LCOV - code coverage report
Current view: top level - pageserver/src/tenant/storage_layer/layer - tests.rs (source / functions) Coverage Total Hit
Test: 07bee600374ccd486c69370d0972d9035964fe68.info Lines: 99.6 % 927 923
Test Date: 2025-02-20 13:11:02 Functions: 100.0 % 41 41

            Line data    Source code
       1              : use std::time::UNIX_EPOCH;
       2              : 
       3              : use pageserver_api::key::{Key, CONTROLFILE_KEY};
       4              : use tokio::task::JoinSet;
       5              : use utils::{
       6              :     completion::{self, Completion},
       7              :     id::TimelineId,
       8              : };
       9              : 
      10              : use super::failpoints::{Failpoint, FailpointKind};
      11              : use super::*;
      12              : use crate::{
      13              :     context::DownloadBehavior,
      14              :     tenant::{
      15              :         harness::test_img,
      16              :         storage_layer::{IoConcurrency, LayerVisibilityHint},
      17              :     },
      18              : };
      19              : use crate::{task_mgr::TaskKind, tenant::harness::TenantHarness};
      20              : 
      21              : /// Used in tests to advance a future to wanted await point, and not futher.
      22              : const ADVANCE: std::time::Duration = std::time::Duration::from_secs(3600);
      23              : 
      24              : /// Used in tests to indicate forever long timeout; has to be longer than the amount of ADVANCE
      25              : /// timeout uses to advance futures.
      26              : const FOREVER: std::time::Duration = std::time::Duration::from_secs(ADVANCE.as_secs() * 24 * 7);
      27              : 
      28              : /// Demonstrate the API and resident -> evicted -> resident -> deleted transitions.
      29              : #[tokio::test]
      30            4 : async fn smoke_test() {
      31            4 :     let handle = tokio::runtime::Handle::current();
      32            4 : 
      33            4 :     let h = TenantHarness::create("smoke_test").await.unwrap();
      34            4 :     let span = h.span();
      35            4 :     let download_span = span.in_scope(|| tracing::info_span!("downloading", timeline_id = 1));
      36            4 :     let (tenant, _) = h.load().await;
      37            4 :     let io_concurrency = IoConcurrency::spawn_for_test();
      38            4 : 
      39            4 :     let ctx = RequestContext::new(TaskKind::UnitTest, DownloadBehavior::Download);
      40            4 : 
      41            4 :     let image_layers = vec![(
      42            4 :         Lsn(0x40),
      43            4 :         vec![(
      44            4 :             Key::from_hex("620000000033333333444444445500000000").unwrap(),
      45            4 :             test_img("foo"),
      46            4 :         )],
      47            4 :     )];
      48            4 : 
      49            4 :     // Create a test timeline with one real layer, and one synthetic test layer.  The synthetic
      50            4 :     // one is only there so that we can GC the real one without leaving the timeline's metadata
      51            4 :     // empty, which is an illegal state (see [`IndexPart::validate`]).
      52            4 :     let timeline = tenant
      53            4 :         .create_test_timeline_with_layers(
      54            4 :             TimelineId::generate(),
      55            4 :             Lsn(0x10),
      56            4 :             14,
      57            4 :             &ctx,
      58            4 :             Default::default(),
      59            4 :             image_layers,
      60            4 :             Lsn(0x100),
      61            4 :         )
      62            4 :         .await
      63            4 :         .unwrap();
      64            4 : 
      65            4 :     // Grab one of the timeline's layers to exercise in the test, and the other layer that is just
      66            4 :     // there to avoid the timeline being illegally empty
      67            4 :     let (layer, dummy_layer) = {
      68            4 :         let mut layers = {
      69            4 :             let layers = timeline.layers.read().await;
      70            4 :             layers.likely_resident_layers().cloned().collect::<Vec<_>>()
      71            4 :         };
      72            4 : 
      73            4 :         assert_eq!(layers.len(), 2);
      74            4 : 
      75            8 :         layers.sort_by_key(|l| l.layer_desc().get_key_range().start);
      76            4 :         let synthetic_layer = layers.pop().unwrap();
      77            4 :         let real_layer = layers.pop().unwrap();
      78            4 :         tracing::info!(
      79            4 :             "real_layer={:?} ({}), synthetic_layer={:?} ({})",
      80            0 :             real_layer,
      81            0 :             real_layer.layer_desc().file_size,
      82            0 :             synthetic_layer,
      83            0 :             synthetic_layer.layer_desc().file_size
      84            4 :         );
      85            4 :         (real_layer, synthetic_layer)
      86            4 :     };
      87            4 : 
      88            4 :     // all layers created at pageserver are like `layer`, initialized with strong
      89            4 :     // Arc<DownloadedLayer>.
      90            4 : 
      91            4 :     let controlfile_keyspace = KeySpace {
      92            4 :         ranges: vec![CONTROLFILE_KEY..CONTROLFILE_KEY.next()],
      93            4 :     };
      94            4 : 
      95            4 :     let img_before = {
      96            4 :         let mut data = ValuesReconstructState::new(io_concurrency.clone());
      97            4 :         layer
      98            4 :             .get_values_reconstruct_data(
      99            4 :                 controlfile_keyspace.clone(),
     100            4 :                 Lsn(0x10)..Lsn(0x11),
     101            4 :                 &mut data,
     102            4 :                 &ctx,
     103            4 :             )
     104            4 :             .await
     105            4 :             .unwrap();
     106            4 : 
     107            4 :         data.keys
     108            4 :             .remove(&CONTROLFILE_KEY)
     109            4 :             .expect("must be present")
     110            4 :             .collect_pending_ios()
     111            4 :             .await
     112            4 :             .expect("must not error")
     113            4 :             .img
     114            4 :             .take()
     115            4 :             .expect("tenant harness writes the control file")
     116            4 :     };
     117            4 : 
     118            4 :     // important part is evicting the layer, which can be done when there are no more ResidentLayer
     119            4 :     // instances -- there currently are none, only two `Layer` values, one in the layermap and on
     120            4 :     // in scope.
     121            4 :     layer.evict_and_wait(FOREVER).await.unwrap();
     122            4 : 
     123            4 :     // double-evict returns an error, which is valid if both eviction_task and disk usage based
     124            4 :     // eviction would both evict the same layer at the same time.
     125            4 : 
     126            4 :     let e = layer.evict_and_wait(FOREVER).await.unwrap_err();
     127            4 :     assert!(matches!(e, EvictionError::NotFound));
     128            4 : 
     129            4 :     // on accesses when the layer is evicted, it will automatically be downloaded.
