rust/neon
1
0
Fork 0
mirror of https://github.com/neondatabase/neon.git synced 2026-01-15 09:22:55 +00:00
Code Issues Packages Projects Releases Wiki Activity

doc: residentlayer vs. downloadedlayer and eviction

Browse Source
This commit is contained in:
Joonas Koivunen
2023-08-29 10:51:08 +03:00
parent 55c42da91b
commit 44ef584842
1 changed files with 7 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
pageserver/src/tenant/storage_layer/layer.rs
View File

@@ -816,7 +816,7 @@ impl LayerInner {
}
}
/// Our resident layer has been dropped, we might hold the lock elsewhere.
/// `DownloadedLayer` is being dropped, so it calls this method.
fn on_drop(self: Arc<LayerInner>) {
let gc = self.wanted_garbage_collected.load(Ordering::Acquire);
let evict = self.wanted_evicted.load(Ordering::Acquire);
@@ -830,14 +830,16 @@ impl LayerInner {
let span = tracing::info_span!(parent: None, "layer_evict", tenant_id = %self.desc.tenant_id, timeline_id = %self.desc.timeline_id, layer=%self);
// downgrade in case there's a queue backing up, or we are just tearing stuff down, and
// would soon delete anyways.
// downgrade for the duration of the queue, in case there's a shutdown already ongoing
// we should not hold it up.
let this = Arc::downgrade(&self);
drop(self);
crate::task_mgr::BACKGROUND_RUNTIME.spawn_blocking(move || {
let _g = span.entered();
// if LayerInner is already dropped here, do nothing for the garbage collection has
// already ran while we were in queue
let Some(this) = this.upgrade() else { return; };
this.evict_blocking(version);
});
@@ -849,8 +851,7 @@ impl LayerInner {
let Some(timeline) = self.timeline.upgrade() else { return; };
// to avoid starting a new download while we evict, keep holding on to the
// permit. note that we will not close the semaphore when done, because it will
// be used by the re-download.
// permit.
let _permit = {
let maybe_downloaded = self.inner.get();
@@ -910,6 +911,7 @@ impl LayerInner {
}
}
// we are still holding the permit, so no new spawn_download_and_wait can happen
drop(self.status.send(Status::Evicted));
}
}