HCHttp refactoring - splitting HCHttp and ClientObjectFactory (#60)

* BatchingClientObjectFactory added to separate batching logic from HCHttp
* Batch and Item interfaces added (finally!) to handle API-specific implementations of "Batch domain"
* BatchOperations can now be configured with HCHttp.Builder (configurable provider of "Batch domain")
* HCHttp.Builder.pooledItemSourceFactory deprecated
* HCHttp.itemSourceFactory removed
* HCHttp.Builder.mappingType deprecated
* HCHttp.mappingType removed
* OperationFactory MUST be provided

log4j2-elasticsearch-core/src/main/java/org/appenders/log4j2/elasticsearch/BatchListenerFactory.java

@@ -0,0 +1,41 @@
+package org.appenders.log4j2.elasticsearch;
+
+/*-
+ * #%L
+ * log4j2-elasticsearch
+ * %%
+ * Copyright (C) 2021 Rafal Foltynski
+ * %%
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * #L%
+ */
+
+import java.util.function.Function;
+
+public interface BatchListenerFactory<BATCH_TYPE> {
+
+    /**
+     * Listener that MUST accept and send prepared batch and handle the exceptions
+     * @param failoverPolicy sink for failed batch items
+     * @return prepared batch handler
+     */
+    Function<BATCH_TYPE, Boolean> createBatchListener(FailoverPolicy failoverPolicy);
+
+    /**
+     * Failed batch handler. SHOULD deliver the batch to alternate target or provided failover policy
+     * @param failover optional failover strategy
+     * @return prepared failed batch handler
+     */
+    Function<BATCH_TYPE, Boolean> createFailureHandler(FailoverPolicy failover);
+
+}

log4j2-elasticsearch-core/src/main/java/org/appenders/log4j2/elasticsearch/ClientFactory.java

@@ -0,0 +1,37 @@
+package org.appenders.log4j2.elasticsearch;
+
+/*-
+ * #%L
+ * log4j2-elasticsearch
+ * %%
+ * Copyright (C) 2021 Rafal Foltynski
+ * %%
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * #L%
+ */
+
+import java.util.Collection;
+
+public interface ClientFactory<CLIENT_TYPE> {
+
+    /**
+     * @return Collection of configured addresses
+     */
+    Collection<String> getServerList();
+
+    /**
+     * @return CLIENT_TYPE Fully configured client
+     */
+    CLIENT_TYPE createClient();
+
+}

log4j2-elasticsearch-core/src/main/java/org/appenders/log4j2/elasticsearch/ClientObjectFactory.java

@@ -21,9 +21,6 @@
  */
 
 
-import java.util.Collection;
-import java.util.function.Function;
-
 /**
  * Factory for client-specific objects:
  * <ul>
@@ -38,34 +35,10 @@
  * @param <CLIENT_TYPE> type of client object produced by this factory
  * @param <BATCH_TYPE> type of batch objects handled by the client
  */
-public interface ClientObjectFactory<CLIENT_TYPE, BATCH_TYPE> extends LifeCycle {
+public interface ClientObjectFactory<CLIENT_TYPE, BATCH_TYPE> extends LifeCycle, BatchListenerFactory<BATCH_TYPE>, ClientFactory<CLIENT_TYPE> {
 
     String ELEMENT_TYPE = "objectFactory";
 
-    /**
-     * @return Collection of configured addresses
-     */
-    Collection<String> getServerList();
-
-    /**
-     * @return CLIENT_TYPE Fully configured client
-     */
-    CLIENT_TYPE createClient();
-
-    /**
-     * Listener that MUST accept and send prepared batch and handle the exceptions
-     * @param failoverPolicy sink for failed batch items
-     * @return prepared batch handler
-     */
-    Function<BATCH_TYPE, Boolean> createBatchListener(FailoverPolicy failoverPolicy);
-
-    /**
-     * Failed batch handler. SHOULD deliver the batch to alternate target or provided failover policy
-     * @param failover optional failover strategy
-     * @return prepared failed batch handler
-     */
-    Function<BATCH_TYPE, Boolean> createFailureHandler(FailoverPolicy failover);
-
     /**
      * @return batch items creator
      */
@@ -84,7 +57,9 @@ public interface ClientObjectFactory<CLIENT_TYPE, BATCH_TYPE> extends LifeCycle
      *
      * NOTE: {@code default} added for backwards compatibility. {@code default} will be removed future releases
      * @param operation operation to be executed
+     * @deprecated As of 1.6, this method will be wrapped by batch-phase-based queue
      */
+    @Deprecated
     default void addOperation(Operation operation) {}
 
     /**

log4j2-elasticsearch-hc/src/main/java/org/appenders/log4j2/elasticsearch/hc/Batch.java

@@ -0,0 +1,28 @@
+package org.appenders.log4j2.elasticsearch.hc;
+
+/*-
+ * #%L
+ * log4j2-elasticsearch
+ * %%
+ * Copyright (C) 2021 Rafal Foltynski
+ * %%
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * #L%
+ */
+
+import java.util.Collection;
+
+public interface Batch<I> extends Request {
+    Collection<I> getItems();
+    void completed();
+}

log4j2-elasticsearch-hc/src/main/java/org/appenders/log4j2/elasticsearch/hc/BatchRequest.java

@@ -36,7 +36,7 @@
  * Allows to index multiple {@link org.appenders.log4j2.elasticsearch.hc.IndexRequest} documents
  * in a single request.
  */
-public class BatchRequest implements Request {
+public class BatchRequest implements Batch<IndexRequest> {
 
     public static final String HTTP_METHOD_NAME = "POST";
     public static final char LINE_SEPARATOR = '\n';
@@ -121,10 +121,23 @@ public void completed() {
 
     }
 
-    public Collection<IndexRequest> getIndexRequests() {
+    /**
+     * @return collection of batch items
+     */
+    @Override
+    public Collection<IndexRequest> getItems() {
         return indexRequests;
     }
 
+    /**
+     * @return collection of batch items
+     * @deprecated As of 1.6, this method will be removed. Use {@link #getItems()} instead
+     */
+    @Deprecated
+    public Collection<IndexRequest> getIndexRequests() {
+        return getItems();
+    }
+
     @Override
     public String getURI() {
         return "/_bulk";