maintenance: test commit-graph auto condition

From: Derrick Stolee <[email protected]>

The auto condition for the commit-graph maintenance task walks refs looking for commits that are not in the commit-graph file. This was added in 4ddc79b2 (maintenance: add auto condition for commit-graph task, 2020-09-17) but was left untested.

The initial goal of this change was to demonstrate the feature works properly by adding tests. However, there was an off-by-one error that caused the basic tests around maintenance.commit-graph.auto=1 to fail when it should work.

The subtlety is that if a ref tip is not in the commit-graph, then we were not adding that to the total count. In the test, we see that we have only added one commit since our last commit-graph write, so the auto condition would say there is nothing to do.

The fix is simple: add the check for the commit-graph position to see that the tip is not in the commit-graph file before starting our walk. Since this happens before adding to the DFS stack, we do not need to clear our (currently empty) commit list.

This does add some extra complexity for the test, because we also want to verify that the walk along the parents actually does some work. This means we need to add at least two commits in a row without writing the commit-graph. However, we also need to make sure no additional refs are pointing to the middle of this list or else the for_each_ref() in should_write_commit_graph() might visit these commits as tips instead of doing a DFS walk. Hence, the last two commits are added with "git commit" instead of "test_commit".

---
maintenance: test commit-graph auto condition

As promised [1], here is a test to check that maintenance.commit-graph.auto behaves correctly. In the process, I found a small off-by-one error that is not super-critical, but worth fixing.

Thanks, -Stolee

[1]
https://lore.kernel.org/git/[email protected]/

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-746%2Fderrickstolee%2Fmaintenance%2Fcg-auto-test-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-746/derrickstolee/maintenance/cg-auto-test-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/746

 builtin/gc.c           |  8 +++++++-
 t/t7900-maintenance.sh | 29 +++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 1 deletion(-)

index 090959350e..12ddb68bba 100644
@@ -737,9 +737,15 @@ static int dfs_on_ref(const char *refname,
 	commit = lookup_commit(the_repository, oid);
 	if (!commit)
 		return 0;
-	if (parse_commit(commit))
+	if (parse_commit(commit) ||
+	    commit_graph_position(commit) != COMMIT_NOT_FROM_GRAPH)
 		return 0;
 
+	data->num_not_in_graph++;
+
+	if (data->num_not_in_graph >= data->limit)
+		return 1;
+
 	commit_list_append(commit, &stack);
 
 	while (!result && stack) {

index 53c883531e..3e16439bf6 100755
@@ -52,6 +52,35 @@ test_expect_success 'run --task=<task>' '
 	test_subcommand git commit-graph write --split --reachable --no-progress <run-both.txt
 '
 
+test_expect_success 'commit-graph auto condition' '
+	COMMAND="maintenance run --task=commit-graph --auto --quiet" &&
+
+	GIT_TRACE2_EVENT="$(pwd)/cg-no.txt" \
+		git -c maintenance.commit-graph.auto=1 $COMMAND &&
+	GIT_TRACE2_EVENT="$(pwd)/cg-negative-means-yes.txt" \
+		git -c maintenance.commit-graph.auto="-1" $COMMAND &&
+
+	test_commit one &&
+
+	GIT_TRACE2_EVENT="$(pwd)/cg-zero-means-no.txt" \
+		git -c maintenance.commit-graph.auto=0 $COMMAND &&
+	GIT_TRACE2_EVENT="$(pwd)/cg-one-satisfied.txt" \
+		git -c maintenance.commit-graph.auto=1 $COMMAND &&
+
+	git commit --allow-empty -m "two" &&
+	git commit --allow-empty -m "three" &&
+
+	GIT_TRACE2_EVENT="$(pwd)/cg-two-satisfied.txt" \
+		git -c maintenance.commit-graph.auto=2 $COMMAND &&
+
+	COMMIT_GRAPH_WRITE="git commit-graph write --split --reachable --no-progress" &&
+	test_subcommand ! $COMMIT_GRAPH_WRITE <cg-no.txt &&
+	test_subcommand $COMMIT_GRAPH_WRITE <cg-negative-means-yes.txt &&
+	test_subcommand ! $COMMIT_GRAPH_WRITE <cg-zero-means-no.txt &&
+	test_subcommand $COMMIT_GRAPH_WRITE <cg-one-satisfied.txt &&
+	test_subcommand $COMMIT_GRAPH_WRITE <cg-two-satisfied.txt
+'
+
 test_expect_success 'run --task=bogus' '
 	test_must_fail git maintenance run --task=bogus 2>err &&
 	test_i18ngrep "is not a valid task" err

