Avoid retrying the last server on reconnect

Signed-off-by: Colin Sullivan <[email protected]>
nats-io · May 13, 2020 · 17eda5a · 17eda5a
1 parent 8fdccec
commit 17eda5a
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Showing 2 changed files with 16 additions and 7 deletions.
diff --git a/src/main/java/io/nats/client/impl/NatsConnection.java b/src/main/java/io/nats/client/impl/NatsConnection.java
@@ -192,7 +192,7 @@ void connect(boolean reconnectOnConnect) throws InterruptedException, IOExceptio
 
         timeTrace(trace, "starting connect loop");
 
-        Collection<String> serversToTry = buildServerList();
+        Collection<String> serversToTry = buildServerList(false);
         for (String serverURI : serversToTry) {
             if (isClosed()) {
                 break;
@@ -263,7 +263,7 @@ void reconnect() throws InterruptedException {
         boolean doubleAuthError = false;
 
         while (!isConnected() && !isClosed() && !this.isClosing()) {
-            Collection<String> serversToTry = buildServerList();
+            Collection<String> serversToTry = buildServerList(true);
 
             for (String server : serversToTry) {
                 if (isClosed()) {
@@ -1643,7 +1643,7 @@ void waitForReconnectTimeout() {
         this.reconnectWaiter.complete(Boolean.TRUE);
     }
 
-    Collection<String> buildServerList() {
+    Collection<String> buildServerList(boolean isReconnecting) {
         ArrayList<String> reconnectList = new ArrayList<>();
 
         reconnectList.addAll(getServers());
@@ -1652,8 +1652,18 @@ Collection<String> buildServerList() {
             return reconnectList;
         }
 
-        Collections.shuffle(reconnectList);
-
+        if (!isReconnecting) {
+            Collections.shuffle(reconnectList);
+        } else {
+            // Remove the current (first) server from the list, shuffle if it makes sense,
+            // and then add it to the end of the list.  This prevents the client
+            // from immediately reconnecting to a server it just lost connection with.
+            String s = reconnectList.remove(0);
+            if (reconnectList.size() > 1) {
+                Collections.shuffle(reconnectList);
+            }
+            reconnectList.add(s);
+        }
         return reconnectList;
     }
 

diff --git a/src/test/java/io/nats/client/impl/ReconnectTests.java b/src/test/java/io/nats/client/impl/ReconnectTests.java
@@ -341,7 +341,6 @@ public void testReconnectToSecondServer() throws Exception {
         }
     }
 
-
     @Test
     public void testNoRandomizeReconnectToSecondServer() throws Exception {
         NatsConnection nc = null;
@@ -615,7 +614,7 @@ public void testReconnectNoIPTLSConnection() throws Exception {
                                         server(ts.getURI()).
                                         secure().
                                         connectionListener(handler).
-                                        maxReconnects(10). // we get multiples for some, so need enough
+                                        maxReconnects(20). // we get multiples for some, so need enough
                                         reconnectWait(Duration.ofMillis(100)).
                                         connectionTimeout(Duration.ofSeconds(5)).
                                         noRandomize().