From ab2af85d89d5627be8e3c8cce209739b9c902344 Mon Sep 17 00:00:00 2001
From: "Leo Zhang (zhangchiqing)" <zhangchiqing@gmail.com>
Date: Thu, 27 Oct 2022 16:30:59 -0700
Subject: [PATCH] no migration optimization

---
 ledger/complete/ledger.go | 107 +++++++++++++++++++++-----------------
 1 file changed, 59 insertions(+), 48 deletions(-)

diff --git a/ledger/complete/ledger.go b/ledger/complete/ledger.go
index 19490d0e49d..bb370972285 100644
--- a/ledger/complete/ledger.go
+++ b/ledger/complete/ledger.go
@@ -363,61 +363,66 @@ func (l *Ledger) ExportCheckpointAt(
 			fmt.Errorf("failed to clean up tries to reduce memory usage: %w", err)
 	}
 
-	// TODO enable validity check of trie
-	// only check validity of the trie we are interested in
-	// l.logger.Info().Msg("Checking validity of the trie at the given state...")
-	// if !t.IsAValidTrie() {
-	//	 return nil, fmt.Errorf("trie is not valid: %w", err)
-	// }
-	// l.logger.Info().Msg("Trie is valid.")
-
-	// get all payloads
-	payloads := t.AllPayloads()
-	payloadSize := len(payloads)
-
-	// migrate payloads
-	for i, migrate := range migrations {
-		l.logger.Info().Msgf("migration %d/%d is underway", i, len(migrations))
-
-		start := time.Now()
-		payloads, err = migrate(payloads)
-		elapsed := time.Since(start)
-
-		if err != nil {
-			return ledger.State(hash.DummyHash), fmt.Errorf("error applying migration (%d): %w", i, err)
+	var payloads []ledger.Payload
+	var newTrie *trie.MTrie
+
+	noMigration := len(migrations) == 0
+
+	if noMigration {
+		// when there is no migration, reuse the trie without rebuilding it
+		newTrie = t
+		// when there is no migration, we don't generate the payloads here until later running the
+		// postCheckpointReporters, because the ExportReporter is currently the only
+		// preCheckpointReporters, which doesn't use the payloads.
+	} else {
+		// get all payloads
+		payloads = t.AllPayloads()
+		payloadSize := len(payloads)
+
+		// migrate payloads
+		for i, migrate := range migrations {
+			l.logger.Info().Msgf("migration %d/%d is underway", i, len(migrations))
+
+			start := time.Now()
+			payloads, err = migrate(payloads)
+			elapsed := time.Since(start)
+
+			if err != nil {
+				return ledger.State(hash.DummyHash), fmt.Errorf("error applying migration (%d): %w", i, err)
+			}
+
+			newPayloadSize := len(payloads)
+
+			if payloadSize != newPayloadSize {
+				l.logger.Warn().
+					Int("migration_step", i).
+					Int("expected_size", payloadSize).
+					Int("outcome_size", newPayloadSize).
+					Msg("payload counts has changed during migration, make sure this is expected.")
+			}
+			l.logger.Info().Str("timeTaken", elapsed.String()).Msgf("migration %d is done", i)
+
+			payloadSize = newPayloadSize
 		}
 
-		newPayloadSize := len(payloads)
+		l.logger.Info().Msgf("creating paths for %v payloads", len(payloads))
 
-		if payloadSize != newPayloadSize {
-			l.logger.Warn().
-				Int("migration_step", i).
-				Int("expected_size", payloadSize).
-				Int("outcome_size", newPayloadSize).
-				Msg("payload counts has changed during migration, make sure this is expected.")
+		// get paths
+		paths, err := pathfinder.PathsFromPayloads(payloads, targetPathFinderVersion)
+		if err != nil {
+			return ledger.State(hash.DummyHash), fmt.Errorf("cannot export checkpoint, can't construct paths: %w", err)
 		}
-		l.logger.Info().Str("timeTaken", elapsed.String()).Msgf("migration %d is done", i)
-
-		payloadSize = newPayloadSize
-	}
-
-	l.logger.Info().Msgf("creating paths for %v payloads", len(payloads))
-
-	// get paths
-	paths, err := pathfinder.PathsFromPayloads(payloads, targetPathFinderVersion)
-	if err != nil {
-		return ledger.State(hash.DummyHash), fmt.Errorf("cannot export checkpoint, can't construct paths: %w", err)
-	}
 
-	l.logger.Info().Msgf("constructing a new trie with migrated payloads (count: %d)...", len(payloads))
+		l.logger.Info().Msgf("constructing a new trie with migrated payloads (count: %d)...", len(payloads))
 
-	emptyTrie := trie.NewEmptyMTrie()
+		emptyTrie := trie.NewEmptyMTrie()
 
-	// no need to prune the data since it has already been prunned through migrations
-	applyPruning := false
-	newTrie, _, err := trie.NewTrieWithUpdatedRegisters(emptyTrie, paths, payloads, applyPruning)
-	if err != nil {
-		return ledger.State(hash.DummyHash), fmt.Errorf("constructing updated trie failed: %w", err)
+		// no need to prune the data since it has already been prunned through migrations
+		applyPruning := false
+		newTrie, _, err = trie.NewTrieWithUpdatedRegisters(emptyTrie, paths, payloads, applyPruning)
+		if err != nil {
+			return ledger.State(hash.DummyHash), fmt.Errorf("constructing updated trie failed: %w", err)
+		}
 	}
 
 	statecommitment := ledger.State(newTrie.RootHash())
@@ -467,6 +472,12 @@ func (l *Ledger) ExportCheckpointAt(
 
 	l.logger.Info().Msgf("start running post-checkpoint reporters")
 
+	if noMigration {
+		// when there is no mgiration, we generate the payloads now before
+		// running the postCheckpointReporters
+		payloads = newTrie.AllPayloads()
+	}
+
 	// running post checkpoint reporters
 	for i, reporter := range postCheckpointReporters {
 		l.logger.Info().Msgf("running a post-checkpoint generation reporter: %s, (%v/%v)", reporter.Name(), i, len(postCheckpointReporters))