1 files changed, 91 insertions, 0 deletions
diff --git a/netconfsimulator/src/main/java/org/onap/netconfsimulator/kafka/StoreService.java b/netconfsimulator/src/main/java/org/onap/netconfsimulator/kafka/StoreService.java
new file mode 100644
index 0000000..5fddff5
--- /dev/null
+++ b/netconfsimulator/src/main/java/org/onap/netconfsimulator/kafka/StoreService.java
@@ -0,0 +1,91 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * Simulator
+ * ================================================================================
+ * Copyright (C) 2019 Nokia. All rights reserved.
+ * ================================================================================
+ * 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.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.netconfsimulator.kafka;
+
+import lombok.extern.slf4j.Slf4j;
+import org.apache.kafka.clients.consumer.Consumer;
+import org.apache.kafka.clients.consumer.ConsumerRecords;
+import org.apache.kafka.common.TopicPartition;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.kafka.core.ConsumerFactory;
+import org.springframework.stereotype.Service;
+
+import java.time.Instant;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+@Slf4j
+@Service
+public class StoreService {
+
+    private static final String CONFIG_TOPIC = "config";
+    private static final long CONSUMING_DURATION_IN_MS = 1000;
+
+    private ConsumerFactory<String, String> consumerFactory;
+    static final List<String> TOPICS_TO_SUBSCRIBE = Collections.singletonList(CONFIG_TOPIC);
+
+    @Autowired
+    StoreService(ConsumerFactory<String, String> consumerFactory) {
+        this.consumerFactory = consumerFactory;
+    }
+
+    List<MessageDTO> getAllMessages() {
+        List<MessageDTO> messages = new ArrayList<>();
+        String clientID = Long.toString(Instant.now().getEpochSecond());
+        try (Consumer<String, String> consumer = consumerFactory.createConsumer(clientID, clientID)) {
+            consumer.subscribe(TOPICS_TO_SUBSCRIBE);
+            ConsumerRecords<String, String> consumerRecords = consumer.poll(CONSUMING_DURATION_IN_MS);
+            consumerRecords.forEach(
+                consumerRecord ->
+                    messages.add(new MessageDTO(consumerRecord.timestamp(), consumerRecord.value())));
+            log.debug(String.format("consumed %d messages", consumerRecords.count()));
+            }
+        return messages;
+    }
+
+    List<MessageDTO> getLastMessages(long offset) {
+        List<MessageDTO> messages = new ArrayList<>();
+        try (Consumer<String, String> consumer = createConsumer(offset)) {
+            ConsumerRecords<String, String> consumerRecords = consumer.poll(CONSUMING_DURATION_IN_MS);
+            consumerRecords.forEach(consumerRecord ->
+                    messages.add(new MessageDTO(consumerRecord.timestamp(), consumerRecord.value())));
+        }
+        return messages;
+    }
+
+    private Consumer<String, String> createConsumer(long offsetFromLastIndex) {
+        String clientID = Long.toString(Instant.now().getEpochSecond());
+        Consumer<String, String> consumer = consumerFactory.createConsumer(clientID, clientID);
+        consumer.subscribe(TOPICS_TO_SUBSCRIBE);
+        seekConsumerTo(consumer, offsetFromLastIndex);
+        return consumer;
+    }
+
+    private void seekConsumerTo(Consumer<String, String> consumer, long offsetFromLastIndex) {
+        consumer.seekToEnd(consumer.assignment());
+        consumer.poll(CONSUMING_DURATION_IN_MS);
+        TopicPartition topicPartition = consumer.assignment().iterator().next();
+        long topicCurrentSize = consumer.position(topicPartition);
+        long indexToSeek = offsetFromLastIndex > topicCurrentSize ? 0 : topicCurrentSize - offsetFromLastIndex;
+        consumer.seek(topicPartition, indexToSeek);
+    }
+}