Merge branch 'ps/reftable-exclude' into seen

The reftable backend learned to more efficiently handle exclude
patterns while enumerating the refs.

* ps/reftable-exclude:
  refs/reftable: wire up support for exclude patterns
  reftable/reader: make table iterator reseekable
  t/unit-tests: introduce reftable library
  Makefile: stop listing test library objects twice
  builtin/receive-pack: fix exclude patterns when announcing refs
  refs: properly apply exclude patterns to namespaced refs

Makefile

@@ -1362,6 +1362,7 @@ UNIT_TEST_PROGRAMS += t-reftable-basics
 UNIT_TEST_PROGRAMS += t-reftable-block
 UNIT_TEST_PROGRAMS += t-reftable-merged
 UNIT_TEST_PROGRAMS += t-reftable-pq
+UNIT_TEST_PROGRAMS += t-reftable-reader
 UNIT_TEST_PROGRAMS += t-reftable-readwrite
 UNIT_TEST_PROGRAMS += t-reftable-record
 UNIT_TEST_PROGRAMS += t-reftable-stack
@@ -1371,9 +1372,9 @@ UNIT_TEST_PROGRAMS += t-strcmp-offset
 UNIT_TEST_PROGRAMS += t-trailer
 UNIT_TEST_PROGRAMS += t-urlmatch-normalization
 UNIT_TEST_PROGS = $(patsubst %,$(UNIT_TEST_BIN)/%$X,$(UNIT_TEST_PROGRAMS))
-UNIT_TEST_OBJS = $(patsubst %,$(UNIT_TEST_DIR)/%.o,$(UNIT_TEST_PROGRAMS))
 UNIT_TEST_OBJS += $(UNIT_TEST_DIR)/test-lib.o
 UNIT_TEST_OBJS += $(UNIT_TEST_DIR)/lib-oid.o
+UNIT_TEST_OBJS += $(UNIT_TEST_DIR)/lib-reftable.o
 
 # xdiff and reftable libs may in turn depend on what is in libgit.a
 GITLIBS = common-main.o $(LIB_FILE) $(XDIFF_LIB) $(REFTABLE_LIB) $(LIB_FILE)
@@ -2755,6 +2756,7 @@ OBJECTS += $(FUZZ_OBJS)
 OBJECTS += $(REFTABLE_OBJS) $(REFTABLE_TEST_OBJS)
 OBJECTS += $(UNIT_TEST_OBJS)
 OBJECTS += $(UNIT_TESTS_OBJS)
+OBJECTS += $(patsubst %,$(UNIT_TEST_DIR)/%.o,$(UNIT_TEST_PROGRAMS))
 
 ifndef NO_CURL
 	OBJECTS += http.o http-walker.o remote-curl.o
@@ -3894,9 +3896,7 @@ $(FUZZ_PROGRAMS): %: %.o oss-fuzz/dummy-cmd-main.o $(GITLIBS) GIT-LDFLAGS
 		-Wl,--allow-multiple-definition \
 		$(filter %.o,$^) $(filter %.a,$^) $(LIBS) $(LIB_FUZZING_ENGINE)
 
-$(UNIT_TEST_PROGS): $(UNIT_TEST_BIN)/%$X: $(UNIT_TEST_DIR)/%.o \
-	$(UNIT_TEST_DIR)/test-lib.o \
-	$(UNIT_TEST_DIR)/lib-oid.o \
+$(UNIT_TEST_PROGS): $(UNIT_TEST_BIN)/%$X: $(UNIT_TEST_DIR)/%.o $(UNIT_TEST_OBJS) \
 	$(GITLIBS) GIT-LDFLAGS
 	$(call mkdir_p_parent_template)
 	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) \

builtin/receive-pack.c

@@ -340,12 +340,26 @@ static void show_one_alternate_ref(const struct object_id *oid,
 static void write_head_info(void)
 {
 	static struct oidset seen = OIDSET_INIT;
+	struct strvec excludes_vector = STRVEC_INIT;
+	const char **exclude_patterns;
+
+	/*
+	 * We need access to the reference names both with and without their
+	 * namespace and thus cannot use `refs_for_each_namespaced_ref()`. We
+	 * thus have to adapt exclude patterns to carry the namespace prefix
+	 * ourselves.
+	 */
+	exclude_patterns = get_namespaced_exclude_patterns(
+		hidden_refs_to_excludes(&hidden_refs),
+		get_git_namespace(), &excludes_vector);
 
