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130 lines
4.2 KiB
130 lines
4.2 KiB
package p2p
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import (
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"sync"
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"github.com/gogo/protobuf/proto"
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)
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// ChannelID is an arbitrary channel ID.
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type ChannelID uint16
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// Envelope specifies the message receiver and sender.
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type Envelope struct {
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From NodeID // Message sender, or empty for outbound messages.
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To NodeID // Message receiver, or empty for inbound messages.
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Broadcast bool // Send message to all connected peers, ignoring To.
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Message proto.Message // Payload.
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// For internal use in the Router.
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channelID ChannelID
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}
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// Strip strips internal information from the envelope. Primarily used for
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// testing, such that returned envelopes can be compared with literals.
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func (e Envelope) Strip() Envelope {
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e.channelID = 0
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return e
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}
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// Channel is a bidirectional channel for Protobuf message exchange with peers.
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// A Channel is safe for concurrent use by multiple goroutines.
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type Channel struct {
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closeOnce sync.Once
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// id defines the unique channel ID.
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id ChannelID
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// messageType specifies the type of messages exchanged via the channel, and
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// is used e.g. for automatic unmarshaling.
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messageType proto.Message
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// inCh is a channel for receiving inbound messages. Envelope.From is always
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// set.
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inCh chan Envelope
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// outCh is a channel for sending outbound messages. Envelope.To or Broadcast
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// must be set, otherwise the message is discarded.
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outCh chan Envelope
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// errCh is a channel for reporting peer errors to the router, typically used
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// when peers send an invalid or malignant message.
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errCh chan PeerError
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// doneCh is used to signal that a Channel is closed. A Channel is bi-directional
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// and should be closed by the reactor, where as the router is responsible
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// for explicitly closing the internal In channel.
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doneCh chan struct{}
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}
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// NewChannel returns a reference to a new p2p Channel. It is the reactor's
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// responsibility to close the Channel. After a channel is closed, the router may
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// safely and explicitly close the internal In channel.
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func NewChannel(id ChannelID, mType proto.Message, in, out chan Envelope, errCh chan PeerError) *Channel {
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return &Channel{
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id: id,
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messageType: mType,
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inCh: in,
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outCh: out,
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errCh: errCh,
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doneCh: make(chan struct{}),
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}
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}
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// ID returns the Channel's ID.
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func (c *Channel) ID() ChannelID {
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return c.id
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}
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// In returns a read-only inbound go channel. This go channel should be used by
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// reactors to consume Envelopes sent from peers.
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func (c *Channel) In() <-chan Envelope {
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return c.inCh
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}
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// Out returns a write-only outbound go channel. This go channel should be used
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// by reactors to route Envelopes to other peers.
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func (c *Channel) Out() chan<- Envelope {
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return c.outCh
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}
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// Error returns a write-only outbound go channel designated for peer errors only.
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// This go channel should be used by reactors to send peer errors when consuming
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// Envelopes sent from other peers.
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func (c *Channel) Error() chan<- PeerError {
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return c.errCh
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}
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// Close closes the outbound channel and marks the Channel as done. Internally,
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// the outbound outCh and peer error errCh channels are closed. It is the reactor's
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// responsibility to invoke Close. Any send on the Out or Error channel will
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// panic after the Channel is closed.
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//
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// NOTE: After a Channel is closed, the router may safely assume it can no longer
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// send on the internal inCh, however it should NEVER explicitly close it as
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// that could result in panics by sending on a closed channel.
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func (c *Channel) Close() {
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c.closeOnce.Do(func() {
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close(c.doneCh)
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close(c.outCh)
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close(c.errCh)
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})
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}
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// Done returns the Channel's internal channel that should be used by a router
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// to signal when it is safe to send on the internal inCh go channel.
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func (c *Channel) Done() <-chan struct{} {
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return c.doneCh
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}
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// Wrapper is a Protobuf message that can contain a variety of inner messages.
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// If a Channel's message type implements Wrapper, the channel will
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// automatically (un)wrap passed messages using the container type, such that
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// the channel can transparently support multiple message types.
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type Wrapper interface {
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// Wrap will take a message and wrap it in this one.
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Wrap(proto.Message) error
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// Unwrap will unwrap the inner message contained in this message.
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Unwrap() (proto.Message, error)
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}
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