pseudo-merge: implement support for selecting pseudo-merge commits

Teach the new pseudo-merge machinery how to select non-bitmapped commits
for inclusion in different pseudo-merge group(s) based on a handful of
criteria.

Note that the selected pseudo-merge commits aren't actually used or
written anywhere yet. This will be done in the following commit.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 94 insertions, 0 deletions

diff --git a/pseudo-merge.h b/pseudo-merge.h
index cab8ff6960..f809cf42ae 100644
--- a/pseudo-merge.h
+++ b/pseudo-merge.h
@@ -2,5 +2,99 @@
 #define PSEUDO_MERGE_H
 
 #include "git-compat-util.h"
+#include "strmap.h"
+#include "khash.h"
+#include "ewah/ewok.h"
+
+struct commit;
+struct string_list;
+struct bitmap_index;
+struct bitmap_writer;
+
+/*
+ * A pseudo-merge group tracks the set of non-bitmapped reference tips
+ * that match the given pattern.
+ *
+ * Within those matches, they are further segmented by separating
+ * consecutive capture groups with '-' dash character capture groups
+ * with '-' dash characters.
+ *
+ * Those groups are then ordered by committer date and partitioned
+ * into individual pseudo-merge(s) according to the decay, max_merges,
+ * sample_rate, and threshold parameters.
+ */
+struct pseudo_merge_group {
+	regex_t *pattern;
+
+	/* capture group(s) -> struct pseudo_merge_matches */
+	struct strmap matches;
+
+	/*
+	 * The individual pseudo-merge(s) that are generated from the
+	 * above array of matches, partitioned according to the below
+	 * parameters.
+	 */
+	struct commit **merges;
+	size_t merges_nr;
+	size_t merges_alloc;
+
+	/*
+	 * Pseudo-merge grouping parameters. See git-config(1) for
+	 * more information.
+	 */
+	double decay;
+	int max_merges;
+	double sample_rate;
+	int stable_size;
+	timestamp_t threshold;
+	timestamp_t stable_threshold;
+};
+
+struct pseudo_merge_matches {
+	struct commit **stable;
+	struct commit **unstable;
+	size_t stable_nr, stable_alloc;
+	size_t unstable_nr, unstable_alloc;
+};
+
+/*
+ * Read the repository's configuration:
+ *
+ *   - bitmapPseudoMerge.<name>.pattern
+ *   - bitmapPseudoMerge.<name>.decay
+ *   - bitmapPseudoMerge.<name>.sampleRate
+ *   - bitmapPseudoMerge.<name>.threshold
+ *   - bitmapPseudoMerge.<name>.maxMerges
+ *   - bitmapPseudoMerge.<name>.stableThreshold
+ *   - bitmapPseudoMerge.<name>.stableSize
+ *
+ * and populates the given `list` with pseudo-merge groups. String
+ * entry keys are the pseudo-merge group names, and the values are
+ * pointers to the pseudo_merge_group structure itself.
+ */
+void load_pseudo_merges_from_config(struct string_list *list);
+
+/*
+ * A pseudo-merge commit index (pseudo_merge_commit_idx) maps a
+ * particular (non-pseudo-merge) commit to the list of pseudo-merge(s)
+ * it appears in.
+ */
+struct pseudo_merge_commit_idx {
+	uint32_t *pseudo_merge;
+	size_t nr, alloc;
+};
+
+/*
+ * Selects pseudo-merges from a list of commits, populating the given
+ * string_list of pseudo-merge groups.
+ *
+ * Populates the pseudo_merge_commits map with a commit_idx
+ * corresponding to each commit in the list. Counts the total number
+ * of pseudo-merges generated.
+ *
+ * Optionally shows a progress meter.
+ */
+void select_pseudo_merges(struct bitmap_writer *writer,
+			  struct commit **commits, size_t commits_nr);
 
 #endif