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cuckoo.c
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cuckoo.c
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/*
* Copyright Redis Ltd. 2017 - present
* Licensed under your choice of the Redis Source Available License 2.0 (RSALv2) or
* the Server Side Public License v1 (SSPLv1).
*/
#include "cuckoo.h"
#include <string.h>
#include <stdio.h>
#include <assert.h>
#include <math.h>
/*
#ifndef CUCKOO_MALLOC
#define CUCKOO_MALLOC malloc
#define CUCKOO_CALLOC calloc
#define CUCKOO_REALLOC realloc
#define CUCKOO_FREE free
#endif
*/
// int globalCuckooHash64Bit;
static int CuckooFilter_Grow(CuckooFilter *filter);
static int isPower2(uint64_t num) { return (num & (num - 1)) == 0 && num != 0; }
static uint64_t getNextN2(uint64_t n) {
n--;
n |= n >> 1;
n |= n >> 2;
n |= n >> 4;
n |= n >> 8;
n |= n >> 16;
n |= n >> 32;
n++;
return n;
}
int CuckooFilter_Init(CuckooFilter *filter, uint64_t capacity, uint16_t bucketSize,
uint16_t maxIterations, uint16_t expansion) {
memset(filter, 0, sizeof(*filter));
filter->expansion = getNextN2(expansion);
filter->bucketSize = bucketSize;
filter->maxIterations = maxIterations;
filter->numBuckets = getNextN2(capacity / bucketSize);
if (filter->numBuckets == 0) {
filter->numBuckets = 1;
}
assert(isPower2(filter->numBuckets));
if (CuckooFilter_Grow(filter) != 0) {
return -1; // LCOV_EXCL_LINE memory failure
}
return 0;
}
void CuckooFilter_Free(CuckooFilter *filter) {
for (uint16_t ii = 0; ii < filter->numFilters; ++ii) {
CUCKOO_FREE(filter->filters[ii].data);
}
CUCKOO_FREE(filter->filters);
}
static int CuckooFilter_Grow(CuckooFilter *filter) {
SubCF *filtersArray =
CUCKOO_REALLOC(filter->filters, sizeof(*filtersArray) * (filter->numFilters + 1));
if (!filtersArray) {
return -1; // LCOV_EXCL_LINE memory failure
}
SubCF *currentFilter = filtersArray + filter->numFilters;
size_t growth = pow(filter->expansion, filter->numFilters);
currentFilter->bucketSize = filter->bucketSize;
currentFilter->numBuckets = filter->numBuckets * growth;
currentFilter->data =
CUCKOO_CALLOC((size_t)currentFilter->numBuckets * filter->bucketSize, sizeof(CuckooBucket));
if (!currentFilter->data) {
return -1; // LCOV_EXCL_LINE memory failure
}
filter->numFilters++;
filter->filters = filtersArray;
return 0;
}
typedef struct {
CuckooHash h1;
CuckooHash h2;
CuckooFingerprint fp;
} LookupParams;
static CuckooHash getAltHash(CuckooFingerprint fp, CuckooHash index) {
return ((CuckooHash)(index ^ ((CuckooHash)fp * 0x5bd1e995)));
}
static void getLookupParams(CuckooHash hash, LookupParams *params) {
params->fp = hash % 255 + 1;
params->h1 = hash;
params->h2 = getAltHash(params->fp, params->h1);
// assert(getAltHash(params->fp, params->h2, numBuckets) == params->h1);
}
static uint32_t SubCF_GetIndex(const SubCF *subCF, CuckooHash hash) {
return (hash % subCF->numBuckets) * subCF->bucketSize;
}
static uint8_t *Bucket_Find(CuckooBucket bucket, uint16_t bucketSize, CuckooFingerprint fp) {
for (uint16_t ii = 0; ii < bucketSize; ++ii) {
if (bucket[ii] == fp) {
return bucket + ii;
}
}
return NULL;
}
static int Filter_Find(const SubCF *filter, const LookupParams *params) {
uint8_t bucketSize = filter->bucketSize;
uint64_t loc1 = SubCF_GetIndex(filter, params->h1);
uint64_t loc2 = SubCF_GetIndex(filter, params->h2);
return Bucket_Find(&filter->data[loc1], bucketSize, params->fp) != NULL ||
