vm*: doubly-linked list from ccan to manage vm->living_threads

A doubly-linked list for tracking living threads guarantees
constant-time insert/delete performance with no corner cases of a
hash table.  I chose this ccan implementation of doubly-linked
lists over the BSD sys/queue.h implementation since:

1) insertion and removal are both branchless
2) locality is improved if a struct may be a member of multiple lists
   (0002 patch in Feature 9632 will introduce a secondary list
   for waiting FDs)

This also increases cache locality during iteration: improving
performance in a new IO#close benchmark with many sleeping threads
while still scanning the same number of threads.

	vm_thread_close 1.762

* vm_core.h (rb_vm_t): list_head and counter for living_threads
  (rb_thread_t): vmlt_node for living_threads linkage
  (rb_vm_living_threads_init): new function wrapper
  (rb_vm_living_threads_insert): ditto
  (rb_vm_living_threads_remove): ditto
* vm.c (rb_vm_living_threads_foreach): new function wrapper
* thread.c (terminate_i, thread_start_func_2, thread_create_core,
  thread_fd_close_i, thread_fd_close): update to use new APIs
* vm.c (vm_mark_each_thread_func, rb_vm_mark, ruby_vm_destruct,
  vm_memsize, vm_init2, Init_VM): ditto
* vm_trace.c (clear_trace_func_i, rb_clear_trace_func): ditto
* benchmark/bm_vm_thread_close.rb: added to show improvement
* ccan/build_assert/build_assert.h: added as a dependency of list.h
* ccan/check_type/check_type.h: ditto
* ccan/container_of/container_of.h: ditto
* ccan/licenses/BSD-MIT: ditto
* ccan/licenses/CC0: ditto
* ccan/str/str.h: ditto (stripped of unused macros)
* ccan/list/list.h: ditto
* common.mk: add CCAN_LIST_INCLUDES
  [ruby-core:61871][Feature 9632 (part 1)]

Apologies for the size of this commit, but I think a good
doubly-linked list will be useful for future features, too.
This may be used to add ordering to a container_of-based hash
table to preserve compatibility if required (e.g. feature 9614).

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45913 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 63 insertions, 0 deletions

diff --git a/ccan/check_type/check_type.h b/ccan/check_type/check_type.h
new file mode 100644
index 0000000000..1f77a535e4
--- /dev/null
+++ b/ccan/check_type/check_type.h
@@ -0,0 +1,63 @@
+/* CC0 (Public domain) - see ccan/licenses/CC0 file for details */
+#ifndef CCAN_CHECK_TYPE_H
+#define CCAN_CHECK_TYPE_H
+
+/**
+ * check_type - issue a warning or build failure if type is not correct.
+ * @expr: the expression whose type we should check (not evaluated).
+ * @type: the exact type we expect the expression to be.
+ *
+ * This macro is usually used within other macros to try to ensure that a macro
+ * argument is of the expected type.  No type promotion of the expression is
+ * done: an unsigned int is not the same as an int!
+ *
+ * check_type() always evaluates to 0.
+ *
+ * If your compiler does not support typeof, then the best we can do is fail
+ * to compile if the sizes of the types are unequal (a less complete check).
+ *
+ * Example:
+ *	// They should always pass a 64-bit value to _set_some_value!
+ *	#define set_some_value(expr)			\
+ *		_set_some_value((check_type((expr), uint64_t), (expr)))
+ */
+
+/**
+ * check_types_match - issue a warning or build failure if types are not same.
+ * @expr1: the first expression (not evaluated).
+ * @expr2: the second expression (not evaluated).
+ *
+ * This macro is usually used within other macros to try to ensure that
+ * arguments are of identical types.  No type promotion of the expressions is
+ * done: an unsigned int is not the same as an int!
+ *
+ * check_types_match() always evaluates to 0.
+ *
+ * If your compiler does not support typeof, then the best we can do is fail
+ * to compile if the sizes of the types are unequal (a less complete check).
+ *
+ * Example:
+ *	// Do subtraction to get to enclosing type, but make sure that
+ *	// pointer is of correct type for that member.
+ *	#define container_of(mbr_ptr, encl_type, mbr)			\
+ *		(check_types_match((mbr_ptr), &((encl_type *)0)->mbr),	\
+ *		 ((encl_type *)						\
+ *		  ((char *)(mbr_ptr) - offsetof(enclosing_type, mbr))))
+ */
+#if HAVE_TYPEOF
+#define check_type(expr, type)			\
+	((typeof(expr) *)0 != (type *)0)
+
+#define check_types_match(expr1, expr2)		\
+	((typeof(expr1) *)0 != (typeof(expr2) *)0)
+#else
+#include "ccan/build_assert/build_assert.h"
+/* Without typeof, we can only test the sizes. */
+#define check_type(expr, type)					\
+	BUILD_ASSERT_OR_ZERO(sizeof(expr) == sizeof(type))
+
+#define check_types_match(expr1, expr2)				\
+	BUILD_ASSERT_OR_ZERO(sizeof(expr1) == sizeof(expr2))
+#endif /* HAVE_TYPEOF */
+
+#endif /* CCAN_CHECK_TYPE_H */