nostrdb/Initial nostrdb queries

Still a lot more work to do, but this is at least a proof of concept for
querying nostrdb using filters.

Signed-off-by: William Casarin <jb55@jb55.com>

nostrdb/src/nostrdb.c

@@ -836,7 +836,8 @@ static int compare_kinds(const void *pa, const void *pb)
 
 
 // returns 1 if a filter matches a note
-int ndb_filter_matches(struct ndb_filter *filter, struct ndb_note *note)
+static int ndb_filter_matches_with(struct ndb_filter *filter,
+				   struct ndb_note *note, int already_matched)
 {
 	int i, j;
 	unsigned char *id;
@@ -845,6 +846,11 @@ int ndb_filter_matches(struct ndb_filter *filter, struct ndb_note *note)
 	for (i = 0; i < filter->num_elements; i++) {
 		els = filter->elements[i];
 
+		// if we know we already match from a query scan result,
+		// we can skip this check
+		if ((1 << els->field.type) & already_matched)
+			continue;
+
 		switch (els->field.type) {
 		case NDB_FILTER_KINDS:
 			for (j = 0; j < els->count; j++) {
@@ -891,6 +897,11 @@ cont:
 	return 1;
 }
 
+int ndb_filter_matches(struct ndb_filter *filter, struct ndb_note *note)
+{
+	return ndb_filter_matches_with(filter, note, 0);
+}
+
 void ndb_filter_end_field(struct ndb_filter *filter)
 {
 	struct ndb_filter_elements *cur;
@@ -2279,22 +2290,232 @@ static int ndb_write_note_id_index(struct ndb_txn *txn, struct ndb_note *note,
 	return 1;
 }
 
-/*
+static int ndb_filter_group_add_filters(struct ndb_filter_group *group,
-static int ndb_filter_query(struct ndb *ndb, struct ndb_filter *filter)
+					struct ndb_filter *filters,
+					int num_filters)
 {
+	int i;
+
+	for (i = 0; i < num_filters; i++) {
+		if (!ndb_filter_group_add(group, &filters[i]))
+			return 0;
+	}
+
+	return 1;
 }
 
-static int ndb_filter_cursors(struct ndb_filter *filter, struct ndb_cursor)
+static int ndb_filter_int(struct ndb_filter *filter,
+			  enum ndb_filter_fieldtype typ, uint64_t *lim)
 {
+	int i;
+	struct ndb_filter_elements *els;
+
+	for (i = 0; i < filter->num_elements; i++) {
+		els = filter->elements[i];
+		if (els->field.type == typ) {
+			*lim = els->elements[0].integer;
+			return 1;
+		}
+	}
+
+	return 0;
 }
 
