Official Go implementation of the Ethereum protocol
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go-ethereum/beacon/light/head_tracker.go

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4.4 KiB

// Copyright 2023 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 light
import (
"errors"
"sync"
"time"
"github.com/ethereum/go-ethereum/beacon/types"
"github.com/ethereum/go-ethereum/log"
)
// HeadTracker keeps track of the latest validated head and the "prefetch" head
// which is the (not necessarily validated) head announced by the majority of
// servers.
type HeadTracker struct {
lock sync.RWMutex
committeeChain *CommitteeChain
minSignerCount int
signedHead types.SignedHeader
hasSignedHead bool
finalityUpdate types.FinalityUpdate
hasFinalityUpdate bool
prefetchHead types.HeadInfo
changeCounter uint64
}
// NewHeadTracker creates a new HeadTracker.
func NewHeadTracker(committeeChain *CommitteeChain, minSignerCount int) *HeadTracker {
return &HeadTracker{
committeeChain: committeeChain,
minSignerCount: minSignerCount,
}
}
// ValidatedHead returns the latest validated head.
func (h *HeadTracker) ValidatedHead() (types.SignedHeader, bool) {
h.lock.RLock()
defer h.lock.RUnlock()
return h.signedHead, h.hasSignedHead
}
// ValidatedHead returns the latest validated head.
func (h *HeadTracker) ValidatedFinality() (types.FinalityUpdate, bool) {
h.lock.RLock()
defer h.lock.RUnlock()
return h.finalityUpdate, h.hasFinalityUpdate
}
// Validate validates the given signed head. If the head is successfully validated
// and it is better than the old validated head (higher slot or same slot and more
// signers) then ValidatedHead is updated. The boolean return flag signals if
// ValidatedHead has been changed.
func (h *HeadTracker) ValidateHead(head types.SignedHeader) (bool, error) {
h.lock.Lock()
defer h.lock.Unlock()
replace, err := h.validate(head, h.signedHead)
if replace {
h.signedHead, h.hasSignedHead = head, true
h.changeCounter++
}
return replace, err
}
func (h *HeadTracker) ValidateFinality(update types.FinalityUpdate) (bool, error) {
h.lock.Lock()
defer h.lock.Unlock()
replace, err := h.validate(update.SignedHeader(), h.finalityUpdate.SignedHeader())
if replace {
h.finalityUpdate, h.hasFinalityUpdate = update, true
h.changeCounter++
}
return replace, err
}
func (h *HeadTracker) validate(head, oldHead types.SignedHeader) (bool, error) {
signerCount := head.Signature.SignerCount()
if signerCount < h.minSignerCount {
return false, errors.New("low signer count")
}
if head.Header.Slot < oldHead.Header.Slot || (head.Header.Slot == oldHead.Header.Slot && signerCount <= oldHead.Signature.SignerCount()) {
return false, nil
}
sigOk, age, err := h.committeeChain.VerifySignedHeader(head)
if err != nil {
return false, err
}
if age < 0 {
log.Warn("Future signed head received", "age", age)
}
if age > time.Minute*2 {
log.Warn("Old signed head received", "age", age)
}
if !sigOk {
return false, errors.New("invalid header signature")
}
return true, nil
}
// PrefetchHead returns the latest known prefetch head's head info.
// This head can be used to start fetching related data hoping that it will be
// validated soon.
// Note that the prefetch head cannot be validated cryptographically so it should
// only be used as a performance optimization hint.
func (h *HeadTracker) PrefetchHead() types.HeadInfo {
h.lock.RLock()
defer h.lock.RUnlock()
return h.prefetchHead
}
// SetPrefetchHead sets the prefetch head info.
// Note that HeadTracker does not verify the prefetch head, just acts as a thread
// safe bulletin board.
func (h *HeadTracker) SetPrefetchHead(head types.HeadInfo) {
h.lock.Lock()
defer h.lock.Unlock()
if head == h.prefetchHead {
return
}
h.prefetchHead = head
h.changeCounter++
}
func (h *HeadTracker) ChangeCounter() uint64 {
h.lock.RLock()
defer h.lock.RUnlock()
return h.changeCounter
}