Bucket_Find(&filter->data[loc2], bucketSize, params->fp) != NULL;
}
static int Bucket_Delete(CuckooBucket bucket, uint16_t bucketSize, CuckooFingerprint fp) {
for (uint16_t ii = 0; ii < bucketSize; ii++) {
if (bucket[ii] == fp) {
bucket[ii] = CUCKOO_NULLFP;
return 1;
}
}
return 0;
}
static int Filter_Delete(const SubCF *filter, const LookupParams *params) {
uint8_t bucketSize = filter->bucketSize;
uint64_t loc1 = SubCF_GetIndex(filter, params->h1);
uint64_t loc2 = SubCF_GetIndex(filter, params->h2);
return Bucket_Delete(&filter->data[loc1], bucketSize, params->fp) ||
Bucket_Delete(&filter->data[loc2], bucketSize, params->fp);
}
static int CuckooFilter_CheckFP(const CuckooFilter *filter, const LookupParams *params) {
for (uint16_t ii = 0; ii < filter->numFilters; ++ii) {
if (Filter_Find(&filter->filters[ii], params)) {
return 1;
}
}
return 0;
}
int CuckooFilter_Check(const CuckooFilter *filter, CuckooHash hash) {
LookupParams params;
getLookupParams(hash, ¶ms);
return CuckooFilter_CheckFP(filter, ¶ms);
}
static uint16_t bucketCount(const CuckooBucket bucket, uint16_t bucketSize, CuckooFingerprint fp) {
uint16_t ret = 0;
for (uint16_t ii = 0; ii < bucketSize; ++ii) {
if (bucket[ii] == fp) {
ret++;
}
}
return ret;
}
static uint64_t subFilterCount(const SubCF *filter, const LookupParams *params) {
uint8_t bucketSize = filter->bucketSize;
uint64_t loc1 = SubCF_GetIndex(filter, params->h1);
uint64_t loc2 = SubCF_GetIndex(filter, params->h2);
return bucketCount(&filter->data[loc1], bucketSize, params->fp) +
bucketCount(&filter->data[loc2], bucketSize, params->fp);
}
uint64_t CuckooFilter_Count(const CuckooFilter *filter, CuckooHash hash) {
LookupParams params;
getLookupParams(hash, ¶ms);
uint64_t ret = 0;
for (uint16_t ii = 0; ii < filter->numFilters; ++ii) {
ret += subFilterCount(&filter->filters[ii], ¶ms);
}
return ret;
}
int CuckooFilter_Delete(CuckooFilter *filter, CuckooHash hash) {
LookupParams params;
getLookupParams(hash, ¶ms);
for (uint16_t ii = filter->numFilters; ii > 0; --ii) {
if (Filter_Delete(&filter->filters[ii - 1], ¶ms)) {
filter->numItems--;
filter->numDeletes++;
if (filter->numFilters > 1 && filter->numDeletes > (double)filter->numItems * 0.10) {
CuckooFilter_Compact(filter, false);
}
return 1;
}
}
return 0;
}
static uint8_t *Bucket_FindAvailable(CuckooBucket bucket, uint16_t bucketSize) {
for (uint16_t ii = 0; ii < bucketSize; ++ii) {
if (bucket[ii] == CUCKOO_NULLFP) {
return &bucket[ii];
}
}
return NULL;
}
static uint8_t *Filter_FindAvailable(SubCF *filter, const LookupParams *params) {
uint8_t *slot;
uint8_t bucketSize = filter->bucketSize;
uint64_t loc1 = SubCF_GetIndex(filter, params->h1);
uint64_t loc2 = SubCF_GetIndex(filter, params->h2);
if ((slot = Bucket_FindAvailable(&filter->data[loc1], bucketSize)) ||
(slot = Bucket_FindAvailable(&filter->data[loc2], bucketSize))) {
return slot;
}
return NULL;
}
static CuckooInsertStatus Filter_KOInsert(CuckooFilter *filter, SubCF *curFilter,
const LookupParams *params);
static CuckooInsertStatus CuckooFilter_InsertFP(CuckooFilter *filter, const LookupParams *params) {
for (uint16_t ii = filter->numFilters; ii > 0; --ii) {
uint8_t *slot = Filter_FindAvailable(&filter->filters[ii - 1], params);
if (slot) {
*slot = params->fp;
filter->numItems++;
return CuckooInsert_Inserted;
}
}
// No space. Time to evict!
