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pcompress/rabin/rabin_dedup.c
Moinak Ghosh e6f042aaf8 Allow user-specified minimum Dedupe block size. 
Compute similarity sketch only if Delta Compression enabled.
2012-09-05 22:43:54 +05:30

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/*
* The rabin polynomial computation is derived from:
* http://code.google.com/p/rabin-fingerprint-c/
*
* originally created by Joel Lawrence Tucci on 09-March-2011.
*
* Rabin polynomial portions Copyright (c) 2011 Joel Lawrence Tucci
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* Neither the name of the project's author nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
/*
* This file is a part of Pcompress, a chunked parallel multi-
* algorithm lossless compression and decompression program.
*
* Copyright (C) 2012 Moinak Ghosh. All rights reserved.
* Use is subject to license terms.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 3 of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* moinakg@belenix.org, http://moinakg.wordpress.com/
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <allocator.h>
#include <utils.h>
#include <pthread.h>
#include "rabin_dedup.h"
extern int lzma_init(void **data, int *level, ssize_t chunksize);
extern int lzma_compress(void *src, size_t srclen, void *dst,
size_t *destlen, int level, uchar_t chdr, void *data);
extern int lzma_decompress(void *src, size_t srclen, void *dst,
size_t *dstlen, int level, uchar_t chdr, void *data);
extern int lzma_deinit(void **data);
extern int bsdiff(u_char *old, bsize_t oldsize, u_char *new, bsize_t newsize,
u_char *diff, u_char *scratch, bsize_t scratchsize);
extern bsize_t get_bsdiff_sz(u_char *pbuf);
extern int bspatch(u_char *pbuf, u_char *old, bsize_t oldsize, u_char *new,
bsize_t *_newsize);
static pthread_mutex_t init_lock = PTHREAD_MUTEX_INITIALIZER;
uint64_t ir[256];
static int inited = 0;
static uint32_t
rabin_min_blksz(uint64_t chunksize, int rab_blk_sz, const char *algo, int delta_flag)
{
uint32_t min_blk;
min_blk = 1 << (rab_blk_sz + RAB_BLK_MIN_BITS);
if (rab_blk_sz > 1)
return (min_blk);
if (((memcmp(algo, "lzma", 4) == 0 || memcmp(algo, "adapt", 5) == 0) &&
chunksize <= LZMA_WINDOW_MAX) || delta_flag) {
if (memcmp(algo, "lzfx", 4) == 0 || memcmp(algo, "lz4", 3) == 0 ||
memcmp(algo, "zlib", 4) == 0 || memcmp(algo, "none", 4) == 0) {
min_blk = 1 << (rab_blk_sz + RAB_BLK_MIN_BITS - 1);
}
} else {
min_blk = 1 << (rab_blk_sz + RAB_BLK_MIN_BITS - 1);
}
return (min_blk);
}
uint32_t
rabin_buf_extra(uint64_t chunksize, int rab_blk_sz, const char *algo, int delta_flag)
{
if (rab_blk_sz < 1 || rab_blk_sz > 5)
rab_blk_sz = RAB_BLK_DEFAULT;
return ((chunksize / rabin_min_blksz(chunksize, rab_blk_sz, algo, delta_flag))
* sizeof (uint32_t));
}
/*
* Initialize the algorithm with the default params.
*/
rabin_context_t *
create_rabin_context(uint64_t chunksize, uint64_t real_chunksize, int rab_blk_sz,
const char *algo, int delta_flag) {
rabin_context_t *ctx;
unsigned char *current_window_data;
uint32_t i;
if (rab_blk_sz < 1 || rab_blk_sz > 5)
rab_blk_sz = RAB_BLK_DEFAULT;
/*
* Pre-compute a table of irreducible polynomial evaluations for each
* possible byte value.
