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author | normal <normal@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2014-05-10 23:48:51 +0000 |
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committer | normal <normal@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2014-05-10 23:48:51 +0000 |
commit | f11db2a605d99ef6a0943eba34db355188f8efcb (patch) | |
tree | 277ff70e7cc260d26f3028d89f25d5b4603675b4 /ccan/build_assert | |
parent | 3771a370ad64aae87f751751e80d52d02a1735a9 (diff) |
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
Diffstat (limited to 'ccan/build_assert')
-rw-r--r-- | ccan/build_assert/build_assert.h | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/ccan/build_assert/build_assert.h b/ccan/build_assert/build_assert.h new file mode 100644 index 0000000000..a04d1d4709 --- /dev/null +++ b/ccan/build_assert/build_assert.h @@ -0,0 +1,40 @@ +/* CC0 (Public domain) - see ccan/licenses/CC0 file for details */ +#ifndef CCAN_BUILD_ASSERT_H +#define CCAN_BUILD_ASSERT_H + +/** + * BUILD_ASSERT - assert a build-time dependency. + * @cond: the compile-time condition which must be true. + * + * Your compile will fail if the condition isn't true, or can't be evaluated + * by the compiler. This can only be used within a function. + * + * Example: + * #include <stddef.h> + * ... + * static char *foo_to_char(struct foo *foo) + * { + * // This code needs string to be at start of foo. + * BUILD_ASSERT(offsetof(struct foo, string) == 0); + * return (char *)foo; + * } + */ +#define BUILD_ASSERT(cond) \ + do { (void) sizeof(char [1 - 2*!(cond)]); } while(0) + +/** + * BUILD_ASSERT_OR_ZERO - assert a build-time dependency, as an expression. + * @cond: the compile-time condition which must be true. + * + * Your compile will fail if the condition isn't true, or can't be evaluated + * by the compiler. This can be used in an expression: its value is "0". + * + * Example: + * #define foo_to_char(foo) \ + * ((char *)(foo) \ + * + BUILD_ASSERT_OR_ZERO(offsetof(struct foo, string) == 0)) + */ +#define BUILD_ASSERT_OR_ZERO(cond) \ + (sizeof(char [1 - 2*!(cond)]) - 1) + +#endif /* CCAN_BUILD_ASSERT_H */ |