Xuanwo commented on code in PR #5871: URL: https://github.com/apache/opendal/pull/5871#discussion_r2011882574
########## core/src/docs/rfcs/5871_read_returns_metadata.md: ########## @@ -0,0 +1,141 @@ +- Proposal Name: `read_returns_metadata` +- Start Date: 2025-03-24 +- RFC PR: [apache/opendal#5871](https://github.com/apache/opendal/pull/5871) +- Tracking Issue: [apache/opendal#5872](https://github.com/apache/opendal/issues/5872) + +# Summary + +Enhance read operations by returning metadata along with data in read operations. + +# Motivation + +Currently, read operations (`read`, `read_with`, `reader`, `reader_with`) only return the data content. Users who need metadata +during reads (like `Content-Type`, `ETag`, `version_id`, etc.) must make an additional `stat()` call. This is inefficient and +can lead to race conditions if the file is modified between the read and stat operations. + +Many storage services (like S3, GCS, Azure Blob) return metadata in their read responses. For example, S3's GetObject API returns +important metadata like `ContentType`, `ETag`, `VersionId`, `LastModified`, etc. We should expose this information to users +directly during read operations. + +# Guide-level explanation + +The read operations will be enhanced to return both data and metadata: + +```rust +// Before +let data = op.read("path/to/file").await?; +let meta = op.stat("path/to/file").await?; +if let Some(content_type) = meta.content_type() { + println!("Content-Type: {}", content_type); +} + +// After +let (data, meta) = op.read("path/to/file").await?; Review Comment: Unlike the modification of `write(path) -> Result<()>` to `write(path) -> Result<Metadata>`, which mostly allows existing code to compile without issues, changing `Result<Buffer>` to `Result<(Buffer, Metadata)>` could break every call to this API. We need to weigh in 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
