From fdd877534f6b55f2f84c3302ab4a2b72549014a9 Mon Sep 17 00:00:00 2001
From: vyzo <vyzo@hackzen.org>
Date: Wed, 3 Mar 2021 11:15:26 +0200
Subject: [PATCH] walk at boundary epoch, 2 finalities from current epoch, to
 find live objects

objects written after that are retained anyway.
---
 blockstore/splitstore/splitstore.go | 35 ++++++++++++++++++++---------
 1 file changed, 24 insertions(+), 11 deletions(-)

diff --git a/blockstore/splitstore/splitstore.go b/blockstore/splitstore/splitstore.go
index 92e765261..787c8cd46 100644
--- a/blockstore/splitstore/splitstore.go
+++ b/blockstore/splitstore/splitstore.go
@@ -29,10 +29,10 @@ var (
 	//
 	//        |················· CompactionThreshold ··················|
 	//        |                                                        |
-	// =======‖≡≡≡≡≡≡≡‖-------------------------------------------------»
-	//        |       |                           chain -->             ↑__ current epoch
-	//        |·······|
-	//            ↑________ CompactionCold.
+	// =======‖≡≡≡≡≡≡≡‖-----------------------|------------------------»
+	//        |       |                       |   chain -->             ↑__ current epoch
+	//        |·······|                       |
+	//            ↑________ CompactionCold    ↑________ CompactionBoundary
 	//
 	// === :: cold (already archived)
 	// ≡≡≡ :: to be archived in this compaction
@@ -43,6 +43,10 @@ var (
 	// cold store on compaction. See diagram on CompactionThreshold for a
 	// better sense.
 	CompactionCold = build.Finality
+
+	// CompactionBoundary is the number of epochs from the current epoch at which
+	// we will walk the chain for live objects
+	CompactionBoundary = 2 * build.Finality
 )
 
 var (
@@ -536,8 +540,10 @@ func (s *SplitStore) estimateMarkSetSize(curTs *types.TipSet) {
 
 func (s *SplitStore) compactSimple(curTs *types.TipSet) {
 	coldEpoch := s.baseEpoch + CompactionCold
+	currentEpoch := curTs.Height()
+	boundaryEpoch := currentEpoch - CompactionBoundary
 
-	log.Infow("running simple compaction", "currentEpoch", curTs.Height(), "baseEpoch", s.baseEpoch, "coldEpoch", coldEpoch)
+	log.Infow("running simple compaction", "currentEpoch", currentEpoch, "baseEpoch", s.baseEpoch, "coldEpoch", coldEpoch, "boundaryEpoch", boundaryEpoch)
 
 	coldSet, err := s.env.Create("cold", s.markSetSize)
 	if err != nil {
@@ -547,17 +553,17 @@ func (s *SplitStore) compactSimple(curTs *types.TipSet) {
 	defer coldSet.Close() //nolint:errcheck
 
 	// 1. mark reachable cold objects by looking at the objects reachable only from the cold epoch
-	log.Infow("marking reachable cold objects", "coldEpoch", coldEpoch)
+	log.Infow("marking reachable cold objects", "boundaryEpoch", boundaryEpoch)
 	startMark := time.Now()
 
-	coldTs, err := s.chain.GetTipsetByHeight(context.Background(), coldEpoch, curTs, true)
+	boundaryTs, err := s.chain.GetTipsetByHeight(context.Background(), boundaryEpoch, curTs, true)
 	if err != nil {
 		// TODO do something better here
 		panic(err)
 	}
 
 	var count int64
-	err = s.chain.WalkSnapshot(context.Background(), coldTs, 1, s.skipOldMsgs, s.skipMsgReceipts,
+	err = s.chain.WalkSnapshot(context.Background(), boundaryTs, 1, s.skipOldMsgs, s.skipMsgReceipts,
 		func(cid cid.Cid) error {
 			count++
 			return coldSet.Mark(cid)
@@ -754,10 +760,11 @@ func (s *SplitStore) purgeTracking(cids []cid.Cid) error {
 }
 
 func (s *SplitStore) compactFull(curTs *types.TipSet) {
-	epoch := curTs.Height()
+	currentEpoch := curTs.Height()
 	coldEpoch := s.baseEpoch + CompactionCold
+	boundaryEpoch := currentEpoch - CompactionBoundary
 
-	log.Infow("running full compaction", "currentEpoch", curTs.Height(), "baseEpoch", s.baseEpoch, "coldEpoch", coldEpoch)
+	log.Infow("running full compaction", "currentEpoch", currentEpoch, "baseEpoch", s.baseEpoch, "coldEpoch", coldEpoch, "boundaryEpoch", boundaryEpoch)
 
 	// create two mark sets, one for marking the cold finality region
 	// and one for marking the hot region
@@ -780,8 +787,14 @@ func (s *SplitStore) compactFull(curTs *types.TipSet) {
 	startMark := time.Now()
 
 	// Phase 1a: mark all reachable CIDs in the hot range
+	boundaryTs, err := s.chain.GetTipsetByHeight(context.Background(), boundaryEpoch, curTs, true)
+	if err != nil {
+		// TODO do something better here
+		panic(err)
+	}
+
 	count := int64(0)
-	err = s.chain.WalkSnapshot(context.Background(), curTs, epoch-coldEpoch, s.skipOldMsgs, s.skipMsgReceipts,
+	err = s.chain.WalkSnapshot(context.Background(), boundaryTs, boundaryEpoch-coldEpoch, s.skipOldMsgs, s.skipMsgReceipts,
 		func(cid cid.Cid) error {
 			count++
 			return hotSet.Mark(cid)