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session.go
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session.go
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package peerleecher
import (
"errors"
"sync"
"time"
"github.com/Ecosystem-Knowledge/lachesis-base/hash"
"github.com/Ecosystem-Knowledge/lachesis-base/inter/dag"
)
var (
errTerminated = errors.New("terminated")
)
// OnlyNotConnectedFn returns only not connected events.
type OnlyNotConnectedFn func(ids hash.Events) hash.Events
type receivedChunk struct {
last hash.Event
}
type EpochDownloaderCallbacks struct {
OnlyNotConnected OnlyNotConnectedFn
RequestChunks func(n dag.Metric, maxChunks uint32) error
Suspend func() bool
Done func() bool
}
// PeerLeecher is responsible for accumulating pack announcements from various peers
// and scheduling them for retrieval.
type PeerLeecher struct {
cfg EpochDownloaderConfig
totalRequested int
totalProcessed int
processingChunks []receivedChunk
// Various event channels
notifyReceivedChunk chan *receivedChunk
quitMu sync.Mutex
quit chan struct{}
done bool
wg *sync.WaitGroup
// Callbacks
callback EpochDownloaderCallbacks
}
// New creates a packs fetcher to retrieve events based on pack announcements. Works only with 1 peer.
func New(wg *sync.WaitGroup, cfg EpochDownloaderConfig, callback EpochDownloaderCallbacks) *PeerLeecher {
quit := make(chan struct{})
return &PeerLeecher{
processingChunks: make([]receivedChunk, 0, cfg.ParallelChunksDownload*2),
notifyReceivedChunk: make(chan *receivedChunk, cfg.ParallelChunksDownload*2),
quit: quit,
cfg: cfg,
callback: callback,
wg: wg,
}
}
// Start boots up the announcement based synchroniser, accepting and processing
// hash notifications and event fetches until termination requested.
func (d *PeerLeecher) Start() {
d.wg.Add(1)
go func() {
defer d.wg.Done()
d.loop()
}()
}
// Stop terminates the announcement based synchroniser, canceling all pending
// operations.
func (d *PeerLeecher) Stop() {
d.Terminate()
d.wg.Wait()
}
func (d *PeerLeecher) Terminate() {
d.quitMu.Lock()
defer d.quitMu.Unlock()
if !d.done {
close(d.quit)
d.done = true
}
}
func (d *PeerLeecher) Stopped() bool {
return d.done
}
// NotifyPackInfo injects new pack infos from a peer
func (d *PeerLeecher) NotifyChunkReceived(last hash.Event) error {
op := &receivedChunk{
last: last,
}
select {
case d.notifyReceivedChunk <- op:
return nil
case <-d.quit:
return errTerminated
}
}
// Loop is the main leecher's loop, checking and processing various notifications
func (d *PeerLeecher) loop() {
// Iterate the event fetching until a quit is requested
syncTicker := time.NewTicker(d.cfg.RecheckInterval)
defer syncTicker.Stop()
for {
// Wait for an outside event to occur
select {
case <-d.quit:
// terminating, abort all operations
return
case op := <-d.notifyReceivedChunk:
if d.done {
d.Terminate()
continue
}
if len(d.processingChunks) < d.cfg.ParallelChunksDownload*2 {
d.processingChunks = append(d.processingChunks, *op)
d.routine()
}
case <-syncTicker.C:
d.routine()
}
}
}
func (d *PeerLeecher) routine() {
if d.callback.Done() {
d.Terminate()
return
}
d.processingChunks = d.sweepProcessedChunks()
d.tryToSync()
}
func (d *PeerLeecher) sweepProcessedChunks() []receivedChunk {
notProcessed := make([]receivedChunk, 0, len(d.processingChunks))
for _, op := range d.processingChunks {
if len(d.callback.OnlyNotConnected(hash.Events{op.last})) != 0 {
notProcessed = append(notProcessed, op)
} else {
d.totalProcessed++
}
}
return notProcessed
}
func (d *PeerLeecher) tryToSync() {
if d.callback.Suspend() {
return
}
if d.totalRequested < d.totalProcessed+d.cfg.ParallelChunksDownload {
requestsToSend := (d.totalProcessed + d.cfg.ParallelChunksDownload) - d.totalRequested
d.totalRequested += requestsToSend
_ = d.callback.RequestChunks(d.cfg.DefaultChunkSize, uint32(requestsToSend))
}
}