# HG changeset patch
# User Maxim Dounin <mdounin@mdounin.ru>
# Date 1340650553 -14400
# Node ID 489c5d4318ff3271370fc60db5f213c3811acebc
# Parent  d9ac9ad67f45fe9cbec0b609b7ce4387c4bb45d1
Keepalive: "single" parameter deprecated.

The original idea was to optimize edge cases in case of interchangeable
backends, i.e. don't establish a new connection if we have any one
cached.  This causes more harm than good though, as it screws up
underlying balancer's idea about backends used and may result in
various unexpected problems.

diff --git a/README b/README
--- a/README
+++ b/README
@@ -19,10 +19,6 @@ Configuration directives:
               room to cache new connections - last recently used connections
               will be kicked off the cache.
 
-            - single
-              Treat everything as single host.  With this flag connections
-              to different backends are treated as equal.
-
 Sample configuration:
 
     upstream memd {
diff --git a/ngx_http_upstream_keepalive_module.c b/ngx_http_upstream_keepalive_module.c
--- a/ngx_http_upstream_keepalive_module.c
+++ b/ngx_http_upstream_keepalive_module.c
@@ -11,7 +11,6 @@
 
 typedef struct {
     ngx_uint_t                         max_cached;
-    ngx_uint_t                         single;       /* unsigned:1 */
 
     ngx_queue_t                        cache;
     ngx_queue_t                        free;
@@ -222,38 +221,11 @@ ngx_http_upstream_get_keepalive_peer(ngx
 
     kp->failed = 0;
 
-    /* single pool of cached connections */
-
-    if (kp->conf->single && !ngx_queue_empty(&kp->conf->cache)) {
-
-        q = ngx_queue_head(&kp->conf->cache);
-
-        item = ngx_queue_data(q, ngx_http_upstream_keepalive_cache_t, queue);
-        c = item->connection;
-
-        ngx_queue_remove(q);
-        ngx_queue_insert_head(&kp->conf->free, q);
-
-        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
-                       "get keepalive peer: using connection %p", c);
-
-        c->idle = 0;
-        c->log = pc->log;
-        c->read->log = pc->log;
-        c->write->log = pc->log;
-#if (NGX_UPSTREAM_KEEPALIVE_PATCHED)
-        c->pool->log = pc->log;
-#endif
-
-        pc->connection = c;
-        pc->cached = 1;
-
-        return NGX_DONE;
-    }
+    /* ask balancer */
 
     rc = kp->original_get_peer(pc, kp->data);
 
-    if (kp->conf->single || rc != NGX_OK) {
+    if (rc != NGX_OK) {
         return rc;
     }
 
@@ -599,7 +571,8 @@ ngx_http_upstream_keepalive(ngx_conf_t *
     for (i = 2; i < cf->args->nelts; i++) {
 
         if (ngx_strcmp(value[i].data, "single") == 0) {
-            kcf->single = 1;
+            ngx_conf_log_error(NGX_LOG_WARN, cf, 0,
+                               "the \"single\" parameter is deprecated");
             continue;
         }
 
diff --git a/t/memcached-keepalive.t b/t/memcached-keepalive.t
--- a/t/memcached-keepalive.t
+++ b/t/memcached-keepalive.t
@@ -20,7 +20,7 @@ select STDOUT; $| = 1;
 eval { require Cache::Memcached; };
 plan(skip_all => 'Cache::Memcached not installed') if $@;
 
-my $t = Test::Nginx->new()->has('rewrite')->has_daemon('memcached')->plan(17)
+my $t = Test::Nginx->new()->has('rewrite')->has_daemon('memcached')->plan(16)
 	->write_file_expand('nginx.conf', <<'EOF');
 
 %%TEST_GLOBALS%%
@@ -38,12 +38,6 @@ http {
         keepalive 1;
     }
 
-    upstream memd2 {
-        server 127.0.0.1:8081;
-        server 127.0.0.1:8082;
-        keepalive 1 single;
-    }
-
     upstream memd3 {
         server 127.0.0.1:8081;
         server 127.0.0.1:8082;
@@ -71,11 +65,6 @@ http {
             memcached_pass memd;
         }
 
-        location /memd2 {
-            set $memcached_key "/";
-            memcached_pass memd2;
-        }
-
         location /memd3 {
             set $memcached_key "/";
             memcached_pass memd3;
@@ -160,25 +149,12 @@ like(http_get('/'), qr/SEE-THIS/, 'get a
 is($memd1->stats()->{total}->{total_connections}, $total + 1,
 	'big head request closes connection');
 
-# two backends with 'single' option - should establish only one connection
+# two backends with maximum number of cached connections set to 1,
+# should establish new connection on each request
 
 $total = $memd1->stats()->{total}->{total_connections} +
 	$memd2->stats()->{total}->{total_connections};
 
-http_get('/memd2');
-http_get('/memd2');
-http_get('/memd2');
-
-is($memd1->stats()->{total}->{total_connections} +
-	$memd2->stats()->{total}->{total_connections}, $total + 1,
-	'only one connection with two backends and single');
-
-$total = $memd1->stats()->{total}->{total_connections} +
-	$memd2->stats()->{total}->{total_connections};
-
-# two backends without 'single' option and maximum number of cached
-# connections set to 1 - should establish new connection on each request
-
 http_get('/memd3');
 http_get('/memd3');
 http_get('/memd3');
@@ -187,8 +163,8 @@ is($memd1->stats()->{total}->{total_conn
 	$memd2->stats()->{total}->{total_connections}, $total + 3,
 	'3 connections should be established');
 
-# two backends without 'single' option and maximum number of cached
-# connections set to 10 - should establish only two connections (1 per backend)
+# two backends with maximum number of cached connections set to 10,
+# should establish only two connections (1 per backend)
 
 $total = $memd1->stats()->{total}->{total_connections} +
         $memd2->stats()->{total}->{total_connections};