ref-filter: use generation number for --contains
A commit A can reach a commit B only if the generation number of A is strictly larger than the generation number of B. This condition allows significantly short-circuiting commit-graph walks. Use generation number for '--contains' type queries. On a copy of the Linux repository where HEAD is contained in v4.13 but no earlier tag, the command 'git tag --contains HEAD' had the following peformance improvement: Before: 0.81s After: 0.04s Rel %: -95% Helped-by: Jeff King <peff@peff.net> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Derrick Stolee committed
May 1, 2018 at 12:47 UTC
819807b33f820dc17d96f043747daf18c5e38516
1 file changed
+20
-4
ref-filter.c
+20
-4
@@ -16,6 +16,7 @@
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#include "trailer.h"
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#include "wt-status.h"
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#include "commit-slab.h"
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+#include "commit-graph.h"
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static struct ref_msg {
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const char *gone;
@@ -1587,7 +1588,8 @@ static int in_commit_list(const struct commit_list *want, struct commit *c)
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*/
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static enum contains_result contains_test(struct commit *candidate,
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const struct commit_list *want,
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- struct contains_cache *cache)
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+ struct contains_cache *cache,
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+ uint32_t cutoff)
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{
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enum contains_result *cached = contains_cache_at(cache, candidate);
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@@ -1603,6 +1605,10 @@ static enum contains_result contains_test(struct commit *candidate,
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/* Otherwise, we don't know; prepare to recurse */
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parse_commit_or_die(candidate);
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+
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+ if (candidate->generation < cutoff)
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+ return CONTAINS_NO;
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+
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return CONTAINS_UNKNOWN;
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}
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@@ -1618,8 +1624,18 @@ static enum contains_result contains_tag_algo(struct commit *candidate,
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struct contains_cache *cache)
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{
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struct contains_stack contains_stack = { 0, 0, NULL };
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- enum contains_result result = contains_test(candidate, want, cache);
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+ enum contains_result result;
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+ uint32_t cutoff = GENERATION_NUMBER_INFINITY;
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+ const struct commit_list *p;
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+
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+ for (p = want; p; p = p->next) {
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+ struct commit *c = p->item;
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+ load_commit_graph_info(c);
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+ if (c->generation < cutoff)
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+ cutoff = c->generation;
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+ }
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+ result = contains_test(candidate, want, cache, cutoff);
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if (result != CONTAINS_UNKNOWN)
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return result;
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@@ -1637,7 +1653,7 @@ static enum contains_result contains_tag_algo(struct commit *candidate,
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* If we just popped the stack, parents->item has been marked,
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* therefore contains_test will return a meaningful yes/no.
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*/
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- else switch (contains_test(parents->item, want, cache)) {
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+ else switch (contains_test(parents->item, want, cache, cutoff)) {
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case CONTAINS_YES:
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*contains_cache_at(cache, commit) = CONTAINS_YES;
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contains_stack.nr--;
@@ -1651,7 +1667,7 @@ static enum contains_result contains_tag_algo(struct commit *candidate,
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}
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}
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free(contains_stack.contains_stack);
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- return contains_test(candidate, want, cache);
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+ return contains_test(candidate, want, cache, cutoff);
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}
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static int commit_contains(struct ref_filter *filter, struct commit *commit,