     130            4 :     let img_after = {
     131            4 :         let mut data = ValuesReconstructState::new(io_concurrency.clone());
     132            4 :         layer
     133            4 :             .get_values_reconstruct_data(
     134            4 :                 controlfile_keyspace.clone(),
     135            4 :                 Lsn(0x10)..Lsn(0x11),
     136            4 :                 &mut data,
     137            4 :                 &ctx,
     138            4 :             )
     139            4 :             .instrument(download_span.clone())
     140            4 :             .await
     141            4 :             .unwrap();
     142            4 :         data.keys
     143            4 :             .remove(&CONTROLFILE_KEY)
     144            4 :             .expect("must be present")
     145            4 :             .collect_pending_ios()
     146            4 :             .await
     147            4 :             .expect("must not error")
     148            4 :             .img
     149            4 :             .take()
     150            4 :             .expect("tenant harness writes the control file")
     151            4 :     };
     152            4 : 
     153            4 :     assert_eq!(img_before, img_after);
     154            4 : 
     155            4 :     // evict_and_wait can timeout, but it doesn't cancel the evicting itself
     156            4 :     //
     157            4 :     // ZERO for timeout does not work reliably, so first take up all spawn_blocking slots to
     158            4 :     // artificially slow it down.
     159            4 :     let helper = SpawnBlockingPoolHelper::consume_all_spawn_blocking_threads(&handle).await;
     160            4 : 
     161            4 :     match layer
     162            4 :         .evict_and_wait(std::time::Duration::ZERO)
     163            4 :         .await
     164            4 :         .unwrap_err()
     165            4 :     {
     166            4 :         EvictionError::Timeout => {
     167            4 :             // expected, but note that the eviction is "still ongoing"
     168            4 :             helper.release().await;
     169            4 :             // exhaust spawn_blocking pool to ensure it is now complete
     170            4 :             SpawnBlockingPoolHelper::consume_and_release_all_of_spawn_blocking_threads(&handle)
     171            4 :                 .await;
     172            4 :         }
     173            4 :         other => unreachable!("{other:?}"),
     174            4 :     }
     175            4 : 
     176            4 :     // only way to query if a layer is resident is to acquire a ResidentLayer instance.
     177            4 :     // Layer::keep_resident never downloads, but it might initialize if the layer file is found
     178            4 :     // downloaded locally.
     179            4 :     let none = layer.keep_resident().await;
     180            4 :     assert!(
     181            4 :         none.is_none(),
     182            4 :         "Expected none, because eviction removed the local file, found: {none:?}"
     183            4 :     );
     184            4 : 
     185            4 :     // plain downloading is rarely needed
     186            4 :     layer
     187            4 :         .download_and_keep_resident()
     188            4 :         .instrument(download_span)
     189            4 :         .await
     190            4 :         .unwrap();
     191            4 : 
     192            4 :     // last important part is deletion on drop: gc and compaction use it for compacted L0 layers
     193            4 :     // or fully garbage collected layers. deletion means deleting the local file, and scheduling a
     194            4 :     // deletion of the already unlinked from index_part.json remote file.
     195            4 :     //
     196            4 :     // marking a layer to be deleted on drop is irreversible; there is no technical reason against
     197            4 :     // reversiblity, but currently it is not needed so it is not provided.
     198            4 :     layer.delete_on_drop();
     199            4 : 
     200            4 :     let path = layer.local_path().to_owned();
     201            4 : 
     202            4 :     // wait_drop produces an unconnected to Layer future which will resolve when the
     203            4 :     // LayerInner::drop has completed.
     204            4 :     let mut wait_drop = std::pin::pin!(layer.wait_drop());
     205            4 : 
     206            4 :     // paused time doesn't really work well with timeouts and evict_and_wait, so delay pausing
     207            4 :     // until here
     208            4 :     tokio::time::pause();
     209            4 :     tokio::time::timeout(ADVANCE, &mut wait_drop)
     210            4 :         .await
     211            4 :         .expect_err("should had timed out because two strong references exist");
     212            4 : 
     213            4 :     tokio::fs::metadata(&path)
     214            4 :         .await
     215            4 :         .expect("the local layer file still exists");
     216            4 : 
     217            4 :     let rtc = &timeline.remote_client;
     218            4 : 
     219            4 :     // Simulate GC removing our test layer.
     220            4 :     {
     221            4 :         let mut g = timeline.layers.write().await;
     222            4 : 
     223            4 :         let layers = &[layer];
     224            4 :         g.open_mut().unwrap().finish_gc_timeline(layers);
     225            4 : 
     226            4 :         // this just updates the remote_physical_size for demonstration purposes
     227            4 :         rtc.schedule_gc_update(layers).unwrap();
     228            4 :     }
     229            4 : 
     230            4 :     // when strong references are dropped, the file is deleted and remote deletion is scheduled
     231            4 :     wait_drop.await;
     232            4 : 
     233            4 :     let e = tokio::fs::metadata(&path)
     234            4 :         .await
     235            4 :         .expect_err("the local file is deleted");
     236            4 :     assert_eq!(e.kind(), std::io::ErrorKind::NotFound);
     237            4 : 
     238            4 :     rtc.wait_completion().await.unwrap();
     239            4 : 
     240            4 :     assert_eq!(
     241            4 :         rtc.get_remote_physical_size(),
     242            4 :         dummy_layer.metadata().file_size
     243            4 :     );
     244            4 :     assert_eq!(0, LAYER_IMPL_METRICS.inits_cancelled.get())
     245            4 : }
     246              : 
     247              : /// This test demonstrates a previous hang when a eviction and deletion were requested at the same
     248              : /// time. Now both of them complete per Arc drop semantics.
