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b517c791e9
Instead of using O_SYNC, we are better off using O_DSYNC instead since we are only ever interested in data to be persisted to disk not the associated filesystem metadata. For reads we ask customers to turn off noatime, but instead we can proactively use O_NOATIME flag to avoid atime updates upon reads.
75 lines
2.0 KiB
Go
75 lines
2.0 KiB
Go
/*
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* MinIO Cloud Storage, (C) 2021 MinIO, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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// Forked from golang.org/pkg/os.ReadFile with NOATIME support.
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// Copyright 2009 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 ioutil
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import (
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"io"
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"os"
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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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defer f.Close()
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var size int
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if info, err := f.Stat(); err == nil {
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size64 := info.Size()
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if int64(int(size64)) == size64 {
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size = int(size64)
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}
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}
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size++ // one byte for final read at EOF
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// If a file claims a small size, read at least 512 bytes.
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// In particular, files in Linux's /proc claim size 0 but
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// then do not work right if read in small pieces,
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// so an initial read of 1 byte would not work correctly.
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if size < 512 {
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size = 512
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}
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data := make([]byte, 0, size)
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for {
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if len(data) >= cap(data) {
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d := append(data[:cap(data)], 0)
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data = d[:len(data)]
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}
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n, err := f.Read(data[len(data):cap(data)])
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data = data[:len(data)+n]
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if err != nil {
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if err == io.EOF {
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err = nil
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}
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return data, err
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}
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}
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}
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