[PATCH gwproxy v6 06/11] dns: Remove code block related to the usage of glibc's getaddrinfo_a function

[Ahmad Gani <reyuki@gnuweeb.org>]

This change is required for preparation in migration to no dedicated DNS
threads alternative.

Signed-off-by: Ahmad Gani <reyuki@gnuweeb.org>
---
 configure         |  20 -----
 src/gwproxy/dns.c | 220 ----------------------------------------------
 2 files changed, 240 deletions(-)

diff --git a/configure b/configure
index cef07b1cb652..19baa1585237 100755
--- a/configure
+++ b/configure
@@ -355,26 +355,6 @@ else
 	CXXFLAGS="${CXXFLAGS} -DNDEBUG";
 fi;
 
-# ------ Check for getaddrinfo_a() ------
-cat > $tmp_c << EOF
-#include <netdb.h>
-int main(void)
-{
-	struct sigevent ev;
-	struct gaicb *gc = (void *)0;
-	getaddrinfo_a(GAI_NOWAIT, &gc, 1, &ev);
-	return 0;
-}
-EOF
-l="Do we have getaddrinfo_a()?";
-if compile_cc "" "-lanl" "getaddrinfo_a()"; then
-	add_config "CONFIG_HAVE_GETADDRINFO_A";
-	print_supp "yes" "${l}";
-	LIB_LDFLAGS="${LIB_LDFLAGS} -lanl";
-else
-	print_supp "no" "${l}";
-fi;
-
 add_make_var "CC" "${cc}";
 add_make_var "CXX" "${cxx}";
 add_make_var "CFLAGS" "$(echo "${CFLAGS} ${USER_CFLAGS}" | awk '{$1=$1};1')";
diff --git a/src/gwproxy/dns.c b/src/gwproxy/dns.c
index cdc62a5bcf78..1e271a388493 100644
--- a/src/gwproxy/dns.c
+++ b/src/gwproxy/dns.c
@@ -234,204 +234,6 @@ static void wait_for_queue_entry(struct gwp_dns_ctx *ctx)
 	cond_scan_cache(ctx);
 }
 
