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Merge branch 'sb/histogram-less-memory'

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"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
This commit is contained in:
Junio C Hamano 2018-08-15 15:08:25 -07:00
commit 57fbd8efb0
1 changed files with 78 additions and 55 deletions
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133
xdiff/xhistogram.c
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@ -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)
{
xdl_free(index->records);
xdl_free(index->line_map);
xdl_free(index->next_ptrs);
xdl_cha_free(&index->rcha);
}
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;
struct region lcs;
int sz;
int 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(&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;
}