features/changelog: Change barrier notification mechanism

Backport of http://review.gluster.org/14272

The barrier notification mechanism was fd based and 'select'
was being used. 'select' breaks when number of fds opened
by brick process exceeds 1024. To avoid this and also
the maintainance of pipe between notify and 'changelog_rollover',
the pipe has been replaced with pthread condition signal
and timed wait mechanism.

Change-Id: I530ea90d9a06953f8b23b4e12d122872ee1925de
BUG: 1341952
Signed-off-by: Kotresh HR <khiremat@redhat.com>
Reviewed-on: http://review.gluster.org/14615
Smoke: Gluster Build System <jenkins@build.gluster.org>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Raghavendra Bhat <raghavendra@redhat.com>
Reviewed-by: Jeff Darcy <jdarcy@redhat.com>

1 files changed, 26 insertions, 27 deletions

diff --git a/xlators/features/changelog/src/changelog.c b/xlators/features/changelog/src/changelog.c
index 8898d51344f..6c38293f640 100644
--- a/xlators/features/changelog/src/changelog.c
+++ b/xlators/features/changelog/src/changelog.c
@@ -2028,11 +2028,6 @@ changelog_cleanup_helper_threads (xlator_t *this, changelog_priv_t *priv)
         if (priv->cr.rollover_th) {
                 (void) changelog_thread_cleanup (this, priv->cr.rollover_th);
                 priv->cr.rollover_th = 0;
-                ret = close (priv->cr_wfd);
-                if (ret)
-                        gf_log (this->name, GF_LOG_ERROR,
-                                "error closing write end of rollover pipe"
-                                " (reason: %s)", strerror (errno));
         }
 
         if (priv->cf.fsync_th) {
@@ -2047,7 +2042,6 @@ changelog_spawn_helper_threads (xlator_t *this, changelog_priv_t *priv)
 {
         int ret = 0;
         int flags = 0;
-        int pipe_fd[2] = {0, 0};
 
         /* Geo-Rep snapshot dependency:
          *
@@ -2061,27 +2055,7 @@ changelog_spawn_helper_threads (xlator_t *this, changelog_priv_t *priv)
          * the write end of the pipe in 'reconfigure'.
          */
 
-        ret = pipe (pipe_fd);
-        if (ret == -1) {
-                gf_log (this->name, GF_LOG_ERROR,
-                        "Cannot create pipe (reason: %s)", strerror (errno));
-                goto out;
-        }
-
-        /* writer is non-blocking */
-        flags = fcntl (pipe_fd[1], F_GETFL);
-        flags |= O_NONBLOCK;
-
-        ret = fcntl (pipe_fd[1], F_SETFL, flags);
-        if (ret) {
-                gf_log (this->name, GF_LOG_ERROR,
-                        "failed to set O_NONBLOCK flag");
-                goto out;
-        }
-
-        priv->cr_wfd = pipe_fd[1];
-        priv->cr.rfd = pipe_fd[0];
-
+        priv->cr.notify = _gf_false;
         priv->cr.this = this;
         ret = gf_thread_create (&priv->cr.rollover_th,
 				NULL, changelog_rollover, priv);
@@ -2384,6 +2358,8 @@ changelog_barrier_pthread_init (xlator_t *this, changelog_priv_t *priv)
         gf_boolean_t    dm_cond_black_init    = _gf_false;
         gf_boolean_t    dm_mutex_white_init   = _gf_false;
         gf_boolean_t    dm_cond_white_init    = _gf_false;
+        gf_boolean_t    cr_mutex_init         = _gf_false;
+        gf_boolean_t    cr_cond_init          = _gf_false;
         int             ret                   = 0;
 
         if ((ret = pthread_mutex_init(&priv->bn.bnotify_mutex, NULL)) != 0) {
@@ -2435,6 +2411,22 @@ changelog_barrier_pthread_init (xlator_t *this, changelog_priv_t *priv)
                 goto out;
         }
         dm_cond_white_init = _gf_true;
+
+        if ((pthread_mutex_init(&priv->cr.lock, NULL)) != 0) {
+                gf_log (this->name, GF_LOG_ERROR,
+                        "changelog_rollover lock init failed (%d)", ret);
+                ret = -1;
+                goto out;
+        }
+        cr_mutex_init = _gf_true;
+
+        if ((pthread_cond_init(&priv->cr.cond, NULL)) != 0) {
+                gf_log (this->name, GF_LOG_ERROR,
+                        "changelog_rollover cond init failed (%d)", ret);
+                ret = -1;
+                goto out;
+        }
+        cr_cond_init = _gf_true;
  out:
         if (ret) {
                 if (bn_mutex_init)
@@ -2449,6 +2441,10 @@ changelog_barrier_pthread_init (xlator_t *this, changelog_priv_t *priv)
                         pthread_mutex_destroy(&priv->dm.drain_white_mutex);
                 if (dm_cond_white_init)
                         pthread_cond_destroy (&priv->dm.drain_white_cond);
+                if (cr_mutex_init)
+                        pthread_mutex_destroy(&priv->cr.lock);
+                if (cr_cond_init)
+                        pthread_cond_destroy (&priv->cr.cond);
         }
         return ret;
 }
@@ -2463,6 +2459,8 @@ changelog_barrier_pthread_destroy (changelog_priv_t *priv)
         pthread_cond_destroy (&priv->dm.drain_black_cond);
         pthread_mutex_destroy (&priv->dm.drain_white_mutex);
         pthread_cond_destroy (&priv->dm.drain_white_cond);
+        pthread_mutex_destroy(&priv->cr.lock);
+        pthread_cond_destroy (&priv->cr.cond);
         LOCK_DESTROY (&priv->bflags.lock);
 }
 
@@ -2786,6 +2784,7 @@ init (xlator_t *this)
         priv->current_color = FOP_COLOR_BLACK;
         priv->explicit_rollover = _gf_false;
 
+        priv->cr.notify = _gf_false;
         /* Mutex is not needed as threads are not spawned yet */
         priv->bn.bnotify = _gf_false;
         priv->bn.bnotify_error = _gf_false;