feat: create shared InternalCaching entity

Author: mikededo

src/main/java/io/pakland/mdas/githubstats/domain/lib/InternalCaching.java

@@ -0,0 +1,46 @@
+package io.pakland.mdas.githubstats.domain.lib;
+
+import java.util.*;
+
+public class InternalCaching<K, T> {
+
+    private final Map<K, Integer> cacheIndex = new HashMap<>();
+    private final List<T> cacheStore = new ArrayList<>();
+
+    public InternalCaching() {
+    }
+
+    protected boolean has(K key) {
+        return this.cacheIndex.containsKey(key);
+    }
+
+    protected Integer size() {
+        return this.cacheIndex.size();
+    }
+
+    public void add(K key, T value) {
+        if (!cacheIndex.containsKey(key)) {
+            cacheStore.add(value);
+            cacheIndex.put(key, cacheStore.size() - 1);
+        }
+    }
+
+    public T get(K key) {
+        Integer index = cacheIndex.get(key);
+        if (index == null) {
+            return null;
+        }
+        return cacheStore.get(index);
+    }
+
+    public T delete(K key) {
+        Integer index = cacheIndex.get(key);
+        if (index == null) {
+            return null;
+        }
+        T element = cacheStore.get(index);
+        cacheStore.remove(element);
+        cacheIndex.remove(key);
+        return element;
+    }
+}

src/main/java/io/pakland/mdas/githubstats/infrastructure/github/repository/CommentGitHubRepository.java

@@ -3,6 +3,7 @@
 import io.pakland.mdas.githubstats.application.exceptions.HttpException;
 import io.pakland.mdas.githubstats.application.mappers.CommentMapper;
 import io.pakland.mdas.githubstats.domain.entity.Comment;
+import io.pakland.mdas.githubstats.domain.lib.InternalCaching;
 import io.pakland.mdas.githubstats.domain.repository.CommentExternalRepository;
 import io.pakland.mdas.githubstats.infrastructure.github.model.GitHubCommentDTO;
 import java.util.*;
@@ -15,8 +16,7 @@ public class CommentGitHubRepository implements CommentExternalRepository {
     private final WebClientConfiguration webClientConfiguration;
     private final Logger logger = LoggerFactory.getLogger(CommentGitHubRepository.class);
 
-    private final Map<Integer, Integer> internalQueryCache = new HashMap<>();
-    private final List<List<Comment>> commentStore = new ArrayList<>();
+    private final InternalCaching<String, List<Comment>> cache = new InternalCaching<>();
 
     public CommentGitHubRepository(WebClientConfiguration webClientConfiguration) {
         this.webClientConfiguration = webClientConfiguration;
@@ -29,9 +29,9 @@ public List<Comment> fetchCommentsFromPullRequest(
         throws HttpException {
         String query = String.format("/repos/%s/%s/pulls/%s/comments?%s", repositoryOwner,
             repositoryName, pullRequestNumber, getRequestParams(page, perPage));
-        Integer dataPosition = internalQueryCache.get(query.hashCode());
-        if (dataPosition != null) {
-            return commentStore.get(dataPosition);
+        List<Comment> maybeResult = cache.get(query);
+        if (maybeResult != null) {
+            return maybeResult;
         }
 
         try {
@@ -43,8 +43,7 @@ public List<Comment> fetchCommentsFromPullRequest(
                 .map(CommentMapper::dtoToEntity)
                 .collectList()
                 .block();
-            commentStore.add(result);
-            internalQueryCache.put(query.hashCode(), commentStore.size() - 1);
+            cache.add(query, result);
 
             return result;
 

src/main/java/io/pakland/mdas/githubstats/infrastructure/github/repository/CommitGitHubRepository.java