 	refs_for_each_fullref_in(get_main_ref_store(the_repository), "",
-				 hidden_refs_to_excludes(&hidden_refs),
-				 show_ref_cb, &seen);
+				 exclude_patterns, show_ref_cb, &seen);
 	for_each_alternate_ref(show_one_alternate_ref, &seen);
+
 	oidset_clear(&seen);
+	strvec_clear(&excludes_vector);
+
 	if (!sent_capabilities)
 		show_ref("capabilities^{}", null_oid());
 

refs.c

@@ -1518,6 +1518,19 @@ const char **hidden_refs_to_excludes(const struct strvec *hide_refs)
 	return hide_refs->v;
 }
 
+const char **get_namespaced_exclude_patterns(const char **exclude_patterns,
+					     const char *namespace,
+					     struct strvec *out)
+{
+	if (!namespace || !*namespace || !exclude_patterns || !*exclude_patterns)
+		return exclude_patterns;
+
+	for (size_t i = 0; exclude_patterns[i]; i++)
+		strvec_pushf(out, "%s%s", namespace, exclude_patterns[i]);
+
+	return out->v;
+}
+
 const char *find_descendant_ref(const char *dirname,
 				const struct string_list *extras,
 				const struct string_list *skip)
@@ -1635,11 +1648,19 @@ int refs_for_each_namespaced_ref(struct ref_store *refs,
 				 const char **exclude_patterns,
 				 each_ref_fn fn, void *cb_data)
 {
-	struct strbuf buf = STRBUF_INIT;
+	struct strvec namespaced_exclude_patterns = STRVEC_INIT;
+	struct strbuf prefix = STRBUF_INIT;
 	int ret;
-	strbuf_addf(&buf, "%srefs/", get_git_namespace());
-	ret = do_for_each_ref(refs, buf.buf, exclude_patterns, fn, 0, 0, cb_data);
-	strbuf_release(&buf);
+
+	exclude_patterns = get_namespaced_exclude_patterns(exclude_patterns,
+							   get_git_namespace(),
+							   &namespaced_exclude_patterns);
+
+	strbuf_addf(&prefix, "%srefs/", get_git_namespace());
+	ret = do_for_each_ref(refs, prefix.buf, exclude_patterns, fn, 0, 0, cb_data);
+
+	strvec_clear(&namespaced_exclude_patterns);
+	strbuf_release(&prefix);
 	return ret;
 }
 
@@ -1720,6 +1741,7 @@ int refs_for_each_fullref_in_prefixes(struct ref_store *ref_store,
 				      const char **exclude_patterns,
 				      each_ref_fn fn, void *cb_data)
 {
+	struct strvec namespaced_exclude_patterns = STRVEC_INIT;
 	struct string_list prefixes = STRING_LIST_INIT_DUP;
 	struct string_list_item *prefix;
 	struct strbuf buf = STRBUF_INIT;
@@ -1731,6 +1753,10 @@ int refs_for_each_fullref_in_prefixes(struct ref_store *ref_store,
 		strbuf_addstr(&buf, namespace);
 	namespace_len = buf.len;
 
+	exclude_patterns = get_namespaced_exclude_patterns(exclude_patterns,
+							   namespace,
+							   &namespaced_exclude_patterns);
+
 	for_each_string_list_item(prefix, &prefixes) {
 		strbuf_addstr(&buf, prefix->string);
 		ret = refs_for_each_fullref_in(ref_store, buf.buf,
@@ -1740,6 +1766,7 @@ int refs_for_each_fullref_in_prefixes(struct ref_store *ref_store,
 		strbuf_setlen(&buf, namespace_len);
 	}
 
+	strvec_clear(&namespaced_exclude_patterns);
 	string_list_clear(&prefixes, 0);
 	strbuf_release(&buf);
 	return ret;

refs.h

@@ -861,6 +861,15 @@ int ref_is_hidden(const char *, const char *, const struct strvec *);
  */
 const char **hidden_refs_to_excludes(const struct strvec *hide_refs);
 
