[RFC PATCH 03/13] commit-reach: move commit_contains from ref-filter

[Derrick Stolee <dstolee@microsoft.com>]

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 commit-reach.c | 119 +++++++++++++++++++++++++++++++++++++++
 commit-reach.h |  44 +++++----------
 fast-import.c  |   1 +
 ref-filter.c   | 147 +++----------------------------------------------
 4 files changed, 141 insertions(+), 170 deletions(-)

diff --git a/commit-reach.c b/commit-reach.c
index 80cdb738f6..6cfd7379ce 100644
--- a/commit-reach.c
+++ b/commit-reach.c
@@ -409,3 +409,122 @@ int ref_newer(const struct object_id *new_oid, const struct object_id *old_oid)
 	unmark_and_free(used, TMP_MARK);
 	return found;
 }
+
+/*
+ * Mimicking the real stack, this stack lives on the heap, avoiding stack
+ * overflows.
+ *
+ * At each recursion step, the stack items points to the commits whose
+ * ancestors are to be inspected.
+ */
+struct contains_stack {
+	int nr, alloc;
+	struct contains_stack_entry {
+		struct commit *commit;
+		struct commit_list *parents;
+	} *contains_stack;
+};
+
+static int in_commit_list(const struct commit_list *want, struct commit *c)
+{
+	for (; want; want = want->next)
+		if (!oidcmp(&want->item->object.oid, &c->object.oid))
+			return 1;
+	return 0;
+}
+
+/*
+ * Test whether the candidate is contained in the list.
+ * Do not recurse to find out, though, but return -1 if inconclusive.
+ */
+static enum contains_result contains_test(struct commit *candidate,
+					  const struct commit_list *want,
+					  struct contains_cache *cache,
+					  uint32_t cutoff)
+{
+	enum contains_result *cached = contains_cache_at(cache, candidate);
+
+	/* If we already have the answer cached, return that. */
+	if (*cached)
+		return *cached;
+
+	/* or are we it? */
+	if (in_commit_list(want, candidate)) {
+		*cached = CONTAINS_YES;
+		return CONTAINS_YES;
+	}
+
+	/* Otherwise, we don't know; prepare to recurse */
+	parse_commit_or_die(candidate);
+
+	if (candidate->generation < cutoff)
+		return CONTAINS_NO;
+
+	return CONTAINS_UNKNOWN;
+}
+
+static void push_to_contains_stack(struct commit *candidate, struct contains_stack *contains_stack)
+{
+	ALLOC_GROW(contains_stack->contains_stack, contains_stack->nr + 1, contains_stack->alloc);
+	contains_stack->contains_stack[contains_stack->nr].commit = candidate;
+	contains_stack->contains_stack[contains_stack->nr++].parents = candidate->parents;
+}
+
+static enum contains_result contains_tag_algo(struct commit *candidate,
+					      const struct commit_list *want,
+					      struct contains_cache *cache)
+{
+	struct contains_stack contains_stack = { 0, 0, NULL };
+	enum contains_result result;
+	uint32_t cutoff = GENERATION_NUMBER_INFINITY;
+	const struct commit_list *p;
+
+	for (p = want; p; p = p->next) {
+		struct commit *c = p->item;
+		load_commit_graph_info(c);
+		if (c->generation < cutoff)
+			cutoff = c->generation;
+	}
+
+	result = contains_test(candidate, want, cache, cutoff);
+	if (result != CONTAINS_UNKNOWN)
+		return result;
+
+	push_to_contains_stack(candidate, &contains_stack);
+	while (contains_stack.nr) {
+		struct contains_stack_entry *entry = &contains_stack.contains_stack[contains_stack.nr - 1];
+		struct commit *commit = entry->commit;
+		struct commit_list *parents = entry->parents;
+
+		if (!parents) {
+			*contains_cache_at(cache, commit) = CONTAINS_NO;
+			contains_stack.nr--;
+		}
+		/*
+		 * If we just popped the stack, parents->item has been marked,
+		 * therefore contains_test will return a meaningful yes/no.
+		 */
+		else switch (contains_test(parents->item, want, cache, cutoff)) {
+		case CONTAINS_YES:
+			*contains_cache_at(cache, commit) = CONTAINS_YES;
+			contains_stack.nr--;
+			break;
+		case CONTAINS_NO:
+			entry->parents = parents->next;
+			break;
+		case CONTAINS_UNKNOWN:
+			push_to_contains_stack(parents->item, &contains_stack);
+			break;
+		}
+	}
+	free(contains_stack.contains_stack);
+	return contains_test(candidate, want, cache, cutoff);
+}
+
+int commit_contains(struct ref_filter *filter, struct commit *commit,
+		    struct commit_list *list, struct contains_cache *cache)
+{
+	if (filter->with_commit_tag_algo)
+		return contains_tag_algo(commit, list, cache) == CONTAINS_YES;
+	return is_descendant_of(commit, list);
+}
diff --git a/commit-reach.h b/commit-reach.h
index 35ec9f0ddb..986fb388d5 100644
--- a/commit-reach.h
+++ b/commit-reach.h
@@ -2,42 +2,24 @@
 #define __COMMIT_REACH_H__
 