@@ -3,9 +3,10 @@
 import io.pakland.mdas.githubstats.application.exceptions.HttpException;
 import io.pakland.mdas.githubstats.application.mappers.CommitMapper;
 import io.pakland.mdas.githubstats.domain.entity.Commit;
+import io.pakland.mdas.githubstats.domain.lib.InternalCaching;
 import io.pakland.mdas.githubstats.domain.repository.CommitExternalRepository;
 import io.pakland.mdas.githubstats.infrastructure.github.model.GitHubCommitDTO;
-import java.util.*;
+import java.util.List;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.web.reactive.function.client.WebClientResponseException;
@@ -15,8 +16,7 @@ public class CommitGitHubRepository implements CommitExternalRepository {
     private final WebClientConfiguration webClientConfiguration;
     private final Logger logger = LoggerFactory.getLogger(CommitGitHubRepository.class);
 
-    private final Map<Integer, Integer> internalQueryCache = new HashMap<>();
-    private final List<List<Commit>> commitStore = new ArrayList<>();
+    private final InternalCaching<String, List<Commit>> cache = new InternalCaching<>();
 
     public CommitGitHubRepository(WebClientConfiguration webClientConfiguration) {
         this.webClientConfiguration = webClientConfiguration;
@@ -29,9 +29,9 @@ public List<Commit> fetchCommitsFromPullRequest(FetchCommitsFromPullRequestReque
             request.getRepositoryOwner(),
             request.getRepositoryName(), request.getPullRequestNumber(),
             getRequestParams(request));
-        Integer resultPosition = internalQueryCache.get(query.hashCode());
-        if (resultPosition != null) {
-            return commitStore.get(resultPosition);
+        List<Commit> maybeResult = cache.get(query);
+        if (maybeResult != null) {
+            return maybeResult;
         }
 
         try {
@@ -44,8 +44,7 @@ public List<Commit> fetchCommitsFromPullRequest(FetchCommitsFromPullRequestReque
                 .map(CommitMapper::dtoToEntity)
                 .collectList()
                 .block();
-            commitStore.add(result);
-            internalQueryCache.put(query.hashCode(), commitStore.size() - 1);
+            cache.add(query, result);
 
             return result;
         } catch (WebClientResponseException ex) {

src/test/java/io/pakland/mdas/githubstats/domain/lib/InternalCachingTest.java

@@ -0,0 +1,63 @@
+package io.pakland.mdas.githubstats.domain.lib;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+public class InternalCachingTest {
+
+    @Test
+    public void shouldAddAnElement() {
+        InternalCaching<Integer, Integer> cache = new InternalCaching<>();
+        cache.add(1, 1);
+        assertTrue(cache.has(1));
+        assertEquals(cache.size(), 1);
+    }
+
+    @Test
+    public void shouldNotAddRepeatedElement() {
+        InternalCaching<Integer, Integer> cache = new InternalCaching<>();
+        cache.add(1, 1);
+        cache.add(2, 1);
+        assertTrue(cache.has(1));
+        assertTrue(cache.has(2));
+        assertEquals(cache.size(), 2);
+
+        cache.add(2, 1);
+        assertEquals(cache.size(), 2);
+    }
+
+    @Test
+    public void shouldReturnAnElementIfExists() {
+        InternalCaching<Integer, Integer> cache = new InternalCaching<>();
+        cache.add(3, 1);
+        assertEquals(cache.get(3), 1);
+    }
+
+    @Test
+    public void shouldReturnNullIfKeyDoesNotExist(){
+        InternalCaching<Integer, Integer> cache = new InternalCaching<>();
+        cache.add(3, 1);
+        assertNull(cache.get(4));
+    }
+
+    @Test
+    public void shouldDeleteExistingElement() {
+        InternalCaching<Integer, Integer> cache = new InternalCaching<>();
+        cache.add(4, 1);
+        assertEquals(cache.size(), 1);
+
+        assertEquals(cache.delete(4), 1);
+        assertEquals(cache.size(), 0);
+    }
+
+    @Test
+    public void shouldReturnNullIfDeletingNonExistingElement() {
+        InternalCaching<Integer, Integer> cache = new InternalCaching<>();
+        cache.add(4, 1);
+        assertEquals(cache.size(), 1);
+        assertNull(cache.delete(5));
+    }
+}