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38027c8f52
This PR brings two optimizations mainly for page-cache build-up and how to avoid getting OOM killed in the process. Although these memories are reclaimable Linux is not fast enough to reclaim them as needed on a very busy system. fadvise is a system call implemented in Linux to advise page-cache to avoid overload as we get significant amount of requests on the server. - FADV_SEQUENTIAL tells that all I/O from now is going to be sequential, allowing for more resposive throughput. - FADV_NOREUSE tells kernel to start removing things for this 'fd' from page-cache.
51 lines
1.5 KiB
Go
51 lines
1.5 KiB
Go
// Copyright (c) 2015-2021 MinIO, Inc.
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//
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// This file is part of MinIO Object Storage stack
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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package ioutil
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import (
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"io"
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"os"
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"github.com/minio/minio/internal/disk"
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)
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// ReadFile reads the named file and returns the contents.
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// A successful call returns err == nil, not err == EOF.
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// Because ReadFile reads the whole file, it does not treat an EOF from Read
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// as an error to be reported.
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//
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// passes NOATIME flag for reads on Unix systems to avoid atime updates.
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func ReadFile(name string) ([]byte, error) {
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f, err := os.OpenFile(name, readMode, 0)
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if err != nil {
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return nil, err
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}
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if err := disk.Fadvise(f, disk.FadvSequential); err != nil {
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return nil, err
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}
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defer disk.Fadvise(f, disk.FadvNoReuse)
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defer f.Close()
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st, err := f.Stat()
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if err != nil {
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return io.ReadAll(f)
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}
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dst := make([]byte, st.Size())
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_, err = io.ReadFull(f, dst)
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return dst, err
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}
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