[Tarantool-patches] [PATCH 1/2] errinj: introduce delayed injection
Konstantin Osipov
kostja.osipov at gmail.com
Thu Apr 30 23:15:19 MSK 2020
* Nikita Pettik <korablev at tarantool.org> [20/04/30 22:51]:
This is not exactly a time delay, this is a skip-first-n kind of
postponed enable?
Having a time delay is not such a bad idea (as well as a
probabilistic failure).
> With new macro ERROR_INJECT_DELAYED it is possible to delay error
> injection by DELAY parameter: injection will be set only after DELAY
> times the path is executed. For instance:
>
> void
> foo(int i)
> {
> /* 2 is delay counter. */
> ERROR_INJECT_DELAYED(ERRINJ_FOO, 2, {
> printf("Error injection on %d cycle!\n", i);
> });
> }
>
> void
> boo(void)
> {
> for (int i = 0; i < 10; ++i)
> foo(i);
> }
>
> The result is "Error injection on 2 cycle!". This type of error
> injection can turn out to be useful to set injection in the middle of
> query processing. Imagine following scenario:
>
> void
> foo(void)
> {
> int *fds[10];
> for (int i = 0; i < 10; ++i) {
> fds[i] = malloc(sizeof(int));
> if (fds[i] == NULL)
> goto cleanup;
> }
> cleanup:
> free(fds[0]);
> }
>
> "cleanup" section obviously contains error and leads to memory leak.
> But using means of casual error injection without delay such situation
> can't be detected: OOM can be set only for first cycle iteration and in
> this particular case no leaks take place.
> ---
> src/errinj.h | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/src/errinj.h b/src/errinj.h
> index 2cb090b68..990f4921d 100644
> --- a/src/errinj.h
> +++ b/src/errinj.h
> @@ -149,6 +149,7 @@ errinj_foreach(errinj_cb cb, void *cb_ctx);
> #ifdef NDEBUG
> # define ERROR_INJECT(ID, CODE)
> # define errinj(ID, TYPE) ((struct errinj *) NULL)
> +# define ERROR_INJECT_DELAYED(ID, DELAY, CODE)
> #else
> # /* Returns the error injection by id */
> # define errinj(ID, TYPE) \
> @@ -162,6 +163,14 @@ errinj_foreach(errinj_cb cb, void *cb_ctx);
> if (errinj(ID, ERRINJ_BOOL)->bparam) \
> CODE; \
> } while (0)
> +# define ERROR_INJECT_DELAYED(ID, DELAY, CODE) \
> + do { \
> + static int _DELAY##ID = DELAY; \
> + if (errinj(ID, ERRINJ_BOOL)->bparam) { \
> + if (_DELAY##ID-- == 0) \
> + CODE; \
> + } \
> + } while (0)
> #endif
>
> #define ERROR_INJECT_RETURN(ID) ERROR_INJECT(ID, return -1)
> --
> 2.17.1
>
--
Konstantin Osipov, Moscow, Russia
https://scylladb.com
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