123 lines
2.7 KiB
Go
123 lines
2.7 KiB
Go
package swarm
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import (
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"context"
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"sync"
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"github.com/libp2p/go-libp2p-core/network"
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"github.com/libp2p/go-libp2p-core/peer"
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)
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// DialWorerFunc is used by DialSync to spawn a new dial worker
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type dialWorkerFunc func(context.Context, peer.ID, <-chan dialRequest) error
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// newDialSync constructs a new DialSync
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func newDialSync(worker dialWorkerFunc) *DialSync {
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return &DialSync{
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dials: make(map[peer.ID]*activeDial),
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dialWorker: worker,
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}
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}
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// DialSync is a dial synchronization helper that ensures that at most one dial
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// to any given peer is active at any given time.
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type DialSync struct {
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dials map[peer.ID]*activeDial
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dialsLk sync.Mutex
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dialWorker dialWorkerFunc
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}
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type activeDial struct {
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id peer.ID
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refCnt int
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ctx context.Context
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cancel func()
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reqch chan dialRequest
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ds *DialSync
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}
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func (ad *activeDial) decref() {
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ad.ds.dialsLk.Lock()
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ad.refCnt--
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if ad.refCnt == 0 {
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ad.cancel()
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close(ad.reqch)
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delete(ad.ds.dials, ad.id)
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}
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ad.ds.dialsLk.Unlock()
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}
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func (ad *activeDial) dial(ctx context.Context, p peer.ID) (*Conn, error) {
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dialCtx := ad.ctx
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if forceDirect, reason := network.GetForceDirectDial(ctx); forceDirect {
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dialCtx = network.WithForceDirectDial(dialCtx, reason)
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}
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if simConnect, reason := network.GetSimultaneousConnect(ctx); simConnect {
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dialCtx = network.WithSimultaneousConnect(dialCtx, reason)
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}
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resch := make(chan dialResponse, 1)
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select {
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case ad.reqch <- dialRequest{ctx: dialCtx, resch: resch}:
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case <-ctx.Done():
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return nil, ctx.Err()
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}
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select {
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case res := <-resch:
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return res.conn, res.err
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case <-ctx.Done():
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return nil, ctx.Err()
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}
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}
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func (ds *DialSync) getActiveDial(p peer.ID) (*activeDial, error) {
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ds.dialsLk.Lock()
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defer ds.dialsLk.Unlock()
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actd, ok := ds.dials[p]
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if !ok {
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// This code intentionally uses the background context. Otherwise, if the first call
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// to Dial is canceled, subsequent dial calls will also be canceled.
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// XXX: this also breaks direct connection logic. We will need to pipe the
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// information through some other way.
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adctx, cancel := context.WithCancel(context.Background())
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actd = &activeDial{
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id: p,
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ctx: adctx,
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cancel: cancel,
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reqch: make(chan dialRequest),
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ds: ds,
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}
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err := ds.dialWorker(adctx, p, actd.reqch)
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if err != nil {
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cancel()
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return nil, err
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}
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ds.dials[p] = actd
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}
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// increase ref count before dropping dialsLk
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actd.refCnt++
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return actd, nil
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}
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// DialLock initiates a dial to the given peer if there are none in progress
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// then waits for the dial to that peer to complete.
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func (ds *DialSync) DialLock(ctx context.Context, p peer.ID) (*Conn, error) {
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ad, err := ds.getActiveDial(p)
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if err != nil {
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return nil, err
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}
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defer ad.decref()
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return ad.dial(ctx, p)
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}
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