memzap

replay memory writes
git clone git://git.2f30.org/memzap.git
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commit 1ead999b8cca9588a8e0a74d67590dd8f01d86eb
parent 634a1c5d750f77ea0f2bc8f51d1a92e31b1f61ef
Author: sin <sin@2f30.org>
Date:   Wed Mar  6 17:03:18 +0000

mem: Remove rbtree optimization

This is not needed so far and it only complicates the code.  We'll
revisit it in the future.  For now keep the code in a separate
branch named `mem-rbtree'.

Diffstat:
mem.c | 146++++++++++---------------------------------------------------------------------
memzap.c | 9+--------
proto.h | 26+-------------------------
3 files changed, 20 insertions(+), 161 deletions(-)
diff --git a/mem.c b/mem.c @@ -127,113 +127,18 @@ free_mem_region(struct mem_region *mr) free(mr); } -RB_GENERATE(mem_tree, mem_tree_entry, entry, - mem_cmp); -int -mem_cmp(struct mem_tree_entry *a, struct mem_tree_entry *b) -{ - if (a->weak_sum < b->weak_sum) - return -1; - if (a->weak_sum > b->weak_sum) - return 1; - return 0; -} - -/* Given a memory region, build an rbtree - * of the checksums. We use this rbtree later on - * when we want to find the differences between - * two memory regions */ -struct mem_tree * -build_mem_tree(struct mem_region *mr) -{ - struct mem_blk *mb; - struct mem_tree_entry *me, *n; - struct mem_tree *mt; - size_t i; - - if (!mr) - return NULL; - - mt = xmalloc(sizeof(*mt)); - RB_INIT(mt); - - for (i = 0; i < mr->nblocks; i++) { - mb = &mr->mblks[i]; - me = xmalloc(sizeof(*me)); - me->weak_sum = mb->weak_sum; - me->mr = mr; - n = RB_INSERT(mem_tree, mt, me); - if (!n) { - me->mblks = xmalloc(sizeof(*me->mblks)); - me->mblks[0] = mb; - me->nmblks = 1; - continue; - } - /* If we have two blocks with the same weak - * sum then try to chain the MD5 hash so we can keep track - * of it */ - n->mblks = xrealloc(n->mblks, - (n->nmblks + 1) * sizeof(*me->mblks)); - n->mblks[n->nmblks] = mb; - n->nmblks++; - } - return mt; -} - -void -dump_mem_tree(struct mem_tree *mt) -{ - - struct mem_tree_entry *me; - struct mem_blk *mb; - size_t i; - - if (!mt) - return; - - RB_FOREACH(me, mem_tree, mt) { - for (i = 0; i < me->nmblks; i++) { - mb = me->mblks[i]; - dump_mem_blk(mb); - } - } -} - -void -free_mem_tree(struct mem_tree *mt) -{ - - struct mem_tree_entry *me, *next; - - if (!mt) - return; - - next = RB_MIN(mem_tree, mt); - while (next) { - me = next; - next = RB_NEXT(mem_tree, mt, me); - RB_REMOVE(mem_tree, mt, me); - free(me->mblks); - free(me); - } - free(mt); -} - /* Diff the two memory regions and return a - * a diff structure. In fact `dst' is an rbtree - * that describes the *old* memory region - * and `src' is the *new* and updated version of - * the memory region. */ + * a diff structure. In fact `dst' describes + * the *old* memory region and `src' is the + * *new* and updated copy */ struct mem_region_diff * -diff_mem_region(struct mem_tree *dst, +diff_mem_region(struct mem_region *dst, struct mem_region *src) { - struct mem_blk *mb; + struct mem_blk *mb_src, *mb_dst; struct mem_diff *mdiff; struct mem_region_diff *rdiff; - struct mem_region *mr_old; - struct mem_tree_entry find, *me; - size_t i, j; + size_t i; bool found; size_t size; @@ -243,47 +148,32 @@ diff_mem_region(struct mem_tree *dst, rdiff = xmalloc(sizeof(*rdiff)); rdiff->mrdiffs = NULL; rdiff->nmrdiffs = 0; - me = RB_MIN(mem_tree, dst); - mr_old = me->mr; /* We can only diff regions of the same size */ - if (mr_old->rsize != src->rsize) + if (dst->rsize != src->rsize) return NULL; for (i = 0; i < src->nblocks; i++) { found = false; - mb = &src->mblks[i]; - find.weak_sum = mb->weak_sum; - me = RB_FIND(mem_tree, dst, &find); - if (me) { - for (j = 0; j < me->nmblks; j++) { - if (me->mblks[j]->offset == mb->offset) { + mb_src = &src->mblks[i]; + mb_dst = &dst->mblks[i]; + if (mb_src->weak_sum == mb_dst->weak_sum) { + if (mb_src->offset == mb_dst->offset) { + if (!memcmp(mb_src->digest, + mb_dst->digest, + MD5_DIGEST_LENGTH)) { found = true; - break; - } - } - if (found) { - /* We might have a weak sum collision - * so check the strong sum as well */ - for (j = 0; j < me->nmblks; j++) { - if (!memcmp(me->mblks[j]->digest, - mb->digest, - MD5_DIGEST_LENGTH)) { - found = true; - break; - } } } } if (!found) { - /* Cool, this is a modified block - update the rdiff */ size = (rdiff->nmrdiffs + 1) * sizeof(*rdiff->mrdiffs); rdiff->mrdiffs = xrealloc(rdiff->mrdiffs, size); mdiff = &rdiff->mrdiffs[rdiff->nmrdiffs]; - mdiff->buf = xmalloc(mb->len); - memcpy(mdiff->buf, mb->buf, mb->len); - mdiff->offset = mb->offset; - mdiff->len = mb->len; + mdiff->buf = xmalloc(mb_src->len); + memcpy(mdiff->buf, mb_src->buf, mb_src->len); + mdiff->offset = mb_src->offset; + mdiff->len = mb_src->len; mdiff->index = i; rdiff->nmrdiffs++; } diff --git a/memzap.c b/memzap.c @@ -44,7 +44,6 @@ int main(int argc, char *argv[]) { struct mem_region *mr_old, *mr_new; - struct mem_tree *mt_old; struct mem_region_diff *rdiff; struct mdiff_hdr hdr; int c; @@ -214,10 +213,6 @@ main(int argc, char *argv[]) mr_old = build_mem_region(buf, len); if (!mr_old) errx(1, "failed to build memory region\n"); - /* Build an rbtree that tracks this memory region */ - mt_old = build_mem_tree(mr_old); - if (!mt_old) - errx(1, "failed to build memory tree\n"); /* Single step the child in order to get the next * generation */ @@ -225,7 +220,6 @@ main(int argc, char *argv[]) wait(&stat); if (!WIFSTOPPED(stat)) { free_mem_region(mr_old); - free_mem_tree(mt_old); break; } cycle++; @@ -240,7 +234,7 @@ main(int argc, char *argv[]) errx(1, "failed to build memory region\n"); /* Diff the original copy with the updated copy */ - rdiff = diff_mem_region(mt_old, mr_new); + rdiff = diff_mem_region(mr_old, mr_new); if (rdiff->nmrdiffs) { /* If we've found differences, then apply them on * the Nth generation */ @@ -250,7 +244,6 @@ main(int argc, char *argv[]) /* Free these and go up for another run */ free_mem_region(mr_old); - free_mem_tree(mt_old); free_mem_region(mr_new); free_mem_region_diff(rdiff); } while(1); diff --git a/proto.h b/proto.h @@ -83,24 +83,6 @@ struct mem_region_diff { size_t nmrdiffs; }; -struct mem_tree_entry { - /* The rolling sum for this rbnode, we sort - * based on this property */ - uint32_t weak_sum; - /* Pointers to memory blocks, normally there - * will be only 1 memory block here, however, - * if we have weak sum collisions, then we will - * chain more entries here */ - struct mem_blk **mblks; - /* Actual number of tracked memory blocks */ - size_t nmblks; - /* The memory region this tree is generated - * from */ - struct mem_region *mr; - RB_ENTRY(mem_tree_entry) entry; -}; -RB_HEAD(mem_tree, mem_tree_entry); - struct mdiff_hdr { /* MDIFF */ uint8_t magic[8]; @@ -150,13 +132,7 @@ void dump_mem_blk(struct mem_blk *mb); struct mem_region *build_mem_region(unsigned char *buf, size_t len); void dump_mem_region(struct mem_region *mr); void free_mem_region(struct mem_region *mr); -int mem_cmp(struct mem_tree_entry *a, struct mem_tree_entry *b); -RB_PROTOTYPE(mem_tree, mem_tree_entry, entry, - mem_cmp); -struct mem_tree *build_mem_tree(struct mem_region *mr); -void dump_mem_tree(struct mem_tree *mt); -void free_mem_tree(struct mem_tree *mt); -struct mem_region_diff *diff_mem_region(struct mem_tree *dst, +struct mem_region_diff *diff_mem_region(struct mem_region *dst, struct mem_region *src); struct mem_region *apply_diff(struct mem_region *dst, struct mem_region_diff *rdiff);