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HLLSELFTEST command implemented.

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To test the bitfield array of counters set/get macros from the Redis Tcl
suite is hard, so a specialized command that is able to test the
internals was developed.
This commit is contained in:
antirez
2014-03-28 12:11:36 +01:00
parent 0609380603
commit 552eb5407a
4 changed files with 53 additions and 8 deletions
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55
src/hyperloglog.c
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@ -53,6 +53,7 @@
#define REDIS_HLL_REGISTERS 16384
#define REDIS_HLL_BITS 6
#define REDIS_HLL_REGISTER_MAX ((1<<REDIS_HLL_BITS)-1)
#define REDIS_HLL_SIZE ((REDIS_HLL_REGISTERS*REDIS_HLL_BITS+7)/8)
/* =========================== Low level bit macros ========================= */
@ -158,18 +159,60 @@
/* Set the value of the register at position 'regnum' to 'val'.
* 'p' is an array of unsigned bytes. */
#define HLL_SET_REGISTER(val,p,regnum) do { \
#define HLL_SET_REGISTER(p,regnum,val) do { \
int _byte = regnum*REDIS_HLL_BITS/8; \
int _leftshift = regnum*REDIS_HLL_BITS&7; \
int _rightshift = 8 - _leftshift; \
unsigned int m1 = 255, m2 = (1<<REDIS_HLL_BITS)-1; \
p[byte] &= m1 << _rightshift; \
p[byte] |= val >> _leftshift; \
p[byte+1] &= ~(m2 << _rightshift); \
p[byte+1] |= val << _rightshift; \
unsigned int m1 = 255, m2 = REDIS_HLL_REGISTER_MAX; \
p[_byte] &= m1 << _rightshift; \
p[_byte] |= val >> _leftshift; \
p[_byte+1] &= ~(m2 << _rightshift); \
p[_byte+1] |= val << _rightshift; \
} while(0)
/* ========================= HyperLogLog algorithm ========================= */
/* ========================== HyperLogLog commands ========================== */
/* 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. */
#define REDIS_HLL_TEST_CYCLES 1000
void hllSelftestCommand(redisClient *c) {
int j, i;
sds bitcounters = sdsnewlen(NULL,REDIS_HLL_SIZE);
uint8_t bytecounters[REDIS_HLL_REGISTERS];
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. */
for (i = 0; i < REDIS_HLL_REGISTERS; i++) {
unsigned int r = rand() & REDIS_HLL_REGISTER_MAX;
bytecounters[i] = r;
HLL_SET_REGISTER(bitcounters,i,r);
}
/* Check that we are able to retrieve the same values. */
for (i = 0; i < REDIS_HLL_REGISTERS; i++) {
unsigned int val;
HLL_GET_REGISTER(val,bitcounters,i);
if (val != bytecounters[i]) {
addReplyErrorFormat(c,
"TESTFAILED Register %d should be %d but is %d",
i, (int) bytecounters[i], (int) val);
goto cleanup;
}
}
}
/* Success! */
addReply(c,shared.ok);
cleanup:
sdsfree(bitcounters);
}