Official Go implementation of the Ethereum protocol
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go-ethereum/core/rawdb/freezer.go

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// 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/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/ethdb"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/metrics"
"github.com/gofrs/flock"
)
var (
// errReadOnly is returned if the freezer is opened in read only mode. All the
// mutations are disallowed.
errReadOnly = errors.New("read only")
// 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")
)
// freezerTableSize defines the maximum size of freezer data files.
const freezerTableSize = 2 * 1000 * 1000 * 1000
// Freezer is a memory mapped append-only database to store immutable ordered
// 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` and `tail` fields are 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
tail uint64 // Number of the first stored item in the freezer
// This lock synchronizes writers and the truncate operation, as well as
// the "atomic" (batched) read operations.
writeLock sync.RWMutex
writeBatch *freezerBatch
readonly bool
tables map[string]*freezerTable // Data tables for storing everything
instanceLock *flock.Flock // File-system lock to prevent double opens
closeOnce sync.Once
}
// NewChainFreezer is a small utility method around NewFreezer that sets the
// default parameters for the chain storage.
func NewChainFreezer(datadir string, namespace string, readonly bool) (*Freezer, error) {
return NewFreezer(datadir, namespace, readonly, freezerTableSize, chainFreezerNoSnappy)
}
// NewFreezer creates a freezer instance for maintaining immutable ordered
// data according to the given parameters.
//
// The 'tables' argument defines the data tables. If the value of a map
// entry is true, snappy compression is disabled for the table.
func NewFreezer(datadir string, namespace string, readonly bool, maxTableSize uint32, tables map[string]bool) (*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
}
}
flockFile := filepath.Join(datadir, "FLOCK")
if err := os.MkdirAll(filepath.Dir(flockFile), 0755); err != nil {
return nil, err
}
// Leveldb uses LOCK as the filelock filename. To prevent the
// name collision, we use FLOCK as the lock name.
lock := flock.New(flockFile)
if locked, err := lock.TryLock(); err != nil {
return nil, err
} else if !locked {
return nil, errors.New("locking failed")
}
// Open all the supported data tables
freezer := &Freezer{
readonly: readonly,
tables: make(map[string]*freezerTable),
instanceLock: lock,
}
// Create the tables.
for name, disableSnappy := range tables {
table, err := newTable(datadir, name, readMeter, writeMeter, sizeGauge, maxTableSize, disableSnappy, readonly)
if err != nil {
for _, table := range freezer.tables {
table.Close()
}
lock.Unlock()
return nil, err
}
freezer.tables[name] = table
}
var err error
if freezer.readonly {
// In readonly mode only validate, don't truncate.
// validate also sets `freezer.frozen`.
err = freezer.validate()
} else {
// Truncate all tables to common length.
err = freezer.repair()
}
if err != nil {
for _, table := range freezer.tables {
table.Close()
}
lock.Unlock()
return nil, err
}
// Create the write batch.
freezer.writeBatch = newFreezerBatch(freezer)
log.Info("Opened ancient database", "database", datadir, "readonly", readonly)
return freezer, nil
}
// Close terminates the chain freezer, unmapping all the data files.
func (f *Freezer) Close() error {
f.writeLock.Lock()
defer f.writeLock.Unlock()
var errs []error
f.closeOnce.Do(func() {
for _, table := range f.tables {
if err := table.Close(); err != nil {
errs = append(errs, err)
}
}
if err := f.instanceLock.Unlock(); 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
}
// AncientRange retrieves multiple items in sequence, starting from the index 'start'.
