path: root/core/rawdb/freezer.go

// Copyright 2019 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"
	"os"
	"path/filepath"
	"sync/atomic"
	"time"

	"github.com/ava-labs/coreth/params"
	"github.com/ava-labs/go-ethereum/common"
	"github.com/ava-labs/go-ethereum/ethdb"
	"github.com/ava-labs/go-ethereum/log"
	"github.com/ava-labs/go-ethereum/metrics"
	"github.com/prometheus/tsdb/fileutil"
)

var (
	// errUnknownTable is returned if the user attempts to read from a table that is
	// not tracked by the freezer.
	errUnknownTable = errors.New("unknown table")

	// errOutOrderInsertion is returned if the user attempts to inject out-of-order
	// binary blobs into the freezer.
	errOutOrderInsertion = errors.New("the append operation is out-order")

	// errSymlinkDatadir is returned if the ancient directory specified by user
	// is a symbolic link.
	errSymlinkDatadir = errors.New("symbolic link datadir is not supported")
)

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

	// 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 {
	// WARNING: The `frozen` field is accessed atomically. On 32 bit platforms, only
	// 64-bit aligned fields can be atomic. The struct is guaranteed to be so aligned,
	// so take advantage of that (https://golang.org/pkg/sync/atomic/#pkg-note-BUG).
	frozen uint64 // Number of blocks already frozen

	tables       map[string]*freezerTable // Data tables for storing everything
	instanceLock fileutil.Releaser        // File-system lock to prevent double opens
}

// 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)
		sizeCounter = metrics.NewRegisteredCounter(namespace+"ancient/size", nil)
	)
	// Ensure the datadir is not a symbolic link if it exists.
	if info, err := os.Lstat(datadir); !os.IsNotExist(err) {
		if info.Mode()&os.ModeSymlink != 0 {
			log.Warn("Symbolic link ancient database is not supported", "path", datadir)
			return nil, errSymlinkDatadir
		}
	}
	// Leveldb uses LOCK as the filelock filename. To prevent the
	// name collision, we use FLOCK as the lock name.
	lock, _, err := fileutil.Flock(filepath.Join(datadir, "FLOCK"))
	if err != nil {
		return nil, err
	}
	// Open all the supported data tables
	freezer := &freezer{
		tables:       make(map[string]*freezerTable),
		instanceLock: lock,
	}
	for name, disableSnappy := range freezerNoSnappy {
		table, err := newTable(datadir, name, readMeter, writeMeter, sizeCounter, disableSnappy)
		if err != nil {
			for _, table := range freezer.tables {
				table.Close()
			}
			lock.Release()
			return nil, err
		}
		freezer.tables[name] = table
	}
	if err := freezer.repair(); err != nil {
		for _, table := range freezer.tables {
			table.Close()
		}
		lock.Release()
		return nil, err
	}
	log.Info("Opened ancient database", "database", datadir)
	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 err := f.instanceLock.Release(); err != nil {
		errs = append(errs, err)
	}
	if errs != nil {
		return fmt.Errorf("%v", errs)
	}
	return nil
}

// HasAncient returns an indicator whether the specified ancient data exists
// in the freezer.
func (f *freezer) HasAncient(kind string, number uint64) (bool, error) {
	if table := f.tables[kind]; table != nil {
		return table.has(number), nil
	}
	return false, 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
}

// Ancients returns the length of the frozen items.
func (f *freezer) Ancients() (uint64, error) {
	return atomic.LoadUint64(&f.frozen), nil
}

// AncientSize returns the ancient size of the specified category.
func (f *freezer) AncientSize(kind string) (uint64, error) {
	if table := f.tables[kind]; table != nil {
		return table.size()
	}
	return 0, errUnknownTable
}

// AppendAncient injects all binary blobs belong to block at the end of the
// append-only immutable table files.
//
// Notably, this function is lock free but kind of thread-safe. All out-of-order
// injection will be rejected. But if two injections with same number happen at
// the same time, we can get into the trouble.
func (f *freezer) AppendAncient(number uint64, hash, header, body, receipts, td []byte) (err error) {
	// Ensure the binary blobs we are appending is continuous with freezer.
	if atomic.LoadUint64(&f.frozen) != number {
		return errOutOrderInsertion
	}
	// Rollback all inserted data if any insertion below failed to ensure
	// the tables won't out of sync.
	defer func() {
		if err != nil {
			rerr := f.repair()
			if rerr != nil {
				log.Crit("Failed to repair freezer", "err", rerr)
			}
			log.Info("Append ancient failed", "number", number, "err", err)
		}
	}()
	// Inject all the components into the relevant data tables
	if err := f.tables[freezerHashTable].Append(f.frozen, hash[:]); err != nil {
		log.Error("Failed to append ancient hash", "number", f.frozen, "hash", hash, "err", err)
		return err
	}
	if err := f.tables[freezerHeaderTable].Append(f.frozen, header); err != nil {
		log.Error("Failed to append ancient header", "number", f.frozen, "hash", hash, "err", err)
		return err
	}
	if err := f.tables[freezerBodiesTable].Append(f.frozen, body); err != nil {
		log.Error("Failed to append ancient body", "number", f.frozen, "hash", hash, "err", err)
		return err
	}
	if err := f.tables[freezerReceiptTable].Append(f.frozen, receipts); err != nil {
		log.Error("Failed to append ancient receipts", "number", f.frozen, "hash", hash, "err", err)
		return err
	}
	if err := f.tables[freezerDifficultyTable].Append(f.frozen, td); err != nil {
		log.Error("Failed to append ancient difficulty", "number", f.frozen, "hash", hash, "err", err)
		return err
	}
	atomic.AddUint64(&f.frozen, 1) // Only modify atomically
	return nil
}

// Truncate discards any recent data above the provided threshold number.
func (f *freezer) TruncateAncients(items uint64) error {
	if atomic.LoadUint64(&f.frozen) <= items {
		return nil
	}
	for _, table := range f.tables {
		if err := table.truncate(items); err != nil {
			return err
		}
	}
	atomic.StoreUint64(&f.frozen, items)
	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 =