alamb commented on code in PR #19127:
URL: https://github.com/apache/datafusion/pull/19127#discussion_r2617033035
##########
datafusion-cli/src/object_storage/instrumented.rs:
##########
@@ -896,13 +961,15 @@ mod tests {
instrumented.set_instrument_mode(InstrumentedObjectStoreMode::Trace);
assert!(instrumented.requests.lock().is_empty());
- let _ = instrumented.list(Some(&path));
+ let mut stream = instrumented.list(Some(&path));
+ // Consume at least one item from the stream to trigger duration
measurement
Review Comment:
I recommend also testing the duration value -- perhaps
```rust
let start = Instant::now();
let mut stream = instrumented.list(Some(&path));
// Consume at least one item from the stream to trigger duration
measurement
let time_before_start = start.elapsed();
let _ = stream.next().await;
...
assert!(request.duration.unwrap() > time_before_start);
```
##########
datafusion-cli/src/object_storage/instrumented.rs:
##########
@@ -35,14 +35,66 @@ use datafusion::{
error::DataFusionError,
execution::object_store::{DefaultObjectStoreRegistry, ObjectStoreRegistry},
};
-use futures::stream::BoxStream;
+use futures::stream::{BoxStream, Stream};
use object_store::{
path::Path, GetOptions, GetRange, GetResult, ListResult, MultipartUpload,
ObjectMeta,
ObjectStore, PutMultipartOptions, PutOptions, PutPayload, PutResult,
Result,
};
use parking_lot::{Mutex, RwLock};
use url::Url;
+/// A stream wrapper that measures the time until the first response(item or
end of stream) is yielded
+struct TimeToFirstItemStream<S> {
+ inner: S,
+ start: Instant,
+ request_index: usize,
+ requests: Arc<Mutex<Vec<RequestDetails>>>,
+ first_item_yielded: bool,
+}
+
+impl<S> TimeToFirstItemStream<S> {
+ fn new(
+ inner: S,
+ start: Instant,
+ request_index: usize,
+ requests: Arc<Mutex<Vec<RequestDetails>>>,
+ ) -> Self {
+ Self {
+ inner,
+ start,
+ request_index,
+ requests,
+ first_item_yielded: false,
+ }
+ }
+}
+
+impl<S> Stream for TimeToFirstItemStream<S>
+where
+ S: Stream<Item = Result<ObjectMeta>> + Unpin,
+{
+ type Item = Result<ObjectMeta>;
+
+ fn poll_next(
+ mut self: std::pin::Pin<&mut Self>,
+ cx: &mut std::task::Context<'_>,
+ ) -> std::task::Poll<Option<Self::Item>> {
+ let poll_result = std::pin::Pin::new(&mut self.inner).poll_next(cx);
+
+ if !self.first_item_yielded && poll_result.is_ready() {
+ self.first_item_yielded = true;
+ let elapsed = self.start.elapsed();
+
+ let mut requests = self.requests.lock();
+ if let Some(request) = requests.get_mut(self.request_index) {
+ request.duration = Some(elapsed);
+ }
Review Comment:
How about instead of relying on some potentially tricky race condition, we
instead use an `Arc<AtomicU64>` for the duration? Then instead of
```rust
request_index: usize,
requests: Arc<Mutex<Vec<RequestDetails>>>,
```
We could just pass in
```rust
request_duration: Arc<AtomicU64>,
```
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