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authorJunio C Hamano <gitster@pobox.com>2018-08-15 22:08:25 (GMT)
committerJunio C Hamano <gitster@pobox.com>2018-08-15 22:08:25 (GMT)
commit57fbd8efb0ac6d85bde612eb06b9ff4415e21503 (patch)
tree465fe17410b4ec4a6faf6bdb16890a5822990524 /xdiff
parent4bea8485e395769951c6b9eddfba1081ea7ef47f (diff)
parent79cb2ebb92c18af11edf5eea238425d86eef173d (diff)
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Merge branch 'sb/histogram-less-memory'
"git diff --histogram" had a bad memory usage pattern, which has been rearranged to reduce the peak usage. * sb/histogram-less-memory: xdiff/histogram: remove tail recursion xdiff/xhistogram: move index allocation into find_lcs xdiff/xhistogram: factor out memory cleanup into free_index() xdiff/xhistogram: pass arguments directly to fall_back_to_classic_diff
Diffstat (limited to 'xdiff')
-rw-r--r--xdiff/xhistogram.c133
1 files changed, 78 insertions, 55 deletions
diff --git a/xdiff/xhistogram.c b/xdiff/xhistogram.c
index 73210cb..ec85f59 100644
--- a/xdiff/xhistogram.c
+++ b/xdiff/xhistogram.c
@@ -233,54 +233,31 @@ static int try_lcs(struct histindex *index, struct region *lcs, int b_ptr,
return b_next;
}
-static int find_lcs(struct histindex *index, struct region *lcs,
- int line1, int count1, int line2, int count2) {
- int b_ptr;
-
- if (scanA(index, line1, count1))
- return -1;
-
- index->cnt = index->max_chain_length + 1;
-
- for (b_ptr = line2; b_ptr <= LINE_END(2); )
- b_ptr = try_lcs(index, lcs, b_ptr, line1, count1, line2, count2);
-
- return index->has_common && index->max_chain_length < index->cnt;
-}
-
-static int fall_back_to_classic_diff(struct histindex *index,
+static int fall_back_to_classic_diff(xpparam_t const *xpp, xdfenv_t *env,
int line1, int count1, int line2, int count2)
{
- xpparam_t xpp;
- xpp.flags = index->xpp->flags & ~XDF_DIFF_ALGORITHM_MASK;
+ xpparam_t xpparam;
+ xpparam.flags = xpp->flags & ~XDF_DIFF_ALGORITHM_MASK;
- return xdl_fall_back_diff(index->env, &xpp,
+ return xdl_fall_back_diff(env, &xpparam,
line1, count1, line2, count2);
}
-static int histogram_diff(xpparam_t const *xpp, xdfenv_t *env,
- int line1, int count1, int line2, int count2)
+static inline void free_index(struct histindex *index)
{
- struct histindex index;
- struct region lcs;
- int sz;
- int result = -1;
-
- if (count1 <= 0 && count2 <= 0)
- return 0;
-
- if (LINE_END(1) >= MAX_PTR)
- return -1;
+ xdl_free(index->records);
+ xdl_free(index->line_map);
+ xdl_free(index->next_ptrs);
+ xdl_cha_free(&index->rcha);
+}
- if (!count1) {
- while(count2--)
- env->xdf2.rchg[line2++ - 1] = 1;
- return 0;
- } else if (!count2) {
- while(count1--)
- env->xdf1.rchg[line1++ - 1] = 1;
- return 0;
- }
+static int find_lcs(xpparam_t const *xpp, xdfenv_t *env,
+ struct region *lcs,
+ int line1, int count1, int line2, int count2)
+{
+ int b_ptr;
+ int sz, ret = -1;
+ struct histindex index;
memset(&index, 0, sizeof(index));
@@ -318,9 +295,55 @@ static int histogram_diff(xpparam_t const *xpp, xdfenv_t *env,
index.ptr_shift = line1;
index.max_chain_length = 64;
+ if (scanA(&index, line1, count1))
+ goto cleanup;
+
+ index.cnt = index.max_chain_length + 1;
+
+ for (b_ptr = line2; b_ptr <= LINE_END(2); )
+ b_ptr = try_lcs(&index, lcs, b_ptr, line1, count1, line2, count2);
+
+ if (index.has_common && index.max_chain_length < index.cnt)
+ ret = 1;
+ else
+ ret = 0;
+
+cleanup:
+ free_index(&index);
+ return ret;
+}
+
+static int histogram_diff(xpparam_t const *xpp, xdfenv_t *env,
+ int line1, int count1, int line2, int count2)
+{
+ struct region lcs;
+ int lcs_found;
+ int result;
+redo:
+ result = -1;
+
+ if (count1 <= 0 && count2 <= 0)
+ return 0;
+
+ if (LINE_END(1) >= MAX_PTR)
+ return -1;
+
+ if (!count1) {
+ while(count2--)
+ env->xdf2.rchg[line2++ - 1] = 1;
+ return 0;
+ } else if (!count2) {
+ while(count1--)
+ env->xdf1.rchg[line1++ - 1] = 1;
+ return 0;
+ }
+
memset(&lcs, 0, sizeof(lcs));
- if (find_lcs(&index, &lcs, line1, count1, line2, count2))
- result = fall_back_to_classic_diff(&index, line1, count1, line2, count2);
+ lcs_found = find_lcs(xpp, env, &lcs, line1, count1, line2, count2);
+ if (lcs_found < 0)
+ goto out;
+ else if (lcs_found)
+ result = fall_back_to_classic_diff(xpp, env, line1, count1, line2, count2);
else {
if (lcs.begin1 == 0 && lcs.begin2 == 0) {
while (count1--)
@@ -333,21 +356,21 @@ static int histogram_diff(xpparam_t const *xpp, xdfenv_t *env,
line1, lcs.begin1 - line1,
line2, lcs.begin2 - line2);
if (result)
- goto cleanup;
- result = histogram_diff(xpp, env,
- lcs.end1 + 1, LINE_END(1) - lcs.end1,
- lcs.end2 + 1, LINE_END(2) - lcs.end2);
- if (result)
- goto cleanup;
+ goto out;
+ /*
+ * result = histogram_diff(xpp, env,
+ * lcs.end1 + 1, LINE_END(1) - lcs.end1,
+ * lcs.end2 + 1, LINE_END(2) - lcs.end2);
+ * but let's optimize tail recursion ourself:
+ */
+ count1 = LINE_END(1) - lcs.end1;
+ line1 = lcs.end1 + 1;
+ count2 = LINE_END(2) - lcs.end2;
+ line2 = lcs.end2 + 1;
+ goto redo;
}
}
-
-cleanup:
- xdl_free(index.records);
- xdl_free(index.line_map);
- xdl_free(index.next_ptrs);
- xdl_cha_free(&index.rcha);
-
+out:
return result;
}