Merge branch 'jc/diff' into next

* jc/diff:
  diffcore-rename: somewhat optimized.

diff --git a/diff.c b/diff.c
index c0548ee..c73a40b 100644 (file)
--- a/diff.c
+++ b/diff.c
@@ -463,6 +463,8 @@ void diff_free_filespec_data(struct diff_filespec *s)
                munmap(s->data, s->size);
        s->should_free = s->should_munmap = 0;
        s->data = NULL;
+       free(s->cnt_data);
+       s->cnt_data = NULL;
 }
 
 static void prep_temp_blob(struct diff_tempfile *temp,

diff --git a/diffcore-break.c b/diffcore-break.c
index 71ad58a..ed0e14c 100644 (file)
--- a/diffcore-break.c
+++ b/diffcore-break.c
@@ -68,6 +68,7 @@ static int should_break(struct diff_filespec *src,
 
        if (diffcore_count_changes(src->data, src->size,
                                   dst->data, dst->size,
+                                  NULL, NULL,
                                   0,
                                   &src_copied, &literal_added))
                return 0;

diff --git a/diffcore-delta.c b/diffcore-delta.c
index 70bacff..471b98f 100644 (file)
--- a/diffcore-delta.c
+++ b/diffcore-delta.c
@@ -24,11 +24,106 @@
  * The length of the sequence is arbitrarily set to 8 for now.
  */
 
+/* Wild guess at the initial hash size */
+#define INITIAL_HASH_SIZE 10
 #define HASHBASE 65537 /* next_prime(2^16) */
 
-static void hash_chars(unsigned char *buf, unsigned long sz, int *count)
+struct spanhash {
+       unsigned long hashval;
+       unsigned long cnt;
+};
+struct spanhash_top {
+       int alloc_log2;
+       int free;
+       struct spanhash data[FLEX_ARRAY];
+};
+
+static struct spanhash *spanhash_find(struct spanhash_top *top, unsigned long hashval)
+{
+       int sz = 1 << top->alloc_log2;
+       int bucket = hashval & (sz - 1);
+       while (1) {
+               struct spanhash *h = &(top->data[bucket++]);
+               if (!h->cnt)
+                       return NULL;
+               if (h->hashval == hashval)
+                       return h;
+               if (sz <= bucket)
+                       bucket = 0;
+       }
+}
+
+static struct spanhash_top *spanhash_rehash(struct spanhash_top *orig)
+{
+       struct spanhash_top *new;
+       int i;
+       int osz = 1 << orig->alloc_log2;
+       int sz = osz << 1;
+
+       new = xmalloc(sizeof(*orig) + sizeof(struct spanhash) * sz);
+       new->alloc_log2 = orig->alloc_log2 + 1;
+       new->free = osz;
+       memset(new->data, 0, sizeof(struct spanhash) * sz);
+       for (i = 0; i < osz; i++) {
+               struct spanhash *o = &(orig->data[i]);
+               int bucket;
+               if (!o->cnt)
+                       continue;
+               bucket = o->hashval & (sz - 1);
+               while (1) {
+                       struct spanhash *h = &(new->data[bucket++]);
+                       if (!h->cnt) {
+                               h->hashval = o->hashval;
+                               h->cnt = o->cnt;
+                               new->free--;
+                               break;
+                       }
+                       if (sz <= bucket)
+                               bucket = 0;
+               }
+       }
+       free(orig);
+       return new;
+}
+
+static struct spanhash_top *add_spanhash(struct spanhash_top *top,
+                                        unsigned long hashval)
+{
+       int bucket, lim;
+       struct spanhash *h;
+
+       lim = (1 << top->alloc_log2);
+       bucket = hashval & (lim - 1);
+       while (1) {
+               h = &(top->data[bucket++]);
+               if (!h->cnt) {
+                       h->hashval = hashval;
+                       h->cnt = 1;
+                       top->free--;
+                       if (top->free < 0)
+                               return spanhash_rehash(top);
+                       return top;
+               }
+               if (h->hashval == hashval) {
+                       h->cnt++;
+                       return top;
+               }
+               if (lim <= bucket)
+                       bucket = 0;
+       }
+}
+
+static struct spanhash_top *hash_chars(unsigned char *buf, unsigned long sz)
 {
-       unsigned int accum1, accum2, i;
+       int i;
+       unsigned long accum1, accum2, hashval;
+       struct spanhash_top *hash;
+
+       i = INITIAL_HASH_SIZE;
+       hash = xmalloc(sizeof(*hash) + sizeof(struct spanhash) * (1<<i));
+       hash->alloc_log2 = i;
+       hash->free = (1<<i)/2;
+       memset(hash->data, 0, sizeof(struct spanhash) * (1<<i));
 
