event: Idle connection management

Summary:
- This diff adds support for detecting and tracking idle client connections.
- It allows *service translators* (server, nfs) to opt-in to detect and close idle client connections.
- Right now it explicitly restricts the service to NFS as a safety.

Here are the debug logs when a client connection gets closed:

  [2016-03-29 17:27:06.154232] W [socket.c:2426:socket_timeout_handler] 0-socket: Shutting down idle client connection (idle=20s,fd=20,conn=[2401:db00:11:d0af:face:0:3:0:957]->[2401:db00:11:d0af:face:0:3:0:2049])!
  [2016-03-29 17:27:06.154292] D [event-epoll.c:655:__event_epoll_timeout_slot] 0-epoll: Connection on slot->fd=9 was idle for 20 seconds!
  [2016-03-29 17:27:06.163282] D [socket.c:629:__socket_rwv] 0-socket.nfs-server: EOF on socket
  [2016-03-29 17:27:06.163298] D [socket.c:2474:socket_event_handler] 0-transport: disconnecting now
  [2016-03-29 17:27:06.163316] D [event-epoll.c:614:event_dispatch_epoll_handler] 0-epoll: generation bumped on idx=9 from gen=4 to slot->gen=5, fd=20, slot->fd=20

Test Plan: - Used stuck NFS mounts to create idle clients and unstuck them.

Reviewers: kvigor, rwareing

Reviewed By: rwareing

Subscribers: dld, moox, dph

Differential Revision: https://phabricator.fb.com/D3112099

Change-Id: Ic06c89e03f87daabab7f07f892390edd1a1fcc20
Signed-off-by: Jeff Darcy <jdarcy@fb.com>
Reviewed-on: https://review.gluster.org/18265
Reviewed-by: Jeff Darcy <jeff@pl.atyp.us>
Tested-by: Jeff Darcy <jeff@pl.atyp.us>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Smoke: Gluster Build System <jenkins@build.gluster.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/libglusterfs/src/event.c b/libglusterfs/src/event.c
index 09ecce1599d..a8351977f12 100644
--- a/libglusterfs/src/event.c
+++ b/libglusterfs/src/event.c
@@ -57,14 +57,15 @@ event_pool_new (int count, int eventthreadcount)
 
 int
 event_register (struct event_pool *event_pool, int fd,
-                event_handler_t handler,
+                event_handler_t handler, timeout_event_handler_t timeout_handler,
                 void *data, int poll_in, int poll_out)
 {
         int ret = -1;
 
         GF_VALIDATE_OR_GOTO ("event", event_pool, out);
 
-        ret = event_pool->ops->event_register (event_pool, fd, handler, data,
+        ret = event_pool->ops->event_register (event_pool, fd, handler,
+                                               timeout_handler, data,
                                                poll_in, poll_out);
 out:
         return ret;
@@ -225,7 +226,7 @@ event_dispatch_destroy (struct event_pool *event_pool)
 
         /* From the main thread register an event on the pipe fd[0],
          */
-        idx = event_register (event_pool, fd[0], poller_destroy_handler,
+        idx = event_register (event_pool, fd[0], poller_destroy_handler, NULL,
                               &fd[1], 1, 0);
         if (idx < 0)
                 goto out;