nsr: Introducing a happy path test case

Write infra for nsr_server to not send a
CHILD_UP before it gets a CHILD_UP from a
quorum of it's children. Using the CHILD_UP
received in the nsr client translator from
the server, to decide the right time for
starting the I/Os

Change-Id: I9551638b306bdcbc6bae6aeda00316576ea832fe
Signed-off-by: Avra Sengupta <asengupt@redhat.com>
Reviewed-on: http://review.gluster.org/13623
CentOS-regression: Gluster Build System <jenkins@build.gluster.com>
Smoke: Gluster Build System <jenkins@build.gluster.com>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
Reviewed-by: Jeff Darcy <jdarcy@redhat.com>

5 files changed, 197 insertions, 20 deletions

diff --git a/xlators/experimental/nsr-client/src/nsrc.c b/xlators/experimental/nsr-client/src/nsrc.c
index dd3ad20544e..13f1a2d38c5 100644
--- a/xlators/experimental/nsr-client/src/nsrc.c
+++ b/xlators/experimental/nsr-client/src/nsrc.c
@@ -18,6 +18,7 @@
 #include "xlator.h"
 #include "nsr-messages.h"
 #include "nsrc.h"
+#include "statedump.h"
 
 #define SCAR_LIMIT      20
 #define HILITE(x)       (""x"")
@@ -168,6 +169,7 @@ int32_t
 nsrc_init (xlator_t *this)
 {
         nsrc_private_t  *priv   = NULL;
+        xlator_list_t   *trav   = NULL;
 
         this->local_pool = mem_pool_new (nsrc_local_t, 128);
         if (!this->local_pool) {
@@ -181,6 +183,10 @@ nsrc_init (xlator_t *this)
                 goto err;
         }
 
+        for (trav = this->children; trav; trav = trav->next) {
+                ++(priv->n_children);
+        }
+
         priv->active = FIRST_CHILD(this);
         this->private = priv;
         return 0;
@@ -198,33 +204,111 @@ nsrc_fini (xlator_t *this)
         GF_FREE(this->private);
 }
 
+int
+nsrc_get_child_index (xlator_t *this, xlator_t *kid)
+{
+        xlator_list_t   *trav;
+        int             retval = -1;
+
+        for (trav = this->children; trav; trav = trav->next) {
+                ++retval;
+                if (trav->xlator == kid) {
+                        return retval;
+                }
+        }
+
+        return -1;
+}
+
+uint8_t
+nsrc_count_up_kids (nsrc_private_t *priv)
+{
+        uint8_t         retval  = 0;
+        uint8_t         i;
+
+        for (i = 0; i < priv->n_children; ++i) {
+                if (priv->kid_state & (1 << i)) {
+                        ++retval;
+                }
+        }
+
+        return retval;
+}
+
 int32_t
 nsrc_notify (xlator_t *this, int32_t event, void *data, ...)
 {
-        int32_t         ret     = 0;
+        int32_t           ret        = 0;
+        int32_t           index      = 0;
+        nsrc_private_t   *priv       = NULL;
+
+        GF_VALIDATE_OR_GOTO (THIS->name, this, out);
+        priv = this->private;
+        GF_VALIDATE_OR_GOTO (this->name, priv, out);
 
         switch (event) {
+        case GF_EVENT_CHILD_UP:
+                index = nsrc_get_child_index(this, data);
+                if (index >= 0) {
+                        priv->kid_state |= (1 << index);
+                        priv->up_children = nsrc_count_up_kids(priv);
+                        gf_msg (this->name, GF_LOG_INFO, 0, N_MSG_GENERIC,
+                                "got CHILD_UP for %s, now %u kids",
+                                ((xlator_t *)data)->name,
+                                priv->up_children);
+                }
+                ret = default_notify (this, event, data);
+                break;
         case GF_EVENT_CHILD_DOWN:
-                /*
-                 * TBD: handle this properly
-                 *
-                 * What we really should do is propagate this only if it caused
-                 * us to lose quorum, and likewise for GF_EVENT_CHILD_UP only
-                 * if it caused us to gain quorum.  However, that requires
-                 * tracking child states and for now it's easier to swallow
-                 * these unconditionally.  The consequence of failing to do
-                 * this is that DHT sees the first GF_EVENT_CHILD_DOWN and gets
-                 * confused, so it doesn't call us and doesn't get up-to-date
-                 * directory listings etc.
-                 */
+                index = nsrc_get_child_index(this, data);
+                if (index >= 0) {
+                        priv->kid_state &= ~(1 << index);
+                        priv->up_children = nsrc_count_up_kids(priv);
+                        gf_msg (this->name, GF_LOG_INFO, 0, N_MSG_GENERIC,
+                                "got CHILD_DOWN for %s, now %u kids",
+                                ((xlator_t *)data)->name,
+                                priv->up_children);
+                }
                 break;
         default:
                 ret = default_notify (this, event, data);
         }
 