*/
pthread_mutex_lock(&init_lock);
if (!inited) {
int term, j;
uint64_t val;
for (j = 0; j < 256; j++) {
term = 1;
val = 0;
for (i=0; i<RAB_POLYNOMIAL_WIN_SIZE; i++) {
if (term & FP_POLY) {
val = (val << 1) + j;
}
term <<= 1;
}
ir[j] = val;
}
inited = 1;
}
pthread_mutex_unlock(&init_lock);
/*
* Rabin window size must be power of 2 for optimization.
*/
if (!ISP2(RAB_POLYNOMIAL_WIN_SIZE)) {
fprintf(stderr, "Rabin window size must be a power of 2 in range 4 <= x <= 64\n");
return (NULL);
}
if (chunksize < RAB_MIN_CHUNK_SIZE) {
fprintf(stderr, "Minimum chunk size for Dedup must be %llu bytes\n",
RAB_MIN_CHUNK_SIZE);
return (NULL);
}
/*
* For LZMA with chunksize <= LZMA Window size and/or Delta enabled we
* use 4K minimum Rabin block size. For everything else it is 2K based
* on experimentation.
*/
ctx = (rabin_context_t *)slab_alloc(NULL, sizeof (rabin_context_t));
ctx->rabin_poly_max_block_size = RAB_POLYNOMIAL_MAX_BLOCK_SIZE;
ctx->rabin_break_patt = 0;
ctx->delta_flag = delta_flag;
ctx->rabin_poly_avg_block_size = 1 << (rab_blk_sz + RAB_BLK_MIN_BITS);
ctx->rabin_avg_block_mask = ctx->rabin_poly_avg_block_size - 1;
ctx->rabin_poly_min_block_size = rabin_min_blksz(chunksize, rab_blk_sz, algo, delta_flag);
ctx->fp_mask = ctx->rabin_avg_block_mask | ctx->rabin_poly_avg_block_size;
ctx->blknum = chunksize / ctx->rabin_poly_min_block_size;
if (chunksize % ctx->rabin_poly_min_block_size)
ctx->blknum++;
if (ctx->blknum > RABIN_MAX_BLOCKS) {
fprintf(stderr, "Chunk size too large for dedup.\n");
destroy_rabin_context(ctx);
return (NULL);
}
current_window_data = slab_alloc(NULL, RAB_POLYNOMIAL_WIN_SIZE);
ctx->blocks = NULL;
if (real_chunksize > 0) {
ctx->blocks = (rabin_blockentry_t **)slab_calloc(NULL,
ctx->blknum, sizeof (rabin_blockentry_t *));
}
if(ctx == NULL || current_window_data == NULL || (ctx->blocks == NULL && real_chunksize > 0)) {
fprintf(stderr,
"Could not allocate rabin polynomial context, out of memory\n");
destroy_rabin_context(ctx);
return (NULL);
}
ctx->lzma_data = NULL;
ctx->level = 14;
if (real_chunksize > 0) {
lzma_init(&(ctx->lzma_data), &(ctx->level), chunksize);
if (!(ctx->lzma_data)) {
fprintf(stderr,
"Could not initialize LZMA data for rabin index, out of memory\n");
destroy_rabin_context(ctx);
return (NULL);
}
}
/*
* We should compute the power for the window size.
