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Daulet Zhanguzin 27c3814275 io: correctly process result of sendfile(2) when src returns 0 bytes
Fixes #53658. io.Copy() uses sendfile(2) to avoid allocating extra buffers when src is a file and dst is a TCPConn. However if src returns no bytes current logic treats it as failure and falls back to copying via user space. The following is a benchmark that illustrates the bug.

Benchmark: https://go.dev/play/p/zgZwpjUatSq

Before:
BenchmarkCopy-16          541006              2137 ns/op            4077 B/op          0 allocs/op

After:
BenchmarkCopy-16          490383              2365 ns/op             174 B/op          8 allocs/op

Change-Id: I703376d53b20e080c6204a73c96867cce16b24cf
GitHub-Last-Rev: 3a50be4f16
GitHub-Pull-Request: golang/go#53659
Reviewed-on: https://go-review.googlesource.com/c/go/+/415834
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
2022-11-09 03:01:33 +00:00
.github .github: update issue label for pkgsite-removal 2022-09-07 16:00:20 +00:00
api context: add APIs for writing and reading cancelation cause 2022-11-08 13:51:16 +00:00
doc doc: add a release note for fewer pre-compiled GOROOT .a files 2022-11-07 15:51:10 +00:00
lib/time lib/time, time/tzdata: update to 2022b 2022-08-11 20:03:19 +00:00
misc misc/cgo/test: skip Test9400 on Alpine 2022-11-07 21:15:29 +00:00
src io: correctly process result of sendfile(2) when src returns 0 bytes 2022-11-09 03:01:33 +00:00
test cmd/compile: fix transitive inlining of generic functions 2022-11-08 21:26:09 +00:00
.gitattributes all: treat all files as binary, but check in .bat with CRLF 2020-06-08 15:31:43 +00:00
.gitignore internal/buildcfg: move build configuration out of cmd/internal/objabi 2021-04-16 19:20:53 +00:00
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README.md README: update from CC-BY-3.0 to CC-BY-4.0 2022-11-02 20:14:56 +00:00
SECURITY.md SECURITY.md: replace golang.org with go.dev 2022-04-26 19:59:47 +00:00
codereview.cfg codereview.cfg: add codereview.cfg for master branch 2021-02-19 18:44:53 +00:00

README.md

The Go Programming Language

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