Add failover policy specific stat counters

Summary: Add failover policy specific stats counters, one for incrementing when failover occurs and another for incrementing when all failover destinations have been exhausted. Without these stats, the failover_all and failover_all_failed stats provide aggregated counts across all failover policies.

Reviewed By: andreazevedo

Differential Revision: D6741561

fbshipit-source-id: 4e44a982f7ceae9604fc5563c57007ca2548af03

mcrouter/routes/FailoverPolicy.h

@@ -1,5 +1,5 @@
 /*
- *  Copyright (c) 2017, Facebook, Inc.
+ *  Copyright (c) 2017-present, Facebook, Inc.
  *  All rights reserved.
  *
  *  This source code is licensed under the BSD-style license found in the
@@ -74,6 +74,16 @@ class FailoverInOrderPolicy {
     return Iterator(children_, children_.size());
   }
 
+  // Returns the stat to increment when failover occurs.
+  stat_name_t getFailoverStat() const {
+    return failover_inorder_policy_stat;
+  }
+
+  // Returns the stat when all failover destinations are exhausted.
+  stat_name_t getFailoverFailedStat() const {
+    return failover_inorder_policy_failed_stat;
+  }
+
  private:
   const std::vector<RouteHandlePtr>& children_;
 };
@@ -166,6 +176,16 @@ class FailoverLeastFailuresPolicy {
     return Iterator(*this, maxTries_);
   }
 
+  // Returns the stat to increment when failover occurs.
+  stat_name_t getFailoverStat() const {
+    return failover_least_failures_policy_stat;
+  }
+
+  // Returns the stat when all failover destinations are exhausted.
+  stat_name_t getFailoverFailedStat() const {
+    return failover_least_failures_policy_failed_stat;
+  }
+
  private:
   std::vector<size_t> getLeastFailureRouteIndices() const {
     std::vector<size_t> indices;

mcrouter/routes/FailoverRoute.h

@@ -1,5 +1,5 @@
 /*
- *  Copyright (c) 2017, Facebook, Inc.
+ *  Copyright (c) 2017-present, Facebook, Inc.
  *  All rights reserved.
  *
  *  This source code is licensed under the BSD-style license found in the
@@ -211,6 +211,7 @@ class FailoverRoute {
     }
 
     proxy.stats().increment(failover_all_stat);
+    proxy.stats().increment(failoverPolicy_.getFailoverStat());
 
     if (rateLimiter_ && !rateLimiter_->failoverAllowed()) {
       proxy.stats().increment(failover_rate_limited_stat);
@@ -263,6 +264,7 @@ class FailoverRoute {
           auto failoverReply = doFailover(cur);
           if (isErrorResult(failoverReply.result())) {
             proxy.stats().increment(failover_all_failed_stat);
+            proxy.stats().increment(failoverPolicy_.getFailoverFailedStat());
           }
 
           return failoverReply;

mcrouter/stat_list.h

@@ -142,6 +142,12 @@ STUIR(failover_all, 0, 1)
 STUIR(failover_conditional, 0, 1)
 STUIR(failover_all_failed, 0, 1)
 STUIR(failover_rate_limited, 0, 1)
+STUIR(failover_inorder_policy, 0, 1)
+STUIR(failover_inorder_policy_failed, 0, 1)
+STUIR(failover_least_failures_policy, 0, 1)
+STUIR(failover_least_failures_policy_failed, 0, 1)
+STUIR(failover_custom_policy, 0, 1)
+STUIR(failover_custom_policy_failed, 0, 1)
 #undef GROUP
 #define GROUP ods_stats | count_stats
 STUI(result_error_count, 0, 1)