// It will return
// - at most 'max' items,
// - at least 1 item (even if exceeding the maxByteSize), but will otherwise
// return as many items as fit into maxByteSize.
func (f *Freezer) AncientRange(kind string, start, count, maxBytes uint64) ([][]byte, error) {
if table := f.tables[kind]; table != nil {
return table.RetrieveItems(start, count, maxBytes)
}
return nil, errUnknownTable
}
// Ancients returns the length of the frozen items.
func (f *Freezer) Ancients() (uint64, error) {
return atomic.LoadUint64(&f.frozen), nil
}
// Tail returns the number of first stored item in the freezer.
func (f *Freezer) Tail() (uint64, error) {
return atomic.LoadUint64(&f.tail), nil
}
// AncientSize returns the ancient size of the specified category.
func (f *Freezer) AncientSize(kind string) (uint64, error) {
// This needs the write lock to avoid data races on table fields.
// Speed doesn't matter here, AncientSize is for debugging.
f.writeLock.RLock()
defer f.writeLock.RUnlock()
if table := f.tables[kind]; table != nil {
return table.size()
}
return 0, errUnknownTable
}
// ReadAncients runs the given read operation while ensuring that no writes take place
// on the underlying freezer.
func (f *Freezer) ReadAncients(fn func(ethdb.AncientReaderOp) error) (err error) {
f.writeLock.RLock()
defer f.writeLock.RUnlock()
return fn(f)
}
// ModifyAncients runs the given write operation.
func (f *Freezer) ModifyAncients(fn func(ethdb.AncientWriteOp) error) (writeSize int64, err error) {
if f.readonly {
return 0, errReadOnly
}
f.writeLock.Lock()
defer f.writeLock.Unlock()
// Roll back all tables to the starting position in case of error.
prevItem := atomic.LoadUint64(&f.frozen)
defer func() {
if err != nil {
// The write operation has failed. Go back to the previous item position.
for name, table := range f.tables {
err := table.truncateHead(prevItem)
if err != nil {
log.Error("Freezer table roll-back failed", "table", name, "index", prevItem, "err", err)
}
}
}
}()
f.writeBatch.reset()
if err := fn(f.writeBatch); err != nil {
return 0, err
}
item, writeSize, err := f.writeBatch.commit()
if err != nil {
return 0, err
}
atomic.StoreUint64(&f.frozen, item)
return writeSize, nil
}
// TruncateHead discards any recent data above the provided threshold number.
func (f *Freezer) TruncateHead(items uint64) error {
if f.readonly {
return errReadOnly
}
f.writeLock.Lock()
defer f.writeLock.Unlock()
if atomic.LoadUint64(&f.frozen) <= items {
return nil
}
for _, table := range f.tables {
if err := table.truncateHead(items); err != nil {
return err
}
}
atomic.StoreUint64(&f.frozen, items)
return nil
}
// TruncateTail discards any recent data below the provided threshold number.
func (f *Freezer) TruncateTail(tail uint64) error {
if f.readonly {
return errReadOnly
}
f.writeLock.Lock()
defer f.writeLock.Unlock()
if atomic.LoadUint64(&f.tail) >= tail {
return nil
}
for _, table := range f.tables {
if err := table.truncateTail(tail); err != nil {
return err
}
}
atomic.StoreUint64(&f.tail, tail)
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
}
// validate checks that every table has the same boundary.
// Used instead of `repair` in readonly mode.
func (f *Freezer) validate() error {
if len(f.tables) == 0 {
return nil
}
var (
head uint64
tail uint64
name string
)
// Hack to get boundary of any table
for kind, table := range f.tables {
head = atomic.LoadUint64(&table.items)
tail = atomic.LoadUint64(&table.itemHidden)
name = kind
break
}
// Now check every table against those boundaries.
for kind, table := range f.tables {
if head != atomic.LoadUint64(&table.items) {
return fmt.Errorf("freezer tables %s and %s have differing head: %d != %d", kind, name, atomic.LoadUint64(&table.items), head)
}
if tail != atomic.LoadUint64(&table.itemHidden) {
return fmt.Errorf("freezer tables %s and %s have differing tail: %d != %d", kind, name, atomic.LoadUint64(&table.itemHidden), tail)
}
}
atomic.StoreUint64(&f.frozen, head)
atomic.StoreUint64(&f.tail, tail)
return nil
}
// repair truncates all data tables to the same length.
