sdd commented on code in PR #373:
URL: https://github.com/apache/iceberg-rust/pull/373#discussion_r1682309951
##########
crates/iceberg/src/scan.rs:
##########
@@ -389,12 +333,158 @@ impl FileScanStreamContext {
file_io,
bound_filter,
case_sensitive,
+ sender,
+ manifest_evaluator_cache: ManifestEvaluatorCache::new(),
+ partition_filter_cache: PartitionFilterCache::new(),
+ expression_evaluator_cache:
Arc::new(Mutex::new(ExpressionEvaluatorCache::new())),
})
}
- /// Returns a reference to the [`BoundPredicate`] filter.
- fn bound_filter(&self) -> Option<&BoundPredicate> {
- self.bound_filter.as_ref()
+ async fn run(&mut self, manifest_list: ManifestList) -> Result<()> {
+ let file_io = self.file_io.clone();
+ let sender = self.sender.clone();
+
+ // This whole Vec-and-for-loop approach feels sub-optimally structured.
+ // I've tried structuring this in multiple ways but run into
+ // issues with ownership. Ideally I'd like to structure this
+ // with a functional programming approach: extracting
+ // sections 1, 2, and 3 out into different methods on Self,
+ // and then use some iterator combinators to orchestrate it all.
+ // Section 1 is pretty trivially refactorable into a static method
+ // that can be used in a closure that can be used with
Iterator::filter.
+ // Similarly, section 3 seems easily factor-able into a method that can
+ // be passed into Iterator::map.
+ // Section 2 turns out trickier - we want to exit the entire `run`
method early
+ // if the eval fails, and filter out any manifest_files from the
iterator / stream
+ // if the eval succeeds but returns true. We bump into ownership
issues due
+ // to needing to pass mut self as the caches need to be able to mutate.
+ // Section 3 runs into ownership issues when trying to refactor its
closure to be
+ // a static or non-static method.
+
+ // 1
+ let filtered_manifest_files = manifest_list
+ .entries()
+ .iter()
+ .filter(Self::reject_unsupported_content_types);
+
+ // 2
+ let mut filtered_manifest_files2 = vec![];
+ for manifest_file in filtered_manifest_files {
+ if !self.apply_evaluator(manifest_file)? {
+ continue;
+ }
+
+ filtered_manifest_files2.push(manifest_file);
+ }
+
+ // 3
+ let filtered_manifest_files =
filtered_manifest_files2.into_iter().map(|manifest_file| {
+ Ok(ManifestFileProcessingContext {
+ manifest_file,
+ file_io: file_io.clone(),
+ sender: sender.clone(),
+ filter: &self.bound_filter,
+ expression_evaluator_cache:
self.expression_evaluator_cache.clone(),
+ })
+ });
+
+ futures::stream::iter(filtered_manifest_files)
+ .try_for_each_concurrent(
Review Comment:
Hey @liurenjie1024 - I think I'm happy with this now. Let me know what you
think.
There is one issue remaining. It seems that our `crate::runtime::spawn` does
not behave exactly the same as `tokio::spawn` for tasks that are passed an
async function that return a `Result`? I could not get this to work with
`crate::runtime::spawn` but it does with `tokio::spawn`. @odysa could you help?
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