80 lines
3.3 KiB
Diff
80 lines
3.3 KiB
Diff
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From fef8644451930464ffd9f13c82bcd451f58fa575 Mon Sep 17 00:00:00 2001
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From: Andy Pan <panjf2000@gmail.com>
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Date: Tue, 17 Oct 2023 22:38:17 +0800
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Subject: [PATCH 03/20] [release-branch.go1.21] internal/poll: add
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SPLICE_F_NONBLOCK flag for splice to avoid inconsistency with O_NONBLOCK
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Fixes #63801
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Updates #59041
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Updates #63795
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Conflict:NA
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Reference:https://go-review.googlesource.com/c/go/+/536015
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Details: https://github.com/golang/go/issues/59041#issuecomment-1766610087
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Change-Id: Id3fc1df6d86b7c4cc383d09f9465fa8f4cc2a559
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Reviewed-on: https://go-review.googlesource.com/c/go/+/536015
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Reviewed-by: Bryan Mills <bcmills@google.com>
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Reviewed-by: Ian Lance Taylor <iant@google.com>
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LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
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Auto-Submit: Ian Lance Taylor <iant@google.com>
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(cherry picked from commit 40cdf69fc9279ab28f84a6e0f965de8382c578fe)
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Reviewed-on: https://go-review.googlesource.com/c/go/+/538117
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Auto-Submit: Heschi Kreinick <heschi@google.com>
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Reviewed-by: Mauri de Souza Meneguzzo <mauri870@gmail.com>
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Reviewed-by: Heschi Kreinick <heschi@google.com>
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---
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src/internal/poll/splice_linux.go | 21 +++++++++++++++++++--
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1 file changed, 19 insertions(+), 2 deletions(-)
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diff --git a/src/internal/poll/splice_linux.go b/src/internal/poll/splice_linux.go
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index 9505c5dcfc1e..72cca34fe4ae 100644
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--- a/src/internal/poll/splice_linux.go
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+++ b/src/internal/poll/splice_linux.go
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@@ -13,6 +13,12 @@ import (
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)
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const (
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+ // spliceNonblock doesn't make the splice itself necessarily nonblocking
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+ // (because the actual file descriptors that are spliced from/to may block
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+ // unless they have the O_NONBLOCK flag set), but it makes the splice pipe
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+ // operations nonblocking.
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+ spliceNonblock = 0x2
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+
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// maxSpliceSize is the maximum amount of data Splice asks
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// the kernel to move in a single call to splice(2).
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// We use 1MB as Splice writes data through a pipe, and 1MB is the default maximum pipe buffer size,
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@@ -89,7 +95,11 @@ func spliceDrain(pipefd int, sock *FD, max int) (int, error) {
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return 0, err
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}
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for {
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- n, err := splice(pipefd, sock.Sysfd, max, 0)
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+ // In theory calling splice(2) with SPLICE_F_NONBLOCK could end up an infinite loop here,
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+ // because it could return EAGAIN ceaselessly when the write end of the pipe is full,
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+ // but this shouldn't be a concern here, since the pipe buffer must be sufficient for
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+ // this data transmission on the basis of the workflow in Splice.
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+ n, err := splice(pipefd, sock.Sysfd, max, spliceNonblock)
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if err == syscall.EINTR {
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continue
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}
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@@ -127,7 +137,14 @@ func splicePump(sock *FD, pipefd int, inPipe int) (int, error) {
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}
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written := 0
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for inPipe > 0 {
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- n, err := splice(sock.Sysfd, pipefd, inPipe, 0)
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+ // In theory calling splice(2) with SPLICE_F_NONBLOCK could end up an infinite loop here,
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+ // because it could return EAGAIN ceaselessly when the read end of the pipe is empty,
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+ // but this shouldn't be a concern here, since the pipe buffer must contain inPipe size of
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+ // data on the basis of the workflow in Splice.
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+ n, err := splice(sock.Sysfd, pipefd, inPipe, spliceNonblock)
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+ if err == syscall.EINTR {
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+ continue
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+ }
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// Here, the condition n == 0 && err == nil should never be
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// observed, since Splice controls the write side of the pipe.
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if n > 0 {
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--
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2.33.0
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