* static uint64_t polynomial_pow;
* polynomial_pow = 1;
* for(index=0; index<RAB_POLYNOMIAL_WIN_SIZE; index++) {
* polynomial_pow *= RAB_POLYNOMIAL_CONST;
* }
* But since RAB_POLYNOMIAL_CONST == 2, any expression of the form
* x * polynomial_pow can we written as x << RAB_POLYNOMIAL_WIN_SIZE
*/
slab_cache_add(sizeof (rabin_blockentry_t));
ctx->current_window_data = current_window_data;
ctx->real_chunksize = real_chunksize;
reset_rabin_context(ctx);
return (ctx);
}
void
reset_rabin_context(rabin_context_t *ctx)
{
memset(ctx->current_window_data, 0, RAB_POLYNOMIAL_WIN_SIZE);
ctx->window_pos = 0;
}
void
destroy_rabin_context(rabin_context_t *ctx)
{
if (ctx) {
uint32_t i;
if (ctx->current_window_data) slab_free(NULL, ctx->current_window_data);
if (ctx->blocks) {
for (i=0; i<ctx->blknum && ctx->blocks[i] != NULL; i++) {
slab_free(NULL, ctx->blocks[i]);
}
slab_free(NULL, ctx->blocks);
}
if (ctx->lzma_data) lzma_deinit(&(ctx->lzma_data));
slab_free(NULL, ctx);
}
}
/*
* Checksum Comparator for qsort
*/
static int
cmpblks(const void *a, const void *b)
{
rabin_blockentry_t *a1 = *((rabin_blockentry_t **)a);
rabin_blockentry_t *b1 = *((rabin_blockentry_t **)b);
if (a1->cksum_n_offset < b1->cksum_n_offset) {
return (-1);
} else if (a1->cksum_n_offset == b1->cksum_n_offset) {
int l1 = a1->length;
int l2 = b1->length;
/*
* If fingerprints match then compare lengths. Length match makes
* for strong exact detection/ordering during sort while stopping
* short of expensive memcmp() during sorting.
*
* Even though rabin_blockentry_t->length is unsigned we use signed
* int here to avoid branches. In practice a rabin block size at
* this point varies from 2K to 128K. The length is unsigned in
* order to support non-duplicate block merging and large blocks
* after this point.
*/
return (l1 - l2);
} else {
return (1);
}
}
/**
* Perform Deduplication based on Rabin Fingerprinting. A 31-byte window is used for
* the rolling checksum and dedup blocks vary in size from 4K-128K.
*/
uint32_t
rabin_dedup(rabin_context_t *ctx, uchar_t *buf, ssize_t *size, ssize_t offset, ssize_t *rabin_pos)
{
ssize_t i, last_offset, j, fplist_sz;
uint32_t blknum;
char *buf1 = (char *)buf;
uint32_t length;
uint64_t cur_roll_checksum, cur_pos_checksum, cur_sketch;
uint64_t *fplist;
uint32_t len1, fpos[2], cur_sketch2;
uint32_t *charcounts, byts;
if (rabin_pos == NULL) {
/*
* Initialize arrays for sketch computation. We re-use memory allocated
* for the compressed chunk temporarily.
*/
fplist_sz = 8 * ctx->rabin_poly_avg_block_size;
fplist = (uint64_t *)(ctx->cbuf + ctx->real_chunksize - fplist_sz - 256 * 4);
charcounts = (uint32_t *)(ctx->cbuf + ctx->real_chunksize - 256 * 4);
memset(fplist, 0, fplist_sz);
memset(charcounts, 0, 256 * 4);
fpos[0] = 0;
fpos[1] = 0;
len1 = 0;
}
length = offset;
last_offset = 0;
blknum = 0;
ctx->valid = 0;
cur_roll_checksum = 0;
j = 0;
cur_sketch = 0;
cur_sketch2 = 0;
/*
* If rabin_pos is non-zero then we are being asked to scan for the last rabin boundary
* in the chunk. We start scanning at chunk end - max rabin block size. We avoid doing
* a full chunk scan.
*
* !!!NOTE!!!: Code duplication below for performance.
*/
if (rabin_pos) {
offset = *size - ctx->rabin_poly_max_block_size;
length = 0;
for (i=offset; i<*size; i++) {
uchar_t cur_byte = buf1[i];
uint64_t pushed_out = ctx->current_window_data[ctx->window_pos];
ctx->current_window_data[ctx->window_pos] = cur_byte;
cur_roll_checksum = (cur_roll_checksum << 1) + cur_byte;
cur_roll_checksum -= (pushed_out << RAB_POLYNOMIAL_WIN_SIZE);
cur_pos_checksum = cur_roll_checksum ^ ir[pushed_out];
ctx->window_pos = (ctx->window_pos + 1) & (RAB_POLYNOMIAL_WIN_SIZE-1);
length++;
if (length < ctx->rabin_poly_min_block_size) continue;
// If we hit our special value update block offset
if ((cur_pos_checksum & ctx->rabin_avg_block_mask) == ctx->rabin_break_patt) {
last_offset = i;
length = 0;
}
}
if (last_offset < *size) {
*rabin_pos = last_offset;
}
return (0);
}
if (*size < ctx->rabin_poly_avg_block_size) return;
for (i=offset; i<*size; i++) {
uint32_t *splits;
uchar_t cur_byte = buf1[i];
uint64_t pushed_out = ctx->current_window_data[ctx->window_pos];
ctx->current_window_data[ctx->window_pos] = cur_byte;
/*
* We want to do:
* cur_roll_checksum = cur_roll_checksum * RAB_POLYNOMIAL_CONST + cur_byte;
* cur_roll_checksum -= pushed_out * polynomial_pow;
*
* However since RAB_POLYNOMIAL_CONST == 2, we use shifts.