     249              : #[tokio::test(start_paused = true)]
     250            4 : async fn evict_and_wait_on_wanted_deleted() {
     251            4 :     // this is the runtime on which Layer spawns the blocking tasks on
     252            4 :     let handle = tokio::runtime::Handle::current();
     253            4 : 
     254            4 :     let h = TenantHarness::create("evict_and_wait_on_wanted_deleted")
     255            4 :         .await
     256            4 :         .unwrap();
     257            4 :     utils::logging::replace_panic_hook_with_tracing_panic_hook().forget();
     258            4 :     let (tenant, ctx) = h.load().await;
     259            4 : 
     260            4 :     let timeline = tenant
     261            4 :         .create_test_timeline(TimelineId::generate(), Lsn(0x10), 14, &ctx)
     262            4 :         .await
     263            4 :         .unwrap();
     264            4 : 
     265            4 :     let layer = {
     266            4 :         let mut layers = {
     267            4 :             let layers = timeline.layers.read().await;
     268            4 :             layers.likely_resident_layers().cloned().collect::<Vec<_>>()
     269            4 :         };
     270            4 : 
     271            4 :         assert_eq!(layers.len(), 1);
     272            4 : 
     273            4 :         layers.swap_remove(0)
     274            4 :     };
     275            4 : 
     276            4 :     // setup done
     277            4 : 
     278            4 :     let resident = layer.keep_resident().await.unwrap();
     279            4 : 
     280            4 :     {
     281            4 :         let mut evict_and_wait = std::pin::pin!(layer.evict_and_wait(FOREVER));
     282            4 : 
     283            4 :         // drive the future to await on the status channel
     284            4 :         tokio::time::timeout(ADVANCE, &mut evict_and_wait)
     285            4 :             .await
     286            4 :             .expect_err("should had been a timeout since we are holding the layer resident");
     287            4 : 
     288            4 :         layer.delete_on_drop();
     289            4 : 
     290            4 :         drop(resident);
     291            4 : 
     292            4 :         // make sure the eviction task gets to run
     293            4 :         SpawnBlockingPoolHelper::consume_and_release_all_of_spawn_blocking_threads(&handle).await;
     294            4 : 
     295            4 :         let resident = layer.keep_resident().await;
     296            4 :         assert!(
     297            4 :             resident.is_none(),
     298            4 :             "keep_resident should not have re-initialized: {resident:?}"
     299            4 :         );
     300            4 : 
     301            4 :         evict_and_wait
     302            4 :             .await
     303            4 :             .expect("evict_and_wait should had succeeded");
     304            4 : 
     305            4 :         // works as intended
     306            4 :     }
     307            4 : 
     308            4 :     // assert that once we remove the `layer` from the layer map and drop our reference,
     309            4 :     // the deletion of the layer in remote_storage happens.
     310            4 :     {
     311            4 :         let mut layers = timeline.layers.write().await;
     312            4 :         layers.open_mut().unwrap().finish_gc_timeline(&[layer]);
     313            4 :     }
     314            4 : 
     315            4 :     SpawnBlockingPoolHelper::consume_and_release_all_of_spawn_blocking_threads(&handle).await;
     316            4 : 
     317            4 :     assert_eq!(1, LAYER_IMPL_METRICS.started_deletes.get());
     318            4 :     assert_eq!(1, LAYER_IMPL_METRICS.completed_deletes.get());
     319            4 :     assert_eq!(1, LAYER_IMPL_METRICS.started_evictions.get());
     320            4 :     assert_eq!(1, LAYER_IMPL_METRICS.completed_evictions.get());
     321            4 :     assert_eq!(0, LAYER_IMPL_METRICS.inits_cancelled.get())
     322            4 : }
     323              : 
     324              : /// This test ensures we are able to read the layer while the layer eviction has been
     325              : /// started but not completed.
     326              : #[test]
     327            4 : fn read_wins_pending_eviction() {
     328            4 :     let rt = tokio::runtime::Builder::new_current_thread()
     329            4 :         .max_blocking_threads(1)
     330            4 :         .enable_all()
     331            4 :         .start_paused(true)
     332            4 :         .build()
     333            4 :         .unwrap();
     334            4 : 
     335            4 :     rt.block_on(async move {
     336            4 :         // this is the runtime on which Layer spawns the blocking tasks on
     337            4 :         let handle = tokio::runtime::Handle::current();
     338            4 :         let h = TenantHarness::create("read_wins_pending_eviction")
     339            4 :             .await
     340            4 :             .unwrap();
     341            4 :         let (tenant, ctx) = h.load().await;
     342            4 :         let span = h.span();
     343            4 :         let download_span = span.in_scope(|| tracing::info_span!("downloading", timeline_id = 1));
     344              : 
     345            4 :         let timeline = tenant
     346            4 :             .create_test_timeline(TimelineId::generate(), Lsn(0x10), 14, &ctx)
     347            4 :             .await
     348            4 :             .unwrap();
     349              : 
     350            4 :         let layer = {
     351            4 :             let mut layers = {
     352            4 :                 let layers = timeline.layers.read().await;
     353            4 :                 layers.likely_resident_layers().cloned().collect::<Vec<_>>()
     354            4 :             };
     355            4 : 
     356            4 :             assert_eq!(layers.len(), 1);
     357              : 
     358            4 :             layers.swap_remove(0)
     359              :         };
     360              : 
     361              :         // setup done
     362              : 
     363            4 :         let resident = layer.keep_resident().await.unwrap();
     364            4 : 
     365            4 :         let mut evict_and_wait = std::pin::pin!(layer.evict_and_wait(FOREVER));
     366            4 : 
     367            4 :         // drive the future to await on the status channel
     368            4 :         tokio::time::timeout(ADVANCE, &mut evict_and_wait)
     369            4 :             .await
     370            4 :             .expect_err("should had been a timeout since we are holding the layer resident");
     371            4 :         assert_eq!(1, LAYER_IMPL_METRICS.started_evictions.get());
     372              : 
     373            4 :         let (completion, barrier) = utils::completion::channel();
     374            4 :         let (arrival, arrived_at_barrier) = utils::completion::channel();
     375            4 :         layer.enable_failpoint(Failpoint::WaitBeforeStartingEvicting(
     376            4 :             Some(arrival),
     377            4 :             barrier,
     378            4 :         ));
     379            4 : 
     380            4 :         // now the eviction cannot proceed because the threads are consumed while completion exists
     381            4 :         drop(resident);
     382            4 :         arrived_at_barrier.wait().await;
     383            4 :         assert!(!layer.is_likely_resident());
     384              : 
     385              :         // because no actual eviction happened, we get to just reinitialize the DownloadedLayer
     386            4 :         layer
     387            4 :             .0
     388            4 :             .get_or_maybe_download(false, None)
     389            4 :             .instrument(download_span)
     390            4 :             .await
     391            4 :             .expect("should had reinitialized without downloading");
     392            4 : 
     393            4 :         assert!(layer.is_likely_resident());
     394              : 
     395              :         // reinitialization notifies of new resident status, which should error out all evict_and_wait
     396            4 :         let e = tokio::time::timeout(ADVANCE, &mut evict_and_wait)
     397            4 :             .await
     398            4 :             .expect("no timeout, because get_or_maybe_download re-initialized")
     399            4 :             .expect_err("eviction should not have succeeded because re-initialized");
     400            4 : 
     401            4 :         // works as intended: evictions lose to "downloads"
     402            4 :         assert!(matches!(e, EvictionError::Downloaded), "{e:?}");
     403            4 :         assert_eq!(0, LAYER_IMPL_METRICS.completed_evictions.get());
     404              : 
     405              :         // this is not wrong: the eviction is technically still "on the way" as it's still queued
     406              :         // because of a failpoint
     407            4 :         assert_eq!(
     408            4 :             0,
     409            4 :             LAYER_IMPL_METRICS
     410            4 :                 .cancelled_evictions
     411            4 :                 .values()
     412           36 :                 .map(|ctr| ctr.get())
     413            4 :                 .sum::<u64>()
     414            4 :         );
     415              : 
     416            4 :         drop(completion);
     417            4 : 
     418            4 :         tokio::time::sleep(ADVANCE).await;
     419            4 :         SpawnBlockingPoolHelper::consume_and_release_all_of_spawn_blocking_threads0(&handle, 1)
     420            4 :             .await;
     421              : 
     422            4 :         assert_eq!(0, LAYER_IMPL_METRICS.completed_evictions.get());
     423              : 
     424              :         // now we finally can observe the original eviction failing
     425              :         // it would had been possible to observe it earlier, but here it is guaranteed to have
     426              :         // happened.
