better way to fix rare GC condition

ruby · funny-falcon · Dec 21, 2011 · Dec 27, 2011 · Dec 27, 2011 · Dec 27, 2011
commit 3371756c4ef2b12e852ca89a6a5d431f0ad4cc82
diff --git a/gc.c b/gc.c
@@ -788,6 +788,15 @@ vm_xmalloc(rb_objspace_t *objspace, size_t size)
     return vm_malloc_fixup(objspace, mem, size);
 }
 
+static void *
+vm_xmalloc_only(rb_objspace_t *objspace, size_t size)
+{
+    void *mem;
+
+    TRY_WITH_GC(mem = malloc(size));
+    return vm_malloc_fixup(objspace, mem, size);
+}
+
 static void *
 vm_xrealloc(rb_objspace_t *objspace, void *ptr, size_t size)
 {
@@ -850,6 +859,18 @@ ruby_xmalloc(size_t size)
     return vm_xmalloc(&rb_objspace, size);
 }
 
+size_t
+ruby_gcprepare(size_t size)
+{
+    return vm_malloc_prepare(&rb_objspace, size);
+}
+
+void *
+ruby_xmalloc_prepared(size_t size)
+{
+    return vm_xmalloc_only(&rb_objspace, size);
+}
+
 static inline size_t
 xmalloc2_size(size_t n, size_t size)
 {

diff --git a/internal.h b/internal.h
@@ -93,6 +93,10 @@ void Init_File(void);
 
 /* gc.c */
 void Init_heap(void);
+#define xgc_prepare ruby_gcprepare
+#define xmalloc_prepared ruby_xmalloc_prepared
+size_t xgc_prepare(size_t);
+void *xmalloc_prepared(size_t);
 
 /* inits.c */
 void rb_call_inits(void);

diff --git a/pool_alloc.inc.h b/pool_alloc.inc.h
@@ -34,7 +34,7 @@ struct entry_typename {
     holder_typename *holder;
 };
 
-#define HOLDER_SIZE (256 / sizeof(entry_typename) - 1)
+#define HOLDER_SIZE ((4096 - sizeof(void*) * 3 - sizeof(int)) / sizeof(entry_typename) )
 struct holder_typename {
     unsigned int free;
     entry_typename items[HOLDER_SIZE];
@@ -65,11 +65,19 @@ entry_chain(entry_typename *entry)
 static void
 holder_alloc()
 {
-    holder_typename *holder = alloc(holder_typename);
-    unsigned int i = HOLDER_SIZE - 1;
-    register entry_typename *ptr = holder->items;
+    holder_typename *holder;
+    unsigned int i;
+    register entry_typename *ptr;
+#ifdef xgc_prepare
+    size_t sz = xgc_prepare(sizeof(holder_typename));
+    if (free_entry_p) return;
+    holder = (holder_typename*)xmalloc_prepared(sz);
+#else
+    holder = alloc(holder_typename);
+#endif 
+    ptr = holder->items;
     holder->free = HOLDER_SIZE;
-    for(; i; ptr++, i-- ) {
+    for(i = HOLDER_SIZE - 1; i; ptr++, i-- ) {
         ptr->holder = holder;
         ptr->fore = ptr + 1;
         (ptr + 1)->back = ptr;

diff --git a/st.c b/st.c
@@ -7,6 +7,7 @@
 #include "st.h"
 #else
 #include "ruby/ruby.h"
+#include "internal.h"
 #endif
 
 #include <stdio.h>