MINOR: proxy: add refcount to proxies

Implement refcount notion into proxy structure. The objective is to be
able to increment refcount on proxy to prevent its deletion temporarily.
This is similar to the server refcount : "del backend" is not blocked
and will remove the targetted instance from the global proxies_list.
However, the final free operation is delayed until the refcount is null.

As stated above, the API is similar to servers. Proxies are initialized
with a refcount of 1. Refcount can be incremented via proxy_take(). When
no longer useful, refcount is decremented via proxy_drop() which
replaces the older free_proxy(). Deinit is only performed once refcount
is null.

This commit also defines flag PR_FL_DELETED. It is set when a proxy
instance has been removed via a "del backend" CLI command. This should
serve as indication to modules which may still have a refcount on the
target proxy so that they can release it as soon as possible.

Note that this new refcount is completely ignored for a default proxy
instance. For them, proxy_take() is pure noop. Free is immediately
performed on first proxy_drop() invokation.

diff --git a/include/haproxy/proxy-t.h b/include/haproxy/proxy-t.h
index fcf9732bd9301d0f8ab42051885228dca7b30590..c233d2909be2403c749d071ba3d27f16c1b885a5 100644 (file)
--- a/include/haproxy/proxy-t.h
+++ b/include/haproxy/proxy-t.h
@@ -247,6 +247,7 @@ enum PR_SRV_STATE_FILE {
 #define PR_FL_PAUSED             0x00000020  /* The proxy was paused at run time (reversible) */
 #define PR_FL_CHECKED            0x00000040  /* The proxy configuration was fully checked (including postparsing checks) */
 #define PR_FL_BE_UNPUBLISHED     0x00000080  /* The proxy cannot be targetted by content switching rules */
+#define PR_FL_DELETED            0x00000100  /* Proxy has been deleted and must be manipulated with care */
 
 struct stream;
 
@@ -508,6 +509,7 @@ struct proxy {
 
        struct guid_node guid;                  /* GUID global tree node */
        struct mt_list watcher_list;            /* list of elems which currently references this proxy instance (currently only used with backends) */
+       uint refcount;                          /* refcount to keep proxy from being deleted during runtime */
 
        EXTRA_COUNTERS(extra_counters_fe);
        EXTRA_COUNTERS(extra_counters_be);

diff --git a/include/haproxy/proxy.h b/include/haproxy/proxy.h
index fa19924f71d45b4f92b737873afc7ce5c767823a..5b73b25d4015dfd2678b8c3d025429ba20120405 100644 (file)
--- a/include/haproxy/proxy.h
+++ b/include/haproxy/proxy.h
@@ -58,7 +58,7 @@ void stop_proxy(struct proxy *p);
 int  stream_set_backend(struct stream *s, struct proxy *be);
 
 void deinit_proxy(struct proxy *p);
-void free_proxy(struct proxy *p);
+void proxy_drop(struct proxy *p);
 const char *proxy_cap_str(int cap);
 const char *proxy_mode_str(int mode);
 enum pr_mode str_to_proxy_mode(const char *mode);
@@ -82,6 +82,7 @@ void proxy_unref_defaults(struct proxy *px);
 int setup_new_proxy(struct proxy *px, const char *name, unsigned int cap, char **errmsg);
 struct proxy *alloc_new_proxy(const char *name, unsigned int cap,
                               char **errmsg);
+void proxy_take(struct proxy *px);
 struct proxy *parse_new_proxy(const char *name, unsigned int cap,
                               const char *file, int linenum,
                               const struct proxy *defproxy);

diff --git a/src/haproxy.c b/src/haproxy.c
index 49640f6ebb74bb010fb20ab1a533205d2e5db9ff..9b13bd2f39cfdce50ad1d9d04d8248feeb73d7ab 100644 (file)
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -2814,7 +2814,7 @@ void deinit(void)
        while (p) {
                p0 = p;
                p = p->next;
-               free_proxy(p0);
+               proxy_drop(p0);
        }/* end while(p) */
 
        /* we don't need to free sink_proxies_list nor cfg_log_forward proxies since

diff --git a/src/hlua.c b/src/hlua.c
index 52884221a98147ca0d326f96a67413fef7b64b07..764c0fb84a4ce92c2872dd56b8d88f2295088083 100644 (file)
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -14726,7 +14726,7 @@ static void hlua_deinit()
                        lua_close(hlua_states[thr]);
        }
 
