glusterd: Client Handling of Elastic Clusters

Configure the list of gluster servers in the key
GLUSTERD_BRICK_SERVERS at the time of GETSPEC RPC CALL
and access the value in client side to update volfile
serve list so that client would be able to connect
next volfile server in case of current volfile server
is down

Updates #741
Signed-off-by: Mohit Agrawal <moagrawa@redhat.com>

Change-Id: I23f36ddb92982bb02ffd83937a8bd8a2c97e8104

1 files changed, 49 insertions, 0 deletions

diff --git a/xlators/mgmt/glusterd/src/glusterd-handshake.c b/xlators/mgmt/glusterd/src/glusterd-handshake.c
index 1671c2481dc..1cbdc304916 100644
--- a/xlators/mgmt/glusterd/src/glusterd-handshake.c
+++ b/xlators/mgmt/glusterd/src/glusterd-handshake.c
@@ -907,10 +907,20 @@ __server_getspec(rpcsvc_request_t *req)
     peer_info_t *peerinfo = NULL;
     xlator_t *this = NULL;
     dict_t *dict = NULL;
+    glusterd_peerinfo_t *peer = NULL;
+    glusterd_conf_t *conf = NULL;
+    int peer_cnt = 0;
+    char *peer_hosts = NULL;
+    char *tmp_str = NULL;
+    char portstr[10] = {
+        0,
+    };
+    int len = 0;
 
     this = THIS;
     GF_ASSERT(this);
 
+    conf = this->private;
     ret = xdr_to_generic(req->msg[0], &args, (xdrproc_t)xdr_gf_getspec_req);
     if (ret < 0) {
         // failed to decode msg;
@@ -998,6 +1008,43 @@ __server_getspec(rpcsvc_request_t *req)
                                  dict);
     }
 
+    RCU_READ_LOCK;
+    cds_list_for_each_entry_rcu(peer, &conf->peers, uuid_list)
+    {
+        if (!peer->connected)
+            continue;
+        if (!peer_hosts) {
+            if (peer->port) {
+                snprintf(portstr, sizeof(portstr), "%d", peer->port);
+            } else {
+                snprintf(portstr, sizeof(portstr), "%d", GLUSTERD_DEFAULT_PORT);
+            }
+            len = strlen(peer->hostname) + strlen(portstr) + 3;
+            tmp_str = GF_CALLOC(1, len, gf_gld_mt_char);
+            snprintf(tmp_str, len, "%s%s%s%s", peer->hostname, ":", portstr,
+                     " ");
+            peer_hosts = tmp_str;
+        } else {
+            len = strlen(peer_hosts) + strlen(peer->hostname) +
+                  strlen(portstr) + 3;
+            tmp_str = GF_CALLOC(1, len, gf_gld_mt_char);
+            snprintf(tmp_str, len, "%s%s%s%s%s", peer_hosts, peer->hostname,
+                     ":", portstr, " ");
+            GF_FREE(peer_hosts);
+            peer_hosts = tmp_str;
+        }
+        peer_cnt++;
+    }
+    RCU_READ_UNLOCK;
+    if (peer_cnt) {
+        ret = dict_set_str(dict, GLUSTERD_BRICK_SERVERS, peer_hosts);
+        if (ret) {
+            gf_msg(this->name, GF_LOG_ERROR, 0, GD_MSG_DICT_SET_FAILED,
+                   "failed to set peer_host in dict");
+            goto fail;
+        }
+    }
+
     if (ret == 0) {
         if (dict->count > 0) {
             ret = dict_allocate_and_serialize(dict, &rsp.xdata.xdata_val,
@@ -1076,6 +1123,8 @@ fail:
     free(args.key);  // malloced by xdr
     free(rsp.spec);
 
+    if (peer_hosts)
+        GF_FREE(peer_hosts);
     if (dict)
         dict_unref(dict);