MXS-1929: Add filter deletion entry points

Added the code required to delete a filter via the REST API. The actual
deleting of the filters is still to be implemented.

server/core/config_runtime.cc

@@ -1078,6 +1078,26 @@ bool runtime_create_filter(const char *name, const char *module, MXS_CONFIG_PARA
     return rval;
 }
 
+bool runtime_destroy_filter(MXS_FILTER_DEF* filter)
+{
+    ss_dassert(filter);
+    bool rval = false;
+    mxs::SpinLockGuard guard(crt_lock);
+
+    if (filter_can_be_destroyed(filter))
+    {
+        filter_destroy(filter);
+        rval = true;
+    }
+    else
+    {
+        runtime_error("Filter '%s' cannot be destroyed: Remove it from all services "
+                      "first", filter->name);
+    }
+
+    return rval;
+}
+
 static bool runtime_create_service(const char *name, const char *router, MXS_CONFIG_PARAMETER* params)
 {
     mxs::SpinLockGuard guard(crt_lock);

server/core/filter.cc

@@ -37,6 +37,7 @@
 
 #include "internal/config.h"
 #include "internal/modules.h"
+#include "internal/service.h"
 
 using std::string;
 using std::set;
@@ -152,6 +153,17 @@ filter_def_find(const char *name)
     return filter;
 }
 
+bool filter_can_be_destroyed(MXS_FILTER_DEF *filter)
+{
+    return !service_filter_in_use(filter);
+}
+
+void filter_destroy(MXS_FILTER_DEF *filter)
+{
+    ss_dassert(filter_can_be_destroyed(filter));
+    ss_info_dassert(!true, "Not yet implemented");
+}
+
 const char* filter_def_get_name(const MXS_FILTER_DEF* filter_def)
 {
     return filter_def->name;

server/core/internal/config_runtime.h

@@ -205,6 +205,17 @@ bool runtime_create_monitor(const char *name, const char *module);
  */
 bool runtime_create_filter(const char *name, const char *module, MXS_CONFIG_PARAMETER* params);
 
+/**
+ * Destroy a filter
+ *
+ * The filter can only be destroyed if no service uses it
+ *
+ * @param service Filter to destroy
+ *
+ * @return True if filter was destroyed
+ */
+bool runtime_destroy_filter(MXS_FILTER_DEF* filter);
+
 /**
  * @brief Destroy a monitor
  *

server/core/internal/filter.h

@@ -46,4 +46,23 @@ MXS_UPSTREAM *filter_upstream(MXS_FILTER_DEF *filter_def,
                               MXS_FILTER_SESSION *fsession,
                               MXS_UPSTREAM *upstream);
 
+/**
+ * Check if filter can be destroyed
+ *
+ * A filter can be destroyed if no service uses it.
+ *
+ * @param filter Filter to check
+ *
+ * @return True if filter can be destroyed
+ */
+bool filter_can_be_destroyed(MXS_FILTER_DEF *filter);
+
+/**
+ * Destroy a filter
+ *
+ * @param filter Filter to destroy
+ */
+void filter_destroy(MXS_FILTER_DEF *filter);
+
+
 MXS_END_DECLS

server/core/internal/service.h

@@ -148,6 +148,15 @@ int      service_isvalid(SERVICE *service);
  */
 bool service_server_in_use(const SERVER *server);
 
+/**
+ * Check if filter is used by any service
+ *
+ * @param filter Filter to inspect
+ *
+ * @return True if at least one service uses the filter
+ */
+bool service_filter_in_use(const MXS_FILTER_DEF *filter);
+
 /** Update the server weights used by services */
 void service_update_weights();
 

server/core/resource.cc

@@ -484,6 +484,18 @@ HttpResponse cb_delete_service(const HttpRequest& request)
     return HttpResponse(MHD_HTTP_FORBIDDEN, runtime_get_json_error());
 }
 
+HttpResponse cb_delete_filter(const HttpRequest& request)
+{
+    MXS_FILTER_DEF* filter = filter_def_find(request.uri_part(1).c_str());
+    ss_dassert(filter);
+
+    if (runtime_destroy_filter(filter))
+    {
+        return HttpResponse(MHD_HTTP_NO_CONTENT);
+    }
+
+    return HttpResponse(MHD_HTTP_FORBIDDEN, runtime_get_json_error());
+}
 HttpResponse cb_all_servers(const HttpRequest& request)
 {
     return HttpResponse(MHD_HTTP_OK, server_list_to_json(request.host()));
@@ -957,6 +969,7 @@ public:
         m_delete.push_back(SResource(new Resource(cb_delete_server, 2, "servers", ":server")));
         m_delete.push_back(SResource(new Resource(cb_delete_monitor, 2, "monitors", ":monitor")));
         m_delete.push_back(SResource(new Resource(cb_delete_service, 2, "services", ":service")));
+        m_delete.push_back(SResource(new Resource(cb_delete_filter, 2, "filters", ":filter")));
 
         m_delete.push_back(SResource(new Resource(cb_delete_user, 3, "users", "inet", ":inetuser")));
         m_delete.push_back(SResource(new Resource(cb_delete_user, 3, "users", "unix", ":unixuser")));

server/core/service.cc

@@ -2196,6 +2196,33 @@ bool service_server_in_use(const SERVER *server)
     return rval;
 }
 
+bool service_filter_in_use(const MXS_FILTER_DEF *filter)
+{
+    ss_dassert(filter);
+    bool rval = false;
+
+    spinlock_acquire(&service_spin);
+
+    for (SERVICE *service = allServices; service && !rval; service = service->next)
+    {
+        spinlock_acquire(&service->spin);
+        for (int i = 0; i < service->n_filters; i++)
+        {
+            if (service->filters[i] == filter)
+            {
+                rval = true;
+                break;
+            }
+        }
+
+        spinlock_release(&service->spin);
+    }
+
+    spinlock_release(&service_spin);
+
+    return rval;
+}
+
 /**
  * Creates a service configuration at the location pointed by @c filename
  *