[Tarantool-patches] [PATCH] box: add binary search for _session settings space
Vladislav Shpilevoy
v.shpilevoy at tarantool.org
Wed Jan 15 23:24:16 MSK 2020
Hi! Thanks for the patch!
On 10/01/2020 08:46, Chris Sosnin wrote:
> box: add binary search for _session settings space
There is no '_session' space. Please, add '_' between
'_session' and 'settings'.
> As it is mentioned in implementation, it is important
> that _session_settings options are sorted by name, so
> there is no need in linear lookup and we can replace it
> with binary search.
>
> Closes #4712
> ---
> branch: https://github.com/tarantool/tarantool/tree/ksosnin/gh-4712-search-settings
> issue: https://github.com/tarantool/tarantool/issues/4712
>
> src/box/session_settings.c | 10 ++++++----
> src/lib/core/util.c | 22 ++++++++++++++++++++++
> src/trivia/util.h | 3 +++
> 3 files changed, 31 insertions(+), 4 deletions(-)
>
> diff --git a/src/box/session_settings.c b/src/box/session_settings.c
> index a969d3d10..ec87641be 100644
> --- a/src/box/session_settings.c
> +++ b/src/box/session_settings.c
> @@ -265,9 +265,10 @@ session_settings_index_get(struct index *base, const char *key,
> struct session_setting_module *module = &session_setting_modules[0];
> struct session_setting_module *end = module + session_setting_type_MAX;
> int sid = 0;
> + int count = module->setting_count;
1. 'Module' is different on each iteration, because I do '++module'
each time. Here you took count only for the first module, but use it
for all of them.
The same below.
> for (; module < end; ++module, sid = 0) {
> - if (session_settings_next_in_module(module, &sid, key, true,
> - true) == 0)
> + if ((sid = str_bin_search(module->settings, key,
> + count)) != count)
> goto found;
> }
> *result = NULL;
> @@ -372,9 +373,10 @@ session_settings_space_execute_update(struct space *space, struct txn *txn,
> key = tt_cstr(key, key_len);
> struct session_setting_module *module = &session_setting_modules[0];
> struct session_setting_module *end = module + session_setting_type_MAX;
> + int count = module->setting_count;
> for (; module < end; ++module, sid = 0) {
> - if (session_settings_next_in_module(module, &sid, key, true,
> - true) == 0)
> + if ((sid = str_bin_search(module->settings, key,
> + count)) != count)
> goto found;
> }
> *result = NULL;
> diff --git a/src/lib/core/util.c b/src/lib/core/util.c
> index ffa1d2b51..6553d6626 100644
> --- a/src/lib/core/util.c
> +++ b/src/lib/core/util.c
> @@ -84,6 +84,28 @@ strnindex(const char **haystack, const char *needle, uint32_t len, uint32_t hmax
> return hmax;
> }
>
> +/**
> + * Same as strindex(), but assuming the array is sorted and it's
> + * size is known.
> + */
> +uint32_t
> +str_bin_search(const char **haystack, const char *needle, uint32_t hmax) {
2. We don't really need this function anywhere except session_settings.c.
Besides, even in that file it is needed only in session_settings_next_in_module().
So you can just patch the latter function.
> + int cmp;
> + uint32_t index, start = 0;
> + uint32_t end = hmax;
> + while (start < end) {
> + index = (start + end) / 2;
> + cmp = strcmp(haystack[index], needle);
> + if (cmp < 0)
> + start = index + 1;
> + else
> + end = index;
> + }
> + if (start < hmax && strcmp(haystack[start], needle) == 0)
> + return start;
> + return hmax;
> +}
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