CDRIVER-424 filter out non-matching nodes before those that are far

Author: TylerBrock

src/mongoc/mongoc-cluster.c

@@ -740,9 +740,6 @@ _mongoc_cluster_select (mongoc_cluster_t             *cluster,
     *       in the fast path of command dispatching.
     */
 
-#define IS_NEARER_THAN(n, msec) \
-   ((msec < 0 && (n)->ping_avg_msec >= 0) || ((n)->ping_avg_msec < msec))
-
    count = 0;
 
    for (i = 0; i < MONGOC_CLUSTER_MAX_NODES; i++) {
@@ -759,10 +756,33 @@ _mongoc_cluster_select (mongoc_cluster_t             *cluster,
             }
 
          }
+         count++;
+      }
+   }
+
+   /*
+    * Filter nodes with score less than highest score.
+    */
+   if (max_score) {
+      for (i = 0; i < MONGOC_CLUSTER_MAX_NODES; i++) {
+         if (nodes[i] && (scores[i] < max_score)) {
+             nodes[i] = NULL;
+             count--;
+         }
+      }
+   }
+
+   /*
+    * Get the nearest node among those which have not been filtered out
+    */
+#define IS_NEARER_THAN(n, msec) \
+   ((msec < 0 && (n)->ping_avg_msec >= 0) || ((n)->ping_avg_msec < msec))
+
+   for (i = 0; i < MONGOC_CLUSTER_MAX_NODES; i++) {
+      if (nodes[i]) {
          if (IS_NEARER_THAN(nodes[i], nearest)) {
             nearest = nodes[i]->ping_avg_msec;
          }
-         count++;
       }
    }
 
@@ -775,27 +795,14 @@ _mongoc_cluster_select (mongoc_cluster_t             *cluster,
       watermark = nearest + cluster->sec_latency_ms;
       for (i = 0; i < MONGOC_CLUSTER_MAX_NODES; i++) {
          if (nodes[i]) {
-			 if (nodes[i]->ping_avg_msec >(int32_t)watermark) {
+            if (nodes[i]->ping_avg_msec > (int32_t)watermark) {
                nodes[i] = NULL;
                count--;
             }
          }
       }
    }
 
-   /*
-    * Filter nodes with score less than highest score.
-    */
-   if (max_score) {
-      for (i = 0; i < MONGOC_CLUSTER_MAX_NODES; i++) {
-         if (nodes[i] && (scores[i] < max_score)) {
-             nodes[i] = NULL;
-             count--;
-         }
-      }
-   }
-
-
    /*
     * Mark the error as unable to locate a target node.
     */