MEDIUM: filters: Add attch/detach and stream_set_backend callbacks

New callbacks have been added to handle creation and destruction of filter
instances:

* 'attach' callback is called after a filter instance creation, when it is
  attached to a stream. This happens when the stream is started for filters
  defined on the stream's frontend and when the backend is set for filters
  declared on the stream's backend. It is possible to ignore the filter, if
  needed, by returning 0. This could be useful to have conditional filtering.

* 'detach' callback is called when a filter instance is detached from a stream,
  before its destruction. This happens when the stream is stopped for filters
  defined on the stream's frontend and when the analyze ends for filters defined
  on the stream's backend.

In addition, the callback 'stream_set_backend' has been added to know when a
backend is set for a stream. It is only called when the frontend and the backend
are not the same. And it is called for all filters attached to a stream
(frontend and backend).

Finally, the TRACE filter has been updated.

diff --git a/include/types/filters.h b/include/types/filters.h
index 62fcfb1291e73552e969c52b90039164c57b19ca..62b457de7ad6d0888544dbad4377f8adf103fcc7 100644 (file)
--- a/include/types/filters.h
+++ b/include/types/filters.h
@@ -64,14 +64,32 @@ struct flt_kw_list {
  *                          number of errors encountered.
  *
  *
+ *  - attach              : Called after a filter instance creation, when it is
+ *                          attached to a stream. This happens when the stream
+ *                          is started for filters defined on the stream's
+ *                          frontend and when the backend is set for filters
+ *                          declared on the stream's backend.
+ *                          Returns a negative value if an error occurs, 0 if
+ *                          the filter must be ignored for the stream, any other
+ *                          value otherwise.
  *  - stream_start        : Called when a stream is started. This callback will
- *                          only be called for filters defined on a proxy with
- *                          the frontend capability.
+ *                          only be called for filters defined on the stream's
+ *                          frontend.
+ *                          Returns a negative value if an error occurs, any
+ *                          other value otherwise.
+ *  - stream_set_backend  : Called when a backend is set for a stream. This
+ *                          callbacks will be called for all filters attached
+ *                          to a stream (frontend and backend).
  *                          Returns a negative value if an error occurs, any
  *                          other value otherwise.
  *  - stream_stop         : Called when a stream is stopped. This callback will
- *                          only be called for filters defined on a proxy with
- *                          the frontend capability.
+ *                          only be called for filters defined on the stream's
+ *                          frontend.
+ *  - detach              : Called when a filter instance is detached from a
+ *                          stream, before its destruction. This happens when
+ *                          the stream is stopped for filters defined on the
+ *                          stream's frontend and when the analyze ends for
+ *                          filters defined on the stream's backend.
  *
  *
  *  - channel_start_analyze: Called when a filter starts to analyze a channel.
@@ -133,12 +151,14 @@ struct flt_ops {
        int  (*init)  (struct proxy *p, struct flt_conf *fconf);
        void (*deinit)(struct proxy *p, struct flt_conf *fconf);
        int  (*check) (struct proxy *p, struct flt_conf *fconf);
-
        /*
         * Stream callbacks
         */
-       int  (*stream_start)     (struct stream *s, struct filter *f);
-       void (*stream_stop)      (struct stream *s, struct filter *f);
+       int  (*attach)            (struct stream *s, struct filter *f);
+       int  (*stream_start)      (struct stream *s, struct filter *f);
+       int  (*stream_set_backend)(struct stream *s, struct filter *f, struct proxy *be);
+       void (*stream_stop)       (struct stream *s, struct filter *f);
+       void (*detach)            (struct stream *s, struct filter *f);
 
        /*
         * Channel callbacks

diff --git a/src/filters.c b/src/filters.c
index 7f8fae43fbc125310573d2f4904b1f66039d5706..a1b36ba448d9bdb4f71b6437e312a0cdab7c2379 100644 (file)
--- a/src/filters.c
+++ b/src/filters.c
@@ -304,11 +304,21 @@ static int
 flt_stream_add_filter(struct stream *s, struct flt_conf *fconf, unsigned int flags)
 {
        struct filter *f = pool_alloc2(pool2_filter);
+
        if (!f) /* not enough memory */
                return -1;
        memset(f, 0, sizeof(*f));
        f->config = fconf;
        f->flags |= flags;
+
+       if (FLT_OPS(f)->attach) {
+               int ret = FLT_OPS(f)->attach(s, f);
+               if (ret <= 0) {
+                       pool_free2(pool2_filter, f);
+                       return ret;
+               }
+       }
+
        LIST_ADDQ(&strm_flt(s)->filters, &f->list);
        strm_flt(s)->flags |= STRM_FLT_FL_HAS_FILTERS;
        return 0;
@@ -345,6 +355,8 @@ flt_stream_release(struct stream *s, int only_backend)
 
        list_for_each_entry_safe(filter, back, &strm_flt(s)->filters, list) {
                if (!only_backend || (filter->flags & FLT_FL_IS_BACKEND_FILTER)) {
+                       if (FLT_OPS(filter)->detach)
+                               FLT_OPS(filter)->detach(s, filter);
                        LIST_DEL(&filter->list);
                        pool_free2(pool2_filter, filter);
                }
@@ -387,21 +399,30 @@ flt_stream_stop(struct stream *s)
 