base-commit: 25914c4fdeefd99b06e134496dfb9bbb58a5c417

gitgitgadget

Hmph. Something in ds/maintenance-part-2 series does not seem to work well with this change. I noticed it when testing today's first integration cycle of jch and seen branches, but even when applied to ds/maintenance-part-2 alone without any other topics in seen, it seems to break in an unexpected place.

    $ git checkout -b ds/maintenance-commit-graph-auto-fix
    $ git am -s $this_message
    $ git checkout ds/maintenance-part-2^0
    $ git cherry-pick ds/maintenance-commit-graph-auto-fix
    $ make && (cd t && sh t7900-maintenance.sh -i -v)
    ...
    expecting success of 7900.9 'prefetch multiple remotes':
    ...
    Cloning into 'clone1'...
    done.
    Cloning into 'clone2'...
    done.
    Switched to a new branch 'one'
    Switched to a new branch 'two'
    On branch one
    nothing to commit, working tree clean
    not ok 9 - prefetch multiple remotes

Perhaps the new test added here breaks the expectation of tests added in the other series?

Thank you for alerting me to this. I should have ran the tests after merging with the other branches in progress.

It seems my issue is that I use "test_commit one" in two places now, so the second complains that nothing is new to commit.

The simplest fix is to use "first", "second", and "third" in this patch, so I'll send a v2 soon with that change.

Thanks,
-Stolee

From: Derrick Stolee <[email protected]>

The auto condition for the commit-graph maintenance task walks refs looking for commits that are not in the commit-graph file. This was added in 4ddc79b2 (maintenance: add auto condition for commit-graph task, 2020-09-17) but was left untested.

The initial goal of this change was to demonstrate the feature works properly by adding tests. However, there was an off-by-one error that caused the basic tests around maintenance.commit-graph.auto=1 to fail when it should work.

The subtlety is that if a ref tip is not in the commit-graph, then we were not adding that to the total count. In the test, we see that we have only added one commit since our last commit-graph write, so the auto condition would say there is nothing to do.

The fix is simple: add the check for the commit-graph position to see that the tip is not in the commit-graph file before starting our walk. Since this happens before adding to the DFS stack, we do not need to clear our (currently empty) commit list.

This does add some extra complexity for the test, because we also want to verify that the walk along the parents actually does some work. This means we need to add at least two commits in a row without writing the commit-graph. However, we also need to make sure no additional refs are pointing to the middle of this list or else the for_each_ref() in should_write_commit_graph() might visit these commits as tips instead of doing a DFS walk. Hence, the last two commits are added with "git commit" instead of "test_commit".

---
maintenance: test commit-graph auto condition

As promised [1], here is a test to check that maintenance.commit-graph.auto behaves correctly. In the process, I found a small off-by-one error that is not super-critical, but worth fixing.

This is based on ds/maintenance-part-1, but my GGG pull request targets ds/maintenance-part-3 to make sure it merges cleanly and the result builds & tests cleanly.