     427            4 :         assert_eq!(
     428            4 :             1,
     429            4 :             LAYER_IMPL_METRICS
     430            4 :                 .cancelled_evictions
     431            4 :                 .values()
     432           36 :                 .map(|ctr| ctr.get())
     433            4 :                 .sum::<u64>()
     434            4 :         );
     435              : 
     436            4 :         assert_eq!(
     437            4 :             1,
     438            4 :             LAYER_IMPL_METRICS.cancelled_evictions[EvictionCancelled::AlreadyReinitialized].get()
     439            4 :         );
     440              : 
     441            4 :         assert_eq!(0, LAYER_IMPL_METRICS.inits_cancelled.get())
     442            4 :     });
     443            4 : }
     444              : 
     445              : /// Use failpoint to delay an eviction starting to get a VersionCheckFailed.
     446              : #[test]
     447            4 : fn multiple_pending_evictions_in_order() {
     448            4 :     let name = "multiple_pending_evictions_in_order";
     449            4 :     let in_order = true;
     450            4 :     multiple_pending_evictions_scenario(name, in_order);
     451            4 : }
     452              : 
     453              : /// Use failpoint to reorder later eviction before first to get a UnexpectedEvictedState.
     454              : #[test]
     455            4 : fn multiple_pending_evictions_out_of_order() {
     456            4 :     let name = "multiple_pending_evictions_out_of_order";
     457            4 :     let in_order = false;
     458            4 :     multiple_pending_evictions_scenario(name, in_order);
     459            4 : }
     460              : 
     461            8 : fn multiple_pending_evictions_scenario(name: &'static str, in_order: bool) {
     462            8 :     let rt = tokio::runtime::Builder::new_current_thread()
     463            8 :         .max_blocking_threads(1)
     464            8 :         .enable_all()
     465            8 :         .start_paused(true)
     466            8 :         .build()
     467            8 :         .unwrap();
     468            8 : 
     469            8 :     rt.block_on(async move {
     470            8 :         // this is the runtime on which Layer spawns the blocking tasks on
     471            8 :         let handle = tokio::runtime::Handle::current();
     472            8 :         let h = TenantHarness::create(name).await.unwrap();
     473            8 :         let (tenant, ctx) = h.load().await;
     474            8 :         let span = h.span();
     475            8 :         let download_span = span.in_scope(|| tracing::info_span!("downloading", timeline_id = 1));
     476              : 
     477            8 :         let timeline = tenant
     478            8 :             .create_test_timeline(TimelineId::generate(), Lsn(0x10), 14, &ctx)
     479            8 :             .await
     480            8 :             .unwrap();
     481              : 
     482            8 :         let layer = {
     483            8 :             let mut layers = {
     484            8 :                 let layers = timeline.layers.read().await;
     485            8 :                 layers.likely_resident_layers().cloned().collect::<Vec<_>>()
     486            8 :             };
     487            8 : 
     488            8 :             assert_eq!(layers.len(), 1);
     489              : 
     490            8 :             layers.swap_remove(0)
     491              :         };
     492              : 
     493              :         // setup done
     494              : 
     495            8 :         let resident = layer.keep_resident().await.unwrap();
     496            8 : 
     497            8 :         let mut evict_and_wait = std::pin::pin!(layer.evict_and_wait(FOREVER));
     498            8 : 
     499            8 :         // drive the future to await on the status channel
     500            8 :         tokio::time::timeout(ADVANCE, &mut evict_and_wait)
     501            8 :             .await
     502            8 :             .expect_err("should had been a timeout since we are holding the layer resident");
     503            8 :         assert_eq!(1, LAYER_IMPL_METRICS.started_evictions.get());
     504              : 
     505            8 :         let (completion1, barrier) = utils::completion::channel();
     506            8 :         let mut completion1 = Some(completion1);
     507            8 :         let (arrival, arrived_at_barrier) = utils::completion::channel();
     508            8 :         layer.enable_failpoint(Failpoint::WaitBeforeStartingEvicting(
     509            8 :             Some(arrival),
     510            8 :             barrier,
     511            8 :         ));
     512            8 : 
     513            8 :         // now the eviction cannot proceed because we are simulating arbitrary long delay for the
     514            8 :         // eviction task start.
     515            8 :         drop(resident);
     516            8 :         assert!(!layer.is_likely_resident());
     517              : 
     518            8 :         arrived_at_barrier.wait().await;
     519              : 
     520              :         // because no actual eviction happened, we get to just reinitialize the DownloadedLayer
     521            8 :         layer
     522            8 :             .0
     523            8 :             .get_or_maybe_download(false, None)
     524            8 :             .instrument(download_span)
     525            8 :             .await
     526            8 :             .expect("should had reinitialized without downloading");
     527            8 : 
     528            8 :         assert!(layer.is_likely_resident());
     529              : 
     530              :         // reinitialization notifies of new resident status, which should error out all evict_and_wait
     531            8 :         let e = tokio::time::timeout(ADVANCE, &mut evict_and_wait)
     532            8 :             .await
     533            8 :             .expect("no timeout, because get_or_maybe_download re-initialized")
     534            8 :             .expect_err("eviction should not have succeeded because re-initialized");
     535            8 : 
     536            8 :         // works as intended: evictions lose to "downloads"
     537            8 :         assert!(matches!(e, EvictionError::Downloaded), "{e:?}");
     538            8 :         assert_eq!(0, LAYER_IMPL_METRICS.completed_evictions.get());
     539              : 
     540              :         // this is not wrong: the eviction is technically still "on the way" as it's still queued
     541              :         // because of a failpoint
     542            8 :         assert_eq!(
     543            8 :             0,
     544            8 :             LAYER_IMPL_METRICS
     545            8 :                 .cancelled_evictions
     546            8 :                 .values()
     547           72 :                 .map(|ctr| ctr.get())
     548            8 :                 .sum::<u64>()
     549            8 :         );
     550              : 
     551            8 :         assert_eq!(0, LAYER_IMPL_METRICS.completed_evictions.get());
     552              : 
     553              :         // configure another failpoint for the second eviction -- evictions are per initialization,
     554              :         // so now that we've reinitialized the inner, we get to run two of them at the same time.