*/
cur_roll_checksum = (cur_roll_checksum << 1) + cur_byte;
cur_roll_checksum -= (pushed_out << RAB_POLYNOMIAL_WIN_SIZE);
cur_pos_checksum = cur_roll_checksum ^ ir[pushed_out];
/*
* Compute a super sketch value of the block. We store a sum of relative
* maximal rabin hash values per 1K(SKETCH_BASIC_BLOCK_SZ) of data. So we
* get upto 128 sums for a max block size of 128K. The bottom blocksize bits
* of the hash are only used which are then biased with the occurrence count.
* This is a representative fingerprint sketch of the block. Storing and
* comparing upto 128 fingerprints per block is very expensive (compute & RAM)
* so we eventually sum all the fingerprints for the block to create a single
* super sketch value representing maximal features of the block. In addition
* the top 2 commonly occuring byte values are used to compute a second sketch
* to refine the earlier one.
*
* This value can be used for similarity detection for delta encoding. Exact
* match for deduplication is additionally detected via a memcmp(). This is a
* variant of some approaches detailed in:
* http://www.armedia.com/wp/SimilarityIndex.pdf
*/
len1++;
fpos[1] = cur_pos_checksum & ctx->rabin_avg_block_mask;
splits = (uint32_t *)(&fplist[fpos[1]]);
#if BYTE_ORDER == BIG_ENDIAN
splits[0]++;
splits[1] += cur_pos_checksum & ctx->fp_mask;
#else
splits[1]++;
splits[0] += cur_pos_checksum & ctx->fp_mask;
#endif
charcounts[cur_byte]++;
/*
* Perform the following statement without branching:
* if (fplist[fpos[1]] > fplist[fpos[0]]) fpos[0] = fpos[1];
*/
fpos[0] = fpos[(fplist[fpos[1]] > fplist[fpos[0]])];
if (len1 == SKETCH_BASIC_BLOCK_SZ && ctx->delta_flag) {
uint32_t p1, p2, p3;
/*
* Compute the super sketch value by summing all the representative
* fingerprints of the block.
*/
cur_sketch += fplist[fpos[0]];
memset(fplist, 0, fplist_sz);
fpos[0] = 0;
/*
* Find out the top 2 occurring byte values and compute
* a secondary sketch from them.
