mirror of https://go.googlesource.com/go
65 lines
1.7 KiB
Go
65 lines
1.7 KiB
Go
// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package net
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import (
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"internal/poll"
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"io"
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)
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var pollSplice = poll.Splice
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// spliceFrom transfers data from r to c using the splice system call to minimize
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// copies from and to userspace. c must be a TCP connection.
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// Currently, spliceFrom is only enabled if r is a TCP or a stream-oriented Unix connection.
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//
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// If spliceFrom returns handled == false, it has performed no work.
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func spliceFrom(c *netFD, r io.Reader) (written int64, err error, handled bool) {
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var remain int64 = 1<<63 - 1 // by default, copy until EOF
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lr, ok := r.(*io.LimitedReader)
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if ok {
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remain, r = lr.N, lr.R
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if remain <= 0 {
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return 0, nil, true
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}
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}
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var s *netFD
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switch v := r.(type) {
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case *TCPConn:
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s = v.fd
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case tcpConnWithoutWriteTo:
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s = v.fd
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case *UnixConn:
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if v.fd.net != "unix" {
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return 0, nil, false
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}
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s = v.fd
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default:
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return 0, nil, false
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}
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written, handled, err = pollSplice(&c.pfd, &s.pfd, remain)
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if lr != nil {
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lr.N -= written
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}
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return written, wrapSyscallError("splice", err), handled
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}
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// spliceTo transfers data from c to w using the splice system call to minimize
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// copies from and to userspace. c must be a TCP connection.
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// Currently, spliceTo is only enabled if w is a stream-oriented Unix connection.
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//
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// If spliceTo returns handled == false, it has performed no work.
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func spliceTo(w io.Writer, c *netFD) (written int64, err error, handled bool) {
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uc, ok := w.(*UnixConn)
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if !ok || uc.fd.net != "unix" {
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return
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}
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written, handled, err = pollSplice(&uc.fd.pfd, &c.pfd, 1<<63-1)
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return written, wrapSyscallError("splice", err), handled
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}
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