     555            8 :         let (completion2, barrier) = utils::completion::channel();
     556            8 :         let (arrival, arrived_at_barrier) = utils::completion::channel();
     557            8 :         layer.enable_failpoint(Failpoint::WaitBeforeStartingEvicting(
     558            8 :             Some(arrival),
     559            8 :             barrier,
     560            8 :         ));
     561            8 : 
     562            8 :         let mut second_eviction = std::pin::pin!(layer.evict_and_wait(FOREVER));
     563            8 : 
     564            8 :         // advance to the wait on the queue
     565            8 :         tokio::time::timeout(ADVANCE, &mut second_eviction)
     566            8 :             .await
     567            8 :             .expect_err("timeout because failpoint is blocking");
     568            8 : 
     569            8 :         arrived_at_barrier.wait().await;
     570              : 
     571            8 :         assert_eq!(2, LAYER_IMPL_METRICS.started_evictions.get());
     572              : 
     573            8 :         let mut release_earlier_eviction = |expected_reason| {
     574            8 :             assert_eq!(
     575            8 :                 0,
     576            8 :                 LAYER_IMPL_METRICS.cancelled_evictions[expected_reason].get(),
     577            8 :             );
     578              : 
     579            8 :             drop(completion1.take().unwrap());
     580            8 : 
     581            8 :             let handle = &handle;
     582              : 
     583            8 :             async move {
     584            8 :                 tokio::time::sleep(ADVANCE).await;
     585            8 :                 SpawnBlockingPoolHelper::consume_and_release_all_of_spawn_blocking_threads0(
     586            8 :                     handle, 1,
     587            8 :                 )
     588            8 :                 .await;
     589              : 
     590            8 :                 assert_eq!(
     591            8 :                     1,
     592            8 :                     LAYER_IMPL_METRICS.cancelled_evictions[expected_reason].get(),
     593            8 :                 );
     594            8 :             }
     595            8 :         };
     596              : 
     597            8 :         if in_order {
     598            4 :             release_earlier_eviction(EvictionCancelled::VersionCheckFailed).await;
     599            4 :         }
     600              : 
     601              :         // release the later eviction which is for the current version
     602            8 :         drop(completion2);
     603            8 :         tokio::time::sleep(ADVANCE).await;
     604            8 :         SpawnBlockingPoolHelper::consume_and_release_all_of_spawn_blocking_threads0(&handle, 1)
     605            8 :             .await;
     606              : 
     607            8 :         if !in_order {
     608            4 :             release_earlier_eviction(EvictionCancelled::UnexpectedEvictedState).await;
     609            4 :         }
     610              : 
     611            8 :         tokio::time::timeout(ADVANCE, &mut second_eviction)
     612            8 :             .await
     613            8 :             .expect("eviction goes through now that spawn_blocking is unclogged")
     614            8 :             .expect("eviction should succeed, because version matches");
     615            8 : 
     616            8 :         assert_eq!(1, LAYER_IMPL_METRICS.completed_evictions.get());
     617              : 
     618              :         // ensure the cancelled are unchanged
     619            8 :         assert_eq!(
     620            8 :             1,
     621            8 :             LAYER_IMPL_METRICS
     622            8 :                 .cancelled_evictions
     623            8 :                 .values()
     624           72 :                 .map(|ctr| ctr.get())
     625            8 :                 .sum::<u64>()
     626            8 :         );
     627              : 
     628            8 :         assert_eq!(0, LAYER_IMPL_METRICS.inits_cancelled.get())
     629            8 :     });
     630            8 : }
     631              : 
     632              : /// The test ensures with a failpoint that a pending eviction is not cancelled by what is currently
     633              : /// a `Layer::keep_resident` call.
     634              : ///
     635              : /// This matters because cancelling the eviction would leave us in a state where the file is on
     636              : /// disk but the layer internal state says it has not been initialized. Futhermore, it allows us to
     637              : /// have non-repairing `Layer::is_likely_resident`.
     638              : #[tokio::test(start_paused = true)]
     639            4 : async fn cancelled_get_or_maybe_download_does_not_cancel_eviction() {
     640            4 :     let handle = tokio::runtime::Handle::current();
     641            4 :     let h = TenantHarness::create("cancelled_get_or_maybe_download_does_not_cancel_eviction")
     642            4 :         .await
     643            4 :         .unwrap();
     644            4 :     let (tenant, ctx) = h.load().await;
     645            4 : 
     646            4 :     let timeline = tenant
     647            4 :         .create_test_timeline(TimelineId::generate(), Lsn(0x10), 14, &ctx)
     648            4 :         .await
     649            4 :         .unwrap();
     650            4 : 
     651            4 :     let layer = {
     652            4 :         let mut layers = {
     653            4 :             let layers = timeline.layers.read().await;
     654            4 :             layers.likely_resident_layers().cloned().collect::<Vec<_>>()
     655            4 :         };
     656            4 : 
     657            4 :         assert_eq!(layers.len(), 1);
     658            4 : 
     659            4 :         layers.swap_remove(0)
     660            4 :     };
     661            4 : 
     662            4 :     // this failpoint will simulate the `get_or_maybe_download` becoming cancelled (by returning an
     663            4 :     // Err) at the right time as in "during" the `LayerInner::needs_download`.
