neo-go/pkg/network/blockqueue.go

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package network
import (
"sync"
"github.com/nspcc-dev/neo-go/pkg/core/block"
"go.uber.org/atomic"
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"go.uber.org/zap"
)
// Blockqueuer is the interface for block queue.
type Blockqueuer interface {
AddBlock(block *block.Block) error
AddHeaders(...*block.Header) error
BlockHeight() uint32
}
type blockQueue struct {
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log *zap.Logger
queueLock sync.RWMutex
queue []*block.Block
lastQ uint32
checkBlocks chan struct{}
chain Blockqueuer
relayF func(*block.Block)
discarded *atomic.Bool
len int
}
const (
// blockCacheSize is the amount of blocks above current height
// which are stored in queue.
blockCacheSize = 2000
)
func indexToPosition(i uint32) int {
return int(i) % blockCacheSize
}
func newBlockQueue(capacity int, bc Blockqueuer, log *zap.Logger, relayer func(*block.Block)) *blockQueue {
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if log == nil {
return nil
}
return &blockQueue{
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log: log,
queue: make([]*block.Block, blockCacheSize),
checkBlocks: make(chan struct{}, 1),
chain: bc,
relayF: relayer,
discarded: atomic.NewBool(false),
}
}
func (bq *blockQueue) run() {
var lastHeight = bq.chain.BlockHeight()
for {
_, ok := <-bq.checkBlocks
if !ok {
break
}
for {
h := bq.chain.BlockHeight()
pos := indexToPosition(h + 1)
bq.queueLock.Lock()
b := bq.queue[pos]
// The chain moved forward using blocks from other sources (consensus).
for i := lastHeight; i < h; i++ {
old := indexToPosition(i + 1)
if bq.queue[old] != nil && bq.queue[old].Index == i {
bq.len--
bq.queue[old] = nil
}
}
bq.queueLock.Unlock()
lastHeight = h
if b == nil {
break
}
err := bq.chain.AddBlock(b)
if err != nil {
// The block might already be added by consensus.
if bq.chain.BlockHeight() < b.Index {
bq.log.Warn("blockQueue: failed adding block into the blockchain",
zap.String("error", err.Error()),
zap.Uint32("blockHeight", bq.chain.BlockHeight()),
zap.Uint32("nextIndex", b.Index))
}
} else if bq.relayF != nil {
bq.relayF(b)
}
bq.queueLock.Lock()
bq.len--
l := bq.len
if bq.queue[pos] == b {
bq.queue[pos] = nil
}
bq.queueLock.Unlock()
updateBlockQueueLenMetric(l)
}
}
}
func (bq *blockQueue) putBlock(block *block.Block) error {
h := bq.chain.BlockHeight()
bq.queueLock.Lock()
defer bq.queueLock.Unlock()
if bq.discarded.Load() {
return nil
}
if block.Index <= h || h+blockCacheSize < block.Index {
// can easily happen when fetching the same blocks from
// different peers, thus not considered as error
return nil
}
pos := indexToPosition(block.Index)
// If we already have it, keep the old block, throw away new one.
if bq.queue[pos] == nil || bq.queue[pos].Index < block.Index {
bq.len++
bq.queue[pos] = block
for pos < blockCacheSize && bq.queue[pos] != nil && bq.lastQ+1 == bq.queue[pos].Index {
bq.lastQ = bq.queue[pos].Index
pos++
}
}
l := bq.len
// update metrics
updateBlockQueueLenMetric(l)
select {
case bq.checkBlocks <- struct{}{}:
// ok, signalled to goroutine processing queue
default:
// it's already busy processing blocks
}
return nil
}
func (bq *blockQueue) lastQueued() uint32 {
bq.queueLock.RLock()
defer bq.queueLock.RUnlock()
return bq.lastQ
}
func (bq *blockQueue) discard() {
if bq.discarded.CAS(false, true) {
bq.queueLock.Lock()
close(bq.checkBlocks)
// Technically we could bq.queue = nil, but this would cost
// another if in run().
for i := 0; i < len(bq.queue); i++ {
bq.queue[i] = nil
}
bq.len = 0
bq.queueLock.Unlock()
}
}