allocated immediately after that.  Address of those old/new method
entries/definitions can be the same then, depending on underlying
malloc/free implementation.

So pointer comparison is insufficient.  We have to check the contents.
To do so we introduce def->method_serial, which is an integer unique to
that specific method definition.

PS: Note that method_serial being uintptr_t rather than rb_serial_t is
intentional.  This is because rb_serial_t can be bigger than a pointer
on a 32bit system (rb_serial_t is at least 64bit).  In order to preserve
old packing of struct rb_call_cache, rb_serial_t is inappropriate.
This commit is contained in:
卜部昌平 2019-12-17 15:49:41 +09:00
parent 77e3078ede
commit f054f11a38
Notes: git 2019-12-18 12:52:56 +09:00
6 changed files with 9 additions and 6 deletions
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4
internal.h
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@ -2350,7 +2350,7 @@ struct rb_call_cache {
(CACHELINE
- sizeof(rb_serial_t) /* method_state */
- sizeof(struct rb_callable_method_entry_struct *) /* me */
- sizeof(struct rb_callable_method_definition_struct *) /* def */
- sizeof(uintptr_t) /* method_serial */
- sizeof(enum method_missing_reason) /* aux */
- sizeof(VALUE (*)( /* call */
struct rb_execution_context_struct *e,
@ -2362,7 +2362,7 @@ struct rb_call_cache {
/* inline cache: values */
const struct rb_callable_method_entry_struct *me;
const struct rb_method_definition_struct *def;
uintptr_t method_serial; /* me->def->method_serial */
VALUE (*call)(struct rb_execution_context_struct *ec,
struct rb_control_frame_struct *cfp,