-#ifdef CONFIG_HAVE_GETADDRINFO_A
-/*
- * Must be called with ctx->lock held.
- */
-static struct gwp_dns_entry *unplug_queue_list(struct gwp_dns_ctx *ctx)
-{
-	struct gwp_dns_entry *head = ctx->head;
-
-	ctx->head = ctx->tail = NULL;
-	ctx->nr_entries = 0;
-	return head;
-}
-
-struct dbq_entry {
-	struct gwp_dns_entry	*e;
-	struct gaicb		cb;
-};
-
-struct dns_batch_query {
-	struct dbq_entry	*entries;
-	struct gaicb		**reqs;
-	struct addrinfo		hints;
-	uint32_t		nr_entries;
-	uint32_t		cap;
-};
-
-static void dbq_free(struct dns_batch_query *dbq)
-{
-	uint32_t i;
-
-	if (!dbq)
-		return;
-
-	if (dbq->reqs) {
-		for (i = 0; i < dbq->nr_entries; i++) {
-			if (dbq->reqs[i]->ar_result)
-				freeaddrinfo(dbq->reqs[i]->ar_result);
-		}
-	}
-
-	free(dbq->entries);
-	free(dbq->reqs);
-	free(dbq);
-}
-
-static int dbq_add_entry(struct dns_batch_query *dbq, struct gwp_dns_entry *e)
-{
-	struct dbq_entry *de;
-
-	if (dbq->nr_entries >= dbq->cap) {
-		uint32_t new_cap = dbq->cap ? dbq->cap * 2 : 16;
-		struct dbq_entry *nentries;
-
-		nentries = realloc(dbq->entries, new_cap * sizeof(*nentries));
-		if (!nentries)
-			return -ENOMEM;
-		dbq->entries = nentries;
-		dbq->cap = new_cap;
-	}
-
-	de = &dbq->entries[dbq->nr_entries];
-	de->e = e;
-	memset(&de->cb, 0, sizeof(de->cb));
-	de->cb.ar_name = e->name;
-	de->cb.ar_service = e->service;
-	de->cb.ar_request = &dbq->hints;
-	de->cb.ar_result = NULL;
-	dbq->nr_entries++;
-
-	return 0;
-}
-
-static int collect_active_queries(struct gwp_dns_ctx *ctx,
-				  struct gwp_dns_entry **head_p,
-				  struct dns_batch_query **dbq_p)
-{
-	struct gwp_dns_entry *e, *next, *prev = NULL, *head = *head_p;
-	struct dns_batch_query *dbq;
-
-	dbq = calloc(1, sizeof(*dbq));
-	if (!dbq)
-		return -ENOMEM;
-
-	assert(head);
-	prep_hints(&dbq->hints, ctx->cfg.restyp);
-	for (e = head; e; e = next) {
-		int x = atomic_load(&e->refcnt);
-		next = e->next;
-		if (x > 1) {
-
-			if (dbq_add_entry(dbq, e)) {
-				dbq_free(dbq);
-				return -ENOMEM;
-			}
-
-			prev = e;
-			continue;
-		}
-
-		assert(x == 1);
-		/*
-		 * If the refcnt is 1, it means we are the last reference
-		 * to this entry. The client no longer cares about the
-		 * result. We can free it immediately. No need to resolve
-		 * the query nor to signal the eventfd.
-		 */
-		if (prev)
-			prev->next = next;
-		else
-			head = next;
-
-		gwp_dns_entry_free(e);
-	}
-
-	*head_p = head;
-	*dbq_p = dbq;
-	return 0;
-}
-
-static void dispatch_batch_result(int r, struct gwp_dns_ctx *ctx,
-				  struct dns_batch_query *dbq,
-				  uint32_t restyp)
-{
-	struct gwp_dns_entry *e;
-	struct addrinfo *ai;
-	uint32_t i;
-
-	for (i = 0; i < dbq->nr_entries; i++) {
-		e = dbq->entries[i].e;
-		ai = dbq->reqs[i]->ar_result;
-
-		if (!r) {
-			e->res = gai_error(dbq->reqs[i]);
-			if (!e->res) {
-				if (!iterate_addr_list(ai, &e->addr, restyp))
-					e->res = -EHOSTUNREACH;
-			}
-		} else {
-			e->res = r;
-		}
-
-		eventfd_write(e->ev_fd, 1);
-		if (!e->res)
-			try_pass_result_to_cache(ctx, e->name, ai);
-	}
-}
-
-/*
- * Filling dbq->reqs[n] cannot be done in dbq_add_entry() because
- * the reallocation of dbq->entries may change the address of
- * dbq->entries[n].cb.
- */
-static int prep_reqs(struct dns_batch_query *dbq)
-{
-	uint32_t i;
-
-	dbq->reqs = malloc(dbq->nr_entries * sizeof(*dbq->reqs));
-	if (!dbq->reqs)
-		return -ENOMEM;
-
-	for (i = 0; i < dbq->nr_entries; i++)
-		dbq->reqs[i] = &dbq->entries[i].cb;
-
-	return 0;
-}
-
-/*
- * Must be called with ctx->lock held. May release the lock, but
- * it will reacquire it before returning.
- */
-static void process_queue_entry_batch(struct gwp_dns_ctx *ctx)
-{
-	struct gwp_dns_entry *head = unplug_queue_list(ctx);
-	struct dns_batch_query *dbq = NULL;
-
-	if (!head)
-		return;
-
-	pthread_mutex_unlock(&ctx->lock);
-
-	if (!collect_active_queries(ctx, &head, &dbq)) {
-		if (!prep_reqs(dbq)) {
-			struct sigevent ev;
-			int r;
-
-			memset(&ev, 0, sizeof(ev));
-			ev.sigev_notify = SIGEV_NONE;
-			r = getaddrinfo_a(GAI_WAIT, dbq->reqs, dbq->nr_entries, &ev);
-			dispatch_batch_result(r, ctx, dbq, ctx->cfg.restyp);
-		}
-	}
-
-	dbq_free(dbq);
-	put_all_entries(head);
-	pthread_mutex_lock(&ctx->lock);
-}
-#endif /* #ifdef CONFIG_HAVE_GETADDRINFO_A */
-
 /*
  * Must be called with ctx->lock held. May release the lock, but
  * it will reacquire it before returning.
@@ -477,28 +279,6 @@ out:
  */
 static void process_queue_entry(struct gwp_dns_ctx *ctx)
 {
-	/*
-	 * There are two cases here:
-	 *
-	 * 1. All of the DNS threads are busy, and there are still a lot
-	 *    of queued entries. Process them in batch via getaddrinfo_a().
-	 *
-	 * 2. The number of threads is sufficient to handle the queued
-	 *    entries, so process them one by one.
-	 *
-	 * Why not always getaddrinfo_a()? Because getaddrinfo_a() has
-	 * a higher overhead than processing entries individually as it
-	 * will spawn a new thread for each query. Don't bother invoking
-	 * clone() for each entry if we can process them in the current
-	 * thread.
-	 */
-#ifdef CONFIG_HAVE_GETADDRINFO_A
-	if (ctx->nr_entries > (ctx->nr_sleeping + 16)) {
-		process_queue_entry_batch(ctx);
-		return;
-	}
-#endif
-
 	process_queue_entry_single(ctx);
 }
 
-- 
Ahmad Gani