+out:
         return ret;
 }
 
+int
+nsrc_priv_dump (xlator_t *this)
+{
+        nsrc_private_t     *priv = NULL;
+        char                key_prefix[GF_DUMP_MAX_BUF_LEN];
+        xlator_list_t      *trav = NULL;
+        int32_t             i    = -1;
+
+        GF_VALIDATE_OR_GOTO (THIS->name, this, out);
+        priv = this->private;
+        GF_VALIDATE_OR_GOTO (this->name, priv, out);
+
+        snprintf(key_prefix, GF_DUMP_MAX_BUF_LEN, "%s.%s",
+                 this->type, this->name);
+        gf_proc_dump_add_section(key_prefix);
+
+        gf_proc_dump_write("up_children", "%u", priv->up_children);
+
+        for (trav = this->children, i = 0; trav; trav = trav->next, i++) {
+                snprintf(key_prefix, GF_DUMP_MAX_BUF_LEN, "child_%d", i);
+                gf_proc_dump_write(key_prefix, "%s", trav->xlator->name);
+        }
+
+out:
+        return 0;
+}
+
+struct xlator_dumpops dumpops = {
+        .priv       = nsrc_priv_dump,
+};
+
 class_methods_t class_methods = {
         .init           = nsrc_init,
         .fini           = nsrc_fini,
diff --git a/xlators/experimental/nsr-client/src/nsrc.h b/xlators/experimental/nsr-client/src/nsrc.h
index 0c61d7a9fa8..15f0d7c85a0 100644
--- a/xlators/experimental/nsr-client/src/nsrc.h
+++ b/xlators/experimental/nsr-client/src/nsrc.h
@@ -13,6 +13,9 @@
 
 typedef struct {
         xlator_t        *active;
+        uint8_t          up_children;
+        uint8_t          n_children;
+        uint32_t         kid_state;
 } nsrc_private_t;
 
 typedef struct {
diff --git a/xlators/experimental/nsr-server/src/all-templates.c b/xlators/experimental/nsr-server/src/all-templates.c
index 300abea959d..c3819d2af54 100644
--- a/xlators/experimental/nsr-server/src/all-templates.c
+++ b/xlators/experimental/nsr-server/src/all-templates.c
@@ -83,6 +83,9 @@ nsr_@NAME@ (call_frame_t *frame, xlator_t *this,
 
                 if (result == _gf_false) {
                         /* Emulate the AFR client-side-quorum behavior. */
+                        gf_msg (this->name, GF_LOG_ERROR, EROFS,
+                                N_MSG_QUORUM_NOT_MET, "Sufficient number of "
+                                "subvolumes are not up to meet quorum.");
                         op_errno = EROFS;
                         goto err;
                 }
@@ -309,6 +312,10 @@ nsr_@NAME@_continue (call_frame_t *frame, xlator_t *this,
         result = fop_quorum_check (this, (double)priv->n_children,
                                    (double)local->successful_acks + 1);
         if (result == _gf_false) {
+                gf_msg (this->name, GF_LOG_ERROR, EROFS,
+                        N_MSG_QUORUM_NOT_MET, "Didn't receive enough acks "
+                        "to meet quorum. Failing the operation without trying "
+                        "it on the leader.");
                 STACK_UNWIND_STRICT (@NAME@, frame, -1, EROFS,
                                      @ERROR_ARGS@);
         } else {
@@ -406,8 +413,9 @@ nsr_@NAME@_complete (call_frame_t *frame, void *cookie, xlator_t *this,
                 if (result == _gf_false) {
                         op_ret = -1;
                         op_errno = EROFS;
-                        gf_msg_debug (this->name, 0,
-                                      "Quorum is not met. The operation has failed.");
+                        gf_msg (this->name, GF_LOG_ERROR, EROFS,
+                                N_MSG_QUORUM_NOT_MET, "Quorum is not met. "
+                                "The operation has failed.");
                 } else {
 #if defined(NSR_CG_NEED_FD)
                         op_ret = local->successful_op_ret;
diff --git a/xlators/experimental/nsr-server/src/nsr-internal.h b/xlators/experimental/nsr-server/src/nsr-internal.h
index b8c7fc314b7..d43fbac9a53 100644
--- a/xlators/experimental/nsr-server/src/nsr-internal.h
+++ b/xlators/experimental/nsr-server/src/nsr-internal.h
@@ -74,6 +74,8 @@ typedef struct {
          * TBD: re-evaluate how to manage this
          */
         char                    term_buf[CHANGELOG_ENTRY_SIZE];
+        gf_boolean_t            child_up; /* To maintain the state of *
+                                           * the translator */
 } nsr_private_t;
 
