// connects to providers for the given keys
func (bs *Bitswap) providerConnector(parent context.Context) {
defer log.Info("bitswap client worker shutting down...")
for {
log.Event(parent, "Bitswap.ProviderConnector.Loop")
select {
case req := <-bs.findKeys:
keys := req.keys
if len(keys) == 0 {
log.Warning("Received batch request for zero blocks")
continue
}
log.Event(parent, "Bitswap.ProviderConnector.Work", eventlog.LoggableMap{"Keys": keys})
// NB: Optimization. Assumes that providers of key[0] are likely to
// be able to provide for all keys. This currently holds true in most
// every situation. Later, this assumption may not hold as true.
child, cancel := context.WithTimeout(req.ctx, providerRequestTimeout)
providers := bs.network.FindProvidersAsync(child, keys[0], maxProvidersPerRequest)
for p := range providers {
go bs.network.ConnectTo(req.ctx, p)
}
cancel()
case <-parent.Done():
return
}
}
}
func (cq *ChanQueue) process(ctx context.Context) {
// construct the channels here to be able to use them bidirectionally
enqChan := make(chan peer.ID)
deqChan := make(chan peer.ID)
cq.EnqChan = enqChan
cq.DeqChan = deqChan
go func() {
log.Debug("processing")
defer log.Debug("closed")
defer close(deqChan)
var next peer.ID
var item peer.ID
var more bool
for {
if cq.Queue.Len() == 0 {
// log.Debug("wait for enqueue")
select {
case next, more = <-enqChan:
if !more {
return
}
// log.Debug("got", next)
case <-ctx.Done():
return
}
} else {
next = cq.Queue.Dequeue()
// log.Debug("peek", next)
}
select {
case item, more = <-enqChan:
if !more {
if cq.Queue.Len() > 0 {
return // we're done done.
}
enqChan = nil // closed, so no use.
}
// log.Debug("got", item)
cq.Queue.Enqueue(item)
cq.Queue.Enqueue(next) // order may have changed.
next = ""
case deqChan <- next:
// log.Debug("dequeued", next)
next = ""
case <-ctx.Done():
return
}
}
}()
}
func (bs *Bitswap) rebroadcastWorker(parent context.Context) {
ctx, cancel := context.WithCancel(parent)
defer cancel()
broadcastSignal := time.NewTicker(rebroadcastDelay.Get())
defer broadcastSignal.Stop()
tick := time.NewTicker(10 * time.Second)
defer tick.Stop()
for {
log.Event(ctx, "Bitswap.Rebroadcast.idle")
select {
case <-tick.C:
n := bs.wm.wl.Len()
if n > 0 {
log.Debug(n, "keys in bitswap wantlist")
}
case <-broadcastSignal.C: // resend unfulfilled wantlist keys
log.Event(ctx, "Bitswap.Rebroadcast.active")
entries := bs.wm.wl.Entries()
if len(entries) > 0 {
bs.connectToProviders(ctx, entries)
}
case <-parent.Done():
return
}
}
}
// GetBlocks returns a channel where the caller may receive blocks that
// correspond to the provided |keys|. Returns an error if BitSwap is unable to
// begin this request within the deadline enforced by the context.
//
// NB: Your request remains open until the context expires. To conserve
// resources, provide a context with a reasonably short deadline (ie. not one
// that lasts throughout the lifetime of the server)
func (bs *Bitswap) GetBlocks(ctx context.Context, keys []key.Key) (<-chan *blocks.Block, error) {
select {
case <-bs.process.Closing():
return nil, errors.New("bitswap is closed")
default:
}
promise := bs.notifications.Subscribe(ctx, keys...)
for _, k := range keys {
log.Event(ctx, "Bitswap.GetBlockRequest.Start", &k)
}
bs.wm.WantBlocks(keys)
req := &blockRequest{
keys: keys,
ctx: ctx,
}
select {
case bs.findKeys <- req:
return promise, nil
case <-ctx.Done():
return nil, ctx.Err()
}
}
// GetBlocks gets a list of blocks asynchronously and returns through
// the returned channel.