*/
p1 = 0;
p2 = 0;
p3 = 0;
for (len1=0; len1<256; len1++) {
if (charcounts[len1] > p1) {
p3 = p2;
p2 = p1;
p1 = len1;
}
charcounts[len1] = 0;
}
cur_sketch2 += ((p1 << 16) | (p2 << 8) | p3);
len1 = 0;
j++;
}
/*
* Window pos has to rotate from 0 .. RAB_POLYNOMIAL_WIN_SIZE-1
* We avoid a branch here by masking. This requires RAB_POLYNOMIAL_WIN_SIZE
* to be power of 2
*/
ctx->window_pos = (ctx->window_pos + 1) & (RAB_POLYNOMIAL_WIN_SIZE-1);
length++;
if (length < ctx->rabin_poly_min_block_size) continue;
// If we hit our special value or reached the max block size update block offset
if ((cur_pos_checksum & ctx->rabin_avg_block_mask) == ctx->rabin_break_patt ||
length >= ctx->rabin_poly_max_block_size) {
if (ctx->blocks[blknum] == 0)
ctx->blocks[blknum] = (rabin_blockentry_t *)slab_alloc(NULL, sizeof (rabin_blockentry_t));
ctx->blocks[blknum]->offset = last_offset;
ctx->blocks[blknum]->index = blknum; // Need to store for sorting
ctx->blocks[blknum]->length = length;
ctx->blocks[blknum]->ref = 0;
ctx->blocks[blknum]->similar = 0;
ctx->blocks[blknum]->crc = XXH_strong32(buf1+last_offset, length, 0);
// Accumulate the 2 sketch values into a combined similarity checksum
if (ctx->delta_flag) {
ctx->blocks[blknum]->cksum_n_offset = (cur_sketch + cur_sketch2) / 2;
ctx->blocks[blknum]->mean_n_length = cur_sketch / j;
memset(fplist, 0, fplist_sz);
} else {
ctx->blocks[blknum]->cksum_n_offset = 0;
ctx->blocks[blknum]->mean_n_length = 0;
}
fpos[0] = 0;
len1 = 0;
cur_sketch = 0;
blknum++;
last_offset = i+1;
length = 0;
j = 0;
cur_sketch2 = 0;
}
}
DEBUG_STAT_EN(printf("Original size: %lld, blknum: %u\n", *size, blknum));
// If we found at least a few chunks, perform dedup.
if (blknum > 2) {
uint32_t blk, prev_index, prev_length;
ssize_t pos, matchlen, pos1;
int valid = 1;
char *tmp;
uint32_t *blkarr, *trans, *rabin_index;
ssize_t rabin_index_sz;
rabin_blockentry_t *prev;
DEBUG_STAT_EN(uint32_t delta_calls, delta_fails);
DEBUG_STAT_EN(delta_calls = 0);
DEBUG_STAT_EN(delta_fails = 0);
// Insert the last left-over trailing bytes, if any, into a block.
if (last_offset < *size) {
if (ctx->blocks[blknum] == 0)
ctx->blocks[blknum] = (rabin_blockentry_t *)slab_alloc(NULL, sizeof (rabin_blockentry_t));
ctx->blocks[blknum]->offset = last_offset;
ctx->blocks[blknum]->index = blknum;
ctx->blocks[blknum]->length = *size - last_offset;
ctx->blocks[blknum]->ref = 0;
ctx->blocks[blknum]->similar = 0;
if (ctx->delta_flag) {
j = (j > 0 ? j:1);
ctx->blocks[blknum]->cksum_n_offset = (cur_sketch + cur_sketch2) / 2;
ctx->blocks[blknum]->mean_n_length = cur_sketch / j;
} else {
ctx->blocks[blknum]->cksum_n_offset = 0;
ctx->blocks[blknum]->mean_n_length = 0;
}
ctx->blocks[blknum]->crc = XXH_strong32(buf1+last_offset, ctx->blocks[blknum]->length, 0);
blknum++;
last_offset = *size;
}
rabin_index_sz = (ssize_t)blknum * RABIN_ENTRY_SIZE;
/*
* Now sort the block array based on checksums. This will bring virtually
* all similar block entries together. Effectiveness depends on how strong
* our checksum is. We are using a maximal super-sketch value.
*/
qsort(ctx->blocks, blknum, sizeof (rabin_blockentry_t *), cmpblks);
rabin_index = (uint32_t *)(ctx->cbuf + RABIN_HDR_SIZE);
/*
* We need 2 temporary arrays. We just use available space in the last
* portion of the buffer that will hold the deduped segment.
*/
blkarr = (uint32_t *)(ctx->cbuf + ctx->real_chunksize - (rabin_index_sz * 2 + 1));
trans = (uint32_t *)(ctx->cbuf + ctx->real_chunksize - (rabin_index_sz + 1));
matchlen = 0;
/*
* Now make a pass through the sorted block array making identical blocks
* point to the first identical block entry. A simple Run Length Encoding
* sort of. Checksums, length and contents (memcmp()) must match for blocks
* to be considered identical.
