neoneo-go/pkg/core/headerhashes.go

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package core
import (
"fmt"
"sync"
lru "github.com/hashicorp/golang-lru"
"github.com/nspcc-dev/neo-go/pkg/core/block"
"github.com/nspcc-dev/neo-go/pkg/core/dao"
"github.com/nspcc-dev/neo-go/pkg/util"
)
const (
headerBatchCount = 2000
pagesCache = 8
)
// HeaderHashes is a header hash manager part of the Blockchain. It can't be used
// without Blockchain.
type HeaderHashes struct {
// Backing storage.
dao *dao.Simple
// Lock for all internal state fields.
lock sync.RWMutex
// The latest header hashes (storedHeaderCount+).
latest []util.Uint256
// Previously completed page of header hashes (pre-storedHeaderCount).
previous []util.Uint256
// Number of headers stored in the chain file.
storedHeaderCount uint32
// Cache for accessed pages of header hashes.
cache *lru.Cache
}
func (h *HeaderHashes) initGenesis(dao *dao.Simple, hash util.Uint256) {
h.dao = dao
h.cache, _ = lru.New(pagesCache) // Never errors for positive size.
h.previous = make([]util.Uint256, headerBatchCount)
h.latest = make([]util.Uint256, 0, headerBatchCount)
h.latest = append(h.latest, hash)
dao.PutCurrentHeader(hash, 0)
}
func (h *HeaderHashes) init(dao *dao.Simple) error {
h.dao = dao
h.cache, _ = lru.New(pagesCache) // Never errors for positive size.
currHeaderHeight, currHeaderHash, err := h.dao.GetCurrentHeaderHeight()
if err != nil {
return fmt.Errorf("failed to retrieve current header info: %w", err)
}
h.storedHeaderCount = ((currHeaderHeight + 1) / headerBatchCount) * headerBatchCount
if h.storedHeaderCount >= headerBatchCount {
h.previous, err = h.dao.GetHeaderHashes(h.storedHeaderCount - headerBatchCount)
if err != nil {
return fmt.Errorf("failed to retrieve header hash page %d: %w", h.storedHeaderCount-headerBatchCount, err)
}
} else {
h.previous = make([]util.Uint256, headerBatchCount)
}
h.latest = make([]util.Uint256, 0, headerBatchCount)
// There is a high chance that the Node is stopped before the next
// batch of 2000 headers was stored. Via the currentHeaders stored we can sync
// that with stored blocks.
if currHeaderHeight >= h.storedHeaderCount {
hash := currHeaderHash
var targetHash util.Uint256
if h.storedHeaderCount >= headerBatchCount {
targetHash = h.previous[len(h.previous)-1]
}
headers := make([]util.Uint256, 0, headerBatchCount)
for hash != targetHash {
blk, err := h.dao.GetBlock(hash)
if err != nil {
return fmt.Errorf("could not get header %s: %w", hash, err)
}
headers = append(headers, blk.Hash())
hash = blk.PrevHash
}
hashSliceReverse(headers)
h.latest = append(h.latest, headers...)
}
return nil
}
func (h *HeaderHashes) lastHeaderIndex() uint32 {
return h.storedHeaderCount + uint32(len(h.latest)) - 1
}
// HeaderHeight returns the index/height of the highest header.
func (h *HeaderHashes) HeaderHeight() uint32 {
h.lock.RLock()
n := h.lastHeaderIndex()
h.lock.RUnlock()
return n
}
func (h *HeaderHashes) addHeaders(headers ...*block.Header) error {
var (
batch = h.dao.GetPrivate()
lastHeader *block.Header
err error
)
h.lock.Lock()
defer h.lock.Unlock()
for _, head := range headers {
if head.Index != h.lastHeaderIndex()+1 {
continue
}
err = batch.StoreHeader(head)
if err != nil {
return err
}
lastHeader = head
h.latest = append(h.latest, head.Hash())
if len(h.latest) == headerBatchCount {
err = batch.StoreHeaderHashes(h.latest, h.storedHeaderCount)
if err != nil {
return err
}
copy(h.previous, h.latest)
h.latest = h.latest[:0]
h.storedHeaderCount += headerBatchCount
}
}
if lastHeader != nil {
batch.PutCurrentHeader(lastHeader.Hash(), lastHeader.Index)
updateHeaderHeightMetric(lastHeader.Index)
if _, err = batch.Persist(); err != nil {
return err
}
}
return nil
}
// CurrentHeaderHash returns the hash of the latest known header.
func (h *HeaderHashes) CurrentHeaderHash() util.Uint256 {
var hash util.Uint256
h.lock.RLock()
if len(h.latest) > 0 {
hash = h.latest[len(h.latest)-1]
} else {
hash = h.previous[len(h.previous)-1]
}
h.lock.RUnlock()
return hash
}
// GetHeaderHash returns hash of the header/block with specified index, if
// HeaderHashes doesn't have a hash for this height, zero Uint256 value is returned.
func (h *HeaderHashes) GetHeaderHash(i uint32) util.Uint256 {
h.lock.RLock()
res, ok := h.getLocalHeaderHash(i)
h.lock.RUnlock()
if ok {
return res
}
// If it's not in the latest/previous, then it's in the cache or DB, those
// need no additional locks.
page := (i / headerBatchCount) * headerBatchCount
cache, ok := h.cache.Get(page)
if ok {
hashes := cache.([]util.Uint256)
return hashes[i-page]
}
hashes, err := h.dao.GetHeaderHashes(page)
if err != nil {
return util.Uint256{}
}
_ = h.cache.Add(page, hashes)
return hashes[i-page]
}
// getLocalHeaderHash looks for the index in the latest and previous caches.
// Locking is left to the user.
func (h *HeaderHashes) getLocalHeaderHash(i uint32) (util.Uint256, bool) {
if i > h.lastHeaderIndex() {
return util.Uint256{}, false
}
if i >= h.storedHeaderCount {
return h.latest[i-h.storedHeaderCount], true
}
previousStored := h.storedHeaderCount - headerBatchCount
if i >= previousStored {
return h.previous[i-previousStored], true
}
return util.Uint256{}, false
}
func (h *HeaderHashes) haveRecentHash(hash util.Uint256, i uint32) bool {
h.lock.RLock()
defer h.lock.RUnlock()
for ; i > 0; i-- {
lh, ok := h.getLocalHeaderHash(i)
if ok && hash.Equals(lh) {
return true
}
}
return false
}