// Copyright 2018 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package rawdb
import (
"errors"
"fmt"
"math"
"sync/atomic"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/ethdb"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/metrics"
)
// errUnknownTable is returned if the user attempts to read from a table that is
// not tracked by the freezer.
var errUnknownTable = errors.New("unknown table")
const (
// freezerRecheckInterval is the frequency to check the key-value database for
// chain progression that might permit new blocks to be frozen into immutable
// storage.
freezerRecheckInterval = time.Minute
// freezerBlockGraduation is the number of confirmations a block must achieve
// before it becomes elligible for chain freezing. This must exceed any chain
// reorg depth, since the freezer also deletes all block siblings.
freezerBlockGraduation = 60000
// freezerBatchLimit is the maximum number of blocks to freeze in one batch
// before doing an fsync and deleting it from the key-value store.
freezerBatchLimit = 30000
)
// freezer is an memory mapped append-only database to store immutable chain data
// into flat files:
//
// - The append only nature ensures that disk writes are minimized.
// - The memory mapping ensures we can max out system memory for caching without
// reserving it for go-ethereum. This would also reduce the memory requirements
// of Geth, and thus also GC overhead.
type freezer struct {
tables map[string]*freezerTable // Data tables for storing everything
frozen uint64 // Number of blocks already frozen
}
// newFreezer creates a chain freezer that moves ancient chain data into
// append-only flat file containers.
func newFreezer(datadir string, namespace string) (*freezer, error) {
// Create the initial freezer object
var (
readMeter = metrics.NewRegisteredMeter(namespace+"ancient/read", nil)
writeMeter = metrics.NewRegisteredMeter(namespace+"ancient/write", nil)
)
// Open all the supported data tables
freezer := &freezer{
tables: make(map[string]*freezerTable),
}
for _, name := range []string{"hashes", "headers", "bodies", "receipts", "diffs"} {
table, err := newTable(datadir, name, readMeter, writeMeter)
if err != nil {
for _, table := range freezer.tables {
table.Close()
}
return nil, err
}
freezer.tables[name] = table
}
// Truncate all data tables to the same length
freezer.frozen = math.MaxUint64
for _, table := range freezer.tables {
if freezer.frozen > table.items {
freezer.frozen = table.items
}
}
for _, table := range freezer.tables {
if err := table.truncate(freezer.frozen); err != nil {
for _, table := range freezer.tables {
table.Close()
}
return nil, err
}
}
return freezer, nil
}
// Close terminates the chain freezer, unmapping all the data files.
func (f *freezer) Close() error {
var errs []error
for _, table := range f.tables {
if err := table.Close(); err != nil {
errs = append(errs, err)
}
}
if errs != nil {
return fmt.Errorf("%v", errs)
}
return nil
}
// sync flushes all data tables to disk.
func (f *freezer) sync() error {
var errs []error
for _, table := range f.tables {
if err := table.Sync(); err != nil {
errs = append(errs, err)
}
}
if errs != nil {
return fmt.Errorf("%v", errs)
}
return nil
}
// Ancient retrieves an ancient binary blob from the append-only immutable files.
func (f *freezer) Ancient(kind string, number uint64) ([]byte, error) {
if table := f.tables[kind]; table != nil {
return table.Retrieve(number)
}
return nil, errUnknownTable
}
// freeze is a background thread that periodically checks the blockchain for any
// import progress and moves ancient data from the fast database into the freezer.
//
// This functionality is deliberately broken off from block importing to avoid
// incurring additional data shuffling delays on block propagation.
func (f *freezer) freeze(db ethdb.KeyValueStore) {
nfdb := &nofreezedb{KeyValueStore: db}
for {
// Retrieve the freezing threshold. In theory we're interested only in full
// blocks post-sync, but that would keep the live database enormous during
// dast sync. By picking the fast block, we still get to deep freeze all the
// final immutable data without having to wait for sync to finish.
