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Experiment with using a lag when hashing

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This commit is contained in:
Stella Lau
2017-07-17 18:13:09 -07:00
parent a00e406231
commit fc41a87964
7 changed files with 88 additions and 52 deletions
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contrib/long_distance_matching/circular_buffer_table.c
+8 -12
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@@ -9,7 +9,7 @@
// refactor code to scale the number of elements appropriately.
// Number of elements per hash bucket.
#define HASH_BUCKET_SIZE_LOG 1 // MAX is 4 for now
#define HASH_BUCKET_SIZE_LOG 0 // MAX is 4 for now
#define HASH_BUCKET_SIZE (1 << (HASH_BUCKET_SIZE_LOG))
struct LDM_hashTable {
@@ -19,6 +19,7 @@ struct LDM_hashTable {
// Position corresponding to offset=0 in LDM_hashEntry.
const BYTE *offsetBase;
BYTE *bucketOffsets; // Pointer to current insert position.
// Last insert was at bucketOffsets - 1?
};
@@ -35,15 +36,6 @@ static LDM_hashEntry *getBucket(const LDM_hashTable *table, const hash_t hash) {
return table->entries + (hash << HASH_BUCKET_SIZE_LOG);
}
/*
static LDM_hashEntry *getLastInsertFromHash(const LDM_hashTable *table,
const hash_t hash) {
LDM_hashEntry *bucket = getBucket(table, hash);
BYTE offset = (table->bucketOffsets[hash] - 1) & (HASH_BUCKET_SIZE - 1);
return bucket + offset;
}
*/
LDM_hashEntry *HASH_getValidEntry(const LDM_hashTable *table,
const hash_t hash,
const U32 checksum,
@@ -53,7 +45,12 @@ LDM_hashEntry *HASH_getValidEntry(const LDM_hashTable *table,
LDM_hashEntry *cur = bucket;
// TODO: in order of recency?
for (; cur < bucket + HASH_BUCKET_SIZE; ++cur) {
// CHeck checksum for faster check.
/*
if (cur->checksum == 0 && cur->offset == 0) {
return NULL;
}
*/
// Check checksum for faster check.
if (cur->checksum == checksum &&
(*isValid)(pIn, cur->offset + table->offsetBase)) {
return cur;
@@ -62,7 +59,6 @@ LDM_hashEntry *HASH_getValidEntry(const LDM_hashTable *table,
return NULL;
}
LDM_hashEntry *HASH_getEntryFromHash(const LDM_hashTable *table,
const hash_t hash,
const U32 checksum) {