     664            4 :     layer.enable_failpoint(Failpoint::AfterDeterminingLayerNeedsNoDownload);
     665            4 : 
     666            4 :     let (completion, barrier) = utils::completion::channel();
     667            4 :     let (arrival, arrived_at_barrier) = utils::completion::channel();
     668            4 : 
     669            4 :     layer.enable_failpoint(Failpoint::WaitBeforeStartingEvicting(
     670            4 :         Some(arrival),
     671            4 :         barrier,
     672            4 :     ));
     673            4 : 
     674            4 :     tokio::time::timeout(ADVANCE, layer.evict_and_wait(FOREVER))
     675            4 :         .await
     676            4 :         .expect_err("should had advanced to waiting on channel");
     677            4 : 
     678            4 :     arrived_at_barrier.wait().await;
     679            4 : 
     680            4 :     // simulate a cancelled read which is cancelled before it gets to re-initialize
     681            4 :     let e = layer
     682            4 :         .0
     683            4 :         .get_or_maybe_download(false, None)
     684            4 :         .await
     685            4 :         .unwrap_err();
     686            4 :     assert!(
     687            4 :         matches!(
     688            4 :             e,
     689            4 :             DownloadError::Failpoint(FailpointKind::AfterDeterminingLayerNeedsNoDownload)
     690            4 :         ),
     691            4 :         "{e:?}"
     692            4 :     );
     693            4 : 
     694            4 :     assert!(
     695            4 :         layer.0.needs_download().await.unwrap().is_none(),
     696            4 :         "file is still on disk"
     697            4 :     );
     698            4 : 
     699            4 :     // release the eviction task
     700            4 :     drop(completion);
     701            4 :     tokio::time::sleep(ADVANCE).await;
     702            4 :     SpawnBlockingPoolHelper::consume_and_release_all_of_spawn_blocking_threads(&handle).await;
     703            4 : 
     704            4 :     // failpoint is still enabled, but it is not hit
     705            4 :     let e = layer
     706            4 :         .0
     707            4 :         .get_or_maybe_download(false, None)
     708            4 :         .await
     709            4 :         .unwrap_err();
     710            4 :     assert!(matches!(e, DownloadError::DownloadRequired), "{e:?}");
     711            4 : 
     712            4 :     // failpoint is not counted as cancellation either
     713            4 :     assert_eq!(0, LAYER_IMPL_METRICS.inits_cancelled.get())
     714            4 : }
     715              : 
     716              : #[tokio::test(start_paused = true)]
     717            4 : async fn evict_and_wait_does_not_wait_for_download() {
     718            4 :     // let handle = tokio::runtime::Handle::current();
     719            4 :     let h = TenantHarness::create("evict_and_wait_does_not_wait_for_download")
     720            4 :         .await
     721            4 :         .unwrap();
     722            4 :     let (tenant, ctx) = h.load().await;
     723            4 :     let span = h.span();
     724            4 :     let download_span = span.in_scope(|| tracing::info_span!("downloading", timeline_id = 1));
     725            4 : 
     726            4 :     let timeline = tenant
     727            4 :         .create_test_timeline(TimelineId::generate(), Lsn(0x10), 14, &ctx)
     728            4 :         .await
     729            4 :         .unwrap();
     730            4 : 
     731            4 :     let layer = {
     732            4 :         let mut layers = {
     733            4 :             let layers = timeline.layers.read().await;
     734            4 :             layers.likely_resident_layers().cloned().collect::<Vec<_>>()
     735            4 :         };
     736            4 : 
     737            4 :         assert_eq!(layers.len(), 1);
     738            4 : 
     739            4 :         layers.swap_remove(0)
     740            4 :     };
     741            4 : 
     742            4 :     // kind of forced setup: start an eviction but do not allow it progress until we are
     743            4 :     // downloading
     744            4 :     let (eviction_can_continue, barrier) = utils::completion::channel();
     745            4 :     let (arrival, eviction_arrived) = utils::completion::channel();
     746            4 :     layer.enable_failpoint(Failpoint::WaitBeforeStartingEvicting(
     747            4 :         Some(arrival),
     748            4 :         barrier,
     749            4 :     ));
     750            4 : 
     751            4 :     let mut evict_and_wait = std::pin::pin!(layer.evict_and_wait(FOREVER));
     752            4 : 
     753            4 :     // use this once-awaited other_evict to synchronize with the eviction
     754            4 :     let other_evict = layer.evict_and_wait(FOREVER);
     755            4 : 
     756            4 :     tokio::time::timeout(ADVANCE, &mut evict_and_wait)
     757            4 :         .await
     758            4 :         .expect_err("should had advanced");
     759            4 :     eviction_arrived.wait().await;
     760            4 :     drop(eviction_can_continue);
     761            4 :     other_evict.await.unwrap();
     762            4 : 
     763            4 :     // now the layer is evicted, and the "evict_and_wait" is waiting on the receiver
     764            4 :     assert!(!layer.is_likely_resident());
     765            4 : 
     766            4 :     // following new evict_and_wait will fail until we've completed the download
     767            4 :     let e = layer.evict_and_wait(FOREVER).await.unwrap_err();
     768            4 :     assert!(matches!(e, EvictionError::NotFound), "{e:?}");
     769            4 : 
     770            4 :     let (download_can_continue, barrier) = utils::completion::channel();
     771            4 :     let (arrival, _download_arrived) = utils::completion::channel();
     772            4 :     layer.enable_failpoint(Failpoint::WaitBeforeDownloading(Some(arrival), barrier));
     773            4 : 
     774            4 :     let mut download = std::pin::pin!(layer
     775            4 :         .0
     776            4 :         .get_or_maybe_download(true, None)
     777            4 :         .instrument(download_span));
     778            4 : 
     779            4 :     assert!(
     780            4 :         !layer.is_likely_resident(),
     781            4 :         "during download layer is evicted"
     782            4 :     );
     783            4 : 
     784            4 :     tokio::time::timeout(ADVANCE, &mut download)
     785            4 :         .await
     786            4 :         .expect_err("should had timed out because of failpoint");
     787            4 : 
     788            4 :     // now we finally get to continue, and because the latest state is downloading, we deduce that
     789            4 :     // original eviction succeeded
     790            4 :     evict_and_wait.await.unwrap();
     791            4 : 
     792            4 :     // however a new evict_and_wait will fail
     793            4 :     let e = layer.evict_and_wait(FOREVER).await.unwrap_err();
     794            4 :     assert!(matches!(e, EvictionError::NotFound), "{e:?}");
     795            4 : 
     796            4 :     assert!(!layer.is_likely_resident());
     797            4 : 
     798            4 :     drop(download_can_continue);
     799            4 :     download.await.expect("download should had succeeded");
     800            4 :     assert!(layer.is_likely_resident());
     801            4 : 
     802            4 :     // only now can we evict
     803            4 :     layer.evict_and_wait(FOREVER).await.unwrap();
     804            4 : }
     805              : 
     806              : /// Asserts that there is no miscalculation when Layer is dropped while it is being kept resident,
     807              : /// which is the last value.
     808              : ///
     809              : /// Also checks that the same does not happen on a non-evicted layer (regression test).