// NB: No guarantees are made about order.
func (s *BlockService) GetBlocks(ctx context.Context, ks []key.Key) <-chan *blocks.Block {
out := make(chan *blocks.Block, 0)
go func() {
defer close(out)
var misses []key.Key
for _, k := range ks {
hit, err := s.Blockstore.Get(k)
if err != nil {
misses = append(misses, k)
continue
}
log.Debug("Blockservice: Got data in datastore.")
select {
case out <- hit:
case <-ctx.Done():
return
}
}
rblocks, err := s.Exchange.GetBlocks(ctx, misses)
if err != nil {
log.Debugf("Error with GetBlocks: %s", err)
return
}
for b := range rblocks {
select {
case out <- b:
case <-ctx.Done():
return
}
}
}()
return out
}
// Subscribe returns a channel of blocks for the given |keys|. |blockChannel|
// is closed if the |ctx| times out or is cancelled, or after sending len(keys)
// blocks.
func (ps *impl) Subscribe(ctx context.Context, keys ...key.Key) <-chan *blocks.Block {
blocksCh := make(chan *blocks.Block, len(keys))
valuesCh := make(chan interface{}, len(keys)) // provide our own channel to control buffer, prevent blocking
if len(keys) == 0 {
close(blocksCh)
return blocksCh
}
ps.wrapped.AddSubOnceEach(valuesCh, toStrings(keys)...)
go func() {
defer close(blocksCh)
defer ps.wrapped.Unsub(valuesCh) // with a len(keys) buffer, this is an optimization
for {
select {
case <-ctx.Done():
return
case val, ok := <-valuesCh:
if !ok {
return
}
block, ok := val.(*blocks.Block)
if !ok {
return
}
select {
case <-ctx.Done():
return
case blocksCh <- block: // continue
}
}
}
}()
return blocksCh
}
func (e *offlineExchange) GetBlocks(ctx context.Context, ks []key.Key) (<-chan *blocks.Block, error) {
out := make(chan *blocks.Block, 0)
go func() {
defer close(out)
var misses []key.Key
for _, k := range ks {
hit, err := e.bs.Get(k)
if err != nil {
misses = append(misses, k)
// a long line of misses should abort when context is cancelled.
select {
// TODO case send misses down channel
case <-ctx.Done():
return
default:
continue
}
}
select {
case out <- hit:
case <-ctx.Done():
return
}
}
}()
return out, nil
}
func (bs *Bitswap) provideCollector(ctx context.Context) {
defer close(bs.provideKeys)
var toProvide []key.Key
var nextKey key.Key
var keysOut chan key.Key
for {
select {
case blk, ok := <-bs.newBlocks:
if !ok {
log.Debug("newBlocks channel closed")
return
}
if keysOut == nil {
nextKey = blk.Key()
keysOut = bs.provideKeys
} else {
toProvide = append(toProvide, blk.Key())
}
case keysOut <- nextKey:
if len(toProvide) > 0 {
nextKey = toProvide[0]
toProvide = toProvide[1:]
} else {
keysOut = nil
}
case <-ctx.Done():
return
}
}
}
// LogError logs the error to the owner of the context.
//
// If this context was created with ContextWithErrorLog, then this method
// passes the error to context creator over an unbuffered channel.
//
// If this context was created by other means, this method is a no-op.
func LogError(ctx context.Context, err error) {
v := ctx.Value(errLogKey)
errs, ok := v.(privateChanType)
if !ok {
return
}
errs <- err
}
// gatedDialAttempt is an attempt to dial a node. It is gated by the swarm's
// dial synchronization systems: dialsync and dialbackoff.
func (s *Swarm) gatedDialAttempt(ctx context.Context, p peer.ID) (*Conn, error) {
var logdial = lgbl.Dial("swarm", s.LocalPeer(), p, nil, nil)
defer log.EventBegin(ctx, "swarmDialAttemptSync", logdial).Done()
// check if we already have an open connection first
conn := s.bestConnectionToPeer(p)
if conn != nil {
return conn, nil
}
// check if there's an ongoing dial to this peer
if ok, wait := s.dsync.Lock(p); ok {
// ok, we have been charged to dial! let's do it.
// if it succeeds, dial will add the conn to the swarm itself.
defer log.EventBegin(ctx, "swarmDialAttemptStart", logdial).Done()
ctxT, cancel := context.WithTimeout(ctx, s.dialT)
conn, err := s.dial(ctxT, p)
cancel()
s.dsync.Unlock(p)
log.Debugf("dial end %s", conn)
if err != nil {
log.Event(ctx, "swarmDialBackoffAdd", logdial)
s.backf.AddBackoff(p) // let others know to backoff
// ok, we failed. try again. (if loop is done, our error is output)
return nil, fmt.Errorf("dial attempt failed: %s", err)
}
log.Event(ctx, "swarmDialBackoffClear", logdial)
s.backf.Clear(p) // okay, no longer need to backoff
return conn, nil
} else {
// we did not dial. we must wait for someone else to dial.
