snapview-server: register a callback with glusterd to get notifications

* As of now snapview-server is polling (sending rpc requests to glusterd) to
  get the latest list of snapshots at some regular time intervals
  (non configurable). Instead of that register a callback with glusterd so that
  glusterd sends notifications to snapd whenever a snapshot is created/deleted
  and snapview-server can configure itself.

Change-Id: I17a274fd2ab487d030678f0077feb2b0f35e5896
BUG: 1119628
Signed-off-by: Raghavendra Bhat <raghavendra@redhat.com>
Reviewed-on: http://review.gluster.org/8150
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

3 files changed, 44 insertions, 0 deletions

diff --git a/xlators/mgmt/glusterd/src/glusterd-snapshot.c b/xlators/mgmt/glusterd/src/glusterd-snapshot.c
index 09acb25c3f5..99addd165c8 100644
--- a/xlators/mgmt/glusterd/src/glusterd-snapshot.c
+++ b/xlators/mgmt/glusterd/src/glusterd-snapshot.c
@@ -6751,6 +6751,7 @@ glusterd_snapshot_create_postvalidate (dict_t *dict, int32_t op_ret,
                 ret = glusterd_handle_snap_limit (dict, rsp_dict);
         }
         ret = 0;
+
 out:
         return ret;
 }
@@ -7401,6 +7402,7 @@ glusterd_snapshot_postvalidate (dict_t *dict, int32_t op_ret, char **op_errstr,
                                 "post-validation failed");
                         goto out;
                 }
+                glusterd_fetchsnap_notify (this);
                 break;
         case GF_SNAP_OPTION_TYPE_DELETE:
                 if (op_ret) {
@@ -7418,6 +7420,7 @@ glusterd_snapshot_postvalidate (dict_t *dict, int32_t op_ret, char **op_errstr,
                                 "update missed snaps list");
                         goto out;
                 }
+                glusterd_fetchsnap_notify (this);
                 break;
         case GF_SNAP_OPTION_TYPE_RESTORE:
                 ret = glusterd_snapshot_update_snaps_post_validate (dict,
@@ -7436,6 +7439,7 @@ glusterd_snapshot_postvalidate (dict_t *dict, int32_t op_ret, char **op_errstr,
                                 "perform snapshot restore post-op");
                         goto out;
                 }
+                glusterd_fetchsnap_notify (this);
                 break;
         case GF_SNAP_OPTION_TYPE_ACTIVATE:
         case GF_SNAP_OPTION_TYPE_DEACTIVATE:
diff --git a/xlators/mgmt/glusterd/src/glusterd.c b/xlators/mgmt/glusterd/src/glusterd.c
index ab7ab3a2171..b9a43cd32ce 100644
--- a/xlators/mgmt/glusterd/src/glusterd.c
+++ b/xlators/mgmt/glusterd/src/glusterd.c
@@ -216,6 +216,7 @@ glusterd_options_init (xlator_t *this)
 out:
         return 0;
 }
+
 int
 glusterd_fetchspec_notify (xlator_t *this)
 {
@@ -241,6 +242,42 @@ glusterd_fetchspec_notify (xlator_t *this)
 }
 
 int
+glusterd_fetchsnap_notify (xlator_t *this)
+{
+        int              ret   = -1;
+        glusterd_conf_t *priv  = NULL;
+        rpc_transport_t *trans = NULL;
+
+        priv = this->private;
+
+        /*
+         * TODO: As of now, the identification of the rpc clients in the
+         * handshake protocol is not there. So among so many glusterfs processes
+         * registered with glusterd, it is hard to identify one particular
+         * process (in this particular case, the snap daemon). So the callback
+         * notification is sent to all the transports from the transport list.
+         * Only those processes which have a rpc client registered for this
+         * callback will respond to the notification. Once the identification
+         * of the rpc clients becomes possible, the below section can be changed
+         * to send callback notification to only those rpc clients, which have
+         * registered.
+         */
+        pthread_mutex_lock (&priv->xprt_lock);
+        {
+                list_for_each_entry (trans, &priv->xprt_list, list) {
+                        rpcsvc_callback_submit (priv->rpc, trans,
+                                                &glusterd_cbk_prog,
+                                                GF_CBK_GET_SNAPS, NULL, 0);
+                }
+        }
+        pthread_mutex_unlock (&priv->xprt_lock);
+
+        ret = 0;
+
+        return ret;
+}
+
+int
 glusterd_priv (xlator_t *this)
 {
         return 0;
diff --git a/xlators/mgmt/glusterd/src/glusterd.h b/xlators/mgmt/glusterd/src/glusterd.h
index 4763078f028..45656bef8e1 100644
--- a/xlators/mgmt/glusterd/src/glusterd.h
+++ b/xlators/mgmt/glusterd/src/glusterd.h
@@ -836,6 +836,9 @@ int
 glusterd_fetchspec_notify (xlator_t *this);
 
 int
+glusterd_fetchsnap_notify (xlator_t *this);
+
+int
 glusterd_add_volume_detail_to_dict (glusterd_volinfo_t *volinfo,
                                     dict_t  *volumes, int   count);