Aaron Lehmann
dfcca19d95
Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com> Upstream-commit: 99119fcafa41fb8c95e67b225a3da2902ce0e959 Component: engine
111 lines
2.8 KiB
Go
111 lines
2.8 KiB
Go
// Package connectionbroker is a layer on top of remotes that returns
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// a gRPC connection to a manager. The connection may be a local connection
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// using a local socket such as a UNIX socket.
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package connectionbroker
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import (
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"sync"
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"github.com/docker/swarmkit/api"
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"github.com/docker/swarmkit/remotes"
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grpc_prometheus "github.com/grpc-ecosystem/go-grpc-prometheus"
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"google.golang.org/grpc"
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)
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// Broker is a simple connection broker. It can either return a fresh
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// connection to a remote manager selected with weighted randomization, or a
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// local gRPC connection to the local manager.
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type Broker struct {
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mu sync.Mutex
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remotes remotes.Remotes
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localConn *grpc.ClientConn
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}
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// New creates a new connection broker.
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func New(remotes remotes.Remotes) *Broker {
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return &Broker{
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remotes: remotes,
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}
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}
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// SetLocalConn changes the local gRPC connection used by the connection broker.
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func (b *Broker) SetLocalConn(localConn *grpc.ClientConn) {
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b.mu.Lock()
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defer b.mu.Unlock()
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b.localConn = localConn
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}
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// Select a manager from the set of available managers, and return a connection.
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func (b *Broker) Select(dialOpts ...grpc.DialOption) (*Conn, error) {
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b.mu.Lock()
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localConn := b.localConn
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b.mu.Unlock()
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if localConn != nil {
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return &Conn{
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ClientConn: localConn,
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isLocal: true,
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}, nil
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}
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return b.SelectRemote(dialOpts...)
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}
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// SelectRemote chooses a manager from the remotes, and returns a TCP
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// connection.
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func (b *Broker) SelectRemote(dialOpts ...grpc.DialOption) (*Conn, error) {
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peer, err := b.remotes.Select()
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if err != nil {
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return nil, err
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}
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dialOpts = append(dialOpts,
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grpc.WithUnaryInterceptor(grpc_prometheus.UnaryClientInterceptor),
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grpc.WithStreamInterceptor(grpc_prometheus.StreamClientInterceptor))
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cc, err := grpc.Dial(peer.Addr, dialOpts...)
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if err != nil {
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b.remotes.ObserveIfExists(peer, -remotes.DefaultObservationWeight)
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return nil, err
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}
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return &Conn{
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ClientConn: cc,
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remotes: b.remotes,
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peer: peer,
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}, nil
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}
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// Remotes returns the remotes interface used by the broker, so the caller
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// can make observations or see weights directly.
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func (b *Broker) Remotes() remotes.Remotes {
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return b.remotes
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}
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// Conn is a wrapper around a gRPC client connection.
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type Conn struct {
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*grpc.ClientConn
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isLocal bool
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remotes remotes.Remotes
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peer api.Peer
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}
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// Close closes the client connection if it is a remote connection. It also
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// records a positive experience with the remote peer if success is true,
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// otherwise it records a negative experience. If a local connection is in use,
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// Close is a noop.
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func (c *Conn) Close(success bool) error {
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if c.isLocal {
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return nil
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}
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if success {
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c.remotes.ObserveIfExists(c.peer, remotes.DefaultObservationWeight)
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} else {
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c.remotes.ObserveIfExists(c.peer, -remotes.DefaultObservationWeight)
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}
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return c.ClientConn.Close()
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}
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