[PATCH v2 8/9] diffcore-rename: accelerate rename_dst setup
- From
Elijah Newren via GitGitGadget <gitgitgadget@gmail.com>
- Date
- Dec 11, 2020, 09:08 UTC
- Message-ID
- <85714e1583d8c47858e6efd2d5c63bdcca748a25.1607677728.git.gitgitgadget@gmail.com>
- In-Reply-To
- <pull.929.v2.git.git.1607677728.gitgitgadget@gmail.com>
From: Elijah Newren <newren@gmail.com>
register_rename_src() simply references the passed pair inside rename_src. In contrast, add_rename_dst() did something entirely different for rename_dst. Instead of copying the passed pair, it made a copy of the second diff_filespec from the passed pair, referenced it, and then set the diff_rename_dst.pair field to NULL. Later, when a pairing is found, record_rename_pair() allocated a full diff_filepair via diff_queue() and pointed its src and dst fields at the appropriate diff_filespecs. This contrast between register_rename_src() for the rename_src data structure and add_rename_dst() for the rename_dst data structure is oddly inconsistent and requires more memory and work than necessary. Let's just reference the original diff_filepair in rename_dst as-is, just as we do with rename_src. Add a new rename_dst.is_rename field, since the rename_dst.p field is never NULL unlike the old rename_dst.pair field.
Taking advantage of this change and the fact that same-named paths will be adjacent, we can get rid of the sorting of the array and most of the lookups on it, allowing us to instead just append as we go. However, there is one remaining reason to still keep locate_rename_dst(): handling broken pairs (i.e. when break detection is on). Those are somewhat rare, but we can set up a simple strintmap to get the map between the source and the index. Doing that allows us to still have a fast lookup without sorting the rename_dst array. Since the sorting had been done in a weakly quadratic manner, when many renames are involved this time could add up.
There is still a strcmp() in add_rename_dst() that I have left in place to make it easier to verify that the algorithm has the same results. This strcmp() is there to check for duplicate destination entries (which was the easiest way at the time to avoid segfaults in the diffcore-rename code when trees had multiple entries at a given path). The underlying double free()s are no longer an issue with the new algorithm, but that can be addressed in a subsequent commit.
This patch is being submitted in a different order than its original development, but in a large rebase of many commits with lots of renames and with several optimizations to inexact rename detection, both setup time and write back to output queue time from diffcore_rename() were sizeable chunks of overall runtime. This patch accelerated the setup time by about 65%, and final write back to the output queue time by about 50%, resulting in an overall drop of 3.5% on the execution time of rebasing a few dozen patches.
Signed-off-by: Elijah Newren <newren@gmail.com> --- diffcore-rename.c | 148 ++++++++++++++++++++-------------------------- 1 file changed, 65 insertions(+), 83 deletions(-)
diff --git a/diffcore-rename.c b/diffcore-rename.c index a215421a9cb..2a8fcd52928 100644 --- a/diffcore-rename.c +++ b/diffcore-rename.c @@ -9,63 +9,48 @@ #include "hashmap.h" #include "progress.h" #include "promisor-remote.h" +#include "strmap.h" /* Table of rename/copy destinations */ static struct diff_rename_dst { - struct diff_filespec *two; - struct diff_filepair *pair; + struct diff_filepair *p; + struct diff_filespec *filespec_to_free; + int is_rename; /* false -> just a create; true -> rename or copy */ } *rename_dst; static int rename_dst_nr, rename_dst_alloc; +/* Mapping from break source pathname to break destination index */ +static struct strintmap *break_idx = NULL; -static int