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doc: few touches

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This commit is contained in:
Joonas Koivunen
2023-08-24 22:24:12 +03:00
parent c66e859bcc
commit b154a5e908
1 changed files with 12 additions and 3 deletions
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15
pageserver/src/tenant/storage_layer/layer.rs
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@@ -58,6 +58,7 @@ impl AsLayerDesc for Layer {
}
impl Layer {
/// Creates a layer value for a file we know not to be downloaded or resident.
pub(crate) fn for_evicted(
conf: &'static PageServerConf,
timeline: &Arc<Timeline>,
@@ -86,6 +87,7 @@ impl Layer {
owner
}
/// Creates a Layer value for a file we know to be resident in timeline directory.
pub(crate) fn for_resident(
conf: &'static PageServerConf,
timeline: &Arc<Timeline>,
@@ -153,6 +155,12 @@ impl Layer {
Ok(ResidentLayer { downloaded, owner })
}
/// Requests the layer to be evicted and waits for this to be done.
///
/// If the file is not resident, an [`EvictionError::NotFound`] is returned.
///
/// If for a bad luck or blocking of the executor, we miss the actual eviction and the layer is
/// re-downloaded, [`EvictionError::Downloaded`] is returned.
pub(crate) async fn evict_and_wait(
&self,
rtc: &RemoteTimelineClient,
@@ -627,7 +635,7 @@ impl LayerInner {
},
Err(e) => {
// our caller is cancellation safe, but we might be racing with
// another attempt to reinitialize. before we have cancellation
// another attempt to initialize. before we have cancellation
// token support: these attempts should converge regardless of
// their completion order.
tracing::error!("layer file download failed, and additionally failed to communicate this to caller: {e:?}");
@@ -673,8 +681,8 @@ impl LayerInner {
}
}
} else {
// the file is present locally and we could even be running without remote
// storage
// the file is present locally, probably by a previous but cancelled call to
// get_or_maybe_download.
}
let res = Arc::new(DownloadedLayer {
@@ -912,6 +920,7 @@ pub(crate) enum EvictionError {
Downloaded,
}
/// Error internal to the [`LayerInner::get_or_maybe_download`]
#[derive(Debug, thiserror::Error)]
enum DownloadError {
#[error("timeline has already shutdown")]