package memberlist
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// EventDelegate is a simpler delegate that is used only to receive
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// notifications about members joining and leaving. The methods in this
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// delegate may be called by multiple goroutines, but never concurrently.
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// This allows you to reason about ordering.
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type EventDelegate interface {
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// NotifyJoin is invoked when a node is detected to have joined.
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// The Node argument must not be modified.
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NotifyJoin(*Node)
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// NotifyLeave is invoked when a node is detected to have left.
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// The Node argument must not be modified.
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NotifyLeave(*Node)
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// NotifyUpdate is invoked when a node is detected to have
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// updated, usually involving the meta data. The Node argument
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// must not be modified.
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NotifyUpdate(*Node)
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}
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// ChannelEventDelegate is used to enable an application to receive
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// events about joins and leaves over a channel instead of a direct
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// function call.
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//
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// Care must be taken that events are processed in a timely manner from
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// the channel, since this delegate will block until an event can be sent.
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type ChannelEventDelegate struct {
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Ch chan<- NodeEvent
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}
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// NodeEventType are the types of events that can be sent from the
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// ChannelEventDelegate.
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type NodeEventType int
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const (
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NodeJoin NodeEventType = iota
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NodeLeave
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NodeUpdate
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)
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// NodeEvent is a single event related to node activity in the memberlist.
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// The Node member of this struct must not be directly modified. It is passed
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// as a pointer to avoid unnecessary copies. If you wish to modify the node,
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// make a copy first.
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type NodeEvent struct {
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Event NodeEventType
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Node *Node
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}
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func (c *ChannelEventDelegate) NotifyJoin(n *Node) {
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c.Ch <- NodeEvent{NodeJoin, n}
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}
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func (c *ChannelEventDelegate) NotifyLeave(n *Node) {
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c.Ch <- NodeEvent{NodeLeave, n}
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}
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func (c *ChannelEventDelegate) NotifyUpdate(n *Node) {
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c.Ch <- NodeEvent{NodeUpdate, n}
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}
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