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"
	"sync/atomic"
	"time"

	"github.com/ava-labs/coreth/params"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/ethdb"
	"github.com/ethereum/go-ethereum/log"
	"github.com/ethereum/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
	threshold uint64 // Number of recent blocks not to freeze (params.FullImmutabilityThreshold apart from tests)

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

	trigger chan chan struct{} // Manual blocking freeze trigger, test determinism

	quit      chan struct{}
	closeOnce sync.Once
}

// 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)
		sizeGauge  = metrics.NewRegisteredGauge(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{
		threshold:    params.FullImmutabilityThreshold,
		tables:       make(map[string]*freezerTable),
		instanceLock: lock,
		trigger:      make(chan chan struct{}),
		quit:         make(chan struct{}),
	}
	for name, disableSnappy := range freezerNoSnappy {
		table, err