// check whether we should backoff first...
if s.backf.Backoff(p) {
log.Event(ctx, "swarmDialBackoff", logdial)
return nil, ErrDialBackoff
}
defer log.EventBegin(ctx, "swarmDialWait", logdial).Done()
select {
case <-wait: // wait for that other dial to finish.
// see if it worked, OR we got an incoming dial in the meantime...
conn := s.bestConnectionToPeer(p)
if conn != nil {
return conn, nil
}
return nil, ErrDialFailed
case <-ctx.Done(): // or we may have to bail...
return nil, ctx.Err()
}
}
}
func MetadataFromContext(ctx context.Context) (Metadata, error) {
value := ctx.Value(metadataKey)
if value != nil {
metadata, ok := value.(Metadata)
if ok {
return metadata, nil
}
}
return nil, errors.New("context contains no metadata")
}
func (pm *ProviderManager) AddProvider(ctx context.Context, k key.Key, val peer.ID) {
prov := &addProv{
k: k,
val: val,
}
select {
case pm.newprovs <- prov:
case <-ctx.Done():
}
}
// WithContextAndTeardown is a helper function to set teardown at initiation
// of WithContext
func WithContextAndTeardown(ctx context.Context, tf goprocess.TeardownFunc) goprocess.Process {
if ctx == nil {
panic("nil Context")
}
p := goprocess.WithTeardown(tf)
go func() {
<-ctx.Done()
p.Close()
}()
return p
}
func (mq *msgQueue) runQueue(ctx context.Context) {
for {
select {
case <-mq.work: // there is work to be done
mq.doWork(ctx)
case <-mq.done:
return
case <-ctx.Done():
return
}
}
}
// CloseAfterContext schedules the process to close after the given
// context is done. It is the equivalent of:
//
// func CloseAfterContext(p goprocess.Process, ctx context.Context) {
// go func() {
// <-ctx.Done()
// p.Close()
// }()
// }
//
func CloseAfterContext(p goprocess.Process, ctx context.Context) {
if p == nil {
panic("nil Process")
}
if ctx == nil {
panic("nil Context")
}
go func() {
<-ctx.Done()
p.Close()
}()
}
// WithDeadlineFraction returns a Context with a fraction of the
// original context's timeout. This is useful in sequential pipelines
// of work, where one might try options and fall back to others
// depending on the time available, or failure to respond. For example:
//
// // getPicture returns a picture from our encrypted database
// // we have a pipeline of multiple steps. we need to:
// // - get the data from a database
// // - decrypt it
// // - apply many transforms
// //
// // we **know** that each step takes increasingly more time.
// // The transforms are much more expensive than decryption, and
// // decryption is more expensive than the database lookup.
// // If our database takes too long (i.e. >0.2 of available time),
// // there's no use in continuing.
// func getPicture(ctx context.Context, key string) ([]byte, error) {
// // fractional timeout contexts to the rescue!
//
// // try the database with 0.2 of remaining time.
// ctx1, _ := ctxext.WithDeadlineFraction(ctx, 0.2)
// val, err := db.Get(ctx1, key)
// if err != nil {
// return nil, err
// }
//
// // try decryption with 0.3 of remaining time.
// ctx2, _ := ctxext.WithDeadlineFraction(ctx, 0.3)
// if val, err = decryptor.Decrypt(ctx2, val); err != nil {
// return nil, err
// }
//
// // try transforms with all remaining time. hopefully it's enough!