find_rename_dst(struct diff_filespec *two) -{ - int first, last; - - first = 0; - last = rename_dst_nr; - while (last > first) { - int next = first + ((last - first) >> 1); - struct diff_rename_dst *dst = &(rename_dst[next]); - int cmp = strcmp(two->path, dst->two->path); - if (!cmp) - return next; - if (cmp < 0) { - last = next; - continue; - } - first = next+1; - } - return -first - 1; -} - -static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two) +static struct diff_rename_dst *locate_rename_dst(struct diff_filepair *p) { - int ofs = find_rename_dst(two); - return ofs < 0 ? NULL : &rename_dst[ofs]; + /* Lookup by p->ONE->path */ + int idx = break_idx ? strintmap_get(break_idx, p->one->path) : -1; + return (idx == -1) ? NULL : &rename_dst[idx]; } /* * Returns 0 on success, -1 if we found a duplicate. */ -static int add_rename_dst(struct diff_filespec *two) +static int add_rename_dst(struct diff_filepair *p) { - int first = find_rename_dst(two); - - if (first >= 0) + /* + * If we have multiple entries at the same path in the destination + * tree (an invalid tree, to be sure), turn off rename detection + * entirely. Once upon a time, diffcore-rename had double free() + * issues due to such duplicate paths, resulting in segfaults. See + * commit 4d6be03b95 ("diffcore-rename: avoid processing duplicate + * destinations", 2015-02-26). + */ + if (rename_dst_nr > 0 && + !strcmp(rename_dst[rename_dst_nr-1].p->two->path, p->two->path)) return -1; - first = -first - 1; - /* insert to make it at "first" */ ALLOC_GROW(rename_dst, rename_dst_nr + 1, rename_dst_alloc); + rename_dst[rename_dst_nr].p = p; + rename_dst[rename_dst_nr].filespec_to_free = NULL; + rename_dst[rename_dst_nr].is_rename = 0; rename_dst_nr++; - if (first < rename_dst_nr) - MOVE_ARRAY(rename_dst + first + 1, rename_dst + first, - rename_dst_nr - first - 1); - rename_dst[first].two = alloc_filespec(two->path); - fill_filespec(rename_dst[first].two, &two->oid, two->oid_valid, - two->mode); - rename_dst[first].pair = NULL; return 0; } @@ -89,6 +74,14 @@ static void register_rename_src(struct diff_filepair *p) !strcmp(rename_src[rename_src_nr-1].p->one->path, p->one->path)) return; + if (p->broken_pair) { + if (!break_idx) { + break_idx = xmalloc(sizeof(*break_idx)); + strintmap_init(break_idx, -1); + } + strintmap_set(break_idx, p->one->path, rename_dst_nr); + } + ALLOC_GROW(rename_src, rename_src_nr + 1, rename_src_alloc); rename_src[rename_src_nr].p = p; rename_src[rename_src_nr].score = p->score; @@ -128,14 +121,14 @@ static void prefetch(void *prefetch_options) struct oid_array to_fetch = OID_ARRAY_INIT; for (i = 0; i < rename_dst_nr; i++) { - if (rename_dst[i].pair) + if (rename_dst[i].p->renamed_pair) /* * The loop in diffcore_rename() will not need these * blobs, so skip prefetching. */ continue; /* already found exact match */ diff_add_if_missing(options->repo, &to_fetch, - rename_dst[i].two); + rename_dst[i].p->two); } for (i = 0; i < rename_src_nr; i++) { if (options->skip_unmodified && @@ -245,26 +238,24 @@ static int estimate_similarity(struct repository *r, static void record_rename_pair(int dst_index, int src_index, int score) { - struct diff_filespec *src, *dst; - struct diff_filepair *dp; + struct diff_filepair *src = rename_src[src_index].p; + struct diff_filepair *dst = rename_dst[dst_index].p; - if (rename_dst[dst_index].pair) + if (dst->renamed_pair) die("internal error: dst already matched."); - src = rename_src[src_index].p->one; - src->rename_used++; - src->count++; + src->one->rename_used++; + src->one->count++; - dst = rename_dst[dst_index].two; - dst->count++; + rename_dst[dst_index].filespec_to_free = dst->one; + rename_dst[dst_index].is_rename = 1; - dp = diff_queue(NULL, src, dst); - dp->renamed_pair = 1; - if (!strcmp(src->path, dst->path)) - dp->score = rename_src[src_index].score; + dst->one = src->one; + dst->renamed_pair = 1; + if (!strcmp(dst->one->path, dst->two->path)) + dst->score = rename_src[src_index].score; else - dp->score = score; - rename_dst[dst_index].pair = dp; + dst->score = score; } /* @@ -310,7 +301,7 @@ static int find_identical_files(struct hashmap *srcs, struct diff_options *options) { int renames = 0; - struct diff_filespec *target = rename_dst[dst_index].two; + struct diff_filespec *target = rename_dst[dst_index].p->two; struct file_similarity *p, *best = NULL; int i = 100, best_score = -1; unsigned int hash = hash_filespec(options->repo, target); @@ -476,7 +467,7 @@ static int find_renames(struct diff_score *mx, int dst_cnt, int minimum_score, i (mx[i].score < minimum_score)) break; /* there is no more usable pair. */ dst = &rename_dst[mx[i].dst]; - if (dst->pair) + if (dst->is_rename) continue; /* already done, either exact or fuzzy. */ if (!copies && rename_src[mx[i].src].p->one->rename_used) continue; @@ -511,7 +502,7 @@ void diffcore_rename(struct diff_options *options) else if (!options->flags.rename_empty && is_empty_blob_oid(&p->two->oid)) continue; - else if (add_rename_dst(p->two) < 0) { + else if (add_rename_dst(p) < 0) { warning("skipping rename detection, detected" " duplicate destination '%s'", p->two->path); @@ -586,10 +577,10 @@ void diffcore_rename(struct diff_options *options) mx = xcalloc(st_mult(NUM_CANDIDATE_PER_DST, num_destinations), sizeof(*mx)); for (dst_cnt = i = 0; i < rename_dst_nr; i++) { - struct diff_filespec *two = rename_dst[i].two; + struct diff_filespec *two = rename_dst[i].p->two; struct diff_score *m; - if (rename_dst[i].pair) + if (rename_dst[i].is_rename) continue; /* dealt with exact match already. */ m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST]; @@ -646,22 +637,8 @@ void diffcore_rename(struct diff_options *options) diff_q(&outq, p); } else if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) { - /* - * Creation - * - * We would output this create record if it has - * not been turned into a rename/copy already. - */ - struct diff_rename_dst *dst = locate_rename_dst(p->two); - if (dst && dst->pair) { - diff_q(&outq, dst->pair); - pair_to_free = p; - } - else - /* no matching rename/copy source, so - * record this as a creation. - */ - diff_q(&outq, p); + /* Creation */ + diff_q(&outq, p); } else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) { /* @@ -682,8 +659,10 @@ void diffcore_rename(struct diff_options *options) */ if (DIFF_PAIR_BROKEN(p)) { /* broken delete */ - struct diff_rename_dst *dst = locate_rename_dst(p->one); - if (dst && dst->pair) + struct diff_rename_dst *dst = locate_rename_dst(p); + if (!dst) + BUG("tracking failed somehow; failed to find associated dst for broken pair"); + if (dst->is_rename) /* counterpart is now rename/copy */ pair_to_free = p; } @@ -693,16 +672,14 @@ void diffcore_rename(struct diff_options *options) pair_to_free = p; } - if (pair_to_free) - ; - else + if (!pair_to_free) diff_q(&outq, p); } else if (!diff_unmodified_pair(p)) /* all the usual ones need to be kept */ diff_q(&outq, p); else - /* no need to keep unmodified pairs */ + /* no need to keep unmodified pairs; FIXME: remove earlier? */ pair_to_free = p; if (pair_to_free) @@ -715,11 +692,16 @@ void diffcore_rename(struct diff_options *options) diff_debug_queue("done collapsing", q); for (i = 0; i < rename_dst_nr; i++) - free_filespec(rename_dst[i].two); + if (rename_dst[i].filespec_to_free) + free_filespec(rename_dst[i].filespec_to_free); FREE_AND_NULL(rename_dst); rename_dst_nr = rename_dst_alloc = 0; FREE_AND_NULL(rename_src); rename_src_nr = rename_src_alloc = 0; + if (break_idx) { + strintmap_clear(break_idx); + FREE_AND_NULL(break_idx); + } return; }
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