* The block index in the chunk is initialized with pointers into the
* sorted block array.
* A reference count is maintained for blocks that are similar with other
* blocks. This helps in non-duplicate block merging later.
*/
for (blk = 0; blk < blknum; blk++) {
blkarr[ctx->blocks[blk]->index] = blk;
if (blk > 0 && ctx->blocks[blk]->cksum_n_offset == prev->cksum_n_offset &&
ctx->blocks[blk]->length == prev->length &&
ctx->blocks[blk]->crc == prev->crc &&
memcmp(buf1 + prev->offset, buf1 + ctx->blocks[blk]->offset,
prev->length) == 0)
{
ctx->blocks[blk]->similar = SIMILAR_EXACT;
ctx->blocks[blk]->index = prev->index;
prev->ref = 1;
matchlen += prev->length;
continue;
}
prev = ctx->blocks[blk];
}
prev = NULL;
if (ctx->delta_flag) {
for (blk = 0; blk < blknum; blk++) {
if (ctx->blocks[blk]->similar) continue;
/*
* Compare blocks for similarity.
* Note: Block list by now is sorted by length as well.
*/
if (prev != NULL && ctx->blocks[blk]->ref == 0 &&
ctx->blocks[blk]->cksum_n_offset == prev->cksum_n_offset &&
ctx->blocks[blk]->length - prev->length < 512 &&
ctx->blocks[blk]->mean_n_length == prev->mean_n_length
) {
ctx->blocks[blk]->index = prev->index;
ctx->blocks[blk]->similar = SIMILAR_PARTIAL;
prev->ref = 1;
matchlen += (prev->length>>1);
continue;
}
prev = ctx->blocks[blk];
}
}
if (matchlen < rabin_index_sz) {
ctx->valid = 0;
return;
}
/*
* Another pass, this time through the block index in the chunk. We insert
* block length into unique block entries. For block entries that are
* identical with another one we store the index number with msb set.
* This way we can differentiate between a unique block length entry and a
* pointer to another block without needing a separate flag.
*/
prev_index = 0;
prev_length = 0;
pos = 0;
for (blk = 0; blk < blknum; blk++) {
rabin_blockentry_t *be;
be = ctx->blocks[blkarr[blk]];
if (be->similar == 0) {
/*
* Update Index entry with the length. Also try to merge runs
* of unique (non-duplicate/similar) blocks into a single block
* entry as long as the total length does not exceed max block
* size.
*/
if (prev_index == 0) {
if (be->ref == 0) {
prev_index = pos;
prev_length = be->length;
}
rabin_index[pos] = be->length;
ctx->blocks[pos]->cksum_n_offset = be->offset;
trans[blk] = pos;
pos++;
} else {
if (be->ref > 0) {
prev_index = 0;
prev_length = 0;
rabin_index[pos] = be->length;
ctx->blocks[pos]->cksum_n_offset = be->offset;
trans[blk] = pos;
pos++;
} else {
if (prev_length + be->length <= RABIN_MAX_BLOCK_SIZE) {
prev_length += be->length;
rabin_index[prev_index] = prev_length;
} else {
prev_index = 0;
prev_length = 0;
rabin_index[pos] = be->length;
ctx->blocks[pos]->cksum_n_offset = be->offset;
trans[blk] = pos;
pos++;
}
}
}
} else {
prev_index = 0;
prev_length = 0;
ctx->blocks[pos]->cksum_n_offset = be->offset;
ctx->blocks[pos]->mean_n_length = be->length;
trans[blk] = pos;
if (be->similar == SIMILAR_EXACT) {
rabin_index[pos] = (blkarr[be->index] | RABIN_INDEX_FLAG) &
CLEAR_SIMILARITY_FLAG;
} else {
rabin_index[pos] = blkarr[be->index] | RABIN_INDEX_FLAG |
SET_SIMILARITY_FLAG;
}
pos++;
}
}
/*
* Final pass, copy the data and perform delta encoding.
