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author | Christopher Speller <crspeller@gmail.com> | 2018-01-29 14:17:40 -0800 |
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committer | GitHub <noreply@github.com> | 2018-01-29 14:17:40 -0800 |
commit | 961c04cae992eadb42d286d2f85f8a675bdc68c8 (patch) | |
tree | 3408f2d06f847e966c53485e2d54c692cdd037c1 /vendor/google.golang.org/appengine/internal/net.go | |
parent | 8d66523ba7d9a77129844be476732ebfd5272d64 (diff) | |
download | chat-961c04cae992eadb42d286d2f85f8a675bdc68c8.tar.gz chat-961c04cae992eadb42d286d2f85f8a675bdc68c8.tar.bz2 chat-961c04cae992eadb42d286d2f85f8a675bdc68c8.zip |
Upgrading server dependancies (#8154)
Diffstat (limited to 'vendor/google.golang.org/appengine/internal/net.go')
-rw-r--r-- | vendor/google.golang.org/appengine/internal/net.go | 56 |
1 files changed, 56 insertions, 0 deletions
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 000000000..3b94cf0c6 --- /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() +} |