From: Junio C Hamano Date: Mon, 27 Feb 2017 21:57:14 +0000 (-0800) Subject: Merge branch 'bw/attr' X-Git-Tag: v2.13.0-rc0~169 X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/a04855bae8d75d22b0c909c7d1febedcd05ba9b1?hp=-c Merge branch 'bw/attr' The gitattributes machinery is being taught to work better in a multi-threaded environment. * bw/attr: (27 commits) attr: reformat git_attr_set_direction() function attr: push the bare repo check into read_attr() attr: store attribute stack in attr_check structure attr: tighten const correctness with git_attr and match_attr attr: remove maybe-real, maybe-macro from git_attr attr: eliminate global check_all_attr array attr: use hashmap for attribute dictionary attr: change validity check for attribute names to use positive logic attr: pass struct attr_check to collect_some_attrs attr: retire git_check_attrs() API attr: convert git_check_attrs() callers to use the new API attr: convert git_all_attrs() to use "struct attr_check" attr: (re)introduce git_check_attr() and struct attr_check attr: rename function and struct related to checking attributes attr.c: outline the future plans by heavily commenting Documentation: fix a typo attr.c: add push_stack() helper attr: support quoting pathname patterns in C style attr.c: plug small leak in parse_attr_line() attr.c: tighten constness around "git_attr" structure ... --- a04855bae8d75d22b0c909c7d1febedcd05ba9b1 diff --combined builtin/pack-objects.c index c7af475485,181e4a1985..f294dcffa9 --- a/builtin/pack-objects.c +++ b/builtin/pack-objects.c @@@ -894,24 -894,15 +894,15 @@@ static void write_pack_file(void written, nr_result); } - static void setup_delta_attr_check(struct git_attr_check *check) - { - static struct git_attr *attr_delta; - - if (!attr_delta) - attr_delta = git_attr("delta"); - - check[0].attr = attr_delta; - } - static int no_try_delta(const char *path) { - struct git_attr_check check[1]; + static struct attr_check *check; - setup_delta_attr_check(check); - if (git_check_attr(path, ARRAY_SIZE(check), check)) + if (!check) + check = attr_check_initl("delta", NULL); + if (git_check_attr(path, check)) return 0; - if (ATTR_FALSE(check->value)) + if (ATTR_FALSE(check->items[0].value)) return 1; return 0; } @@@ -1539,8 -1530,6 +1530,8 @@@ static int pack_offset_sort(const void * 2. Updating our size/type to the non-delta representation. These were * either not recorded initially (size) or overwritten with the delta type * (type) when check_object() decided to reuse the delta. + * + * 3. Resetting our delta depth, as we are now a base object. */ static void drop_reused_delta(struct object_entry *entry) { @@@ -1554,7 -1543,6 +1545,7 @@@ p = &(*p)->delta_sibling; } entry->delta = NULL; + entry->depth = 0; oi.sizep = &entry->size; oi.typep = &entry->type; @@@ -1573,123 -1561,39 +1564,123 @@@ * Follow the chain of deltas from this entry onward, throwing away any links * that cause us to hit a cycle (as determined by the DFS state flags in * the entries). + * + * We also detect too-long reused chains that would violate our --depth + * limit. */ static void break_delta_chains(struct object_entry *entry) { - /* If it's not a delta, it can't be part of a cycle. */ - if (!entry->delta) { - entry->dfs_state = DFS_DONE; - return; - } + /* + * The actual depth of each object we will write is stored as an int, + * as it cannot exceed our int "depth" limit. But before we break + * changes based no that limit, we may potentially go as deep as the + * number of objects, which is elsewhere bounded to a uint32_t. + */ + uint32_t total_depth; + struct object_entry *cur, *next; + + for (cur = entry, total_depth = 0; + cur; + cur = cur->delta, total_depth++) { + if (cur->dfs_state == DFS_DONE) { + /* + * We've already seen this object and know it isn't + * part of a cycle. We do need to append its depth + * to our count. + */ + total_depth += cur->depth; + break; + } - switch (entry->dfs_state) { - case DFS_NONE: /* - * This is the first time we've seen the object. We mark it as - * part of the active potential cycle and recurse. + * We break cycles before looping, so an ACTIVE state (or any + * other cruft which made its way into the state variable) + * is a bug. */ - entry->dfs_state = DFS_ACTIVE; - break_delta_chains(entry->delta); - entry->dfs_state = DFS_DONE; - break; + if (cur->dfs_state != DFS_NONE) + die("BUG: confusing delta dfs state in first pass: %d", + cur->dfs_state); - case DFS_DONE: - /* object already examined, and not part of a cycle */ - break; + /* + * Now we know this is the first time we've seen the object. If + * it's not a delta, we're done traversing, but we'll mark it + * done to save time on future traversals. + */ + if (!cur->delta) { + cur->dfs_state = DFS_DONE; + break; + } - case DFS_ACTIVE: /* - * We found a cycle that needs broken. It would be correct to - * break any link in the chain, but it's convenient to - * break this one. + * Mark ourselves as active and see if the next step causes + * us to cycle to another active object. It's important to do + * this _before_ we loop, because it impacts where we make the + * cut, and thus how our total_depth counter works. + * E.g., We may see a partial loop like: + * + * A -> B -> C -> D -> B + * + * Cutting B->C breaks the cycle. But now the depth of A is + * only 1, and our total_depth counter is at 3. The size of the + * error is always one less than the size of the cycle we + * broke. Commits C and D were "lost" from A's chain. + * + * If we instead cut D->B, then the depth of A is correct at 3. + * We keep all commits in the chain that we examined. */ - drop_reused_delta(entry); - entry->dfs_state = DFS_DONE; - break; + cur->dfs_state = DFS_ACTIVE; + if (cur->delta->dfs_state == DFS_ACTIVE) { + drop_reused_delta(cur); + cur->dfs_state = DFS_DONE; + break; + } + } + + /* + * And now that we've gone all the way to the bottom of the chain, we + * need to clear the active flags and set the depth fields as + * appropriate. Unlike the loop above, which can quit when it drops a + * delta, we need to keep going to look for more depth cuts. So we need + * an extra "next" pointer to keep going after we reset cur->delta. + */ + for (cur = entry; cur; cur = next) { + next = cur->delta; + + /* + * We should have a chain of zero or more ACTIVE states down to + * a final DONE. We can quit after the DONE, because either it + * has no bases, or we've already handled them in a previous + * call. + */ + if (cur->dfs_state == DFS_DONE) + break; + else if (cur->dfs_state != DFS_ACTIVE) + die("BUG: confusing delta dfs state in second pass: %d", + cur->dfs_state); + + /* + * If the total_depth is more than depth, then we need to snip + * the chain into two or more smaller chains that don't exceed + * the maximum depth. Most of the resulting chains will contain + * (depth + 1) entries (i.e., depth deltas plus one base), and + * the last chain (i.e., the one containing entry) will contain + * whatever entries are left over, namely + * (total_depth % (depth + 1)) of them. + * + * Since we are iterating towards decreasing depth, we need to + * decrement total_depth as we go, and we need to write to the + * entry what its final depth will be after all of the + * snipping. Since we're snipping into chains of length (depth + * + 1) entries, the final depth of an entry will be its + * original depth modulo (depth + 1). Any time we encounter an + * entry whose final depth is supposed to be zero, we snip it + * from its delta base, thereby making it so. + */ + cur->depth = (total_depth--) % (depth + 1); + if (!cur->depth) + drop_reused_delta(cur); + + cur->dfs_state = DFS_DONE; } }