Add Java object file storage utility

src/main/java/edu/tamu/scholars/middleware/service/CachingSolrClient.java

@@ -2,15 +2,15 @@
 
 import javax.servlet.http.HttpServletRequest;
 
+import java.io.BufferedInputStream;
+import java.io.BufferedOutputStream;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
-import java.lang.reflect.Method;
 import java.nio.charset.StandardCharsets;
-import java.util.Collections;
 import java.util.Map;
 import java.util.Objects;
 import java.util.UUID;
@@ -28,10 +28,9 @@
 import org.slf4j.LoggerFactory;
 import org.springframework.web.context.request.RequestContextHolder;
 import org.springframework.web.context.request.ServletRequestAttributes;
-import org.springframework.web.servlet.HandlerMapping;
-import org.springframework.web.util.ServletRequestPathUtils;
 
 import edu.tamu.scholars.middleware.config.model.IndexConfig;
+import edu.tamu.scholars.middleware.utility.JavaObjectStorageFileUtility;
 
 public class CachingSolrClient<C extends SolrClient> extends SolrClient {
 
@@ -53,9 +52,15 @@ public class CachingSolrClient<C extends SolrClient> extends SolrClient {
 
     private final Map<String, File> lookup;
 
+    // TODO: take the average of 5 attempts on cache, repeat until 5 attempts on solr, select more performant and fallback
+
+    // add threshold to solr response to avoid network glitches
+    // add threshold to cached response to avoid unexpected file objects
+
     private final Map<String, Map<String, String>> map;
 
     // there are different type of SolrClient
+    // this provides only interface methods
     C client;
 
     JwtTokenService jwtTokenService;
@@ -186,18 +191,14 @@ public NamedList<Object> request(SolrRequest<?> request, String collection)
 
         File file = new File(filename);
 
-        long startFoundCache = System.currentTimeMillis();
-        long startQueryToSolr = System.currentTimeMillis();
+        long startFoundCache, startQueryToSolr;
 
         if (file.exists()) {
             startFoundCache = System.currentTimeMillis();
 
-            try (
-                FileInputStream fileIn = new FileInputStream(filename);
-                ObjectInputStream in = new ObjectInputStream(fileIn);
-            ) {
-                response = (NamedList<Object>) in.readObject();
-            } catch (IOException | ClassNotFoundException e) {
+            try {
+                response = JavaObjectStorageFileUtility.readObject(filename);
+            } catch (ClassNotFoundException | IOException e) {
                 e.printStackTrace();
             }
 
@@ -206,14 +207,7 @@ public NamedList<Object> request(SolrRequest<?> request, String collection)
             startQueryToSolr = System.currentTimeMillis();
             response = client.request(request, collection);
 
-            try (
-                FileOutputStream fileOut = new FileOutputStream(filename);
-                ObjectOutputStream out = new ObjectOutputStream(fileOut);
-            ) {
-                out.writeObject(response);
-            } catch (IOException e) {
-                e.printStackTrace();
-            }
+            JavaObjectStorageFileUtility.writeObject(response, filename);
 
             logger.info("{}:{}: {} seconds", uuid, "QUERY RESPONSE", (System.currentTimeMillis() - startQueryToSolr) / (double) 1000);
 

src/main/java/edu/tamu/scholars/middleware/utility/JavaObjectStorageFileUtility.java

@@ -0,0 +1,59 @@
+package edu.tamu.scholars.middleware.utility;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.io.Serializable;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.StandardOpenOption;
+
+// https://claude.ai/chat/38a46bde-f2c6-48b8-9a88-c4e286f55776
+public class JavaObjectStorageFileUtility {
+
+    private JavaObjectStorageFileUtility() {
+
+    }
+
+    public static <T extends Serializable> void writeObject(T object, String fileName) throws IOException {
+        Path path = Paths.get(fileName);
+        try (FileChannel channel = FileChannel.open(path, StandardOpenOption.CREATE, StandardOpenOption.WRITE);
+             ByteArrayOutputStream baos = new ByteArrayOutputStream();
+             ObjectOutputStream oos = new ObjectOutputStream(baos)) {
+
+            // Serialize the object
+            oos.writeObject(object);
+            oos.flush();
+
+            // Write the serialized object to the file
+            channel.write(ByteBuffer.wrap(baos.toByteArray()));
+        }
+    }
+
+    public static <T extends Serializable> T readObject(String fileName) throws IOException, ClassNotFoundException {
+        Path path = Paths.get(fileName);
+        try (FileChannel channel = FileChannel.open(path, StandardOpenOption.READ);
+             ByteArrayOutputStream baos = new ByteArrayOutputStream()) {
+
+            // Read the file contents into a ByteArrayOutputStream
+            ByteBuffer buffer = ByteBuffer.allocate(1024);
+            while (channel.read(buffer) > 0) {
+                buffer.flip();
+                baos.write(buffer.array(), 0, buffer.limit());
+                buffer.clear();
+            }
+
+            // Deserialize the object
+            try (ObjectInputStream ois = new ObjectInputStream(new ByteArrayInputStream(baos.toByteArray()))) {
+                @SuppressWarnings("unchecked")
+                T object = (T) ois.readObject();
+                return object;
+            }
+        }
+    }
+
+}