greg/pcompress
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

Compress Dedup index only if it is at least 90 bytes to avoid expansion.

Browse source 
Some minor cleanup.
This commit is contained in:
Moinak Ghosh 2012-07-22 00:00:41 +05:30
parent b69dcf4d55
commit 962a2cae8a
3 changed files with 21 additions and 10 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

24
main.c
View file

@ -216,10 +216,16 @@ redo:
goto cont; goto cont;
} }
rv = 0;
cmpbuf = cseg + RABIN_HDR_SIZE; cmpbuf = cseg + RABIN_HDR_SIZE;
ubuf = tdat->uncompressed_chunk + RABIN_HDR_SIZE; ubuf = tdat->uncompressed_chunk + RABIN_HDR_SIZE;
rv = lzma_decompress(cmpbuf, rabin_index_sz_cmp, ubuf, &rabin_index_sz, if (rabin_index_sz >= 90) {
tdat->rctx->level, 0, tdat->rctx->lzma_data); /* Index should be at least 90 bytes to have been compressed. */
rv = lzma_decompress(cmpbuf, rabin_index_sz_cmp, ubuf,
&rabin_index_sz, tdat->rctx->level, 0, tdat->rctx->lzma_data);
} else {
memcpy(ubuf, cmpbuf, rabin_index_sz);
}
} else { } else {
rv = tdat->decompress(cseg, tdat->len_cmp, tdat->uncompressed_chunk, rv = tdat->decompress(cseg, tdat->len_cmp, tdat->uncompressed_chunk,
&_chunksize, tdat->level, HDR, tdat->data); &_chunksize, tdat->level, HDR, tdat->data);
@ -630,10 +636,16 @@ redo:
index_size_cmp = rabin_index_sz; index_size_cmp = rabin_index_sz;
memcpy(compressed_chunk, tdat->uncompressed_chunk, RABIN_HDR_SIZE); memcpy(compressed_chunk, tdat->uncompressed_chunk, RABIN_HDR_SIZE);
/* Compress index. */ rv = 0;
rv = lzma_compress(tdat->uncompressed_chunk + RABIN_HDR_SIZE, if (rabin_index_sz >= 90) {
rabin_index_sz, compressed_chunk + RABIN_HDR_SIZE, &index_size_cmp, /* Compress index if it is at least 90 bytes. */
tdat->rctx->level, 0, tdat->rctx->lzma_data); rv = lzma_compress(tdat->uncompressed_chunk + RABIN_HDR_SIZE,
rabin_index_sz, compressed_chunk + RABIN_HDR_SIZE,
&index_size_cmp, tdat->rctx->level, 0, tdat->rctx->lzma_data);
} else {
memcpy(compressed_chunk + RABIN_HDR_SIZE,
tdat->uncompressed_chunk + RABIN_HDR_SIZE, rabin_index_sz);
}
index_size_cmp += RABIN_HDR_SIZE; index_size_cmp += RABIN_HDR_SIZE;
rabin_index_sz += RABIN_HDR_SIZE; rabin_index_sz += RABIN_HDR_SIZE;

1
rabin/rabin_polynomial.c
View file

@ -424,7 +424,6 @@ rabin_dedup(rabin_context_t *ctx, uchar_t *buf, ssize_t *size, ssize_t offset, s
if (blk > 0 && ctx->blocks[blk].refcount == 0 && if (blk > 0 && ctx->blocks[blk].refcount == 0 &&
ctx->blocks[blk].cksum_n_offset == prev_cksum) { ctx->blocks[blk].cksum_n_offset == prev_cksum) {
ssize_t sz1, sz2;
ctx->blocks[blk].index = prev_index; ctx->blocks[blk].index = prev_index;
ctx->blocks[blk].similar = SIMILAR_PARTIAL; ctx->blocks[blk].similar = SIMILAR_PARTIAL;
(ctx->blocks[prev_blk].refcount)++; (ctx->blocks[prev_blk].refcount)++;

6
rabin/rabin_polynomial.h
View file

@ -124,9 +124,9 @@
// Mask to extract value from a rabin index entry // Mask to extract value from a rabin index entry
#define RABIN_INDEX_VALUE (0x3FFFFFFFUL) #define RABIN_INDEX_VALUE (0x3FFFFFFFUL)
// Tolerance for partial similarity check. We expect 80% similarity for /*
// delta compression. See: http://www.armedia.com/wp/SimilarityIndex.pdf * Types of block similarity.
#define SIMILARITY_TOLERANCE (0.2f) */
#define SIMILAR_EXACT 1 #define SIMILAR_EXACT 1
#define SIMILAR_PARTIAL 2 #define SIMILAR_PARTIAL 2