435c0d9fc8
This PR switches the Nomad repository from using govendor to Go modules for managing dependencies. Aspects of the Nomad workflow remain pretty much the same. The usual Makefile targets should continue to work as they always did. The API submodule simply defers to the parent Nomad version on the repository, keeping the semantics of API versioning that currently exists.
57 lines
1.2 KiB
Go
57 lines
1.2 KiB
Go
// Copyright 2014 Google Inc. All rights reserved.
|
|
// Use of this source code is governed by the Apache 2.0
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package internal
|
|
|
|
// This file implements a network dialer that limits the number of concurrent connections.
|
|
// It is only used for API calls.
|
|
|
|
import (
|
|
"log"
|
|
"net"
|
|
"runtime"
|
|
"sync"
|
|
"time"
|
|
)
|
|
|
|
var limitSem = make(chan int, 100) // TODO(dsymonds): Use environment variable.
|
|
|
|
func limitRelease() {
|
|
// non-blocking
|
|
select {
|
|
case <-limitSem:
|
|
default:
|
|
// This should not normally happen.
|
|
log.Print("appengine: unbalanced limitSem release!")
|
|
}
|
|
}
|
|
|
|
func limitDial(network, addr string) (net.Conn, error) {
|
|
limitSem <- 1
|
|
|
|
// Dial with a timeout in case the API host is MIA.
|
|
// The connection should normally be very fast.
|
|
conn, err := net.DialTimeout(network, addr, 500*time.Millisecond)
|
|
if err != nil {
|
|
limitRelease()
|
|
return nil, err
|
|
}
|
|
lc := &limitConn{Conn: conn}
|
|
runtime.SetFinalizer(lc, (*limitConn).Close) // shouldn't usually be required
|
|
return lc, nil
|
|
}
|
|
|
|
type limitConn struct {
|
|
close sync.Once
|
|
net.Conn
|
|
}
|
|
|
|
func (lc *limitConn) Close() error {
|
|
defer lc.close.Do(func() {
|
|
limitRelease()
|
|
runtime.SetFinalizer(lc, nil)
|
|
})
|
|
return lc.Conn.Close()
|
|
}
|