HDDS-17302. OM client retry wait time grows without bound with a single OM

hadoop-ozone/common/src/main/java/org/apache/hadoop/ozone/om/ha/OMFailoverProxyProviderBase.java

@@ -399,6 +399,17 @@ private synchronized boolean updateLeaderOMNodeId(String newLeaderOMNodeId) {
    * @return delay in milliseconds
    */
   public synchronized long getWaitTime() {
+    // OMs are being contacted in Round Robin way. If all the OMs have been
+    // contacted once in this attempt, clear the list. The OMs will be retried
+    // in a Round Robin fashion again after a fixed delay. This is checked first
+    // because with a single OM, Round Robin selects the same OM again, which is
+    // not a retry on the same OM based on response from OM.
+    if (attemptedOMs.containsAll(omProxies.getNodeIds())) {
+      attemptedOMs.clear();
+      numAttemptsOnSameOM = 0;
+      return waitBetweenRetries;
+    }
+
     if (omProxies.getNodeId(nextProxyIndex).equals(lastAttemptedOM)) {
       // Clear attemptedOMs list as the same OM has been selected again.
       attemptedOMs.clear();
@@ -409,19 +420,7 @@ public synchronized long getWaitTime() {
     }
     // Reset numAttemptsOnSameOM as we failed over to a different OM.
     numAttemptsOnSameOM = 0;
-
-    // OMs are being contacted in Round Robin way. Check if all the OMs have
-    // been contacted in this attempt.
-    for (String omNodeID : omProxies.getNodeIds()) {
-      if (!attemptedOMs.contains(omNodeID)) {
-        return 0;
-      }
-    }
-    // This implies all the OMs have been contacted once. Return true and
-    // clear the list. The OMs will be retried in a Round Robin fashion again
-    // after a delay.
-    attemptedOMs.clear();
-    return waitBetweenRetries;
+    return 0;
   }
 
   public List<OMProxyInfo<T>> getOMProxies() {

hadoop-ozone/common/src/test/java/org/apache/hadoop/ozone/om/ha/TestOMFailoverProxyProvider.java

@@ -145,6 +145,24 @@ public void testWaitTimeResetWhenAllNodeFailoverAndSameNode() {
     failoverToNextNode(1, waitBetweenRetries);
   }
 
+  /**
+   * Tests waitTime with a single OM: Round Robin failover (e.g. on connection
+   * failure) selects the same OM again, and should not increase the wait time.
+   */
+  @Test
+  public void testWaitTimeWithSingleNode() throws IOException {
+    OzoneConfiguration conf = new OzoneConfiguration();
+    conf.set(OZONE_OM_ADDRESS_KEY, DUMMY_NODE_ADDR);
+    provider = new HadoopRpcOMFailoverProxyProvider<>(conf, UserGroupInformation.getCurrentUser(), null,
+        OzoneManagerProtocolPB.class);
+
+    failoverToNextNode(3, waitBetweenRetries);
+    // Retry on the same OM based on response from OM, waitTime should increase.
+    failoverToSameNode(2);
+    // Round Robin failover again should reset waitTime.
+    failoverToNextNode(1, waitBetweenRetries);
+  }
+
   /**
    * Ensure listener nodes are excluded from provider's proxy list.
    */