MEDIUM: server: extend refcount for all servers
In a future patch, it will be possible to remove at runtime every
servers, both static and dynamic. This requires to extend the server
refcount for all instances.
First, refcount manipulation functions have been renamed to better
express the API usage.
* srv_refcount_use -> srv_take
The refcount is always initialize to 1 on the server creation in
new_server. It's also incremented for each check/agent configured on a
server instance.
* free_server -> srv_drop
This decrements the refcount and if null, the server is freed, so code
calling it must not use the server reference after it. As a bonus, this
function now returns the next server instance. This is useful when
calling on the server loop without having to save the next pointer
before each invocation.
In these functions, remove the checks that prevent refcount on
non-dynamic servers. Each reference to "dynamic" in variable/function
naming have been eliminated as well.
diff --git a/include/haproxy/server-t.h b/include/haproxy/server-t.h
index 02f15fc..a01081d 100644
--- a/include/haproxy/server-t.h
+++ b/include/haproxy/server-t.h
@@ -259,7 +259,7 @@
unsigned cumulative_weight; /* weight of servers prior to this one in the same group, for chash balancing */
int maxqueue; /* maximum number of pending connections allowed */
- uint refcount_dynsrv; /* refcount used for dynamic servers */
+ uint refcount; /* refcount used to remove a server at runtime */
/* The elements below may be changed on every single request by any
* thread, and generally at the same time.
diff --git a/include/haproxy/server.h b/include/haproxy/server.h
index b39be2a..99d26ba 100644
--- a/include/haproxy/server.h
+++ b/include/haproxy/server.h
@@ -59,8 +59,8 @@
int srv_init_addr(void);
struct server *cli_find_server(struct appctx *appctx, char *arg);
struct server *new_server(struct proxy *proxy);
-void srv_use_dynsrv(struct server *srv);
-struct server *free_server(struct server *srv);
+void srv_take(struct server *srv);
+struct server *srv_drop(struct server *srv);
int srv_init_per_thr(struct server *srv);
/* functions related to server name resolution */
diff --git a/src/check.c b/src/check.c
index 4a4e4c7..55f0793 100644
--- a/src/check.c
+++ b/src/check.c
@@ -1241,13 +1241,13 @@
TRACE_LEAVE(CHK_EV_TASK_WAKE, check);
/* Free the check if set to PURGE. After this, the check instance may be
- * freed via the free_server invocation, so it must not be accessed
- * after this point.
+ * freed via the srv_drop invocation, so it must not be accessed after
+ * this point.
*/
if (unlikely(check->state & CHK_ST_PURGE)) {
free_check(check);
if (check->server)
- free_server(check->server);
+ srv_drop(check->server);
t = NULL;
}
@@ -1688,6 +1688,7 @@
goto out;
}
srv->check.state |= CHK_ST_CONFIGURED | CHK_ST_ENABLED;
+ srv_take(srv);
/* Only increment maxsock for servers from the configuration. Dynamic
* servers at the moment are not taken into account for the estimation
@@ -1743,6 +1744,7 @@
srv->agent.inter = srv->check.inter;
srv->agent.state |= CHK_ST_CONFIGURED | CHK_ST_ENABLED | CHK_ST_AGENT;
+ srv_take(srv);
/* Only increment maxsock for servers from the configuration. Dynamic
* servers at the moment are not taken into account for the estimation
diff --git a/src/hlua.c b/src/hlua.c
index 4ec28a0..ea9d31c 100644
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -11759,10 +11759,10 @@
lua_close(hlua_states[thr]);
}
- free_server(socket_tcp);
+ srv_drop(socket_tcp);
#ifdef USE_OPENSSL
- free_server(socket_ssl);
+ srv_drop(socket_ssl);
#endif
free_proxy(socket_proxy);
diff --git a/src/http_client.c b/src/http_client.c
index 6719ce5..9f06ccc 100644
--- a/src/http_client.c
+++ b/src/http_client.c
@@ -738,9 +738,9 @@
err:
ha_alert("httpclient: cannot initialize.\n");
free(errmsg);
- free_server(httpclient_srv_raw);
