* [LTP] [PATCH v2] include: add an exponential backoff macro for function repeat
@ 2018-04-13 11:19 Li Wang
2018-04-16 12:47 ` Richard Palethorpe
0 siblings, 1 reply; 3+ messages in thread
From: Li Wang @ 2018-04-13 11:19 UTC (permalink / raw)
To: ltp
Signed-off-by: Li Wang <liwang@redhat.com>
Cc: Richard Palethorpe <rpalethorpe@suse.de>
Cc: Cyril Hrubis <chrubis@suse.cz>
---
include/tst_common.h | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/include/tst_common.h b/include/tst_common.h
index e4466d5..3c01e26 100644
--- a/include/tst_common.h
+++ b/include/tst_common.h
@@ -35,4 +35,30 @@
#define LTP_ALIGN(x, a) __LTP_ALIGN_MASK(x, (typeof(x))(a) - 1)
#define __LTP_ALIGN_MASK(x, mask) (((x) + (mask)) & ~(mask))
+/*
+ * Exponential backoff usleep for function repeat
+ * @FUNC: the function which will be retried
+ * @ERET: an expected return value from the FUNC
+ */
+#define TST_RETRY_FUNC(FUNC, ERET) \
+ TST_RETRY_FN_EXP_BACKOFF(FUNC, ERET, 1)
+
+#define TST_RETRY_FN_EXP_BACKOFF(FUNC, ERET, MAX_DELAY) \
+do { int tst_delay = 1; \
+ for (;;) { \
+ typeof(FUNC) ret = FUNC; \
+ if (ret == ERET) \
+ break; \
+ if (tst_delay < MAX_DELAY * 1000000) { \
+ tst_res(TINFO, \
+ #FUNC" returned %i, retrying" \
+ " in %ius", ret, tst_delay); \
+ usleep(tst_delay); \
+ tst_delay *= 2; \
+ } else { \
+ tst_brk(TBROK, #FUNC" failed"); \
+ } \
+ } \
+} while(0)
+
#endif /* TST_COMMON_H__ */
--
2.9.3
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [LTP] [PATCH v2] include: add an exponential backoff macro for function repeat
2018-04-13 11:19 [LTP] [PATCH v2] include: add an exponential backoff macro for function repeat Li Wang
@ 2018-04-16 12:47 ` Richard Palethorpe
2018-04-17 3:05 ` Li Wang
0 siblings, 1 reply; 3+ messages in thread
From: Richard Palethorpe @ 2018-04-16 12:47 UTC (permalink / raw)
To: ltp
Hello,
Li Wang writes:
> Signed-off-by: Li Wang <liwang@redhat.com>
> Cc: Richard Palethorpe <rpalethorpe@suse.de>
> Cc: Cyril Hrubis <chrubis@suse.cz>
> ---
> include/tst_common.h | 26 ++++++++++++++++++++++++++
> 1 file changed, 26 insertions(+)
>
> diff --git a/include/tst_common.h b/include/tst_common.h
> index e4466d5..3c01e26 100644
> --- a/include/tst_common.h
> +++ b/include/tst_common.h
> @@ -35,4 +35,30 @@
> #define LTP_ALIGN(x, a) __LTP_ALIGN_MASK(x, (typeof(x))(a) - 1)
> #define __LTP_ALIGN_MASK(x, mask) (((x) + (mask)) & ~(mask))
>
> +/*
> + * Exponential backoff usleep for function repeat
How about:
/**
* TST_RETRY_FUNC() - Repeatedly retry a function with an increasing delay.
* @FUNC - The function which will be retried
* @ERET - The value returned from @FUNC on success
*
* This macro will call @FUNC in a loop with a delay between retries. If @FUNC
* returns @ERET then the loop exits. The delay between retries starts at one
* micro second and is then doubled each iteration until it exceeds one second
* (the total time sleeping will be aproximately one second as well). When the
* delay exceeds one second tst_brk() is called.
*/
> + * @FUNC: the function which will be retried
> + * @ERET: an expected return value from the FUNC
> + */
> +#define TST_RETRY_FUNC(FUNC, ERET) \
> + TST_RETRY_FN_EXP_BACKOFF(FUNC, ERET, 1)
> +
> +#define TST_RETRY_FN_EXP_BACKOFF(FUNC, ERET, MAX_DELAY) \
> +do { int tst_delay = 1; \
> + for (;;) { \
> + typeof(FUNC) ret = FUNC; \
> + if (ret == ERET) \
> + break; \
Maybe it should return ret somehow?
> + if (tst_delay < MAX_DELAY * 1000000) { \
> + tst_res(TINFO, \
> + #FUNC" returned %i, retrying" \
> + " in %ius", ret, tst_delay); \
> + usleep(tst_delay); \
> + tst_delay *= 2; \
> + } else { \
> + tst_brk(TBROK, #FUNC" failed"); \
> + } \
> + } \
> +} while(0)
> +
> #endif /* TST_COMMON_H__ */
--
Thank you,
Richard.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [LTP] [PATCH v2] include: add an exponential backoff macro for function repeat
2018-04-16 12:47 ` Richard Palethorpe
@ 2018-04-17 3:05 ` Li Wang
0 siblings, 0 replies; 3+ messages in thread
From: Li Wang @ 2018-04-17 3:05 UTC (permalink / raw)
To: ltp
Richard Palethorpe <rpalethorpe@suse.de> wrote:
How about:
>
> /**
> * TST_RETRY_FUNC() - Repeatedly retry a function with an increasing delay.
> * @FUNC - The function which will be retried
> * @ERET - The value returned from @FUNC on success
> *
> * This macro will call @FUNC in a loop with a delay between retries. If
> @FUNC
> * returns @ERET then the loop exits. The delay between retries starts at
> one
> * micro second and is then doubled each iteration until it exceeds one
> second
> * (the total time sleeping will be aproximately one second as well). When
> the
> * delay exceeds one second tst_brk() is called.
> */
>
I like this description.
>
> > + * @FUNC: the function which will be retried
> > + * @ERET: an expected return value from the FUNC
> > + */
> > +#define TST_RETRY_FUNC(FUNC, ERET) \
> > + TST_RETRY_FN_EXP_BACKOFF(FUNC, ERET, 1)
> > +
> > +#define TST_RETRY_FN_EXP_BACKOFF(FUNC, ERET, MAX_DELAY) \
> > +do { int tst_delay = 1; \
> > + for (;;) { \
> > + typeof(FUNC) ret = FUNC; \
> > + if (ret == ERET) \
> > + break; \
>
> Maybe it should return ret somehow?
>
Maybe yes!
And, if we do that, the macro should probably be rewritten as:
#define TST_RETRY_FN_EXP_BACKOFF(FUNC, ERET, MAX_DELAY) \
({ int tst_delay = 1; \
for (;;) { \
typeof(FUNC) ret = FUNC; \
if (ret == ERET) \
break; \
if (tst_delay < MAX_DELAY * 1000000) { \
tst_res(TINFO, \
#FUNC" returned %i, retrying" \
" in %ius", ret, tst_delay); \
usleep(tst_delay); \
tst_delay *= 2; \
} else { \
tst_brk(TBROK, #FUNC" failed"); \
} \
} \
ERET; \
})
--
Li Wang
liwang@redhat.com
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2018-04-13 11:19 [LTP] [PATCH v2] include: add an exponential backoff macro for function repeat Li Wang
2018-04-16 12:47 ` Richard Palethorpe
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