CuckooInsertStatus status =
Filter_KOInsert(filter, &filter->filters[filter->numFilters - 1], params);
if (status == CuckooInsert_Inserted) {
filter->numItems++;
return CuckooInsert_Inserted;
}
if (filter->expansion == 0) {
return CuckooInsert_NoSpace;
}
if (CuckooFilter_Grow(filter) != 0) {
return CuckooInsert_MemAllocFailed;
}
// Try to insert the filter again
return CuckooFilter_InsertFP(filter, params);
}
CuckooInsertStatus CuckooFilter_Insert(CuckooFilter *filter, CuckooHash hash) {
LookupParams params;
getLookupParams(hash, ¶ms);
return CuckooFilter_InsertFP(filter, ¶ms);
}
CuckooInsertStatus CuckooFilter_InsertUnique(CuckooFilter *filter, CuckooHash hash) {
LookupParams params;
getLookupParams(hash, ¶ms);
if (CuckooFilter_CheckFP(filter, ¶ms)) {
return CuckooInsert_Exists;
}
return CuckooFilter_InsertFP(filter, ¶ms);
}
static void swapFPs(uint8_t *a, uint8_t *b) {
uint8_t temp = *a;
*a = *b;
*b = temp;
}
static CuckooInsertStatus Filter_KOInsert(CuckooFilter *filter, SubCF *curFilter,
const LookupParams *params) {
uint16_t maxIterations = filter->maxIterations;
uint32_t numBuckets = curFilter->numBuckets;
uint16_t bucketSize = filter->bucketSize;
CuckooFingerprint fp = params->fp;
uint16_t counter = 0;
uint32_t victimIx = 0;
uint32_t ii = params->h1 % numBuckets;
while (counter++ < maxIterations) {
uint8_t *bucket = &curFilter->data[ii * bucketSize];
swapFPs(bucket + victimIx, &fp);
ii = getAltHash(fp, ii) % numBuckets;
// Insert the new item in potentially the same bucket
uint8_t *empty = Bucket_FindAvailable(&curFilter->data[ii * bucketSize], bucketSize);
if (empty) {
// printf("Found slot. Bucket[%lu], Pos=%lu\n", ii, empty - curFilter[ii]);
// printf("Old FP Value: %d\n", *empty);
// printf("Setting FP: %p\n", empty);
*empty = fp;
return CuckooInsert_Inserted;
}
victimIx = (victimIx + 1) % bucketSize;
}
// If we weren't able to insert, we roll back and try to insert new element in new filter
counter = 0;
while (counter++ < maxIterations) {
victimIx = (victimIx + bucketSize - 1) % bucketSize;
ii = getAltHash(fp, ii) % numBuckets;
uint8_t *bucket = &curFilter->data[ii * bucketSize];
swapFPs(bucket + victimIx, &fp);
}
return CuckooInsert_NoSpace;
}
#define RELOC_EMPTY 0
#define RELOC_OK 1
#define RELOC_FAIL -1
/**
* Attempt to move a slot from one bucket to another filter
*/
static int relocateSlot(CuckooFilter *cf, CuckooBucket bucket, uint16_t filterIx, uint64_t bucketIx,
uint16_t slotIx) {
LookupParams params = {0};
if ((params.fp = bucket[slotIx]) == CUCKOO_NULLFP) {
// Nothing in this slot.
return RELOC_EMPTY;
}
// Because We try to insert in sub filter with less or equal number of
// buckets, our current fingerprint is sufficient
params.h1 = bucketIx;
params.h2 = getAltHash(params.fp, bucketIx);
// Look at all the prior filters and attempt to find a home
for (uint16_t ii = 0; ii < filterIx; ++ii) {
uint8_t *slot = Filter_FindAvailable(&cf->filters[ii], ¶ms);
if (slot) {
*slot = params.fp;
bucket[slotIx] = CUCKOO_NULLFP;
return RELOC_OK;
}
}
return RELOC_FAIL;
}
/**
* Attempt to strip a single filter moving it down a slot
*/
static uint64_t CuckooFilter_CompactSingle(CuckooFilter *cf, uint16_t filterIx) {
SubCF *currentFilter = &cf->filters[filterIx];
MyCuckooBucket *filter = currentFilter->data;
int rv = RELOC_OK;
for (uint64_t bucketIx = 0; bucketIx < currentFilter->numBuckets; ++bucketIx) {
for (uint16_t slotIx = 0; slotIx < currentFilter->bucketSize; ++slotIx) {
int status = relocateSlot(cf, &filter[bucketIx * currentFilter->bucketSize], filterIx,
bucketIx, slotIx);
if (status == RELOC_FAIL) {
rv = RELOC_FAIL;
}
}
}
// we free a filter only if it the latest one
if (rv == RELOC_OK && filterIx == cf->numFilters - 1) {
CUCKOO_FREE(filter);
cf->numFilters--;
}
return rv;
}
/**
* Attempt to move elements to older filters. If latest filter is emptied, it is freed.
* `bool` determines whether to continue iteration on other filters once a filter cannot
* be freed and therefore following filter cannot be freed either.
*/
void CuckooFilter_Compact(CuckooFilter *cf, bool cont) {
for (uint64_t ii = cf->numFilters; ii > 1; --ii) {
if (CuckooFilter_CompactSingle(cf, ii - 1) == RELOC_FAIL && !cont) {
// if compacting failed, stop as lower filters cannot be freed.
break;
}
}
cf->numDeletes = 0;
}
/* CF.DEBUG uses another function
void CuckooFilter_GetInfo(const CuckooFilter *cf, CuckooHash hash, CuckooKey *out) {
LookupParams params;
getLookupParams(hash, cf->numBuckets, ¶ms);
out->fp = params.fp;
out->h1 = params.h1;
out->h2 = params.h2;
assert(getAltHash(params.fp, out->h1, cf->numBuckets) == out->h2);
assert(getAltHash(params.fp, out->h2, cf->numBuckets) == out->h1);
}*/
// Returns 0 on success
int CuckooFilter_ValidateIntegrity(const CuckooFilter *cf) {
if (cf->bucketSize == 0 || cf->bucketSize > CF_MAX_BUCKET_SIZE ||
cf->numBuckets == 0 || cf->numBuckets > CF_MAX_NUM_BUCKETS ||
cf->numFilters == 0 || cf->numFilters > CF_MAX_NUM_FILTERS ||
cf->maxIterations == 0 || !isPower2(cf->numBuckets) ) {
return 1;
}
return 0;
}