[PATCH] don't load objects needlessly when repacking
From: Nicolas Pitre <hidden>
Date: 2016-06-15 22:42:32
Subsystem:
the rest · Maintainer:
Linus Torvalds
If no delta is attempted on some objects then it is useless to load them in memory, neither create any delta index for them. The best thing to do is therefore to load and index them only when really needed. Signed-off-by: Nicolas Pitre <redacted> --- With this patch, a git-repack -a on the Linux kernel repo takes 19 seconds instead of 25 seconds on my machine. At this point the cost of creating a pack is largely dominated by git-rev-list alone while the actual pack creation is basically free.
diff --git a/pack-objects.c b/pack-objects.c
index 47da33b..b486ea5 100644
--- a/pack-objects.c
+++ b/pack-objects.c@@ -970,11 +970,12 @@ struct unpacked { * one. */ static int try_delta(struct unpacked *trg, struct unpacked *src, - struct delta_index *src_index, unsigned max_depth) + unsigned max_depth) { struct object_entry *trg_entry = trg->entry; struct object_entry *src_entry = src->entry; - unsigned long size, src_size, delta_size, sizediff, max_size; + unsigned long trg_size, src_size, delta_size, sizediff, max_size, sz; + char type[10]; void *delta_buf; /* Don't bother doing diffs between different types */
@@ -1009,19 +1010,38 @@ static int try_delta(struct unpacked *tr return 0; /* Now some size filtering heuristics. */ - size = trg_entry->size; - max_size = size/2 - 20; + trg_size = trg_entry->size; + max_size = trg_size/2 - 20; max_size = max_size * (max_depth - src_entry->depth) / max_depth; if (max_size == 0) return 0; if (trg_entry->delta && trg_entry->delta_size <= max_size) max_size = trg_entry->delta_size-1; src_size = src_entry->size; - sizediff = src_size < size ? size - src_size : 0; + sizediff = src_size < trg_size ? trg_size - src_size : 0; if (sizediff >= max_size) return 0; - delta_buf = create_delta(src_index, trg->data, size, &delta_size, max_size); + /* Load data if not already done */ + if (!trg->data) { + trg->data = read_sha1_file(trg_entry->sha1, type, &sz); + if (sz != trg_size) + die("object %s inconsistent object length (%lu vs %lu)", + sha1_to_hex(trg_entry->sha1), sz, trg_size); + } + if (!src->data) { + src->data = read_sha1_file(src_entry->sha1, type, &sz); + if (sz != src_size) + die("object %s inconsistent object length (%lu vs %lu)", + sha1_to_hex(src_entry->sha1), sz, src_size); + } + if (!src->index) { + src->index = create_delta_index(src->data, src_size); + if (!src->index) + die("out of memory"); + } + + delta_buf = create_delta(src->index, trg->data, trg_size, &delta_size, max_size); if (!delta_buf) return 0;
@@ -1054,8 +1074,6 @@ static void find_deltas(struct object_en while (--i >= 0) { struct object_entry *entry = list[i]; struct unpacked *n = array + idx; - unsigned long size; - char type[10]; int j; if (!entry->preferred_base)
@@ -1082,11 +1100,8 @@ static void find_deltas(struct object_en free_delta_index(n->index); n->index = NULL; free(n->data); + n->data = NULL; n->entry = entry; - n->data = read_sha1_file(entry->sha1, type, &size); - if (size != entry->size) - die("object %s inconsistent object length (%lu vs %lu)", - sha1_to_hex(entry->sha1), size, entry->size); j = window; while (--j > 0) {
@@ -1097,7 +1112,7 @@ static void find_deltas(struct object_en m = array + other_idx; if (!m->entry) break; - if (try_delta(n, m, m->index, depth) < 0) + if (try_delta(n, m, depth) < 0) break; } /* if we made n a delta, and if n is already at max
@@ -1107,10 +1122,6 @@ static void find_deltas(struct object_en if (entry->delta && depth <= entry->depth) continue; - n->index = create_delta_index(n->data, size); - if (!n->index) - die("out of memory"); - idx++; if (idx >= window) idx = 0;