-int ndb_query(struct ndb *ndb, struct ndb_filter **filters, int num_filters)
+static int ndb_filter_get_limit(struct ndb_filter *filter, uint64_t *lim)
 {
-	struct ndb_filter_group group;
+	return ndb_filter_int(filter, NDB_FILTER_LIMIT, lim);
-	ndb_filter_group_init(&group);
+}
-
+
+static int ndb_filter_get_until(struct ndb_filter *filter, uint64_t *lim)
+{
+	return ndb_filter_int(filter, NDB_FILTER_UNTIL, lim);
+}
+
+static int ndb_filter_get_since(struct ndb_filter *filter, uint64_t *lim)
+{
+	return ndb_filter_int(filter, NDB_FILTER_SINCE, lim);
+}
+
+static int ndb_query_filter_id(struct ndb_txn *txn, struct ndb_filter *filter,
+			       MDB_cursor *cur, const unsigned char *id,
+			       uint64_t since, int *matched,
+			       struct ndb_query_result *res)
+{
+	MDB_val k, v;
+	uint64_t note_id;
+	struct ndb_tsid tsid, *ptsid;
+
+	res->note = NULL;
+
+	ndb_tsid_init(&tsid, (unsigned char *)id, since);
+
+	k.mv_data = &tsid;
+	k.mv_size = sizeof(tsid);
+
+	if (!ndb_cursor_start(cur, &k, &v))
+		return 0;
+
+	ptsid = (struct ndb_tsid *)k.mv_data;
+	note_id = *(uint64_t*)v.mv_data;
+
+	if (memcmp(id, ptsid->id, 32) == 0)
+		*matched |= 1 << NDB_FILTER_AUTHORS;
+	else
+		return 1;
+
+	// get the note because we need it to match against the filter
+	if (!(res->note = ndb_get_note_by_key(txn, note_id, NULL)))
+		return 1;
+
+	// Sure this particular lookup matched the index query, but does it
+	// match the entire filter? Check! We also pass in things we've already
+	// matched via the filter so we don't have to check again. This can be
+	// pretty important for filters with a large number of entries.
+	if (!ndb_filter_matches_with(filter, res->note, *matched))
+		return 1;
+
+	return 2;
+}
+
+static inline int push_query_result(struct cursor *res,
+				    struct ndb_query_result *result)
+{
+	return cursor_push(res, (unsigned char*)result, sizeof(*result));
+}
+
+static int compare_query_results(const void *pa, const void *pb)
+{
+	struct ndb_query_result *a, *b;
+
+	a = (struct ndb_query_result *)pa;
+	b = (struct ndb_query_result *)pb;
+
+	if (a->note->created_at == b->note->created_at) {
+		return memcmp(a->note->id, b->note->id, 32);
+	} else if (a->note->created_at > b->note->created_at) {
+		return -1;
+	} else {
+		return 1;
+	}
+}
+
+static int ndb_query_filter(struct ndb_txn *txn, struct ndb_filter *filter,
+			    struct ndb_query_result *results, int capacity,
+			    int *results_out)
+{
+	struct ndb_filter_elements *els;
+	struct ndb_query_result res;
+	struct cursor results_arr;
+	uint64_t limit, since, until;
+	const unsigned char *id;
+	int i, k, rc;
+	MDB_cursor *cur;
+	MDB_dbi db;
+
+	since = UINT64_MAX;
+	until = UINT64_MAX;
+	limit = capacity;
+
+	ndb_filter_get_limit(filter, &limit);
+	ndb_filter_get_since(filter, &since);
+	ndb_filter_get_until(filter, &until);
+
+	limit = min(capacity, limit);
+	make_cursor((unsigned char *)results,
+		    ((unsigned char *)results) + limit * sizeof(*results),
+		    &results_arr);
+
+	for (i = 0; i < filter->num_elements; i++) {
+		if (results_arr.p >= results_arr.end)
+			goto done;
+
+		els = filter->elements[i];
+		switch (els->field.type) {
+		case NDB_FILTER_IDS:
+			int matched = 0;
+			db = txn->lmdb->dbs[NDB_DB_NOTE_ID];
+			if ((rc = mdb_cursor_open(txn->mdb_txn, db, &cur)))
+				return 0;
+
+			// for each id in our ids filter, find in the db
+			for (k = 0; k < els->count; k++) {
+				if (results_arr.p >= results_arr.end) {
+					mdb_cursor_close(cur);
+					goto done;
+				}
+
+				id = els->elements[k].id;
+				if (!(rc = ndb_query_filter_id(txn, filter, cur,
+							       id, since,
+							       &matched,
+							       &res))) {
+					// there was a fatal error
+					mdb_cursor_close(cur);
+					return 0;
+				}
+
+				// no match, just try next id
+				if (rc == 1)
+					continue;
+
+				// rc > 1, matched!
+				if (!push_query_result(&results_arr, &res)) {
+					// this should never happen, but if
+					// it fails to push that means there
+					// are no more result to push,
+					// so just return
+					mdb_cursor_close(cur);
+					goto done;
+				}
+
+				// look for more ids... continue!
+			}
+
+			mdb_cursor_close(cur);
+			break;
+		case NDB_FILTER_AUTHORS:
+			break;
+		case NDB_FILTER_KINDS:
+			break;
+		case NDB_FILTER_GENERIC:
+			break;
+		case NDB_FILTER_SINCE:
+		case NDB_FILTER_UNTIL:
+		case NDB_FILTER_LIMIT:
+			break;
+		}
+	}
+
+done:
+	*results_out = cursor_count(&results_arr, sizeof(*results));
+	return 1;
+}
+
+int ndb_query(struct ndb_txn *txn, struct ndb_filter *filters, int num_filters,
+	      struct ndb_query_result *results, int result_capacity, int *count)
+{
+	int i, out;
+	struct ndb_query_result *p = results;
+
+	*count = 0;
+
+	for (i = 0; i < num_filters; i++) {
+		if (!ndb_query_filter(txn, &filters[i], p,
+				      result_capacity, &out)) {
+			return 0;
+		}
+
+		*count += out;
+		p += out;
+		result_capacity -= out;
+		if (result_capacity <= 0)
+			break;
+	}
+
+	// sort results
+	qsort(results, *count, sizeof(*results), compare_query_results);
+	return 1;
 }
-*/
 
 static int ndb_write_note_kind_index(struct ndb_txn *txn, struct ndb_note *note,
 				     uint64_t note_key)

nostrdb/src/nostrdb.h

@@ -397,6 +397,10 @@ struct ndb_block_iterator {
 	unsigned char *p;
 };
 
+struct ndb_query_result {
+	struct ndb_note *note;
+};
+
 // CONFIG
 void ndb_default_config(struct ndb_config *);
 void ndb_config_set_ingest_threads(struct ndb_config *config, int threads);
@@ -476,7 +480,7 @@ void ndb_text_search_config_set_order(struct ndb_text_search_config *, enum ndb_
 void ndb_text_search_config_set_limit(struct ndb_text_search_config *, int limit);
 
 // QUERY
-void ndb_query(struct ndb_filter **, int num_filters);
+int ndb_query(struct ndb_txn *txn, struct ndb_filter *filters, int num_filters, struct ndb_query_result *results, int result_capacity, int *count);
 
 // STATS
 int ndb_stat(struct ndb *ndb, struct ndb_stat *stat);