hash := ReadHeadFastBlockHash(nfdb)
if hash == (common.Hash{}) {
log.Debug("Current fast block hash unavailable") // new chain, empty database
time.Sleep(freezerRecheckInterval)
continue
}
number := ReadHeaderNumber(nfdb, hash)
switch {
case number == nil:
log.Error("Current fast block number unavailable", "hash", hash)
time.Sleep(freezerRecheckInterval)
continue
case *number < freezerBlockGraduation:
log.Debug("Current fast block not old enough", "number", *number, "hash", hash, "delay", freezerBlockGraduation)
time.Sleep(freezerRecheckInterval)
continue
case *number-freezerBlockGraduation <= f.frozen:
log.Debug("Ancient blocks frozen already", "number", *number, "hash", hash, "frozen", f.frozen)
time.Sleep(freezerRecheckInterval)
continue
}
head := ReadHeader(nfdb, hash, *number)
if head == nil {
log.Error("Current fast block unavailable", "number", *number, "hash", hash)
time.Sleep(freezerRecheckInterval)
continue
}
// Seems we have data ready to be frozen, process in usable batches
limit := *number - freezerBlockGraduation
if limit-f.frozen > freezerBatchLimit {
limit = f.frozen + freezerBatchLimit
}
var (
start = time.Now()
first = f.frozen
ancients = make([]common.Hash, 0, limit)
)
for f.frozen < limit {
// Retrieves all the components of the canonical block
hash := ReadCanonicalHash(nfdb, f.frozen)
if hash == (common.Hash{}) {
log.Error("Canonical hash missing, can't freeze", "number", f.frozen)
break
}
header := ReadHeaderRLP(nfdb, hash, f.frozen)
if len(header) == 0 {
log.Error("Block header missing, can't freeze", "number", f.frozen, "hash", hash)
break
}
body := ReadBodyRLP(nfdb, hash, f.frozen)
if len(body) == 0 {
log.Error("Block body missing, can't freeze", "number", f.frozen, "hash", hash)
break
}
receipts := ReadReceiptsRLP(nfdb, hash, f.frozen)
if len(receipts) == 0 {
log.Error("Block receipts missing, can't freeze", "number", f.frozen, "hash", hash)
break
}
td := ReadTdRLP(nfdb, hash, f.frozen)
if len(td) == 0 {
log.Error("Total difficulty missing, can't freeze", "number", f.frozen, "hash", hash)
break
}
// Inject all the components into the relevant data tables
if err := f.tables["hashes"].Append(f.frozen, hash[:]); err != nil {
log.Error("Failed to deep freeze hash", "number", f.frozen, "hash", hash, "err", err)
break
}
if err := f.tables["headers"].Append(f.frozen, header); err != nil {
log.Error("Failed to deep freeze header", "number", f.frozen, "hash", hash, "err", err)
break
}
if err := f.tables["bodies"].Append(f.frozen, body); err != nil {
log.Error("Failed to deep freeze body", "number", f.frozen, "hash", hash, "err", err)
break
}
if err := f.tables["receipts"].Append(f.frozen, receipts); err != nil {
log.Error("Failed to deep freeze receipts", "number", f.frozen, "hash", hash, "err", err)
break
}
if err := f.tables["diffs"].Append(f.frozen, td); err != nil {
log.Error("Failed to deep freeze difficulty", "number", f.frozen, "hash", hash, "err", err)
break
}
log.Trace("Deep froze ancient block", "number", f.frozen, "hash", hash)
atomic.AddUint64(&f.frozen, 1) // Only modify atomically
ancients = append(ancients, hash)
}
// Batch of blocks have been frozen, flush them before wiping from leveldb
if err := f.sync(); err != nil {
log.Crit("Failed to flush frozen tables", "err", err)
}
// Wipe out all data from the active database
batch := db.NewBatch()
for number := first; number < f.frozen; number++ {
for _, hash := range readAllHashes(db, number) {
if hash == ancients[number-first] {
deleteBlockWithoutNumber(batch, hash, number)
} else {
DeleteBlock(batch, hash, number)
}
}
}
if err := batch.Write(); err != nil {
log.Crit("Failed to delete frozen items", "err", err)
}
// Log something friendly for the user
context := []interface{}{
"blocks", f.frozen - first, "elapsed", common.PrettyDuration(time.Since(start)), "number", f.frozen - 1,
}
if n := len(ancients); n > 0 {
context = append(context, []interface{}{"hash", ancients[n-1]}...)
}
log.Info("Deep froze chain segment", context...)
// Avoid database thrashing with tiny writes
if f.frozen-first < freezerBatchLimit {
time.Sleep(freezerRecheckInterval)
}
}
}