-       free_proxy(socket_proxy);
+       proxy_drop(socket_proxy);
 }
 
 REGISTER_POST_DEINIT(hlua_deinit);

diff --git a/src/http_client.c b/src/http_client.c
index 64fbc87073e61cf1fa46c130ecd8a79cbc93c4e2..762fc094680179213b02c6dbe7b7d6b8c4d0cd8d 100644 (file)
--- a/src/http_client.c
+++ b/src/http_client.c
@@ -1214,7 +1214,7 @@ err:
        if (err_code & ERR_CODE) {
                ha_alert("httpclient: cannot initialize: %s\n", errmsg);
                free(errmsg);
-               free_proxy(px);
+               proxy_drop(px);
 
                return NULL;
        }

diff --git a/src/log.c b/src/log.c
index 9fc0d86aa5d3e578e119e5a8ff79e3a8af9324f7..f26079b22b7934f0eb209bab2835e6592a49bad8 100644 (file)
--- a/src/log.c
+++ b/src/log.c
@@ -3739,7 +3739,7 @@ void deinit_log_forward()
        while (p) {
                p0 = p;
                p = p->next;
-               free_proxy(p0);
+               proxy_drop(p0);
        }
 }
 

diff --git a/src/proxy.c b/src/proxy.c
index f9241ea1deb1ba171a15ccc59b964e0e44d04732..04982b7055d383dafb52d161a3d99eef2cd9680f 100644 (file)
--- a/src/proxy.c
+++ b/src/proxy.c
@@ -456,9 +456,19 @@ void deinit_proxy(struct proxy *p)
        proxy_unref_defaults(p);
 }
 
-/* deinit and free <p> proxy */
-void free_proxy(struct proxy *p)
+/* Decrement <p> refcount and free it if null. For a default proxy instance,
+ * refcount is ignored and free is immediately performed.
+ */
+void proxy_drop(struct proxy *p)
 {
+       if (!p)
+               return;
+
+       if (!(p->cap & PR_CAP_DEF)) {
+               if (HA_ATOMIC_SUB_FETCH(&p->refcount, 1))
+                       return;
+       }
+
        deinit_proxy(p);
        ha_free(&p);
 }
@@ -3211,6 +3221,8 @@ struct proxy *alloc_new_proxy(const char *name, unsigned int cap, char **errmsg)
        if (!setup_new_proxy(curproxy, name, cap, errmsg))
                goto fail;
 
+       proxy_take(curproxy);
+
  done:
        return curproxy;
 
@@ -3225,6 +3237,13 @@ struct proxy *alloc_new_proxy(const char *name, unsigned int cap, char **errmsg)
        return NULL;
 }
 
+/* Increment <px> refcount. Does nothing for a default proxy instance. */
+void proxy_take(struct proxy *px)
+{
+       if (!(px->cap & PR_CAP_DEF))
+               HA_ATOMIC_INC(&px->refcount);
+}
+
 /* post-check for proxies */
 static int proxy_postcheck(struct proxy *px)
 {
@@ -4955,8 +4974,8 @@ static int cli_parse_add_backend(char **args, char *payload, struct appctx *appc
        return 1;
 
  err:
-       /* free_proxy() ensures any potential refcounting on defpx is decremented. */
-       free_proxy(px);
+       /* This ensures any potential refcounting on defpx is decremented. */
+       proxy_drop(px);
        thread_release();
 
        if (msg) {
@@ -5053,6 +5072,8 @@ static int cli_parse_delete_backend(char **args, char *payload, struct appctx *a
                goto out;
        }
 
+       px->flags |= PR_FL_DELETED;
+
        thread_release();
 
        ha_notice("Backend deleted.\n");

diff --git a/src/resolvers.c b/src/resolvers.c
index b8306d33df82dda2f723da8333895f89a04feb30..5aa2a595f37f899c650673b0dd8a508bcc4ed983 100644 (file)
--- a/src/resolvers.c
+++ b/src/resolvers.c
@@ -2637,7 +2637,7 @@ static void resolvers_destroy(struct resolvers *resolvers)
                resolv_free_resolution(res);
        }
 
-       free_proxy(resolvers->px);
+       proxy_drop(resolvers->px);
        free(resolvers->id);
        free((char *)resolvers->conf.file);
        task_destroy(resolvers->t);
@@ -3586,7 +3586,7 @@ out:
 err_free_conf_file:
        ha_free((void **)&r->conf.file);
 err_free_p:
-       free_proxy(p);
+       proxy_drop(p);
 err_free_r:
        ha_free(&r);
        return err_code;

diff --git a/src/sink.c b/src/sink.c
index 03f57abd8b327ec6181ca3d6278483dcd3cf8cff..e207db871e58e58391314d3d238207450819b50a 100644 (file)
--- a/src/sink.c
+++ b/src/sink.c
@@ -818,7 +818,7 @@ static void sink_free(struct sink *sink)
        }
        LIST_DEL_INIT(&sink->sink_list); // remove from parent list
        task_destroy(sink->forward_task);
-       free_proxy(sink->forward_px);
+       proxy_drop(sink->forward_px);
        ha_free(&sink->name);
        ha_free(&sink->desc);
        while (sink->sft) {
@@ -866,7 +866,7 @@ static struct sink *sink_new_ringbuf(const char *id, const char *description,
        return sink;
 
  err:
-       free_proxy(p);
+       proxy_drop(p);
        return NULL;
 }