        /* an 8-byte shift register made of accum1 and accum2.  New
         * bytes come at LSB of accum2, and shifted up to accum1
@@ -40,44 +135,68 @@ static void hash_chars(unsigned char *buf, unsigned long sz, int *count)
        while (sz) {
                accum1 = (accum1 << 8) | (accum2 >> 24);
                accum2 = (accum2 << 8) | *buf++;
-               /* We want something that hashes permuted byte
-                * sequences nicely; simpler hash like (accum1 ^
-                * accum2) does not perform as well.
-                */
-               i = (accum1 + accum2 * 0x61) % HASHBASE;
-               count[i]++;
+               hashval = (accum1 + accum2 * 0x61) % HASHBASE;
+               hash = add_spanhash(hash, hashval);
                sz--;
        }
+       return hash;
 }
 
 int diffcore_count_changes(void *src, unsigned long src_size,
                           void *dst, unsigned long dst_size,
+                          void **src_count_p,
+                          void **dst_count_p,
                           unsigned long delta_limit,
                           unsigned long *src_copied,
                           unsigned long *literal_added)
 {
-       int *src_count, *dst_count, i;
+       int i, ssz;
+       struct spanhash_top *src_count, *dst_count;
        unsigned long sc, la;
 
        if (src_size < 8 || dst_size < 8)
                return -1;
 
-       src_count = xcalloc(HASHBASE * 2, sizeof(int));
-       dst_count = src_count + HASHBASE;
-       hash_chars(src, src_size, src_count);
-       hash_chars(dst, dst_size, dst_count);
-
+       src_count = dst_count = NULL;
+       if (src_count_p)
+               src_count = *src_count_p;
+       if (!src_count) {
+               src_count = hash_chars(src, src_size);
+               if (src_count_p)
+                       *src_count_p = src_count;
+       }
+       if (dst_count_p)
+               dst_count = *dst_count_p;
+       if (!dst_count) {
+               dst_count = hash_chars(dst, dst_size);
+               if (dst_count_p)
+                       *dst_count_p = dst_count;
+       }
        sc = la = 0;
-       for (i = 0; i < HASHBASE; i++) {
-               if (src_count[i] < dst_count[i]) {
-                       la += dst_count[i] - src_count[i];
-                       sc += src_count[i];
+
+       ssz = 1 << src_count->alloc_log2;
+       for (i = 0; i < ssz; i++) {
+               struct spanhash *s = &(src_count->data[i]);
+               struct spanhash *d;
+               unsigned dst_cnt, src_cnt;
+               if (!s->cnt)
+                       continue;
+               src_cnt = s->cnt;
+               d = spanhash_find(dst_count, s->hashval);
+               dst_cnt = d ? d->cnt : 0;
+               if (src_cnt < dst_cnt) {
+                       la += dst_cnt - src_cnt;
+                       sc += src_cnt;
                }
-               else /* i.e. if (dst_count[i] <= src_count[i]) */
-                       sc += dst_count[i];
+               else
+                       sc += dst_cnt;
        }
+
+       if (!src_count_p)
+               free(src_count);
+       if (!dst_count_p)
+               free(dst_count);
        *src_copied = sc;
        *literal_added = la;
-       free(src_count);
        return 0;
 }

diff --git a/diffcore-rename.c b/diffcore-rename.c
index 625b589..b80b432 100644 (file)
--- a/diffcore-rename.c
+++ b/diffcore-rename.c
@@ -166,6 +166,7 @@ static int estimate_similarity(struct diff_filespec *src,
        delta_limit = base_size * (MAX_SCORE-minimum_score) / MAX_SCORE;
        if (diffcore_count_changes(src->data, src->size,
                                   dst->data, dst->size,
+                                  &src->cnt_data, &dst->cnt_data,
                                   delta_limit,
                                   &src_copied, &literal_added))
                return 0;
@@ -306,6 +307,8 @@ void diffcore_rename(struct diff_options *options)
                        m->score = estimate_similarity(one, two,
                                                       minimum_score);
                }
+               free(two->cnt_data);
+               two->cnt_data = NULL;
                dst_cnt++;
        }
        /* cost matrix sorted by most to least similar pair */

diff --git a/diffcore.h b/diffcore.h
index d31b3b4..73c7842 100644 (file)
--- a/diffcore.h
+++ b/diffcore.h
@@ -26,6 +26,7 @@ struct diff_filespec {
        unsigned char sha1[20];
        char *path;
        void *data;
+       void *cnt_data;
        unsigned long size;
        int xfrm_flags;          /* for use by the xfrm */
        unsigned short mode;     /* file mode */
@@ -103,6 +104,8 @@ void diff_debug_queue(const char *, struct diff_queue_struct *);
 
 extern int diffcore_count_changes(void *src, unsigned long src_size,
                                  void *dst, unsigned long dst_size,
+                                 void **src_count_p,
+                                 void **dst_count_p,
                                  unsigned long delta_limit,
                                  unsigned long *src_copied,
                                  unsigned long *literal_added);