fixed management of hosts marked for deletion (DE-723, #384)

Author: rashtao

Diff for: core/src/main/java/com/arangodb/internal/net/FallbackHostHandler.java

@@ -50,6 +50,9 @@ public FallbackHostHandler(final HostResolver resolver) {
     @Override
     public Host get(final HostHandle hostHandle, AccessType accessType) {
         checkNext(hostHandle, accessType);
+        if (current.isMarkforDeletion()) {
+            fail(new ArangoDBException("Host marked for deletion"));
+        }
         return current;
     }
 

Diff for: core/src/main/java/com/arangodb/internal/net/RandomHostHandler.java

@@ -45,7 +45,7 @@ public RandomHostHandler(final HostResolver resolver, final HostHandler fallback
 
     @Override
     public Host get(final HostHandle hostHandle, AccessType accessType) {
-        if (current == null) {
+        if (current == null || current.isMarkforDeletion()) {
             hosts = resolver.getHosts();
             current = getRandomHost();
         }

Diff for: resilience-tests/src/test/java/resilience/connection/AcquireHostListTest.java

@@ -20,7 +20,7 @@ public class AcquireHostListTest extends ClusterTest {
     @EnumSource(Protocol.class)
     void acquireHostList(Protocol protocol) {
         ArangoDB adb = new ArangoDB.Builder()
-                .host("172.28.0.1", 8529)
+                .host("127.0.0.1", 8529)
                 .password("test")
                 .acquireHostList(true)
                 .protocol(protocol)
@@ -39,5 +39,19 @@ void acquireHostList(Protocol protocol) {
         assertThat(retrievedIds).containsExactlyInAnyOrderElementsOf(serverIds);
     }
 
+    @ParameterizedTest(name = "{index}")
+    @EnumSource(LoadBalancingStrategy.class)
+    void acquireHostListWithLoadBalancingStrategy(LoadBalancingStrategy lb) {
+        ArangoDB adb = new ArangoDB.Builder()
+                .host("127.0.0.1", 8529)
+                .password("test")
+                .acquireHostList(true)
+                .loadBalancingStrategy(lb)
+                .build();
+
+        adb.getVersion();
+        adb.getVersion();
+        adb.getVersion();
+    }
 
 }