From 42bb92cf8fca73ddf940f2257c7fa5f693bc2ca4 Mon Sep 17 00:00:00 2001
From: Kai Moritz <kai@juplo.de>
Date: Thu, 14 Oct 2021 20:39:22 +0200
Subject: [PATCH] WIP: Dirty in-place implementation

---
 .../de/juplo/kafka/wordcount/top10/Entry.java | 11 ----
 .../de/juplo/kafka/wordcount/top10/Key.java   | 13 -----
 .../juplo/kafka/wordcount/top10/Ranking.java  | 53 -------------------
 .../wordcount/top10/Top10StreamProcessor.java | 37 ++++++++++++-
 4 files changed, 35 insertions(+), 79 deletions(-)
 delete mode 100644 src/main/java/de/juplo/kafka/wordcount/top10/Entry.java
 delete mode 100644 src/main/java/de/juplo/kafka/wordcount/top10/Key.java
 delete mode 100644 src/main/java/de/juplo/kafka/wordcount/top10/Ranking.java

diff --git a/src/main/java/de/juplo/kafka/wordcount/top10/Entry.java b/src/main/java/de/juplo/kafka/wordcount/top10/Entry.java
deleted file mode 100644
index 67f45f2..0000000
--- a/src/main/java/de/juplo/kafka/wordcount/top10/Entry.java
+++ /dev/null
@@ -1,11 +0,0 @@
-package de.juplo.kafka.wordcount.top10;
-
-import lombok.Value;
-
-
-@Value(staticConstructor = "of")
-public class Entry
-{
-  private final String word;
-  private final Long count;
-}
diff --git a/src/main/java/de/juplo/kafka/wordcount/top10/Key.java b/src/main/java/de/juplo/kafka/wordcount/top10/Key.java
deleted file mode 100644
index d09dbcc..0000000
--- a/src/main/java/de/juplo/kafka/wordcount/top10/Key.java
+++ /dev/null
@@ -1,13 +0,0 @@
-package de.juplo.kafka.wordcount.top10;
-
-import lombok.Getter;
-import lombok.Setter;
-
-
-@Getter
-@Setter
-public class Key
-{
-  private String username;
-  private String word;
-}
diff --git a/src/main/java/de/juplo/kafka/wordcount/top10/Ranking.java b/src/main/java/de/juplo/kafka/wordcount/top10/Ranking.java
deleted file mode 100644
index b748fe5..0000000
--- a/src/main/java/de/juplo/kafka/wordcount/top10/Ranking.java
+++ /dev/null
@@ -1,53 +0,0 @@
-package de.juplo.kafka.wordcount.top10;
-
-import lombok.Getter;
-import lombok.Setter;
-
-import java.util.Arrays;
-import java.util.LinkedList;
-import java.util.List;
-
-
-@Getter
-@Setter
-public class Ranking
-{
-  private Entry[] entries = new Entry[0];
-
-  public void add(Entry newEntry)
-  {
-    if (entries.length == 0)
-    {
-      entries = new Entry[1];
-      entries[0] = newEntry;
-      return;
-    }
-
-    List<Entry> list = new LinkedList<>(Arrays.asList(entries));
-    for (int i = 0; i < list.size(); i++)
-    {
-      Entry entry;
-
-      entry = list.get(i);
-      if (entry.getCount() <= newEntry.getCount())
-      {
-        list.add(i, newEntry);
-        for (int j = i+1; j < list.size(); j++)
-        {
-          entry = list.get(j);
-          if(entry.getWord().equals(newEntry.getWord()))
-          {
-            list.remove(j);
-            break;
-          }
-        }
-        if (list.size() > 10)
-        {
-          list = list.subList(0,10);
-        }
-        entries = list.toArray(num -> new Entry[num]);
-        return;
-      }
-    }
-  }
-}
diff --git a/src/main/java/de/juplo/kafka/wordcount/top10/Top10StreamProcessor.java b/src/main/java/de/juplo/kafka/wordcount/top10/Top10StreamProcessor.java
index 811cf98..2bc1da7 100644
--- a/src/main/java/de/juplo/kafka/wordcount/top10/Top10StreamProcessor.java
+++ b/src/main/java/de/juplo/kafka/wordcount/top10/Top10StreamProcessor.java
@@ -21,7 +21,9 @@ import org.springframework.stereotype.Component;
 
 import javax.annotation.PostConstruct;
 import javax.annotation.PreDestroy;
+import java.util.Arrays;
 import java.util.LinkedList;
+import java.util.List;
 import java.util.Properties;
 import java.util.concurrent.CompletableFuture;
 import java.util.regex.Pattern;
@@ -53,8 +55,39 @@ public class Top10StreamProcessor
 				.groupByKey(Grouped.keySerde(Serdes.String()))
 				.aggregate(
 						() -> Ranking.newBuilder().setEntries(new LinkedList<Entry>()).build(),
-						(username, entry, ranking) -> {
-							ranking.getEntries().add(entry);
+						(username, newEntry, ranking) -> {
+							List<Entry> entries = new LinkedList<>(ranking.getEntries());
+
+							if (entries.isEmpty())
+							{
+								entries.add(newEntry);
+							}
+							else
+							{
+								for (int i = 0; i < entries.size(); i++)
+								{
+									Entry entry = entries.get(i);
+									if (entry.getCount() <= newEntry.getCount())
+									{
+										entries.add(i, newEntry);
+										for (int j = i + 1; j < entries.size(); j++)
+										{
+											entry = entries.get(j);
+											if (entry.getWord().equals(newEntry.getWord()))
+											{
+												entries.remove(j);
+												break;
+											}
+										}
+										if (entries.size() > 10)
+										{
+											entries = entries.subList(0, 10);
+										}
+									}
+								}
+							}
+
+							ranking.setEntries(entries);
 							return ranking;
 						})
 				.toStream()
-- 
2.20.1