     810              : #[tokio::test(start_paused = true)]
     811            4 : async fn eviction_cancellation_on_drop() {
     812            4 :     use bytes::Bytes;
     813            4 :     use pageserver_api::value::Value;
     814            4 : 
     815            4 :     // this is the runtime on which Layer spawns the blocking tasks on
     816            4 :     let handle = tokio::runtime::Handle::current();
     817            4 : 
     818            4 :     let h = TenantHarness::create("eviction_cancellation_on_drop")
     819            4 :         .await
     820            4 :         .unwrap();
     821            4 :     utils::logging::replace_panic_hook_with_tracing_panic_hook().forget();
     822            4 :     let (tenant, ctx) = h.load().await;
     823            4 : 
     824            4 :     let timeline = tenant
     825            4 :         .create_test_timeline(TimelineId::generate(), Lsn(0x10), 14, &ctx)
     826            4 :         .await
     827            4 :         .unwrap();
     828            4 : 
     829            4 :     {
     830            4 :         // create_test_timeline wrote us one layer, write another
     831            4 :         let mut writer = timeline.writer().await;
     832            4 :         writer
     833            4 :             .put(
     834            4 :                 pageserver_api::key::Key::from_i128(5),
     835            4 :                 Lsn(0x20),
     836            4 :                 &Value::Image(Bytes::from_static(b"this does not matter either")),
     837            4 :                 &ctx,
     838            4 :             )
     839            4 :             .await
     840            4 :             .unwrap();
     841            4 : 
     842            4 :         writer.finish_write(Lsn(0x20));
     843            4 :     }
     844            4 : 
     845            4 :     timeline.freeze_and_flush().await.unwrap();
     846            4 : 
     847            4 :     // wait for the upload to complete so our Arc::strong_count assertion holds
     848            4 :     timeline.remote_client.wait_completion().await.unwrap();
     849            4 : 
     850            4 :     let (evicted_layer, not_evicted) = {
     851            4 :         let mut layers = {
     852            4 :             let mut guard = timeline.layers.write().await;
     853            4 :             let layers = guard.likely_resident_layers().cloned().collect::<Vec<_>>();
     854            4 :             // remove the layers from layermap
     855            4 :             guard.open_mut().unwrap().finish_gc_timeline(&layers);
     856            4 : 
     857            4 :             layers
     858            4 :         };
     859            4 : 
     860            4 :         assert_eq!(layers.len(), 2);
     861            4 : 
     862            4 :         (layers.pop().unwrap(), layers.pop().unwrap())
     863            4 :     };
     864            4 : 
     865            4 :     let victims = [(evicted_layer, true), (not_evicted, false)];
     866            4 : 
     867           12 :     for (victim, evict) in victims {
     868            8 :         let resident = victim.keep_resident().await.unwrap();
     869            8 :         drop(victim);
     870            8 : 
     871            8 :         assert_eq!(Arc::strong_count(&resident.owner.0), 1);
     872            4 : 
     873            8 :         if evict {
     874            4 :             let evict_and_wait = resident.owner.evict_and_wait(FOREVER);
     875            4 : 
     876            4 :             // drive the future to await on the status channel, and then drop it
     877            4 :             tokio::time::timeout(ADVANCE, evict_and_wait)
     878            4 :                 .await
     879            4 :                 .expect_err("should had been a timeout since we are holding the layer resident");
     880            4 :         }
     881            4 : 
     882            4 :         // 1 == we only evict one of the layers
     883            8 :         assert_eq!(1, LAYER_IMPL_METRICS.started_evictions.get());
     884            4 : 
     885            8 :         drop(resident);
     886            8 : 
     887            8 :         // run any spawned
     888            8 :         tokio::time::sleep(ADVANCE).await;
     889            4 : 
     890            8 :         SpawnBlockingPoolHelper::consume_and_release_all_of_spawn_blocking_threads(&handle).await;
     891            4 : 
     892            8 :         assert_eq!(
     893            8 :             1,
     894            8 :             LAYER_IMPL_METRICS.cancelled_evictions[EvictionCancelled::LayerGone].get()
     895            8 :         );
     896            4 :     }
     897            4 : }
     898              : 
     899              : /// A test case to remind you the cost of these structures. You can bump the size limit
     900              : /// below if it is really necessary to add more fields to the structures.
     901              : #[test]
     902              : #[cfg(target_arch = "x86_64")]
     903            4 : fn layer_size() {
     904            4 :     assert_eq!(size_of::<LayerAccessStats>(), 8);
     905            4 :     assert_eq!(size_of::<PersistentLayerDesc>(), 104);
     906            4 :     assert_eq!(size_of::<LayerInner>(), 296);
     907              :     // it also has the utf8 path
     908            4 : }
     909              : 
     910              : struct SpawnBlockingPoolHelper {
     911              :     awaited_by_spawn_blocking_tasks: Completion,
     912              :     blocking_tasks: JoinSet<()>,
     913              : }
     914              : 
     915              : impl SpawnBlockingPoolHelper {
     916              :     /// All `crate::task_mgr::BACKGROUND_RUNTIME` spawn_blocking threads will be consumed until
     917              :     /// release is called.
     918              :     ///
     919              :     /// In the tests this can be used to ensure something cannot be started on the target runtimes
     920              :     /// spawn_blocking pool.
     921              :     ///
     922              :     /// This should be no issue nowdays, because nextest runs each test in it's own process.
     923            4 :     async fn consume_all_spawn_blocking_threads(handle: &tokio::runtime::Handle) -> Self {
     924            4 :         let default_max_blocking_threads = 512;
     925            4 : 
     926            4 :         Self::consume_all_spawn_blocking_threads0(handle, default_max_blocking_threads).await
     927            4 :     }
     928              : 
     929           52 :     async fn consume_all_spawn_blocking_threads0(
     930           52 :         handle: &tokio::runtime::Handle,
     931           52 :         threads: usize,
     932           52 :     ) -> Self {
     933           52 :         assert_ne!(threads, 0);
     934              : 
     935           52 :         let (completion, barrier) = completion::channel();
     936           52 :         let (started, starts_completed) = completion::channel();
     937           52 : 
     938           52 :         let mut blocking_tasks = JoinSet::new();
     939           52 : 
     940        14360 :         for _ in 0..threads {
     941        14360 :             let barrier = barrier.clone();
     942        14360 :             let started = started.clone();
     943        14360 :             blocking_tasks.spawn_blocking_on(
     944        14360 :                 move || {
     945        14360 :                     drop(started);
     946        14360 :                     tokio::runtime::Handle::current().block_on(barrier.wait());
     947        14360 :                 },
     948        14360 :                 handle,
     949        14360 :             );
     950        14360 :         }
     951              : 
     952           52 :         drop(started);
     953           52 : 
     954           52 :         starts_completed.wait().await;
     955              : 
     956           52 :         drop(barrier);
     957           52 : 
     958           52 :         tracing::trace!("consumed all threads");
     959              : 
     960           52 :         SpawnBlockingPoolHelper {
     961           52 :             awaited_by_spawn_blocking_tasks: completion,
     962           52 :             blocking_tasks,
     963           52 :         }
     964           52 :     }
     965              : 
     966              :     /// Release all previously blocked spawn_blocking threads
     967           52 :     async fn release(self) {
     968           52 :         let SpawnBlockingPoolHelper {
     969           52 :             awaited_by_spawn_blocking_tasks,
     970           52 :             mut blocking_tasks,
     971           52 :         } = self;
     972           52 : 
     973           52 :         drop(awaited_by_spawn_blocking_tasks);
     974              : 
     975        14412 :         while let Some(res) = blocking_tasks.join_next().await {
     976        14360 :             res.expect("none of the tasks should had panicked");
     977        14360 :         }
     978              : 
     979           52 :         tracing::trace!("released all threads");
     980           52 :     }
     981              : 
     982              :     /// In the tests it is used as an easy way of making sure something scheduled on the target
     983              :     /// runtimes `spawn_blocking` has completed, because it must've been scheduled and completed
     984              :     /// before our tasks have a chance to schedule and complete.
