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restartable_listener.go
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/
restartable_listener.go
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/*
*
* Copyright 2019 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package testutils
import (
"net"
"sync"
)
type tempError struct{}
func (*tempError) Error() string {
return "restartable listener temporary error"
}
func (*tempError) Temporary() bool {
return true
}
// RestartableListener wraps a net.Listener and supports stopping and restarting
// the latter.
type RestartableListener struct {
lis net.Listener
mu sync.Mutex
stopped bool
conns []net.Conn
}
// NewRestartableListener returns a new RestartableListener wrapping l.
func NewRestartableListener(l net.Listener) *RestartableListener {
return &RestartableListener{lis: l}
}
// Accept waits for and returns the next connection to the listener.
//
// If the listener is currently not accepting new connections, because `Stop`
// was called on it, the connection is immediately closed after accepting
// without any bytes being sent on it.
func (l *RestartableListener) Accept() (net.Conn, error) {
conn, err := l.lis.Accept()
if err != nil {
return nil, err
}
l.mu.Lock()
defer l.mu.Unlock()
if l.stopped {
conn.Close()
return nil, &tempError{}
}
l.conns = append(l.conns, conn)
return conn, nil
}
// Close closes the listener.
func (l *RestartableListener) Close() error {
return l.lis.Close()
}
// Addr returns the listener's network address.
func (l *RestartableListener) Addr() net.Addr {
return l.lis.Addr()
}
// Stop closes existing connections on the listener and prevents new connections
// from being accepted.
func (l *RestartableListener) Stop() {
l.mu.Lock()
l.stopped = true
for _, conn := range l.conns {
conn.Close()
}
l.conns = nil
l.mu.Unlock()
}
// Restart gets a previously stopped listener to start accepting connections.
func (l *RestartableListener) Restart() {
l.mu.Lock()
l.stopped = false
l.mu.Unlock()
}