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ruanhaishen
redis
Commits
be9860d0
Commit
be9860d0
authored
Apr 03, 2014
by
antirez
Browse files
PFSELFTEST improved to test the approximation error.
parent
cf34507b
Changes
1
Show whitespace changes
Inline
Side-by-side
src/hyperloglog.c
View file @
be9860d0
...
...
@@ -628,18 +628,17 @@ void pfmergeCommand(redisClient *c) {
}
/* This command performs a self-test of the HLL registers implementation.
* Something that is not easy to test from within the outside.
*
* The test is conceived to test that the different counters of our data
* structure are accessible and that setting their values both result in
* the correct value to be retained and not affect adjacent values. */
* Something that is not easy to test from within the outside. */
#define REDIS_HLL_TEST_CYCLES 1000
void
pfselftestCommand
(
redisClient
*
c
)
{
int
j
,
i
;
sds
bitcounters
=
sdsnewlen
(
NULL
,
REDIS_HLL_SIZE
);
uint8_t
bytecounters
[
REDIS_HLL_REGISTERS
];
/* Test 1: access registers.
* The test is conceived to test that the different counters of our data
* structure are accessible and that setting their values both result in
* the correct value to be retained and not affect adjacent values. */
for
(
j
=
0
;
j
<
REDIS_HLL_TEST_CYCLES
;
j
++
)
{
/* Set the HLL counters and an array of unsigned byes of the
* same size to the same set of random values. */
...
...
@@ -663,6 +662,36 @@ void pfselftestCommand(redisClient *c) {
}
}
/* Test 2: approximation error.
* The test is adds unique elements and check that the estimated value
* is always reasonable bounds.
*
* We check that the error is smaller than 4 times than the expected
* standard error, to make it very unlikely for the test to fail because
* of a "bad" run. */
memset
(
bitcounters
,
0
,
REDIS_HLL_SIZE
);
double
relerr
=
1
.
04
/
sqrt
(
REDIS_HLL_REGISTERS
);
int64_t
checkpoint
=
1000
;
uint64_t
seed
=
(
uint64_t
)
rand
()
|
(
uint64_t
)
rand
()
<<
32
;
uint64_t
ele
;
for
(
j
=
1
;
j
<=
10000000
;
j
++
)
{
ele
=
j
^
seed
;
hllAdd
((
uint8_t
*
)
bitcounters
,(
unsigned
char
*
)
&
ele
,
sizeof
(
ele
));
if
(
j
==
checkpoint
)
{
int64_t
abserr
=
checkpoint
-
(
int64_t
)
hllCount
((
uint8_t
*
)
bitcounters
);
if
(
abserr
<
0
)
abserr
=
-
abserr
;
if
(
abserr
>
(
uint64_t
)(
relerr
*
4
*
checkpoint
))
{
addReplyErrorFormat
(
c
,
"TESTFAILED Too big error. card:%llu abserr:%llu"
,
(
unsigned
long
long
)
checkpoint
,
(
unsigned
long
long
)
abserr
);
goto
cleanup
;
}
checkpoint
*=
10
;
}
}
/* Success! */
addReply
(
c
,
shared
.
ok
);
...
...
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