// return transformer.Transform(ctx, val)
// }
//
//
func WithDeadlineFraction(ctx context.Context, fraction float64) (
context.Context, context.CancelFunc) {
d, found := ctx.Deadline()
if !found { // no deadline
return context.WithCancel(ctx)
}
left := d.Sub(time.Now())
if left < 0 { // already passed...
return context.WithCancel(ctx)
}
left = time.Duration(float64(left) * fraction)
return context.WithTimeout(ctx, left)
}
func PublishQueryEvent(ctx context.Context, ev *QueryEvent) {
ich := ctx.Value(RoutingQueryKey)
if ich == nil {
return
}
ch, ok := ich.(chan<- *QueryEvent)
if !ok {
return
}
select {
case ch <- ev:
case <-ctx.Done():
}
}
func (pm *ProviderManager) GetProviders(ctx context.Context, k key.Key) []peer.ID {
gp := &getProv{
k: k,
resp: make(chan []peer.ID, 1), // buffered to prevent sender from blocking
}
select {
case <-ctx.Done():
return nil
case pm.getprovs <- gp:
}
select {
case <-ctx.Done():
return nil
case peers := <-gp.resp:
return peers
}
}
func (c *client) FindProvidersAsync(ctx context.Context, k key.Key, max int) <-chan peer.PeerInfo {
out := make(chan peer.PeerInfo)
go func() {
defer close(out)
for i, p := range c.server.Providers(k) {
if max <= i {
return
}
select {
case out <- p:
case <-ctx.Done():
return
}
}
}()
return out
}
// Bootstrap ensures the dht routing table remains healthy as peers come and go.
// it builds up a list of peers by requesting random peer IDs. The Bootstrap
// process will run a number of queries each time, and run every time signal fires.
// These parameters are configurable.
//
// As opposed to BootstrapWithConfig, Bootstrap satisfies the routing interface
func (dht *IpfsDHT) Bootstrap(ctx context.Context) error {
proc, err := dht.BootstrapWithConfig(DefaultBootstrapConfig)
if err != nil {
return err
}
// wait till ctx or dht.Context exits.
// we have to do it this way to satisfy the Routing interface (contexts)
go func() {
defer proc.Close()
select {
case <-ctx.Done():
case <-dht.Context().Done():
}
}()
return nil
}
func (rp *Reprovider) ProvideEvery(ctx context.Context, tick time.Duration) {
// dont reprovide immediately.
// may have just started the daemon and shutting it down immediately.
// probability( up another minute | uptime ) increases with uptime.
after := time.After(time.Minute)
for {
select {
case <-ctx.Done():
return
case <-after:
err := rp.Reprovide(ctx)
if err != nil {
log.Debug(err)
}
after = time.After(tick)
}
}
}
func (e *Engine) taskWorker(ctx context.Context) {
defer close(e.outbox) // because taskWorker uses the channel exclusively
for {
oneTimeUse := make(chan *Envelope, 1) // buffer to prevent blocking
select {
case <-ctx.Done():
return
case e.outbox <- oneTimeUse:
}
// receiver is ready for an outoing envelope. let's prepare one. first,
// we must acquire a task from the PQ...
envelope, err := e.nextEnvelope(ctx)
if err != nil {
close(oneTimeUse)
return // ctx cancelled
}
oneTimeUse <- envelope // buffered. won't block
close(oneTimeUse)
}
}
func readMsgCtx(ctx context.Context, r msgio.Reader, p proto.Message) ([]byte, error) {
var msg []byte
// read in a goroutine so we can exit when our context is cancelled.
done := make(chan error)
go func() {
var err error
msg, err = r.ReadMsg()
select {
case done <- err:
case <-ctx.Done():
}
}()
select {
case <-ctx.Done():
return nil, ctx.Err()
case e := <-done:
if e != nil {
return nil, e
}
}
return msg, proto.Unmarshal(msg, p)
}
func (bs *Bitswap) provideWorker(ctx context.Context, id int) {
idmap := eventlog.LoggableMap{"ID": id}
for {
log.Event(ctx, "Bitswap.ProvideWorker.Loop", idmap)
select {
case k, ok := <-bs.provideKeys:
log.Event(ctx, "Bitswap.ProvideWorker.Work", idmap, &k)
if !ok {
log.Debug("provideKeys channel closed")
return
}
ctx, cancel := context.WithTimeout(ctx, provideTimeout)
err := bs.network.Provide(ctx, k)
if err != nil {
log.Error(err)
}
cancel()
case <-ctx.Done():
return
}
}
}
// GetBlock attempts to retrieve a particular block from peers within the
// deadline enforced by the context.
func (bs *Bitswap) GetBlock(parent context.Context, k key.Key) (*blocks.Block, error) {
// Any async work initiated by this function must end when this function
// returns. To ensure this, derive a new context. Note that it is okay to
// listen on parent in this scope, but NOT okay to pass |parent| to
// functions called by this one. Otherwise those functions won't return
// when this context's cancel func is executed. This is difficult to
// enforce. May this comment keep you safe.
