add ConcurrentMemoryStore

Author: brokkoli71

src/main/java/dev/zarr/zarrjava/store/ConcurrentMemoryStore.java

@@ -0,0 +1,17 @@
+package dev.zarr.zarrjava.store;
+
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+public class ConcurrentMemoryStore extends MemoryStore {
+  @Override
+  protected Map<List<String>, byte[]> map() {
+    return new ConcurrentHashMap<>();
+  }
+
+  @Override
+  public String toString() {
+    return String.format("<ConcurrentMemoryStore {%s}>", hashCode());
+  }
+}

src/main/java/dev/zarr/zarrjava/store/MemoryStore.java

@@ -1,23 +1,16 @@
 package dev.zarr.zarrjava.store;
 
-import dev.zarr.zarrjava.core.chunkkeyencoding.Separator;
-
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 import java.util.*;
 import java.util.stream.Stream;
 
 public class MemoryStore implements Store, Store.ListableStore {
-  private final Map<List<String>, byte[]> map = new HashMap<>();
-  Separator separator;
-
-  public MemoryStore(Separator separator){
-    this.separator = separator;
-  }
+  private final Map<List<String>, byte[]> map = map();
 
-  public MemoryStore(){
-    this(Separator.SLASH);
+  protected Map<List<String>, byte[]> map(){
+    return new HashMap<>();
   }
 
   List<String> resolveKeys(String[] keys) {
@@ -95,3 +88,4 @@ public String toString() {
     return String.format("<MemoryStore {%s}>", hashCode());
   }
 }
+