 #include "commit.h"
+#include "commit-slab.h"
+#include "ref-filter.h"
 
-struct commit_list *get_merge_bases_many(struct commit *one,
-					 int n,
-					 struct commit **twos);
-struct commit_list *get_merge_bases_many_dirty(struct commit *one,
-					       int n,
-					       struct commit **twos);
-struct commit_list *get_merge_bases(struct commit *one, struct commit *two);
-struct commit_list *get_octopus_merge_bases(struct commit_list *in);
-
-/* To be used only when object flags after this call no longer matter */
-struct commit_list *get_merge_bases_many_dirty(struct commit *one, int n, struct commit **twos);
-
-int is_descendant_of(struct commit *commit, struct commit_list *with_commit);
-int in_merge_bases_many(struct commit *commit, int nr_reference, struct commit **reference);
-int in_merge_bases(struct commit *commit, struct commit *reference);
-
+int ref_newer(const struct object_id *new_oid, const struct object_id *old_oid);
 
 /*
- * Takes a list of commits and returns a new list where those
- * have been removed that can be reached from other commits in
- * the list. It is useful for, e.g., reducing the commits
- * randomly thrown at the git-merge command and removing
- * redundant commits that the user shouldn't have given to it.
- *
- * This function destroys the STALE bit of the commit objects'
- * flags.
+ * Unknown has to be "0" here, because that's the default value for
+ * contains_cache slab entries that have not yet been assigned.
  */
-struct commit_list *reduce_heads(struct commit_list *heads);
+enum contains_result {
+	CONTAINS_UNKNOWN = 0,
+	CONTAINS_NO,
+	CONTAINS_YES
+};
 
-/*
- * Like `reduce_heads()`, except it replaces the list. Use this
- * instead of `foo = reduce_heads(foo);` to avoid memory leaks.
- */
-void reduce_heads_replace(struct commit_list **heads);
+define_commit_slab(contains_cache, enum contains_result);
 
-int ref_newer(const struct object_id *new_oid, const struct object_id *old_oid);
+int commit_contains(struct ref_filter *filter, struct commit *commit,
+		    struct commit_list *list, struct contains_cache *cache);
 
 #endif
diff --git a/fast-import.c b/fast-import.c
index 4d55910ab9..49ce8e8426 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -171,6 +171,7 @@ Format of STDIN stream:
 #include "packfile.h"
 #include "object-store.h"
 #include "mem-pool.h"
+#include "commit-reach.h"
 
 #define PACK_ID_BITS 16
 #define MAX_PACK_ID ((1<<PACK_ID_BITS)-1)
diff --git a/ref-filter.c b/ref-filter.c
index fa3685d91f..f4f71728ae 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -16,7 +16,7 @@
 #include "trailer.h"
 #include "wt-status.h"
 #include "commit-slab.h"
-#include "commit-graph.h"
+#include "commit-reach.h"
 
 static struct ref_msg {
 	const char *gone;
@@ -1620,144 +1620,6 @@ static int get_ref_atom_value(struct ref_array_item *ref, int atom,
 	return 0;
 }
 
