| // Licensed to Apache Software Foundation (ASF) under one or more contributor |
| // license agreements. See the NOTICE file distributed with |
| // this work for additional information regarding copyright |
| // ownership. Apache Software Foundation (ASF) licenses this file to you under |
| // the Apache License, Version 2.0 (the "License"); you may |
| // not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, |
| // software distributed under the License is distributed on an |
| // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| // KIND, either express or implied. See the License for the |
| // specific language governing permissions and limitations |
| // under the License. |
| |
| // +build !windows |
| |
| package segment |
| |
| import ( |
| "fmt" |
| "os" |
| "path/filepath" |
| "syscall" |
| |
| "github.com/grandecola/mmap" |
| ) |
| |
| const FileSuffix = "_segment.dat" |
| |
| // NewSegment returns a pointer to a memory mapped file according to the given file name and file size. |
| // The size of each segment file should be a multiple of the page size. |
| func NewSegment(name string, size int) (*mmap.File, error) { |
| name, err := filepath.Abs(name) |
| if err != nil { |
| return nil, fmt.Errorf("error in getting the absolute path of the segment file : %v", err) |
| } |
| paths, _ := filepath.Split(name) |
| _, err = os.Stat(paths) |
| if err != nil && os.IsNotExist(err) && os.MkdirAll(paths, 0744) != nil { |
| return nil, fmt.Errorf("error in creating the parent dirs of the segment file : %v", err) |
| } |
| |
| file, err := os.OpenFile(name, os.O_CREATE|os.O_RDWR, 0744) |
| if err != nil { |
| return nil, fmt.Errorf("error in opening segment file : %v", err) |
| } |
| |
| stat, err := file.Stat() |
| if err != nil { |
| return nil, fmt.Errorf("error in reading info of the segment file : %v", err) |
| } |
| |
| if stat.Size() != int64(size) { |
| if file.Truncate(int64(size)) != nil { |
| return nil, fmt.Errorf("error in truncating file: %v", err) |
| } |
| } |
| |
| segment, err := mmap.NewSharedFileMmap(file, 0, size, syscall.PROT_READ|syscall.PROT_WRITE) |
| if err != nil { |
| return nil, fmt.Errorf("error in creating the mmap segment file : %v", err) |
| } |
| if err := file.Close(); err != nil { |
| return nil, fmt.Errorf("error in closing the segment file : %v", err) |
| } |
| return segment, nil |
| } |