fqaiser94 commented on code in PR #892: URL: https://github.com/apache/iceberg-rust/pull/892#discussion_r1929789733
########## crates/iceberg/src/puffin/reader.rs: ########## @@ -0,0 +1,126 @@ +// 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. + +use crate::io::{FileRead, InputFile}; +use crate::puffin::blob::Blob; +use crate::puffin::metadata::{BlobMetadata, FileMetadata}; +use crate::Result; + +/// Puffin reader +pub(crate) struct PuffinReader { + input_file: InputFile, + file_metadata: Option<FileMetadata>, +} + +impl PuffinReader { + /// Returns a new Puffin reader + pub(crate) fn new(input_file: InputFile) -> Self { + Self { + input_file, + file_metadata: None, + } + } + + /// Returns file metadata + pub(crate) async fn file_metadata(&mut self) -> Result<&FileMetadata> { Review Comment: PTAL, I implemented the lazy initialization using `tokio::sync::OnceCell`. I couldn't get the async lazy crate approach to work because: 1. It doesn't expose any APIs for fallible operations. 2. My `FileMetadata::read` function needs a reference to the `InputFile` which doesn't work well with this approach: ``` let file_metadata: Lazy<Result<FileMetadata>> = Lazy::new(|| Box::pin(async { FileMetadata::read(&input_file).await })); mismatched types expected fn pointer `fn() -> Pin<Box<(dyn futures::Future<Output = std::result::Result<puffin::metadata::FileMetadata, error::Error>> + std::marker::Send + 'static)>>` found closure `{closure@crates/iceberg/src/puffin/reader.rs:36:67: 36:69}`rustc[Click for full compiler diagnostic](rust-analyzer-diagnostics-view:/diagnostic%20message%20[2]?2#file:///Users/fq/src/iceberg-rust/crates/iceberg/src/puffin/reader.rs) reader.rs(36, 57): arguments to this function are incorrect reader.rs(36, 107): closures can only be coerced to `fn` types if they do not capture any variables lib.rs(73, 12): associated function defined here ``` -- 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: issues-unsubscr...@iceberg.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@iceberg.apache.org For additional commands, e-mail: issues-h...@iceberg.apache.org