-/*
- * Unknown has to be "0" here, because that's the default value for
- * contains_cache slab entries that have not yet been assigned.
- */
-enum contains_result {
-	CONTAINS_UNKNOWN = 0,
-	CONTAINS_NO,
-	CONTAINS_YES
-};
-
-define_commit_slab(contains_cache, enum contains_result);
-
-struct ref_filter_cbdata {
-	struct ref_array *array;
-	struct ref_filter *filter;
-	struct contains_cache contains_cache;
-	struct contains_cache no_contains_cache;
-};
-
-/*
- * Mimicking the real stack, this stack lives on the heap, avoiding stack
- * overflows.
- *
- * At each recursion step, the stack items points to the commits whose
- * ancestors are to be inspected.
- */
-struct contains_stack {
-	int nr, alloc;
-	struct contains_stack_entry {
-		struct commit *commit;
-		struct commit_list *parents;
-	} *contains_stack;
-};
-
-static int in_commit_list(const struct commit_list *want, struct commit *c)
-{
-	for (; want; want = want->next)
-		if (!oidcmp(&want->item->object.oid, &c->object.oid))
-			return 1;
-	return 0;
-}
-
-/*
- * Test whether the candidate is contained in the list.
- * Do not recurse to find out, though, but return -1 if inconclusive.
- */
-static enum contains_result contains_test(struct commit *candidate,
-					  const struct commit_list *want,
-					  struct contains_cache *cache,
-					  uint32_t cutoff)
-{
-	enum contains_result *cached = contains_cache_at(cache, candidate);
-
-	/* If we already have the answer cached, return that. */
-	if (*cached)
-		return *cached;
-
-	/* or are we it? */
-	if (in_commit_list(want, candidate)) {
-		*cached = CONTAINS_YES;
-		return CONTAINS_YES;
-	}
-
-	/* Otherwise, we don't know; prepare to recurse */
-	parse_commit_or_die(candidate);
-
-	if (candidate->generation < cutoff)
-		return CONTAINS_NO;
-
-	return CONTAINS_UNKNOWN;
-}
-
-static void push_to_contains_stack(struct commit *candidate, struct contains_stack *contains_stack)
-{
-	ALLOC_GROW(contains_stack->contains_stack, contains_stack->nr + 1, contains_stack->alloc);
-	contains_stack->contains_stack[contains_stack->nr].commit = candidate;
-	contains_stack->contains_stack[contains_stack->nr++].parents = candidate->parents;
-}
-
-static enum contains_result contains_tag_algo(struct commit *candidate,
-					      const struct commit_list *want,
-					      struct contains_cache *cache)
-{
-	struct contains_stack contains_stack = { 0, 0, NULL };
-	enum contains_result result;
-	uint32_t cutoff = GENERATION_NUMBER_INFINITY;
-	const struct commit_list *p;
-
-	for (p = want; p; p = p->next) {
-		struct commit *c = p->item;
-		load_commit_graph_info(c);
-		if (c->generation < cutoff)
-			cutoff = c->generation;
-	}
-
-	result = contains_test(candidate, want, cache, cutoff);
-	if (result != CONTAINS_UNKNOWN)
-		return result;
-
-	push_to_contains_stack(candidate, &contains_stack);
-	while (contains_stack.nr) {
-		struct contains_stack_entry *entry = &contains_stack.contains_stack[contains_stack.nr - 1];
-		struct commit *commit = entry->commit;
-		struct commit_list *parents = entry->parents;
-
-		if (!parents) {
-			*contains_cache_at(cache, commit) = CONTAINS_NO;
-			contains_stack.nr--;
-		}
-		/*
-		 * If we just popped the stack, parents->item has been marked,
-		 * therefore contains_test will return a meaningful yes/no.
-		 */
-		else switch (contains_test(parents->item, want, cache, cutoff)) {
-		case CONTAINS_YES:
-			*contains_cache_at(cache, commit) = CONTAINS_YES;
-			contains_stack.nr--;
-			break;
-		case CONTAINS_NO:
-			entry->parents = parents->next;
-			break;
-		case CONTAINS_UNKNOWN:
-			push_to_contains_stack(parents->item, &contains_stack);
-			break;
-		}
-	}
-	free(contains_stack.contains_stack);
-	return contains_test(candidate, want, cache, cutoff);
-}
-
-static int commit_contains(struct ref_filter *filter, struct commit *commit,
-			   struct commit_list *list, struct contains_cache *cache)
-{
-	if (filter->with_commit_tag_algo)
-		return contains_tag_algo(commit, list, cache) == CONTAINS_YES;
-	return is_descendant_of(commit, list);
-}
-
 /*
  * Return 1 if the refname matches one of the patterns, otherwise 0.
  * A pattern can be a literal prefix (e.g. a refname "refs/heads/master"
@@ -1984,6 +1846,13 @@ static int filter_ref_kind(struct ref_filter *filter, const char *refname)
 	return ref_kind_from_refname(refname);
 }
 
+struct ref_filter_cbdata {
+       struct ref_array *array;
+       struct ref_filter *filter;
+       struct contains_cache contains_cache;
+       struct contains_cache no_contains_cache;
+};
+
 /*
  * A call-back given to for_each_ref().  Filter refs and keep them for
  * later object processing.
-- 
2.18.0.118.gd4f65b8d14