Die Implementierung speichert Zustand & Offsets vor _jedem_ `poll()`

[demos/kafka/training] / src / main / java / de / juplo / kafka / ApplicationRecordHandler.java

diff --git a/src/main/java/de/juplo/kafka/ApplicationRecordHandler.java b/src/main/java/de/juplo/kafka/ApplicationRecordHandler.java
index 596f3da..bc18d59 100644 (file)
--- a/src/main/java/de/juplo/kafka/ApplicationRecordHandler.java
+++ b/src/main/java/de/juplo/kafka/ApplicationRecordHandler.java
@@ -4,8 +4,10 @@ import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 import org.apache.kafka.clients.consumer.ConsumerRecord;
 
+import java.time.Duration;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Optional;
 
 
 @RequiredArgsConstructor
@@ -13,8 +15,11 @@ import java.util.Map;
 public class ApplicationRecordHandler implements RecordHandler<String, String>
 {
   private final AdderResults results;
+  private final Optional<Duration> throttle;
+  private final String id;
 
   private final Map<Integer, AdderBusinessLogic> state = new HashMap<>();
+  private final Map<Integer, Long> next = new HashMap<>();
 
 
   @Override
@@ -24,25 +29,54 @@ public class ApplicationRecordHandler implements RecordHandler<String, String>
     String user = record.key();
     String message = record.value();
 
+    if (record.offset() < next.get(partition))
+    {
+      log.warn(
+        "{}- Dropping duplicate message: offset={} < next={}",
+        id,
+        record.offset(),
+        next.get(partition));
+      return;
+    }
+
     if (message.equals("CALCULATE"))
     {
       AdderResult result = state.get(partition).calculate(user);
-      log.info("New result for {}: {}", user, result);
+      log.info("{} - New result for {}: {}", id, user, result);
       results.addResults(partition, user, result);
-      return;
     }
+    else
+    {
+      state.get(partition).addToSum(user, Integer.parseInt(message));
+    }
+
+    next.put(partition, record.offset() + 1);
 
-    state.get(partition).addToSum(user, Integer.parseInt(message));
+    if (throttle.isPresent())
+    {
+      try
+      {
+        Thread.sleep(throttle.get().toMillis());
+      }
+      catch (InterruptedException e)
+      {
+        log.warn("{} - Intrerrupted while throttling: {}", id, e);
+      }
+    }
   }
 
-  protected void addPartition(Integer partition, Map<String, AdderResult> state)
+  protected void addPartition(Integer partition, Map<String, AdderResult> state, Long offset)
   {
     this.state.put(partition, new AdderBusinessLogic(state));
+    this.next.put(partition, offset);
   }
 
-  protected Map<String, AdderResult> removePartition(Integer partition)
+  protected ApplicationState removePartition(Integer partition)
   {
-    return this.state.remove(partition).getState();
+    ApplicationState state = getState(partition);
+    this.next.remove(partition);
+    this.state.remove(partition);
+    return state;
   }
 
 
@@ -51,8 +85,11 @@ public class ApplicationRecordHandler implements RecordHandler<String, String>
     return state;
   }
 
-  public AdderBusinessLogic getState(Integer partition)
+  public ApplicationState getState(Integer partition)
   {
-    return state.get(partition);
+    return
+      new ApplicationState(
+        this.next.get(partition),
+        this.state.get(partition).getState());
   }
 }