From 5e4a26856c1d9dec0f7145ad038d1319f1d6822e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ond=C5=99ej=20Sur=C3=BD?= <ondrej@isc.org>
Date: Wed, 2 Nov 2022 11:40:19 +0100
Subject: [PATCH] Remove the dead external cache cleaning mechanism from RBTDB

The RBTDB has own cache cleaning mechanism and therefor the iterator
.cleaning member would never be set to true.  Remove the code that
checks for iterator->cleaning from the RBTDB.
---
 lib/dns/rbtdb.c | 79 -------------------------------------------------
 1 file changed, 79 deletions(-)

diff --git a/lib/dns/rbtdb.c b/lib/dns/rbtdb.c
index ec8b9809ab..4557050008 100644
--- a/lib/dns/rbtdb.c
+++ b/lib/dns/rbtdb.c
@@ -809,8 +809,6 @@ typedef struct rbtdb_dbiterator {
 	dns_rbtnodechain_t nsec3chain;
 	dns_rbtnodechain_t *current;
 	dns_rbtnode_t *node;
-	dns_rbtnode_t *deletions[DELETION_BATCH_MAX];
-	int delcnt;
 	bool nsec3only;
 	bool nonsec3;
 } rbtdb_dbiterator_t;
@@ -5867,17 +5865,14 @@ createiterator(dns_db_t *db, unsigned int options,
 	rbtdbiter->common.relative_names = ((options & DNS_DB_RELATIVENAMES) !=
 					    0);
 	rbtdbiter->common.magic = DNS_DBITERATOR_MAGIC;
-	rbtdbiter->common.cleaning = false;
 	rbtdbiter->paused = true;
 	rbtdbiter->tree_locked = isc_rwlocktype_none;
 	rbtdbiter->result = ISC_R_SUCCESS;
 	dns_fixedname_init(&rbtdbiter->name);
 	dns_fixedname_init(&rbtdbiter->origin);
 	rbtdbiter->node = NULL;
-	rbtdbiter->delcnt = 0;
 	rbtdbiter->nsec3only = ((options & DNS_DB_NSEC3ONLY) != 0);
 	rbtdbiter->nonsec3 = ((options & DNS_DB_NONSEC3) != 0);
-	memset(rbtdbiter->deletions, 0, sizeof(rbtdbiter->deletions));
 	dns_rbtnodechain_init(&rbtdbiter->chain);
 	dns_rbtnodechain_init(&rbtdbiter->nsec3chain);
 	if (rbtdbiter->nsec3only) {
@@ -9041,53 +9036,6 @@ dereference_iter_node(rbtdb_dbiterator_t *rbtdbiter) {
 	rbtdbiter->node = NULL;
 }
 
-static void
-flush_deletions(rbtdb_dbiterator_t *rbtdbiter) {
-	dns_rbtdb_t *rbtdb = (dns_rbtdb_t *)rbtdbiter->common.db;
-	isc_rwlocktype_t tlocktype = rbtdbiter->tree_locked;
-
-	if (rbtdbiter->delcnt == 0) {
-		return;
-	}
-
-	/*
-	 * Note that "%d node of %d in tree" can report things like
-	 * "flush_deletions: 59 nodes of 41 in tree".  This means
-	 * That some nodes appear on the deletions list more than
-	 * once.  Only the last occurrence will actually be deleted.
-	 */
-	isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE, DNS_LOGMODULE_CACHE,
-		      ISC_LOG_DEBUG(1),
-		      "flush_deletions: %d nodes of %d in tree",
-		      rbtdbiter->delcnt, dns_rbt_nodecount(rbtdb->tree));
-
-	if (rbtdbiter->tree_locked == isc_rwlocktype_read) {
-		TREE_UNLOCK(&rbtdb->tree_lock, &rbtdbiter->tree_locked);
-	}
-	INSIST(rbtdbiter->tree_locked == isc_rwlocktype_none);
-
-	TREE_WRLOCK(&rbtdb->tree_lock, &rbtdbiter->tree_locked);
-
-	for (size_t i = 0; i < (size_t)rbtdbiter->delcnt; i++) {
-		isc_rwlocktype_t nlocktype = isc_rwlocktype_none;
-		dns_rbtnode_t *node = rbtdbiter->deletions[i];
-		nodelock_t *lock = &rbtdb->node_locks[node->locknum].lock;
-
-		NODE_RDLOCK(lock, &nlocktype);
-		decrement_reference(rbtdb, node, 0, &nlocktype,
-				    &rbtdbiter->tree_locked, true, false);
-		NODE_UNLOCK(lock, &nlocktype);
-	}
-
-	rbtdbiter->delcnt = 0;
-
-	TREE_UNLOCK(&rbtdb->tree_lock, &rbtdbiter->tree_locked);
-	if (tlocktype == isc_rwlocktype_read) {
-		TREE_RDLOCK(&rbtdb->tree_lock, &rbtdbiter->tree_locked);
-	}
-	INSIST(rbtdbiter->tree_locked == tlocktype);
-}
-
 static void
 resume_iteration(rbtdb_dbiterator_t *rbtdbiter) {
 	dns_rbtdb_t *rbtdb = (dns_rbtdb_t *)rbtdbiter->common.db;
@@ -9113,8 +9061,6 @@ dbiterator_destroy(dns_dbiterator_t **iteratorp) {
 
 	dereference_iter_node(rbtdbiter);
 
-	flush_deletions(rbtdbiter);
-
 	dns_db_attach(rbtdbiter->common.db, &db);
 	dns_db_detach(&rbtdbiter->common.db);
 
@@ -9452,29 +9398,6 @@ dbiterator_current(dns_dbiterator_t *iterator, dns_dbnode_t **nodep,
 
 	*nodep = rbtdbiter->node;
 
-	if (iterator->cleaning && result == ISC_R_SUCCESS) {
-		isc_result_t expire_result;
-
-		/*
-		 * If the deletion array is full, flush it before trying
-		 * to expire the current node.  The current node can't
-		 * fully deleted while the iteration cursor is still on it.
-		 */
-		if (rbtdbiter->delcnt == DELETION_BATCH_MAX) {
-			flush_deletions(rbtdbiter);
-		}
-
-		expire_result = expirenode(iterator->db, *nodep, 0);
-
-		/*
-		 * expirenode() currently always returns success.
-		 */
-		if (expire_result == ISC_R_SUCCESS && node->down == NULL) {
-			rbtdbiter->deletions[rbtdbiter->delcnt++] = node;
-			isc_refcount_increment(&node->references);
-		}
-	}
-
 	return (result);
 }
 
@@ -9502,8 +9425,6 @@ dbiterator_pause(dns_dbiterator_t *iterator) {
 	}
 	INSIST(rbtdbiter->tree_locked == isc_rwlocktype_none);
 
-	flush_deletions(rbtdbiter);
-
 	return (ISC_R_SUCCESS);
 }