+ srv_drop(httpclient_srv_raw);
#ifdef USE_OPENSSL
- free_server(httpclient_srv_ssl);
+ srv_drop(httpclient_srv_ssl);
#endif
free_proxy(httpclient_proxy);
return err_code;
diff --git a/src/proxy.c b/src/proxy.c
index 5d70186..3391dc9 100644
--- a/src/proxy.c
+++ b/src/proxy.c
@@ -291,7 +291,7 @@
while (s) {
list_for_each_entry(srvdf, &server_deinit_list, list)
srvdf->fct(s);
- s = free_server(s);
+ s = srv_drop(s);
}/* end while(s) */
list_for_each_entry_safe(l, l_next, &p->conf.listeners, by_fe) {
diff --git a/src/server.c b/src/server.c
index 54a569f..fdce968 100644
--- a/src/server.c
+++ b/src/server.c
@@ -2160,6 +2160,8 @@
if (!srv)
return NULL;
+ srv_take(srv);
+
srv->obj_type = OBJ_TYPE_SERVER;
srv->proxy = proxy;
queue_init(&srv->queue, proxy, srv);
@@ -2196,28 +2198,20 @@
return srv;
}
-/* Increment the dynamic server refcount. */
-void srv_use_dynsrv(struct server *srv)
+/* Increment the server refcount. */
+void srv_take(struct server *srv)
{
- BUG_ON(!(srv->flags & SRV_F_DYNAMIC));
- HA_ATOMIC_INC(&srv->refcount_dynsrv);
+ HA_ATOMIC_INC(&srv->refcount);
}
-/* Decrement the dynamic server refcount. */
-static uint srv_release_dynsrv(struct server *srv)
-{
- BUG_ON(!(srv->flags & SRV_F_DYNAMIC));
- return HA_ATOMIC_SUB_FETCH(&srv->refcount_dynsrv, 1);
-}
-
/* Deallocate a server <srv> and its member. <srv> must be allocated. For
* dynamic servers, its refcount is decremented first. The free operations are
* conducted only if the refcount is nul, unless the process is stopping.
*
* As a convenience, <srv.next> is returned if srv is not NULL. It may be useful
- * when calling free_server on the list of servers.
+ * when calling srv_drop on the list of servers.
*/
-struct server *free_server(struct server *srv)
+struct server *srv_drop(struct server *srv)
{
struct server *next = NULL;
@@ -2230,10 +2224,8 @@
* server when reaching zero.
*/
if (likely(!(global.mode & MODE_STOPPING))) {
- if (srv->flags & SRV_F_DYNAMIC) {
- if (srv_release_dynsrv(srv))
- goto end;
- }
+ if (HA_ATOMIC_SUB_FETCH(&srv->refcount, 1))
+ goto end;
}
task_destroy(srv->warmup);
@@ -4590,7 +4582,6 @@
goto out;
srv->check.state &= ~CHK_ST_ENABLED;
- srv_use_dynsrv(srv);
}
if (srv->do_agent) {
@@ -4598,7 +4589,6 @@
goto out;
srv->agent.state &= ~CHK_ST_ENABLED;
- srv_use_dynsrv(srv);
}
/* Attach the server to the end of the proxy linked list. Note that this
@@ -4649,7 +4639,6 @@
ebis_insert(&be->conf.used_server_name, &srv->conf.name);
ebis_insert(&be->used_server_addr, &srv->addr_node);
- srv_use_dynsrv(srv);
thread_release();
/* Start the check task. The server must be fully initialized.
@@ -4701,7 +4690,7 @@
cli_err(appctx, usermsgs_str());
if (srv)
- free_server(srv);
+ srv_drop(srv);
return 1;
}
@@ -4823,7 +4812,7 @@
thread_release();
ha_notice("Server deleted.\n");
- free_server(srv);
+ srv_drop(srv);
cli_msg(appctx, LOG_INFO, "Server deleted.");
diff --git a/src/stats.c b/src/stats.c
index 8140d87..35415b3 100644
--- a/src/stats.c
+++ b/src/stats.c
@@ -3113,17 +3113,15 @@
case STAT_PX_ST_SV:
/* obj2 points to servers list as initialized above.
*
- * A dynamic server may be removed during the stats dumping.
+ * A server may be removed during the stats dumping.
* Temporarily increment its refcount to prevent its
* anticipated cleaning. Call free_server to release it.
*/
for (; appctx->ctx.stats.obj2 != NULL;
- appctx->ctx.stats.obj2 =
- (!(sv->flags & SRV_F_DYNAMIC)) ? sv->next : free_server(sv)) {
+ appctx->ctx.stats.obj2 = srv_drop(sv)) {
sv = appctx->ctx.stats.obj2;
- if (sv->flags & SRV_F_DYNAMIC)
- srv_use_dynsrv(sv);
+ srv_take(sv);
if (htx) {
if (htx_almost_full(htx))
@@ -3136,8 +3134,7 @@
if (appctx->ctx.stats.flags & STAT_BOUND) {
if (!(appctx->ctx.stats.type & (1 << STATS_TYPE_SV))) {
- if (sv->flags & SRV_F_DYNAMIC)
- free_server(appctx->ctx.stats.obj2);
+ srv_drop(sv);
break;
}