*/
blknum = pos;
rabin_index_sz = (ssize_t)pos * RABIN_ENTRY_SIZE;
pos1 = rabin_index_sz + RABIN_HDR_SIZE;
for (blk = 0; blk < blknum; blk++) {
uchar_t *old, *new;
int32_t bsz;
/*
* If blocks are overflowing the allowed chunk size then dedup did not
* help at all. We invalidate the dedup operation.
*/
if (pos1 > last_offset) {
valid = 0;
break;
}
if (rabin_index[blk] & RABIN_INDEX_FLAG) {
j = rabin_index[blk] & RABIN_INDEX_VALUE;
i = ctx->blocks[j]->index;
if (rabin_index[blk] & GET_SIMILARITY_FLAG) {
old = buf1 + ctx->blocks[j]->offset;
new = buf1 + ctx->blocks[blk]->cksum_n_offset;
matchlen = ctx->real_chunksize - *size;
DEBUG_STAT_EN(delta_calls++);
bsz = bsdiff(old, ctx->blocks[j]->length, new,
ctx->blocks[blk]->mean_n_length, ctx->cbuf + pos1,
buf1 + *size, matchlen);
if (bsz == 0) {
DEBUG_STAT_EN(delta_fails++);
memcpy(ctx->cbuf + pos1, new, ctx->blocks[blk]->mean_n_length);
rabin_index[blk] = htonl(ctx->blocks[blk]->mean_n_length);
pos1 += ctx->blocks[blk]->mean_n_length;
} else {
rabin_index[blk] = htonl(trans[i] |
RABIN_INDEX_FLAG | SET_SIMILARITY_FLAG);
pos1 += bsz;
}
} else {
rabin_index[blk] = htonl(trans[i] | RABIN_INDEX_FLAG);
}
} else {
memcpy(ctx->cbuf + pos1, buf1 + ctx->blocks[blk]->cksum_n_offset,
rabin_index[blk]);
pos1 += rabin_index[blk];
rabin_index[blk] = htonl(rabin_index[blk]);
}
}
cont:
if (valid) {
uchar_t *cbuf = ctx->cbuf;
ssize_t *entries;
*((uint32_t *)cbuf) = htonl(blknum);
cbuf += sizeof (uint32_t);
entries = (ssize_t *)cbuf;
entries[0] = htonll(*size);
entries[1] = 0;
entries[2] = htonll(pos1 - rabin_index_sz - RABIN_HDR_SIZE);
*size = pos1;
ctx->valid = 1;
DEBUG_STAT_EN(printf("Deduped size: %lld, blknum: %u, delta_calls: %u, delta_fails: %u\n",
*size, blknum, delta_calls, delta_fails));
/*
* Remaining header entries: size of compressed index and size of
* compressed data are inserted later via rabin_update_hdr, after actual compression!