     985           24 :     async fn consume_and_release_all_of_spawn_blocking_threads(handle: &tokio::runtime::Handle) {
     986           24 :         Self::consume_and_release_all_of_spawn_blocking_threads0(handle, 512).await
     987           24 :     }
     988              : 
     989           44 :     async fn consume_and_release_all_of_spawn_blocking_threads0(
     990           44 :         handle: &tokio::runtime::Handle,
     991           44 :         threads: usize,
     992           44 :     ) {
     993           44 :         Self::consume_all_spawn_blocking_threads0(handle, threads)
     994           44 :             .await
     995           44 :             .release()
     996           44 :             .await
     997           44 :     }
     998              : }
     999              : 
    1000              : #[test]
    1001            4 : fn spawn_blocking_pool_helper_actually_works() {
    1002            4 :     // create a custom runtime for which we know and control how many blocking threads it has
    1003            4 :     //
    1004            4 :     // because the amount is not configurable for our helper, expect the same amount as
    1005            4 :     // BACKGROUND_RUNTIME using the tokio defaults would have.
    1006            4 :     let rt = tokio::runtime::Builder::new_current_thread()
    1007            4 :         .max_blocking_threads(1)
    1008            4 :         .enable_all()
    1009            4 :         .build()
    1010            4 :         .unwrap();
    1011            4 : 
    1012            4 :     let handle = rt.handle();
    1013            4 : 
    1014            4 :     rt.block_on(async move {
    1015              :         // this will not return until all threads are spun up and actually executing the code
    1016              :         // waiting on `consumed` to be `SpawnBlockingPoolHelper::release`'d.
    1017            4 :         let consumed =
    1018            4 :             SpawnBlockingPoolHelper::consume_all_spawn_blocking_threads0(handle, 1).await;
    1019              : 
    1020            4 :         println!("consumed");
    1021            4 : 
    1022            4 :         let mut jh = std::pin::pin!(tokio::task::spawn_blocking(move || {
    1023            4 :             // this will not get to run before we release
    1024            4 :         }));
    1025            4 : 
    1026            4 :         println!("spawned");
    1027            4 : 
    1028            4 :         tokio::time::timeout(std::time::Duration::from_secs(1), &mut jh)
    1029            4 :             .await
    1030            4 :             .expect_err("the task should not have gotten to run yet");
    1031            4 : 
    1032            4 :         println!("tried to join");
    1033            4 : 
    1034            4 :         consumed.release().await;
    1035              : 
    1036            4 :         println!("released");
    1037            4 : 
    1038            4 :         tokio::time::timeout(std::time::Duration::from_secs(1), jh)
    1039            4 :             .await
    1040            4 :             .expect("no timeout")
    1041            4 :             .expect("no join error");
    1042            4 : 
    1043            4 :         println!("joined");
    1044            4 :     });
    1045            4 : }
    1046              : 
    1047              : /// Drop the low bits from a time, to emulate the precision loss in LayerAccessStats
    1048           16 : fn lowres_time(hires: SystemTime) -> SystemTime {
    1049           16 :     let ts = hires.duration_since(UNIX_EPOCH).unwrap().as_secs();
    1050           16 :     UNIX_EPOCH + Duration::from_secs(ts)
    1051           16 : }
    1052              : 
    1053              : #[test]
    1054            4 : fn access_stats() {
    1055            4 :     let access_stats = LayerAccessStats::default();
    1056            4 :     // Default is visible
    1057            4 :     assert_eq!(access_stats.visibility(), LayerVisibilityHint::Visible);
    1058              : 
    1059            4 :     access_stats.set_visibility(LayerVisibilityHint::Covered);
    1060            4 :     assert_eq!(access_stats.visibility(), LayerVisibilityHint::Covered);
    1061            4 :     access_stats.set_visibility(LayerVisibilityHint::Visible);
    1062            4 :     assert_eq!(access_stats.visibility(), LayerVisibilityHint::Visible);
    1063              : 
    1064            4 :     let rtime = UNIX_EPOCH + Duration::from_secs(2000000000);
    1065            4 :     access_stats.record_residence_event_at(rtime);
    1066            4 :     assert_eq!(access_stats.latest_activity(), lowres_time(rtime));
    1067              : 
    1068            4 :     let atime = UNIX_EPOCH + Duration::from_secs(2100000000);
    1069            4 :     access_stats.record_access_at(atime);
    1070            4 :     assert_eq!(access_stats.latest_activity(), lowres_time(atime));
    1071              : 
    1072              :     // Setting visibility doesn't clobber access time
    1073            4 :     access_stats.set_visibility(LayerVisibilityHint::Covered);
    1074            4 :     assert_eq!(access_stats.latest_activity(), lowres_time(atime));
    1075            4 :     access_stats.set_visibility(LayerVisibilityHint::Visible);
    1076            4 :     assert_eq!(access_stats.latest_activity(), lowres_time(atime));
    1077              : 
    1078              :     // Recording access implicitly makes layer visible, if it wasn't already
    1079            4 :     let atime = UNIX_EPOCH + Duration::from_secs(2200000000);
    1080            4 :     access_stats.set_visibility(LayerVisibilityHint::Covered);
    1081            4 :     assert_eq!(access_stats.visibility(), LayerVisibilityHint::Covered);
    1082            4 :     assert!(access_stats.record_access_at(atime));
    1083            4 :     access_stats.set_visibility(LayerVisibilityHint::Visible);
    1084            4 :     assert!(!access_stats.record_access_at(atime));
    1085            4 :     access_stats.set_visibility(LayerVisibilityHint::Visible);
    1086            4 : }
    1087              : 
    1088              : #[test]
    1089            4 : fn access_stats_2038() {
    1090            4 :     // The access stats structure uses a timestamp representation that will run out
    1091            4 :     // of bits in 2038.  One year before that, this unit test will start failing.
    1092            4 : 
    1093            4 :     let one_year_from_now = SystemTime::now().duration_since(UNIX_EPOCH).unwrap()
    1094            4 :         + Duration::from_secs(3600 * 24 * 365);
    1095            4 : 
    1096            4 :     assert!(one_year_from_now.as_secs() < (2 << 31));
    1097            4 : }
        

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