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Also consider offloaded timelines for obtaining retain_lsn #9308

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merged 5 commits into from
Oct 14, 2024
Merged

Also consider offloaded timelines for obtaining retain_lsn #9308

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3a3b0b0
Also consider offloaded timelines for obtaining retain_lsn
arpad-m Oct 8, 2024
3a0f4f1
Add is_offloaded flag
arpad-m Oct 14, 2024
17b9c12
tests
arpad-m Oct 14, 2024
4d5aaa0
enum
arpad-m Oct 14, 2024
16c3bdb
Clippy and fmt
arpad-m Oct 14, 2024
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47 changes: 36 additions & 11 deletions pageserver/src/tenant.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -493,6 +493,8 @@ pub struct OffloadedTimeline {
pub tenant_shard_id: TenantShardId,
pub timeline_id: TimelineId,
pub ancestor_timeline_id: Option<TimelineId>,
/// Whether to retain the branch lsn at the ancestor or not
pub ancestor_retain_lsn: Option<Lsn>,
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// TODO: once we persist offloaded state, make this lazily constructed
pub remote_client: Arc<RemoteTimelineClient>,
Expand All @@ -504,10 +506,14 @@ pub struct OffloadedTimeline {

impl OffloadedTimeline {
fn from_timeline(timeline: &Timeline) -> Self {
let ancestor_retain_lsn = timeline
.get_ancestor_timeline_id()
.map(|_timeline_id| timeline.get_ancestor_lsn());
Self {
tenant_shard_id: timeline.tenant_shard_id,
timeline_id: timeline.timeline_id,
ancestor_timeline_id: timeline.get_ancestor_timeline_id(),
ancestor_retain_lsn,

remote_client: timeline.remote_client.clone(),
delete_progress: timeline.delete_progress.clone(),
Expand Down Expand Up @@ -2253,12 +2259,13 @@ impl Tenant {

if activating {
let timelines_accessor = self.timelines.lock().unwrap();
let timelines_offloaded_accessor = self.timelines_offloaded.lock().unwrap();
let timelines_to_activate = timelines_accessor
.values()
.filter(|timeline| !(timeline.is_broken() || timeline.is_stopping()));

// Before activation, populate each Timeline's GcInfo with information about its children
self.initialize_gc_info(&timelines_accessor);
self.initialize_gc_info(&timelines_accessor, &timelines_offloaded_accessor);

// Spawn gc and compaction loops. The loops will shut themselves
// down when they notice that the tenant is inactive.
Expand Down Expand Up @@ -3298,27 +3305,45 @@ impl Tenant {
fn initialize_gc_info(
&self,
timelines: &std::sync::MutexGuard<HashMap<TimelineId, Arc<Timeline>>>,
timelines_offloaded: &std::sync::MutexGuard<HashMap<TimelineId, Arc<OffloadedTimeline>>>,
) {
// This function must be called before activation: after activation timeline create/delete operations
// might happen, and this function is not safe to run concurrently with those.
assert!(!self.is_active());

// Scan all timelines. For each timeline, remember the timeline ID and
// the branch point where it was created.
let mut all_branchpoints: BTreeMap<TimelineId, Vec<(Lsn, TimelineId)>> = BTreeMap::new();
let mut all_branchpoints: BTreeMap<TimelineId, Vec<(Lsn, TimelineId, bool)>> =
BTreeMap::new();
timelines.iter().for_each(|(timeline_id, timeline_entry)| {
if let Some(ancestor_timeline_id) = &timeline_entry.get_ancestor_timeline_id() {
let ancestor_children = all_branchpoints.entry(*ancestor_timeline_id).or_default();
ancestor_children.push((timeline_entry.get_ancestor_lsn(), *timeline_id));
ancestor_children.push((
timeline_entry.get_ancestor_lsn(),
*timeline_id,
false,
));
}
});
timelines_offloaded
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.iter()
.for_each(|(timeline_id, timeline_entry)| {
let Some(ancestor_timeline_id) = &timeline_entry.ancestor_timeline_id else {
return;
};
let Some(retain_lsn) = timeline_entry.ancestor_retain_lsn else {
return;
};
let ancestor_children = all_branchpoints.entry(*ancestor_timeline_id).or_default();
ancestor_children.push((retain_lsn, *timeline_id, true));
});

// The number of bytes we always keep, irrespective of PITR: this is a constant across timelines
let horizon = self.get_gc_horizon();

// Populate each timeline's GcInfo with information about its child branches
for timeline in timelines.values() {
let mut branchpoints: Vec<(Lsn, TimelineId)> = all_branchpoints
let mut branchpoints: Vec<(Lsn, TimelineId, bool)> = all_branchpoints
.remove(&timeline.timeline_id)
.unwrap_or_default();

Expand Down Expand Up @@ -4878,7 +4903,7 @@ mod tests {
{
let branchpoints = &tline.gc_info.read().unwrap().retain_lsns;
assert_eq!(branchpoints.len(), 1);
assert_eq!(branchpoints[0], (Lsn(0x40), NEW_TIMELINE_ID));
assert_eq!(branchpoints[0], (Lsn(0x40), NEW_TIMELINE_ID, false));
}

