Merge branch 'tb/bloom-improvements'

"git commit-graph write" learned to limit the number of bloom
filters that are computed from scratch with the --max-new-filters
option.

* tb/bloom-improvements:
  commit-graph: introduce 'commitGraph.maxNewFilters'
  builtin/commit-graph.c: introduce '--max-new-filters=<n>'
  commit-graph: rename 'split_commit_graph_opts'
  bloom: encode out-of-bounds filters as non-empty
  bloom/diff: properly short-circuit on max_changes
  bloom: use provided 'struct bloom_filter_settings'
  bloom: split 'get_bloom_filter()' in two
  commit-graph.c: store maximum changed paths
  commit-graph: respect 'commitGraph.readChangedPaths'
  t/helper/test-read-graph.c: prepare repo settings
  commit-graph: pass a 'struct repository *' in more places
  t4216: use an '&&'-chain
  commit-graph: introduce 'get_bloom_filter_settings()'

4 files changed, 18 insertions, 1 deletions

diff --git a/Documentation/config.txt b/Documentation/config.txt
index f93b6837e4..bf706b950e 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -340,6 +340,8 @@ include::config/column.txt[]
 
 include::config/commit.txt[]
 
+include::config/commitgraph.txt[]
+
 include::config/credential.txt[]
 
 include::config/completion.txt[]
diff --git a/Documentation/config/commitgraph.txt b/Documentation/config/commitgraph.txt
new file mode 100644
index 0000000000..4582c39fc4
--- /dev/null
+++ b/Documentation/config/commitgraph.txt
@@ -0,0 +1,8 @@
+commitGraph.maxNewFilters::
+	Specifies the default value for the `--max-new-filters` option of `git
+	commit-graph write` (c.f., linkgit:git-commit-graph[1]).
+
+commitGraph.readChangedPaths::
+	If true, then git will use the changed-path Bloom filters in the
+	commit-graph file (if it exists, and they are present). Defaults to
+	true. See linkgit:git-commit-graph[1] for more information.
diff --git a/Documentation/git-commit-graph.txt b/Documentation/git-commit-graph.txt
index 17405c73a9..de6b6de230 100644
--- a/Documentation/git-commit-graph.txt
+++ b/Documentation/git-commit-graph.txt
@@ -67,6 +67,13 @@ this option is given, future commit-graph writes will automatically assume
 that this option was intended. Use `--no-changed-paths` to stop storing this
 data.
 +
+With the `--max-new-filters=<n>` option, generate at most `n` new Bloom
+filters (if `--changed-paths` is specified). If `n` is `-1`, no limit is
+enforced. Only commits present in the new layer count against this
+limit. To retroactively compute Bloom filters over earlier layers, it is
+advised to use `--split=replace`.  Overrides the `commitGraph.maxNewFilters`
+configuration.
++
 With the `--split[=<strategy>]` option, write the commit-graph as a
 chain of multiple commit-graph files stored in
 `<dir>/info/commit-graphs`. Commit-graph layers are merged based on the
diff --git a/Documentation/technical/commit-graph-format.txt b/Documentation/technical/commit-graph-format.txt
index 1f86031333..b3b58880b9 100644
--- a/Documentation/technical/commit-graph-format.txt
+++ b/Documentation/technical/commit-graph-format.txt
@@ -125,7 +125,7 @@ CHUNK DATA:
     * The rest of the chunk is the concatenation of all the computed Bloom
       filters for the commits in lexicographic order.
     * Note: Commits with no changes or more than 512 changes have Bloom filters
-      of length zero.
+      of length one, with either all bits set to zero or one respectively.
     * The BDAT chunk is present if and only if BIDX is present.
 
   Base Graphs List (ID: {'B', 'A', 'S', 'E'}) [Optional]