diff --git a/pageserver/src/tenant.rs b/pageserver/src/tenant.rs index 35ea037a55..ff17400d45 100644 --- a/pageserver/src/tenant.rs +++ b/pageserver/src/tenant.rs @@ -3848,6 +3848,8 @@ pub(crate) mod harness { #[cfg(test)] mod tests { + use std::collections::BTreeMap; + use super::*; use crate::keyspace::KeySpaceAccum; use crate::repository::{Key, Value}; @@ -3858,7 +3860,7 @@ mod tests { use hex_literal::hex; use pageserver_api::keyspace::KeySpace; use rand::{thread_rng, Rng}; - use tests::timeline::ShutdownMode; + use tests::timeline::{GetVectoredError, ShutdownMode}; static TEST_KEY: Lazy = Lazy::new(|| Key::from_slice(&hex!("010000000033333333444444445500000001"))); @@ -4794,6 +4796,166 @@ mod tests { Ok(()) } + // Test that vectored get descends into ancestor timelines correctly and + // does not return an image that's newer than requested. + // + // The diagram below ilustrates an interesting case. We have a parent timeline + // (top of the Lsn range) and a child timeline. The request key cannot be reconstructed + // from the child timeline, so the parent timeline must be visited. When advacing into + // the child timeline, the read path needs to remember what the requested Lsn was in + // order to avoid returning an image that's too new. The test below constructs such + // a timeline setup and does a few queries around the Lsn of each page image. + // ``` + // LSN + // ^ + // | + // | + // 500 | --------------------------------------> branch point + // 400 | X + // 300 | X + // 200 | --------------------------------------> requested lsn + // 100 | X + // |---------------------------------------> Key + // | + // ------> requested key + // + // Legend: + // * X - page images + // ``` + #[tokio::test] + async fn test_get_vectored_ancestor_descent() -> anyhow::Result<()> { + let harness = TenantHarness::create("test_get_vectored_on_lsn_axis")?; + let (tenant, ctx) = harness.load().await; + + let start_key = Key::from_hex("010000000033333333444444445500000000").unwrap(); + let end_key = start_key.add(1000); + let child_gap_at_key = start_key.add(500); + let mut parent_gap_lsns: BTreeMap = BTreeMap::new(); + + let mut current_lsn = Lsn(0x10); + + let timeline_id = TimelineId::generate(); + let parent_timeline = tenant + .create_test_timeline(timeline_id, current_lsn, DEFAULT_PG_VERSION, &ctx) + .await?; + + current_lsn += 0x100; + + for _ in 0..3 { + let mut key = start_key; + while key < end_key { + current_lsn += 0x10; + + let image_value = format!("{} at {}", child_gap_at_key, current_lsn); + + let mut writer = parent_timeline.writer().await; + writer + .put( + key, + current_lsn, + &Value::Image(test_img(&image_value)), + &ctx, + ) + .await?; + writer.finish_write(current_lsn); + + if key == child_gap_at_key { + parent_gap_lsns.insert(current_lsn, image_value); + } + + key = key.next(); + } + + parent_timeline.freeze_and_flush().await?; + } + + let child_timeline_id = TimelineId::generate(); + + let child_timeline = tenant + .branch_timeline_test(&parent_timeline, child_timeline_id, Some(current_lsn), &ctx) + .await?; + + let mut key = start_key; + while key < end_key { + if key == child_gap_at_key { + key = key.next(); + continue; + } + + current_lsn += 0x10; + + let mut writer = child_timeline.writer().await; + writer + .put( + key, + current_lsn, + &Value::Image(test_img(&format!("{} at {}", key, current_lsn))), + &ctx, + ) + .await?; + writer.finish_write(current_lsn); + + key = key.next(); + } + + child_timeline.freeze_and_flush().await?; + + let lsn_offsets: [i64; 5] = [-10, -1, 0, 1, 10]; + let mut query_lsns = Vec::new(); + for image_lsn in parent_gap_lsns.keys().rev() { + for offset in lsn_offsets { + query_lsns.push(Lsn(image_lsn + .0 + .checked_add_signed(offset) + .expect("Shouldn't overflow"))); + } + } + + for query_lsn in query_lsns { + let results = child_timeline + .get_vectored_impl( + KeySpace { + ranges: vec![child_gap_at_key..child_gap_at_key.next()], + }, + query_lsn, + &ctx, + ) + .await; + + let expected_item = parent_gap_lsns + .iter() + .rev() + .find(|(lsn, _)| **lsn <= query_lsn); + + info!( + "Doing vectored read at LSN {}. Expecting image to be: {:?}", + query_lsn, expected_item + ); + + match expected_item { + Some((_, img_value)) => { + let key_results = results.expect("No vectored get error expected"); + let key_result = &key_results[&child_gap_at_key]; + let returned_img = key_result + .as_ref() + .expect("No page reconstruct error expected"); + + info!( + "Vectored read at LSN {} returned image {}", + query_lsn, + std::str::from_utf8(returned_img)? + ); + assert_eq!(*returned_img, test_img(img_value)); + } + None => { + assert!(matches!(results, Err(GetVectoredError::MissingKey(_)))); + } + } + } + + Ok(()) + } + #[tokio::test] async fn test_random_updates() -> anyhow::Result<()> { let harness = TenantHarness::create("test_random_updates")?; diff --git a/pageserver/src/tenant/timeline.rs b/pageserver/src/tenant/timeline.rs index 46b3d41e2b..3f2d807ce8 100644 --- a/pageserver/src/tenant/timeline.rs +++ b/pageserver/src/tenant/timeline.rs @@ -2968,7 +2968,8 @@ impl Timeline { break; } - cont_lsn = Lsn(timeline.ancestor_lsn.0 + 1); + // Take the min to avoid reconstructing a page with data newer than request Lsn. + cont_lsn = std::cmp::min(Lsn(request_lsn.0 + 1), Lsn(timeline.ancestor_lsn.0 + 1)); timeline_owned = timeline .get_ready_ancestor_timeline(ctx) .await