Fixed host handler failures count (#398)

* fixed host handler failures count

* fixed host handler tests

Author: rashtao

src/main/java/com/arangodb/internal/net/FallbackHostHandler.java

@@ -55,6 +55,7 @@ public Host get(final HostHandle hostHandle, AccessType accessType) {
     @Override
     public void success() {
         lastSuccess = current;
+        iterations = 0;
     }
 
     @Override

src/main/java/com/arangodb/internal/net/RandomHostHandler.java

@@ -30,27 +30,26 @@ public class RandomHostHandler implements HostHandler {
 
     private final HostResolver resolver;
     private final HostHandler fallback;
-    private Host origin;
     private Host current;
 
     public RandomHostHandler(final HostResolver resolver, final HostHandler fallback) {
         super();
         this.resolver = resolver;
         this.fallback = fallback;
-        origin = current = getRandomHost(true, false);
+        current = getRandomHost(true, false);
     }
 
     @Override
     public Host get(final HostHandle hostHandle, AccessType accessType) {
         if (current == null) {
-            origin = current = getRandomHost(false, true);
+            current = getRandomHost(false, true);
         }
         return current;
     }
 
     @Override
     public void success() {
-        current = origin;
+        fallback.success();
     }
 
     @Override
@@ -60,7 +59,6 @@ public void fail() {
     }
 
     private Host getRandomHost(final boolean initial, final boolean closeConnections) {
-
         final ArrayList<Host> hosts = new ArrayList<>(resolver.resolve(initial, closeConnections).getHostsList());
         Collections.shuffle(hosts);
         return hosts.get(0);

src/main/java/com/arangodb/internal/velocystream/VstCommunication.java

@@ -83,6 +83,7 @@ protected synchronized C connect(final HostHandle hostHandle, final AccessType a
             }
             final C connection = (C) host.connection();
             if (connection.isOpen()) {
+                hostHandler.success();
                 return connection;
             } else {
                 try {

src/test/java/com/arangodb/internal/HostHandlerTest.java

@@ -117,12 +117,18 @@ public void randomHostHandlerSingleHost() {
     @Test
     public void randomHostHandlerMultipeHosts() {
         final HostHandler handler = new RandomHostHandler(MULTIPLE_HOSTS, new FallbackHostHandler(MULTIPLE_HOSTS));
+
         final Host pick0 = handler.get(null, null);
         assertThat(pick0, anyOf(is(HOST_0), is(HOST_1), is(HOST_2)));
         handler.fail();
-        assertThat(handler.get(null, null), anyOf(is(HOST_0), is(HOST_1), is(HOST_2)));
+
+        final Host pick1 = handler.get(null, null);
+        assertThat(pick1, anyOf(is(HOST_0), is(HOST_1), is(HOST_2)));
         handler.success();
-        assertThat(handler.get(null, null), is(pick0));
+
+        final Host pick3 = handler.get(null, null);
+        assertThat(pick3, anyOf(is(HOST_0), is(HOST_1), is(HOST_2)));
+        assertThat(pick3, is(pick1));
     }
 
     @Test