From a18a13fb09eac00cdacf1f74080524182b7243de Mon Sep 17 00:00:00 2001 From: Niall Sheridan Date: Mon, 6 Jun 2016 00:55:30 +0100 Subject: update vendor --- vendor/google.golang.org/appengine/internal/net.go | 56 ++++++++++++++++++++++ 1 file changed, 56 insertions(+) create mode 100644 vendor/google.golang.org/appengine/internal/net.go (limited to 'vendor/google.golang.org/appengine/internal/net.go') diff --git a/vendor/google.golang.org/appengine/internal/net.go b/vendor/google.golang.org/appengine/internal/net.go new file mode 100644 index 0000000..3b94cf0 --- /dev/null +++ b/vendor/google.golang.org/appengine/internal/net.go @@ -0,0 +1,56 @@ +// 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() +} -- cgit v1.2.3