Merge pull request #519 from project-tsurugi/LargeObjectCache

add LargeObjectCache and related APIs

modules/session/src/main/java/com/tsurugidb/tsubakuro/sql/LargeObjectCache.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2023-2025 Project Tsurugi.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.tsurugidb.tsubakuro.sql;
+
+import java.io.IOException;
+import java.nio.file.Path;
+import java.util.Optional;
+
+/**
+ * Represents large object cache.
+ */
+public interface LargeObjectCache extends AutoCloseable {
+
+    /**
+     * Returns the path of the file that represents the large object, only if it exists.
+     * The returned Path is available until close() of this object is invoked.
+     * @return the path of the file, or empty if it does not exist
+     */
+    Optional<Path> find();
+
+    /**
+     * Copy the large object to the file indicated by the given path.
+     * Files created by this method are not affected by close() of this object. 
+     * @param destination the path of the destination file
+     * @throws IOException if I/O error was occurred while copying the large object to the file
+     *                     or it encounters a situation where find() returns an empty Optional
+     */
+    void copyTo(Path destination) throws IOException;
+
+    /**
+     * Closes the object cache. The file whose Path has been returned by find() may be deleted.
+     */
+    @Override
+    void close();
+}

modules/session/src/main/java/com/tsurugidb/tsubakuro/sql/SqlClient.java

@@ -251,6 +251,26 @@ default FutureResponse<Reader> openReader(ClobReference ref) throws IOException
         throw new UnsupportedOperationException();
     }
 
+    /**
+     * Returns an object cache for the blob.
+     * @return a future response of a LargeObjectCache
+     * @param ref the blob reference
+     * @throws IOException if I/O error was occurred while sending request
+     */
+    default FutureResponse<LargeObjectCache> getLargeObjectCache(BlobReference ref) throws IOException {
+        throw new UnsupportedOperationException();
+    }
+
+    /**
+     * Returns an object cache for the clob.
+     * @return a future response of a LargeObjectCache
+     * @param ref the clob reference
+     * @throws IOException if I/O error was occurred while sending request
+     */
+    default FutureResponse<LargeObjectCache> getLargeObjectCache(ClobReference ref) throws IOException {
+        throw new UnsupportedOperationException();
+    }
+
     /**
      * Disposes the underlying server resources.
      * Note that, this never closes the underlying {@link Session}.