per-ractor Random::DEFAULT

Random generators are not Ractor-safe, so we need to prepare
per-ractor default random genearators. This patch set
`Random::DEFAULT = Randm` (not a Random instance, but the Random
class) and singleton methods like `Random.rand()` use a per-ractor
random generator.

[Feature #17322]

1 files changed, 16 insertions, 0 deletions

diff --git a/ractor.c b/ractor.c
index 491a1e3f71..a5f22a4724 100644
--- a/ractor.c
+++ b/ractor.c
@@ -222,6 +222,7 @@ ractor_free(void *ptr)
     rb_native_cond_destroy(&r->wait.cond);
     ractor_queue_free(&r->incoming_queue);
     ractor_waiting_list_free(&r->taking_ractors);
+    if (r->default_rand) ruby_xfree(r->default_rand);
     ruby_xfree(r);
 }
 
@@ -1767,6 +1768,21 @@ rb_ractor_stderr_set(VALUE err)
     }
 }
 
+void *
+rb_ractor_default_rand(void *ptr)
+{
+    if (rb_ractor_main_p()) {
+        static void *default_rnd;
+        if (UNLIKELY(ptr != NULL)) default_rnd = ptr;
+        return default_rnd;
+    }
+    else {
+        rb_ractor_t *cr = GET_RACTOR();
+        if (UNLIKELY(ptr != NULL)) cr->default_rand = ptr;
+        return cr->default_rand;
+    }
+}
+
 /// traverse function
 
 // 2: stop search