implement listFiles method in AlluxioFileSystem

lib/trino-filesystem-alluxio/src/main/java/io/trino/filesystem/alluxio/AlluxioFileIterator.java

@@ -0,0 +1,70 @@
+/*
+ * 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 io.trino.filesystem.alluxio;
+
+import alluxio.client.file.URIStatus;
+import io.trino.filesystem.FileEntry;
+import io.trino.filesystem.FileIterator;
+import io.trino.filesystem.Location;
+
+import java.io.IOException;
+import java.time.Instant;
+import java.util.List;
+import java.util.Optional;
+
+import static java.util.Objects.requireNonNull;
+
+public class AlluxioFileIterator
+        implements FileIterator
+{
+    private final List<URIStatus> files;
+
+    private int index;
+
+    public AlluxioFileIterator(List<URIStatus> files)
+    {
+        this.files = requireNonNull(files, "files is null");
+    }
+
+    @Override
+    public boolean hasNext()
+            throws IOException
+    {
+        if (files.isEmpty() || files.size() < index) {
+            return false;
+        }
+        if (files.get(index) != null) {
+            return true;
+        }
+        else {
+            return false;
+        }
+    }
+
+    @Override
+    public FileEntry next()
+            throws IOException
+    {
+        if (!hasNext()) {
+            return null;
+        }
+        URIStatus fileStatus = files.get(index++);
+        Location location = Location.of(fileStatus.getPath());
+        return new FileEntry(
+                location,
+                fileStatus.getLength(),
+                Instant.ofEpochMilli(fileStatus.getLastModificationTimeMs()),
+                Optional.empty());
+    }
+}

lib/trino-filesystem-alluxio/src/main/java/io/trino/filesystem/alluxio/AlluxioFileSystem.java

@@ -25,6 +25,7 @@
 
 import java.io.FileNotFoundException;
 import java.io.IOException;
+import java.util.List;
 import java.util.Optional;
 import java.util.Set;
 
@@ -96,8 +97,13 @@ public void renameFile(Location source, Location target)
     public FileIterator listFiles(Location location)
             throws IOException
     {
-        //TODO: create a new class AlluxioFileIterator to implement this method
-        return null;
+        try {
+            List<URIStatus> filesStatus = fileSystem.listStatus(getAlluxioURI(location));
+            return new AlluxioFileIterator(filesStatus);
+        }
+        catch (AlluxioException e) {
+            throw new IOException("Error listFiles %s".formatted(location), e);
+        }
     }
 
     @Override