core, eth: split eth package, implement snap protocol (#21482)

This commit splits the eth package, separating the handling of eth and snap protocols. It also includes the capability to run snap sync (https://github.com/ethereum/devp2p/blob/master/caps/snap.md) , but does not enable it by default. 

Co-authored-by: Marius van der Wijden <m.vanderwijden@live.de>
Co-authored-by: Martin Holst Swende <martin@swende.se>

core/rawdb/accessors_snapshot.go

@@ -175,3 +175,24 @@ func DeleteSnapshotRecoveryNumber(db ethdb.KeyValueWriter) {
 		log.Crit("Failed to remove snapshot recovery number", "err", err)
 	}
 }
+
+// ReadSanpshotSyncStatus retrieves the serialized sync status saved at shutdown.
+func ReadSanpshotSyncStatus(db ethdb.KeyValueReader) []byte {
+	data, _ := db.Get(snapshotSyncStatusKey)
+	return data
+}
+
+// WriteSnapshotSyncStatus stores the serialized sync status to save at shutdown.
+func WriteSnapshotSyncStatus(db ethdb.KeyValueWriter, status []byte) {
+	if err := db.Put(snapshotSyncStatusKey, status); err != nil {
+		log.Crit("Failed to store snapshot sync status", "err", err)
+	}
+}
+
+// DeleteSnapshotSyncStatus deletes the serialized sync status saved at the last
+// shutdown
+func DeleteSnapshotSyncStatus(db ethdb.KeyValueWriter) {
+	if err := db.Delete(snapshotSyncStatusKey); err != nil {
+		log.Crit("Failed to remove snapshot sync status", "err", err)
+	}
+}

core/rawdb/schema.go

@@ -57,6 +57,9 @@ var (
 	// snapshotRecoveryKey tracks the snapshot recovery marker across restarts.
 	snapshotRecoveryKey = []byte("SnapshotRecovery")
 
+	// snapshotSyncStatusKey tracks the snapshot sync status across restarts.
+	snapshotSyncStatusKey = []byte("SnapshotSyncStatus")
+
 	// txIndexTailKey tracks the oldest block whose transactions have been indexed.
 	txIndexTailKey = []byte("TransactionIndexTail")