 /*
  * Called when a backend is set for a stream. If the frontend and the backend
- * are the same, this function does nothing. Else it attaches all backend
- * filters to the stream. Returns -1 if an error occurs, 0 otherwise.
+ * are not the same, this function attaches all backend filters to the
+ * stream. Returns -1 if an error occurs, 0 otherwise.
  */
 int
 flt_set_stream_backend(struct stream *s, struct proxy *be)
 {
        struct flt_conf *fconf;
+       struct filter   *filter;
 
        if (strm_fe(s) == be)
-               return 0;
+               goto end;
 
        list_for_each_entry(fconf, &be->filter_configs, list) {
                if (flt_stream_add_filter(s, fconf, FLT_FL_IS_BACKEND_FILTER) < 0)
                        return -1;
        }
+
+  end:
+       list_for_each_entry(filter, &strm_flt(s)->filters, list) {
+               if (FLT_OPS(filter)->stream_set_backend &&
+                   FLT_OPS(filter)->stream_set_backend(s, filter, be) < 0)
+                       return -1;
+       }
+
        return 0;
 }
 

diff --git a/src/flt_trace.c b/src/flt_trace.c
index a052ab59bad98d55bd1715a67f47ebff5ebe9506..ce3bf5ccc71b06af5db4469b4c0cc6ac6eba1196 100644 (file)
--- a/src/flt_trace.c
+++ b/src/flt_trace.c
@@ -66,6 +66,12 @@ stream_pos(const struct stream *s)
        return (s->flags & SF_BE_ASSIGNED) ? "backend" : "frontend";
 }
 
+static const char *
+filter_type(const struct filter *f)
+{
+       return (f->flags & FLT_FL_IS_BACKEND_FILTER) ? "backend" : "frontend";
+}
+
 /***************************************************************************
  * Hooks that manage the filter lifecycle (init/check/deinit)
  **************************************************************************/
@@ -111,6 +117,28 @@ trace_check(struct proxy *px, struct flt_conf *fconf)
 /**************************************************************************
  * Hooks to handle start/stop of streams
  *************************************************************************/
+/* Called when a filter instance is created and attach to a stream */
+static int
+trace_attach(struct stream *s, struct filter *filter)
+{
+       struct trace_config *conf = FLT_CONF(filter);
+
+       STRM_TRACE(conf, s, "%-25s: filter-type=%s",
+                  __FUNCTION__, filter_type(filter));
+       return 1;
+}
+
+/* Called when a filter instance is detach from a stream, just before its
+ * destruction */
+static void
+trace_detach(struct stream *s, struct filter *filter)
+{
+       struct trace_config *conf = FLT_CONF(filter);
+
+       STRM_TRACE(conf, s, "%-25s: filter-type=%s",
+                  __FUNCTION__, filter_type(filter));
+}
+
 /* Called when a stream is created */
 static int
 trace_stream_start(struct stream *s, struct filter *filter)
@@ -122,6 +150,19 @@ trace_stream_start(struct stream *s, struct filter *filter)
        return 0;
 }
 
+
+/* Called when a backend is set for a stream */
+static int
+trace_stream_set_backend(struct stream *s, struct filter *filter,
+                        struct proxy *be)
+{
+       struct trace_config *conf = FLT_CONF(filter);
+
+       STRM_TRACE(conf, s, "%-25s: backend=%s",
+                  __FUNCTION__, be->id);
+       return 0;
+}
+
 /* Called when a stream is destroyed */
 static void
 trace_stream_stop(struct stream *s, struct filter *filter)
@@ -410,8 +451,11 @@ struct flt_ops trace_ops = {
        .check  = trace_check,
 
        /* Handle start/stop of streams */
-       .stream_start = trace_stream_start,
-       .stream_stop  = trace_stream_stop,
+       .attach             = trace_attach,
+       .detach             = trace_detach,
+       .stream_start       = trace_stream_start,
+       .stream_set_backend = trace_stream_set_backend,
+       .stream_stop        = trace_stream_stop,
 
        /* Handle channels activity */
        .channel_start_analyze = trace_chn_start_analyze,