Thanks, -Stolee

[1]
https://lore.kernel.org/git/[email protected]/

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-746%2Fderrickstolee%2Fmaintenance%2Fcg-auto-test-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-746/derrickstolee/maintenance/cg-auto-test-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/746

Range-diff vs v1:

1: 39223f21fb ! 1: 984ee2d9c0 maintenance: test commit-graph auto condition

     @@ t/t7900-maintenance.sh: test_expect_success 'run --task=<task>' '
      +	GIT_TRACE2_EVENT="$(pwd)/cg-negative-means-yes.txt" \
      +		git -c maintenance.commit-graph.auto="-1" $COMMAND &&
      +
     -+	test_commit one &&
     ++	test_commit first &&
      +
      +	GIT_TRACE2_EVENT="$(pwd)/cg-zero-means-no.txt" \
      +		git -c maintenance.commit-graph.auto=0 $COMMAND &&
      +	GIT_TRACE2_EVENT="$(pwd)/cg-one-satisfied.txt" \
      +		git -c maintenance.commit-graph.auto=1 $COMMAND &&
      +
     -+	git commit --allow-empty -m "two" &&
     -+	git commit --allow-empty -m "three" &&
     ++	git commit --allow-empty -m "second" &&
     ++	git commit --allow-empty -m "third" &&
      +
      +	GIT_TRACE2_EVENT="$(pwd)/cg-two-satisfied.txt" \
      +		git -c maintenance.commit-graph.auto=2 $COMMAND &&

 builtin/gc.c           |  8 +++++++-
 t/t7900-maintenance.sh | 29 +++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 1 deletion(-)

index 090959350e..12ddb68bba 100644
@@ -737,9 +737,15 @@ static int dfs_on_ref(const char *refname,
 	commit = lookup_commit(the_repository, oid);
 	if (!commit)
 		return 0;
-	if (parse_commit(commit))
+	if (parse_commit(commit) ||
+	    commit_graph_position(commit) != COMMIT_NOT_FROM_GRAPH)
 		return 0;
 
+	data->num_not_in_graph++;
+
+	if (data->num_not_in_graph >= data->limit)
+		return 1;
+
 	commit_list_append(commit, &stack);
 
 	while (!result && stack) {

index 53c883531e..ee1f4a7ae4 100755
@@ -52,6 +52,35 @@ test_expect_success 'run --task=<task>' '
 	test_subcommand git commit-graph write --split --reachable --no-progress <run-both.txt
 '
 
+test_expect_success 'commit-graph auto condition' '
+	COMMAND="maintenance run --task=commit-graph --auto --quiet" &&
+
+	GIT_TRACE2_EVENT="$(pwd)/cg-no.txt" \
+		git -c maintenance.commit-graph.auto=1 $COMMAND &&
+	GIT_TRACE2_EVENT="$(pwd)/cg-negative-means-yes.txt" \
+		git -c maintenance.commit-graph.auto="-1" $COMMAND &&
+
+	test_commit first &&
+
+	GIT_TRACE2_EVENT="$(pwd)/cg-zero-means-no.txt" \
+		git -c maintenance.commit-graph.auto=0 $COMMAND &&
+	GIT_TRACE2_EVENT="$(pwd)/cg-one-satisfied.txt" \
+		git -c maintenance.commit-graph.auto=1 $COMMAND &&
+
+	git commit --allow-empty -m "second" &&
+	git commit --allow-empty -m "third" &&
+
+	GIT_TRACE2_EVENT="$(pwd)/cg-two-satisfied.txt" \
+		git -c maintenance.commit-graph.auto=2 $COMMAND &&
+
+	COMMIT_GRAPH_WRITE="git commit-graph write --split --reachable --no-progress" &&
+	test_subcommand ! $COMMIT_GRAPH_WRITE <cg-no.txt &&
+	test_subcommand $COMMIT_GRAPH_WRITE <cg-negative-means-yes.txt &&
+	test_subcommand ! $COMMIT_GRAPH_WRITE <cg-zero-means-no.txt &&
+	test_subcommand $COMMIT_GRAPH_WRITE <cg-one-satisfied.txt &&
+	test_subcommand $COMMIT_GRAPH_WRITE <cg-two-satisfied.txt
+'
+
 test_expect_success 'run --task=bogus' '
 	test_must_fail git maintenance run --task=bogus 2>err &&
 	test_i18ngrep "is not a valid task" err

base-commit: 25914c4fdeefd99b06e134496dfb9bbb58a5c417

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