ctx, cancelFunc := context.WithCancel(parent)
ctx = eventlog.ContextWithLoggable(ctx, eventlog.Uuid("GetBlockRequest"))
log.Event(ctx, "Bitswap.GetBlockRequest.Start", &k)
defer log.Event(ctx, "Bitswap.GetBlockRequest.End", &k)
defer func() {
cancelFunc()
}()
promise, err := bs.GetBlocks(ctx, []key.Key{k})
if err != nil {
return nil, err
}
select {
case block, ok := <-promise:
if !ok {
select {
case <-ctx.Done():
return nil, ctx.Err()
default:
return nil, errors.New("promise channel was closed")
}
}
return block, nil
case <-parent.Done():
return nil, parent.Err()
}
}
func (bs *Bitswap) taskWorker(ctx context.Context, id int) {
idmap := eventlog.LoggableMap{"ID": id}
defer log.Info("bitswap task worker shutting down...")
for {
log.Event(ctx, "Bitswap.TaskWorker.Loop", idmap)
select {
case nextEnvelope := <-bs.engine.Outbox():
select {
case envelope, ok := <-nextEnvelope:
if !ok {
continue
}
log.Event(ctx, "Bitswap.TaskWorker.Work", eventlog.LoggableMap{"ID": id, "Target": envelope.Peer.Pretty(), "Block": envelope.Block.Multihash.B58String()})
bs.wm.SendBlock(ctx, envelope)
case <-ctx.Done():
return
}
case <-ctx.Done():
return
}
}
}
func (c *Client) FindProvidersAsync(ctx context.Context, k key.Key, max int) <-chan peer.PeerInfo {
ctx = eventlog.ContextWithLoggable(ctx, eventlog.Uuid("findProviders"))
defer log.EventBegin(ctx, "findProviders", &k).Done()
ch := make(chan peer.PeerInfo)
go func() {
defer close(ch)
request := pb.NewMessage(pb.Message_GET_PROVIDERS, string(k), 0)
response, err := c.proxy.SendRequest(ctx, request)
if err != nil {
log.Debug(err)
return
}
for _, p := range pb.PBPeersToPeerInfos(response.GetProviderPeers()) {
select {
case <-ctx.Done():
log.Debug(ctx.Err())
return
case ch <- p:
}
}
}()
return ch
}
// HasBlock announces the existance of a block to this bitswap service. The
// service will potentially notify its peers.
func (bs *Bitswap) HasBlock(ctx context.Context, blk *blocks.Block) error {
select {
case <-bs.process.Closing():
return errors.New("bitswap is closed")
default:
}
err := bs.tryPutBlock(blk, 4) // attempt to store block up to four times
if err != nil {
log.Errorf("Error writing block to datastore: %s", err)
return err
}
bs.notifications.Publish(blk)
select {
case bs.newBlocks <- blk:
// send block off to be reprovided
case <-ctx.Done():
return ctx.Err()
}
return nil
}
func echoListen(ctx context.Context, listener Listener) {
for {
c, err := listener.Accept()
if err != nil {
select {
case <-ctx.Done():
return
default:
}
if ne, ok := err.(net.Error); ok && ne.Temporary() {
<-time.After(time.Microsecond * 10)
continue
}
log.Debugf("echoListen: listener appears to be closing")
return
}
go echo(c.(Conn))
}
}
// nextEnvelope runs in the taskWorker goroutine. Returns an error if the
// context is cancelled before the next Envelope can be created.
func (e *Engine) nextEnvelope(ctx context.Context) (*Envelope, error) {
for {
nextTask := e.peerRequestQueue.Pop()
for nextTask == nil {
select {
case <-ctx.Done():
return nil, ctx.Err()
case <-e.workSignal:
nextTask = e.peerRequestQueue.Pop()
}
}
// with a task in hand, we're ready to prepare the envelope...
block, err := e.bs.Get(nextTask.Entry.Key)
if err != nil {
// If we don't have the block, don't hold that against the peer
// make sure to update that the task has been 'completed'
nextTask.Done()
continue
}
return &Envelope{
Peer: nextTask.Target,
Block: block,
Sent: func() {
nextTask.Done()
select {
case e.workSignal <- struct{}{}:
// work completing may mean that our queue will provide new
// work to be done.
default:
}
},
}, nil
}
}