+/*
+ * Prefix all exclude patterns with the namespace, if any. This is required
+ * because exclude patterns apply to the stripped reference name, not the full
+ * reference name with the namespace.
+ */
+const char **get_namespaced_exclude_patterns(const char **exclude_patterns,
+					     const char *namespace,
+					     struct strvec *out);
+
 /* Is this a per-worktree ref living in the refs/ namespace? */
 int is_per_worktree_ref(const char *refname);
 

refs/reftable-backend.c

@@ -22,6 +22,7 @@
 #include "../repo-settings.h"
 #include "../setup.h"
 #include "../strmap.h"
+#include "../trace2.h"
 #include "parse.h"
 #include "refs-internal.h"
 
@@ -451,10 +452,81 @@ struct reftable_ref_iterator {
 
 	const char *prefix;
 	size_t prefix_len;
+	char **exclude_patterns;
+	size_t exclude_patterns_index;
+	size_t exclude_patterns_strlen;
 	unsigned int flags;
 	int err;
 };
 
+/*
+ * Handle exclude patterns. Returns either `1`, which tells the caller that the
+ * current reference shall not be shown. Or `0`, which indicates that it should
+ * be shown.
+ */
+static int should_exclude_current_ref(struct reftable_ref_iterator *iter)
+{
+	while (iter->exclude_patterns[iter->exclude_patterns_index]) {
+		const char *pattern = iter->exclude_patterns[iter->exclude_patterns_index];
+		char *ref_after_pattern;
+		int cmp;
+
+		/*
+		 * Lazily cache the pattern length so that we don't have to
+		 * recompute it every time this function is called.
+		 */
+		if (!iter->exclude_patterns_strlen)
+			iter->exclude_patterns_strlen = strlen(pattern);
+
+		/*
+		 * When the reference name is lexicographically bigger than the
+		 * current exclude pattern we know that it won't ever match any
+		 * of the following references, either. We thus advance to the
+		 * next pattern and re-check whether it matches.
+		 *
+		 * Otherwise, if it's smaller, then we do not have a match and
+		 * thus want to show the current reference.
+		 */
+		cmp = strncmp(iter->ref.refname, pattern,
+			      iter->exclude_patterns_strlen);
+		if (cmp > 0) {
+			iter->exclude_patterns_index++;
+			iter->exclude_patterns_strlen = 0;
+			continue;
+		}
+		if (cmp < 0)
+			return 0;
+
+		/*
+		 * The reference shares a prefix with the exclude pattern and
+		 * shall thus be omitted. We skip all references that match the
+		 * pattern by seeking to the first reference after the block of
+		 * matches.
+		 *
+		 * This is done by appending the highest possible character to
+		 * the pattern. Consequently, all references that have the
+		 * pattern as prefix and whose suffix starts with anything in
+		 * the range [0x00, 0xfe] are skipped. And given that 0xff is a
+		 * non-printable character that shouldn't ever be in a ref name,
+		 * we'd not yield any such record, either.
+		 *
+		 * Note that the seeked-to reference may also be excluded. This
+		 * is not handled here though, but the caller is expected to
+		 * loop and re-verify the next reference for us.
+		 */
+		ref_after_pattern = xstrfmt("%s%c", pattern, 0xff);
+		iter->err = reftable_iterator_seek_ref(&iter->iter, ref_after_pattern);
+		iter->exclude_patterns_index++;
+		iter->exclude_patterns_strlen = 0;
+		trace2_counter_add(TRACE2_COUNTER_ID_REFTABLE_RESEEKS, 1);
+
+		free(ref_after_pattern);
+		return 1;
+	}
+
+	return 0;
+}
+
 static int reftable_ref_iterator_advance(struct ref_iterator *ref_iterator)
 {
 	struct reftable_ref_iterator *iter =
@@ -485,6 +557,9 @@ static int reftable_ref_iterator_advance(struct ref_iterator *ref_iterator)
 			break;
 		}
 