*/
return (rabin_index_sz);
}
}
return (0);
}
void
rabin_update_hdr(uchar_t *buf, ssize_t rabin_index_sz_cmp, ssize_t rabin_data_sz_cmp)
{
ssize_t *entries;
buf += sizeof (uint32_t);
entries = (ssize_t *)buf;
entries[1] = htonll(rabin_index_sz_cmp);
entries[3] = htonll(rabin_data_sz_cmp);
}
void
rabin_parse_hdr(uchar_t *buf, uint32_t *blknum, ssize_t *rabin_index_sz,
ssize_t *rabin_data_sz, ssize_t *rabin_index_sz_cmp,
ssize_t *rabin_data_sz_cmp, ssize_t *rabin_deduped_size)
{
ssize_t *entries;
*blknum = ntohl(*((uint32_t *)(buf)));
buf += sizeof (uint32_t);
entries = (ssize_t *)buf;
*rabin_data_sz = ntohll(entries[0]);
*rabin_index_sz = (ssize_t)(*blknum) * RABIN_ENTRY_SIZE;
*rabin_index_sz_cmp = ntohll(entries[1]);
*rabin_deduped_size = ntohll(entries[2]);
*rabin_data_sz_cmp = ntohll(entries[3]);
}
void
rabin_inverse_dedup(rabin_context_t *ctx, uchar_t *buf, ssize_t *size)
{
uint32_t blknum, blk, oblk, len;
uint32_t *rabin_index;
ssize_t data_sz, sz, indx_cmp, data_sz_cmp, deduped_sz;
ssize_t rabin_index_sz, pos1, i;
uchar_t *pos2;
rabin_parse_hdr(buf, &blknum, &rabin_index_sz, &data_sz, &indx_cmp, &data_sz_cmp, &deduped_sz);
rabin_index = (uint32_t *)(buf + RABIN_HDR_SIZE);
pos1 = rabin_index_sz + RABIN_HDR_SIZE;
pos2 = ctx->cbuf;
sz = 0;
ctx->valid = 1;
slab_cache_add(sizeof (rabin_blockentry_t));
for (blk = 0; blk < blknum; blk++) {
if (ctx->blocks[blk] == 0)
ctx->blocks[blk] = (rabin_blockentry_t *)slab_alloc(NULL, sizeof (rabin_blockentry_t));
len = ntohl(rabin_index[blk]);
if (len == 0) {
ctx->blocks[blk]->length = 0;
ctx->blocks[blk]->index = 0;
} else if (!(len & RABIN_INDEX_FLAG)) {
ctx->blocks[blk]->length = len;
ctx->blocks[blk]->offset = pos1;
pos1 += len;
} else {
bsize_t blen;
ctx->blocks[blk]->length = 0;
if (len & GET_SIMILARITY_FLAG) {
ctx->blocks[blk]->offset = pos1;
ctx->blocks[blk]->index = (len & RABIN_INDEX_VALUE) | SET_SIMILARITY_FLAG;
blen = get_bsdiff_sz(buf + pos1);
pos1 += blen;
} else {
ctx->blocks[blk]->index = len & RABIN_INDEX_VALUE;
}
}
}
for (blk = 0; blk < blknum; blk++) {
int rv;
bsize_t newsz;
if (ctx->blocks[blk]->length == 0 && ctx->blocks[blk]->index == 0) continue;
if (ctx->blocks[blk]->length > 0) {
len = ctx->blocks[blk]->length;
pos1 = ctx->blocks[blk]->offset;
} else {
oblk = ctx->blocks[blk]->index;
if (oblk & GET_SIMILARITY_FLAG) {
oblk = oblk & CLEAR_SIMILARITY_FLAG;
len = ctx->blocks[oblk]->length;
pos1 = ctx->blocks[oblk]->offset;
newsz = data_sz - sz;
rv = bspatch(buf + ctx->blocks[blk]->offset, buf + pos1, len, pos2, &newsz);
if (rv == 0) {
fprintf(stderr, "Failed to bspatch block.\n");
ctx->valid = 0;
break;
}
pos2 += newsz;
sz += newsz;
if (sz > data_sz) {
fprintf(stderr, "Dedup data overflows chunk.\n");
ctx->valid = 0;
break;
}
continue;
} else {
len = ctx->blocks[oblk]->length;
pos1 = ctx->blocks[oblk]->offset;
}
}
memcpy(pos2, buf + pos1, len);
pos2 += len;
sz += len;
if (sz > data_sz) {
fprintf(stderr, "Dedup data overflows chunk.\n");
ctx->valid = 0;
break;
}
}
if (ctx->valid && sz < data_sz) {
fprintf(stderr, "Too little dedup data processed.\n");
ctx->valid = 0;
}
*size = data_sz;
}
/*
* TODO: Consolidate rabin dedup and compression/decompression in functions here rather than
* messy code in main program.
int
rabin_compress(rabin_context_t *ctx, uchar_t *from, ssize_t fromlen, uchar_t *to, ssize_t *tolen,
int level, char chdr, void *data, compress_func_ptr cmp)
{
}
*/
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