// You can read the key from the child branch even though the parent is
Expand Down Expand Up @@ -8261,8 +8286,8 @@ mod tests {
let mut guard = tline.gc_info.write().unwrap();
*guard = GcInfo {
retain_lsns: vec![
(Lsn(0x10), tline.timeline_id),
(Lsn(0x20), tline.timeline_id),
(Lsn(0x10), tline.timeline_id, false),
(Lsn(0x20), tline.timeline_id, false),
],
cutoffs: GcCutoffs {
time: Lsn(0x30),
Expand Down Expand Up @@ -8489,8 +8514,8 @@ mod tests {
let mut guard = tline.gc_info.write().unwrap();
*guard = GcInfo {
retain_lsns: vec![
(Lsn(0x10), tline.timeline_id),
(Lsn(0x20), tline.timeline_id),
(Lsn(0x10), tline.timeline_id, false),
(Lsn(0x20), tline.timeline_id, false),
],
cutoffs: GcCutoffs {
time: Lsn(0x30),
Expand Down Expand Up @@ -8723,7 +8748,7 @@ mod tests {
// Update GC info
let mut guard = parent_tline.gc_info.write().unwrap();
*guard = GcInfo {
retain_lsns: vec![(Lsn(0x18), branch_tline.timeline_id)],
retain_lsns: vec![(Lsn(0x18), branch_tline.timeline_id, false)],
cutoffs: GcCutoffs {
time: Lsn(0x10),
space: Lsn(0x10),
Expand All @@ -8737,7 +8762,7 @@ mod tests {
// Update GC info
let mut guard = branch_tline.gc_info.write().unwrap();
*guard = GcInfo {
retain_lsns: vec![(Lsn(0x40), branch_tline.timeline_id)],
retain_lsns: vec![(Lsn(0x40), branch_tline.timeline_id, false)],
cutoffs: GcCutoffs {
time: Lsn(0x50),
space: Lsn(0x50),
Expand Down
4 changes: 2 additions & 2 deletions pageserver/src/tenant/size.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -264,10 +264,10 @@ pub(super) async fn gather_inputs(
let mut lsns: Vec<(Lsn, LsnKind)> = gc_info
.retain_lsns
.iter()
.filter(|(lsn, _child_id)| lsn > &ancestor_lsn)
.filter(|(lsn, _child_id, is_offloaded)| lsn > &ancestor_lsn && !is_offloaded)
.copied()
// this assumes there are no other retain_lsns than the branchpoints
.map(|(lsn, _child_id)| (lsn, LsnKind::BranchPoint))
.map(|(lsn, _child_id, _is_offloaded)| (lsn, LsnKind::BranchPoint))
.collect::<Vec<_>>();

lsns.extend(lease_points.iter().map(|&lsn| (lsn, LsnKind::LeasePoint)));
Expand Down
12 changes: 7 additions & 5 deletions pageserver/src/tenant/timeline.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -450,7 +450,7 @@ pub(crate) struct GcInfo {
/// Currently, this includes all points where child branches have
/// been forked off from. In the future, could also include
/// explicit user-defined snapshot points.
pub(crate) retain_lsns: Vec<(Lsn, TimelineId)>,
pub(crate) retain_lsns: Vec<(Lsn, TimelineId, bool)>,
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/// The cutoff coordinates, which are combined by selecting the minimum.
pub(crate) cutoffs: GcCutoffs,
Expand All @@ -467,8 +467,8 @@ impl GcInfo {
self.cutoffs.select_min()
}

pub(super) fn insert_child(&mut self, child_id: TimelineId, child_lsn: Lsn) {
self.retain_lsns.push((child_lsn, child_id));
pub(super) fn insert_child(&mut self, child_id: TimelineId, child_lsn: Lsn, is_offloaded: bool) {
self.retain_lsns.push((child_lsn, child_id, is_offloaded));
self.retain_lsns.sort_by_key(|i| i.0);
}

Expand Down Expand Up @@ -2164,7 +2164,9 @@ impl Timeline {

if let Some(ancestor) = &ancestor {
let mut ancestor_gc_info = ancestor.gc_info.write().unwrap();
ancestor_gc_info.insert_child(timeline_id, metadata.ancestor_lsn());
// If we construct an explicit timeline object, it's obviously not offloaded
let is_offloaded = false;
ancestor_gc_info.insert_child(timeline_id, metadata.ancestor_lsn(), is_offloaded);
}

Arc::new_cyclic(|myself| {
Expand Down Expand Up @@ -4875,7 +4877,7 @@ impl Timeline {
let retain_lsns = gc_info
.retain_lsns
.iter()
.map(|(lsn, _child_id)| *lsn)
.map(|(lsn, _child_id, _is_offloaded)| *lsn)
.collect();

// Gets the maximum LSN that holds the valid lease.
Expand Down
7 changes: 5 additions & 2 deletions pageserver/src/tenant/timeline/compaction.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -639,7 +639,10 @@ impl Timeline {
let children = self.gc_info.read().unwrap().retain_lsns.clone();

let mut readable_points = Vec::with_capacity(children.len() + 1);
for (child_lsn, _child_timeline_id) in &children {
for (child_lsn, _child_timeline_id, is_offloaded) in &children {
if *is_offloaded {
continue;
}
readable_points.push(*child_lsn);
}
readable_points.push(head_lsn);
Expand Down Expand Up @@ -1741,7 +1744,7 @@ impl Timeline {
let gc_info = self.gc_info.read().unwrap();
let mut retain_lsns_below_horizon = Vec::new();
let gc_cutoff = gc_info.cutoffs.select_min();
for (lsn, _timeline_id) in &gc_info.retain_lsns {
for (lsn, _timeline_id, _is_offloaded) in &gc_info.retain_lsns {
if lsn < &gc_cutoff {
retain_lsns_below_horizon.push(*lsn);
}
Expand Down
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