+		if (iter->exclude_patterns && should_exclude_current_ref(iter))
+			continue;
+
 		if (iter->flags & DO_FOR_EACH_PER_WORKTREE_ONLY &&
 		    parse_worktree_ref(iter->ref.refname, NULL, NULL, NULL) !=
 			    REF_WORKTREE_CURRENT)
@@ -574,6 +649,11 @@ static int reftable_ref_iterator_abort(struct ref_iterator *ref_iterator)
 		(struct reftable_ref_iterator *)ref_iterator;
 	reftable_ref_record_release(&iter->ref);
 	reftable_iterator_destroy(&iter->iter);
+	if (iter->exclude_patterns) {
+		for (size_t i = 0; iter->exclude_patterns[i]; i++)
+			free(iter->exclude_patterns[i]);
+		free(iter->exclude_patterns);
+	}
 	free(iter);
 	return ITER_DONE;
 }
@@ -584,9 +664,45 @@ static struct ref_iterator_vtable reftable_ref_iterator_vtable = {
 	.abort = reftable_ref_iterator_abort
 };
 
+static char **filter_exclude_patterns(const char **exclude_patterns)
+{
+	size_t filtered_size = 0, filtered_alloc = 0;
+	char **filtered = NULL;
+
+	if (!exclude_patterns)
+		return NULL;
+
+	for (size_t i = 0; ; i++) {
+		const char *exclude_pattern = exclude_patterns[i];
+		int has_glob = 0;
+
+		if (!exclude_pattern)
+			break;
+
+		for (const char *p = exclude_pattern; *p; p++) {
+			has_glob = is_glob_special(*p);
+			if (has_glob)
+				break;
+		}
+		if (has_glob)
+			continue;
+
+		ALLOC_GROW(filtered, filtered_size + 1, filtered_alloc);
+		filtered[filtered_size++] = xstrdup(exclude_pattern);
+	}
+
+	if (filtered_size) {
+		ALLOC_GROW(filtered, filtered_size + 1, filtered_alloc);
+		filtered[filtered_size++] = NULL;
+	}
+
+	return filtered;
+}
+
 static struct reftable_ref_iterator *ref_iterator_for_stack(struct reftable_ref_store *refs,
 							    struct reftable_stack *stack,
 							    const char *prefix,
+							    const char **exclude_patterns,
 							    int flags)
 {
 	struct reftable_ref_iterator *iter;
@@ -599,6 +715,7 @@ static struct reftable_ref_iterator *ref_iterator_for_stack(struct reftable_ref_
 	iter->base.oid = &iter->oid;
 	iter->flags = flags;
 	iter->refs = refs;
+	iter->exclude_patterns = filter_exclude_patterns(exclude_patterns);
 
 	ret = refs->err;
 	if (ret)
@@ -620,7 +737,7 @@ static struct reftable_ref_iterator *ref_iterator_for_stack(struct reftable_ref_
 
 static struct ref_iterator *reftable_be_iterator_begin(struct ref_store *ref_store,
 						       const char *prefix,
-						       const char **exclude_patterns UNUSED,
+						       const char **exclude_patterns,
 						       unsigned int flags)
 {
 	struct reftable_ref_iterator *main_iter, *worktree_iter;
@@ -631,7 +748,8 @@ static struct ref_iterator *reftable_be_iterator_begin(struct ref_store *ref_sto
 		required_flags |= REF_STORE_ODB;
 	refs = reftable_be_downcast(ref_store, required_flags, "ref_iterator_begin");
 
-	main_iter = ref_iterator_for_stack(refs, refs->main_stack, prefix, flags);
+	main_iter = ref_iterator_for_stack(refs, refs->main_stack, prefix,
+					   exclude_patterns, flags);
 
 	/*
 	 * The worktree stack is only set when we're in an actual worktree
@@ -645,7 +763,8 @@ static struct ref_iterator *reftable_be_iterator_begin(struct ref_store *ref_sto
 	 * Otherwise we merge both the common and the per-worktree refs into a
 	 * single iterator.
 	 */
-	worktree_iter = ref_iterator_for_stack(refs, refs->worktree_stack, prefix, flags);
+	worktree_iter = ref_iterator_for_stack(refs, refs->worktree_stack, prefix,
+					       exclude_patterns, flags);
 	return merge_ref_iterator_begin(&worktree_iter->base, &main_iter->base,
 					ref_iterator_select, NULL);
 }

reftable/reader.c

@@ -328,6 +328,7 @@ static int table_iter_seek_to(struct table_iter *ti, uint64_t off, uint8_t typ)
 	ti->typ = block_reader_type(&ti->br);
 	ti->block_off = off;
 	block_iter_seek_start(&ti->bi, &ti->br);
+	ti->is_finished = 0;
 	return 0;
 }