func (f *Freezer) repair() error {
var (
head = uint64(math.MaxUint64)
tail = uint64(0)
)
for _, table := range f.tables {
items := atomic.LoadUint64(&table.items)
if head > items {
head = items
}
hidden := atomic.LoadUint64(&table.itemHidden)
if hidden > tail {
tail = hidden
}
}
for _, table := range f.tables {
if err := table.truncateHead(head); err != nil {
return err
}
if err := table.truncateTail(tail); err != nil {
return err
}
}
atomic.StoreUint64(&f.frozen, head)
atomic.StoreUint64(&f.tail, tail)
return nil
}
// convertLegacyFn takes a raw freezer entry in an older format and
// returns it in the new format.
type convertLegacyFn = func([]byte) ([]byte, error)
// MigrateTable processes the entries in a given table in sequence
// converting them to a new format if they're of an old format.
func (f *Freezer) MigrateTable(kind string, convert convertLegacyFn) error {
if f.readonly {
return errReadOnly
}
f.writeLock.Lock()
defer f.writeLock.Unlock()
table, ok := f.tables[kind]
if !ok {
return errUnknownTable
}
// forEach iterates every entry in the table serially and in order, calling `fn`
// with the item as argument. If `fn` returns an error the iteration stops
// and that error will be returned.
forEach := func(t *freezerTable, offset uint64, fn func(uint64, []byte) error) error {
var (
items = atomic.LoadUint64(&t.items)
batchSize = uint64(1024)
maxBytes = uint64(1024 * 1024)
)
for i := offset; i < items; {
if i+batchSize > items {
batchSize = items - i
}
data, err := t.RetrieveItems(i, batchSize, maxBytes)
if err != nil {
return err
}
for j, item := range data {
if err := fn(i+uint64(j), item); err != nil {
return err
}
}
i += uint64(len(data))
}
return nil
}
// TODO(s1na): This is a sanity-check since as of now no process does tail-deletion. But the migration
// process assumes no deletion at tail and needs to be modified to account for that.
if table.itemOffset > 0 || table.itemHidden > 0 {
return fmt.Errorf("migration not supported for tail-deleted freezers")
}
ancientsPath := filepath.Dir(table.index.Name())
// Set up new dir for the migrated table, the content of which
// we'll at the end move over to the ancients dir.
migrationPath := filepath.Join(ancientsPath, "migration")
newTable, err := newFreezerTable(migrationPath, kind, table.noCompression, false)
if err != nil {
return err
}
var (
batch = newTable.newBatch()
out []byte
start = time.Now()
logged = time.Now()
offset = newTable.items
)
if offset > 0 {
log.Info("found previous migration attempt", "migrated", offset)
}
// Iterate through entries and transform them
if err := forEach(table, offset, func(i uint64, blob []byte) error {
if i%10000 == 0 && time.Since(logged) > 16*time.Second {
log.Info("Processing legacy elements", "count", i, "elapsed", common.PrettyDuration(time.Since(start)))
logged = time.Now()
}
out, err = convert(blob)
if err != nil {
return err
}
if err := batch.AppendRaw(i, out); err != nil {
return err
}
return nil
}); err != nil {
return err
}
if err := batch.commit(); err != nil {
return err
}
log.Info("Replacing old table files with migrated ones", "elapsed", common.PrettyDuration(time.Since(start)))
// Release and delete old table files. Note this won't
// delete the index file.
table.releaseFilesAfter(0, true)
if err := newTable.Close(); err != nil {
return err
}
files, err := os.ReadDir(migrationPath)
if err != nil {
return err
}
// Move migrated files to ancients dir.
for _, f := range files {
// This will replace the old index file as a side-effect.
if err := os.Rename(filepath.Join(migrationPath, f.Name()), filepath.Join(ancientsPath, f.Name())); err != nil {
return err
}
}
// Delete by now empty dir.
if err := os.Remove(migrationPath); err != nil {
return err
}
return nil
}