[GitHub] [arrow-datafusion] yjshen commented on a change in pull request #950: ObjectStore API to read from remote storage systems

[GitBox <gi...@apache.org>]

yjshen commented on a change in pull request #950:
URL: https://github.com/apache/arrow-datafusion/pull/950#discussion_r696877841



##########
File path: datafusion/src/datasource/object_store/mod.rs
##########
@@ -0,0 +1,127 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you 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.
+
+//! Object Store abstracts access to an underlying file/object storage.
+
+pub mod local;
+
+use std::collections::HashMap;
+use std::fmt::Debug;
+use std::pin::Pin;
+use std::sync::{Arc, RwLock};
+
+use async_trait::async_trait;
+use futures::{AsyncRead, Stream};
+
+use local::LocalFileSystem;
+
+use crate::error::{DataFusionError, Result};
+use chrono::Utc;
+
+/// Object Reader for one file in a object store
+#[async_trait]
+pub trait ObjectReader {
+    /// Get reader for a part [start, start + length] in the file asynchronously
+    async fn get_reader(&self, start: u64, length: usize) -> Result<Arc<dyn AsyncRead>>;
+
+    /// Get length for the file asynchronously
+    async fn length(&self) -> Result<u64>;
+}
+
+/// File meta we got from object store
+pub struct FileMeta {
+    /// Path of the file
+    pub path: String,
+    /// Last time the file was modified in UTC
+    pub last_modified: Option<chrono::DateTime<Utc>>,
+    /// File size in total
+    pub size: Option<u64>,

Review comment:
       I checked several definitions in rusoto_s3, and it seems Option is used widely for length, size. for example, `rusoto_s3:Object`,  `rusoto_s3:GetObjectOutput`, so it's here. I am neutral on this and please correct me in a more idiomatic way.




-- 
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

To unsubscribe, e-mail: github-unsubscribe@arrow.apache.org

For queries about this service, please contact Infrastructure at:
users@infra.apache.org