235 lines
7.3 KiB
Go
235 lines
7.3 KiB
Go
// Copyright 2019 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package localstore
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import (
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"context"
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"errors"
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"sync"
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"time"
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"github.com/ethereum/go-ethereum/log"
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"github.com/ethereum/go-ethereum/metrics"
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"github.com/ethereum/go-ethereum/swarm/chunk"
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"github.com/ethereum/go-ethereum/swarm/shed"
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"github.com/ethereum/go-ethereum/swarm/spancontext"
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"github.com/opentracing/opentracing-go"
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olog "github.com/opentracing/opentracing-go/log"
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"github.com/syndtr/goleveldb/leveldb"
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)
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// SubscribePull returns a channel that provides chunk addresses and stored times from pull syncing index.
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// Pull syncing index can be only subscribed to a particular proximity order bin. If since
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// is not 0, the iteration will start from the first item stored after that id. If until is not 0,
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// only chunks stored up to this id will be sent to the channel, and the returned channel will be
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// closed. The since-until interval is closed on the both sides [since,until]. Returned stop
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// function will terminate current and further iterations without errors, and also close the returned channel.
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// Make sure that you check the second returned parameter from the channel to stop iteration when its value
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// is false.
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func (db *DB) SubscribePull(ctx context.Context, bin uint8, since, until uint64) (c <-chan chunk.Descriptor, stop func()) {
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metricName := "localstore.SubscribePull"
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metrics.GetOrRegisterCounter(metricName, nil).Inc(1)
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chunkDescriptors := make(chan chunk.Descriptor)
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trigger := make(chan struct{}, 1)
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db.pullTriggersMu.Lock()
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if _, ok := db.pullTriggers[bin]; !ok {
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db.pullTriggers[bin] = make([]chan struct{}, 0)
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}
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db.pullTriggers[bin] = append(db.pullTriggers[bin], trigger)
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db.pullTriggersMu.Unlock()
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// send signal for the initial iteration
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trigger <- struct{}{}
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stopChan := make(chan struct{})
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var stopChanOnce sync.Once
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// used to provide information from the iterator to
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// stop subscription when until chunk descriptor is reached
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var errStopSubscription = errors.New("stop subscription")
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go func() {
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defer metrics.GetOrRegisterCounter(metricName+".stop", nil).Inc(1)
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// close the returned chunk.Descriptor channel at the end to
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// signal that the subscription is done
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defer close(chunkDescriptors)
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// sinceItem is the Item from which the next iteration
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// should start. The first iteration starts from the first Item.
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var sinceItem *shed.Item
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if since > 0 {
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sinceItem = &shed.Item{
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Address: db.addressInBin(bin),
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BinID: since,
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}
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}
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first := true // first iteration flag for SkipStartFromItem
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for {
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select {
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case <-trigger:
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// iterate until:
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// - last index Item is reached
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// - subscription stop is called
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// - context is done
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metrics.GetOrRegisterCounter(metricName+".iter", nil).Inc(1)
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ctx, sp := spancontext.StartSpan(ctx, metricName+".iter")
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sp.LogFields(olog.Int("bin", int(bin)), olog.Uint64("since", since), olog.Uint64("until", until))
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iterStart := time.Now()
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var count int
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err := db.pullIndex.Iterate(func(item shed.Item) (stop bool, err error) {
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select {
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case chunkDescriptors <- chunk.Descriptor{
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Address: item.Address,
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BinID: item.BinID,
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}:
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count++
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// until chunk descriptor is sent
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// break the iteration
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if until > 0 && item.BinID >= until {
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return true, errStopSubscription
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}
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// set next iteration start item
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// when its chunk is successfully sent to channel
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sinceItem = &item
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return false, nil
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case <-stopChan:
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// gracefully stop the iteration
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// on stop
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return true, nil
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case <-db.close:
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// gracefully stop the iteration
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// on database close
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return true, nil
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case <-ctx.Done():
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return true, ctx.Err()
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}
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}, &shed.IterateOptions{
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StartFrom: sinceItem,
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// sinceItem was sent as the last Address in the previous
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// iterator call, skip it in this one, but not the item with
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// the provided since bin id as it should be sent to a channel
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SkipStartFromItem: !first,
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Prefix: []byte{bin},
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})
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totalTimeMetric(metricName+".iter", iterStart)
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sp.FinishWithOptions(opentracing.FinishOptions{
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LogRecords: []opentracing.LogRecord{
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{
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Timestamp: time.Now(),
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Fields: []olog.Field{olog.Int("count", count)},
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},
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},
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})
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if err != nil {
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if err == errStopSubscription {
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// stop subscription without any errors
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// if until is reached
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return
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}
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metrics.GetOrRegisterCounter(metricName+".iter.error", nil).Inc(1)
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log.Error("localstore pull subscription iteration", "bin", bin, "since", since, "until", until, "err", err)
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return
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}
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first = false
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case <-stopChan:
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// terminate the subscription
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// on stop
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return
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case <-db.close:
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// terminate the subscription
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// on database close
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return
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case <-ctx.Done():
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err := ctx.Err()
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if err != nil {
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log.Error("localstore pull subscription", "bin", bin, "since", since, "until", until, "err", err)
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}
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return
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}
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}
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}()
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stop = func() {
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stopChanOnce.Do(func() {
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close(stopChan)
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})
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db.pullTriggersMu.Lock()
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defer db.pullTriggersMu.Unlock()
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for i, t := range db.pullTriggers[bin] {
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if t == trigger {
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db.pullTriggers[bin] = append(db.pullTriggers[bin][:i], db.pullTriggers[bin][i+1:]...)
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break
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}
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}
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}
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return chunkDescriptors, stop
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}
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// LastPullSubscriptionBinID returns chunk bin id of the latest Chunk
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// in pull syncing index for a provided bin. If there are no chunks in
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// that bin, 0 value is returned.
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func (db *DB) LastPullSubscriptionBinID(bin uint8) (id uint64, err error) {
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metrics.GetOrRegisterCounter("localstore.LastPullSubscriptionBinID", nil).Inc(1)
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item, err := db.pullIndex.Last([]byte{bin})
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if err != nil {
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if err == leveldb.ErrNotFound {
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return 0, nil
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}
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return 0, err
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}
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return item.BinID, nil
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}
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// triggerPullSubscriptions is used internally for starting iterations
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// on Pull subscriptions for a particular bin. When new item with address
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// that is in particular bin for DB's baseKey is added to pull index
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// this function should be called.
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func (db *DB) triggerPullSubscriptions(bin uint8) {
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db.pullTriggersMu.RLock()
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triggers, ok := db.pullTriggers[bin]
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db.pullTriggersMu.RUnlock()
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if !ok {
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return
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}
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for _, t := range triggers {
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select {
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case t <- struct{}{}:
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default:
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}
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}
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}
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// addressInBin returns an address that is in a specific
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// proximity order bin from database base key.
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func (db *DB) addressInBin(bin uint8) (addr chunk.Address) {
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addr = append([]byte(nil), db.baseKey...)
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b := bin / 8
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addr[b] = addr[b] ^ (1 << (7 - bin%8))
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return addr
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}
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