go.uber.org/yarpc@v1.72.1/api/peer/peer.go (about)

     1  // Copyright (c) 2022 Uber Technologies, Inc.
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    20  
    21  package peer
    22  
    23  // ConnectionStatus maintains information about the Peer's connection state
    24  type ConnectionStatus int
    25  
    26  const (
    27  	// Unavailable indicates the Peer is unavailable for requests
    28  	Unavailable ConnectionStatus = iota
    29  
    30  	// Connecting indicates the Peer is in the process of connecting
    31  	Connecting
    32  
    33  	// Available indicates the Peer is available for requests
    34  	Available
    35  )
    36  
    37  // Status holds all the information about a peer's state that would be useful to Subscribers
    38  type Status struct {
    39  	// Current number of pending requests on this peer
    40  	PendingRequestCount int
    41  
    42  	// Current status of the Peer's connection
    43  	ConnectionStatus ConnectionStatus
    44  }
    45  
    46  // Identifier is able to uniquely identify a peer (e.g. hostport)
    47  type Identifier interface {
    48  	Identifier() string
    49  }
    50  
    51  // StatusPeer captures a concrete peer implementation for a particular
    52  // transport, exposing its Identifier and Status.
    53  // StatusPeer provides observability without mutability.
    54  type StatusPeer interface {
    55  	Identifier
    56  
    57  	// Get the status of the Peer
    58  	Status() Status
    59  }
    60  
    61  // Peer captures a concrete peer implementation for a particular transport,
    62  // providing both observability (Identifier and Status), along with load change
    63  // notifications (StartRequest) (EndRequest).
    64  // Transports reveal peers to peer lists, which in turn offer them to outbounds
    65  // when they choose a peer.
    66  // Having Start/End request messages allows the outbound to broadcast load
    67  // changes to all subscribed load balancers.
    68  // The peer should be created by a transport so we can maintain multiple
    69  // references to the same peer (e.g., hostport).
    70  type Peer interface {
    71  	StatusPeer
    72  
    73  	// Tell the peer that a request is starting
    74  	StartRequest()
    75  
    76  	// Tell the peer that a request has finished
    77  	EndRequest()
    78  }