 typedef struct {
diff --git a/xlators/experimental/nsr-server/src/nsr.c b/xlators/experimental/nsr-server/src/nsr.c
index 48966ab15a1..0fb618f236e 100644
--- a/xlators/experimental/nsr-server/src/nsr.c
+++ b/xlators/experimental/nsr-server/src/nsr.c
@@ -860,13 +860,23 @@ nsr_get_child_index (xlator_t *this, xlator_t *kid)
 int
 nsr_notify (xlator_t *this, int event, void *data, ...)
 {
-        nsr_private_t   *priv   = this->private;
-        int             index;
+        nsr_private_t   *priv         = this->private;
+        int             index         = -1;
+        int             ret           = -1;
+        gf_boolean_t    result        = _gf_false;
+        gf_boolean_t    relevant      = _gf_false;
 
         switch (event) {
         case GF_EVENT_CHILD_UP:
                 index = nsr_get_child_index(this, data);
                 if (index >= 0) {
+                        /* Check if the child was previously down
+                         * and it's not a false CHILD_UP
+                         */
+                        if (!(priv->kid_state & (1 << index))) {
+                                relevant = _gf_true;
+                        }
+
                         priv->kid_state |= (1 << index);
                         priv->up_children = nsr_count_up_kids(priv);
                         gf_msg (this->name, GF_LOG_INFO, 0, N_MSG_GENERIC,
@@ -876,27 +886,96 @@ nsr_notify (xlator_t *this, int event, void *data, ...)
                         if (!priv->config_leader && (priv->up_children > 1)) {
                                 priv->leader = _gf_false;
                         }
+
+                        /* If it's not relevant, or we have already *
+                         * sent CHILD_UP just break */
+                        if (!relevant || priv->child_up)
+                                break;
+
+                        /* If it's not a leader, just send the notify up */
+                        if (!priv->leader) {
+                                ret = default_notify(this, event, data);
+                                if (!ret)
+                                        priv->child_up = _gf_true;
+                                break;
+                        }
+
+                        result = fop_quorum_check (this,
+                                                (double)(priv->n_children - 1),
+                                               (double)(priv->up_children - 1));
+                        if (result == _gf_false) {
+                                gf_msg (this->name, GF_LOG_INFO, 0,
+                                        N_MSG_GENERIC, "Not enough children "
+                                        "are up to meet quorum. Waiting to "
+                                        "send CHILD_UP from leader");
+                        } else {
+                                gf_msg (this->name, GF_LOG_INFO, 0,
+                                        N_MSG_GENERIC, "Enough children are up "
+                                        "to meet quorum. Sending CHILD_UP "
+                                        "from leader");
+                                ret = default_notify(this, event, data);
+                                if (!ret)
+                                        priv->child_up = _gf_true;
+                        }
                 }
                 break;
         case GF_EVENT_CHILD_DOWN:
                 index = nsr_get_child_index(this, data);
                 if (index >= 0) {
+                        /* Check if the child was previously up
+                         * and it's not a false CHILD_DOWN
+                         */
+                        if (priv->kid_state & (1 << index)) {
+                                relevant = _gf_true;
+                        }
                         priv->kid_state &= ~(1 << index);
                         priv->up_children = nsr_count_up_kids(priv);
                         gf_msg (this->name, GF_LOG_INFO, 0, N_MSG_GENERIC,
                                 "got CHILD_DOWN for %s, now %u kids",
                                 ((xlator_t *)data)->name,
                                 priv->up_children);
-                        if (!priv->config_leader && (priv->up_children < 2)) {
+                        if (!priv->config_leader && (priv->up_children < 2)
+                            && relevant) {
                                 priv->leader = _gf_true;
                         }
+
+                        /* If it's not relevant, or we have already *
+                         * sent CHILD_DOWN just break */
+                        if (!relevant || !priv->child_up)
+                                break;
+
+                        /* If it's not a leader, just break coz we shouldn't  *
+                         * propagate the failure from the failure till it     *
+                         * itself goes down                                   *
+                         */
+                        if (!priv->leader) {
+                                break;
+                        }
+
+                        result = fop_quorum_check (this,
+                                           (double)(priv->n_children - 1),
+                                           (double)(priv->up_children - 1));
+                        if (result == _gf_false) {
+                                gf_msg (this->name, GF_LOG_INFO, 0,
+                                        N_MSG_GENERIC, "Enough children are "
+                                        "to down to fail quorum. "
+                                        "Sending CHILD_DOWN from leader");
+                                ret = default_notify(this, event, data);
+                                if (!ret)
+                                        priv->child_up = _gf_false;
+                        } else {
+                                gf_msg (this->name, GF_LOG_INFO, 0,
+                                        N_MSG_GENERIC, "Not enough children "
+                                        "are down to fail quorum. Waiting to "
+                                        "send CHILD_DOWN from leader");
+                        }
                 }
                 break;
         default:
-                ;
+                ret = default_notify(this, event, data);
         }
 
-        return default_notify(this, event, data);
+        return ret;
 }
 
 
@@ -995,6 +1074,7 @@ nsr_init (xlator_t *this)
         GF_OPTION_INIT ("quorum-percent", priv->quorum_pct, percent, err);
 
         priv->leader = priv->config_leader;
+        priv->child_up = _gf_false;
 
         if (pthread_create(&kid, NULL, nsr_flush_thread,
                            this) != 0) {