github.com/Ptt-official-app/go-bbs@v0.12.0/cache/mmap.go (about)

     1  package cache
     2  
     3  import (
     4  	"fmt"
     5  	"os"
     6  	"runtime"
     7  	// "strings"
     8  )
     9  
    10  type Mmap struct {
    11  	file *os.File
    12  	buf  []byte
    13  }
    14  
    15  func CreateMmap(filePath string, size int64) (*Mmap, error) {
    16  	f, err := os.Create(filePath)
    17  	// f, err := os.Open("../../../dump.shm")
    18  	if err != nil {
    19  		return nil, fmt.Errorf("create error: %w", err)
    20  	}
    21  	err = f.Truncate(size)
    22  	if err != nil {
    23  		return nil, fmt.Errorf("truncate error: %v", err)
    24  	}
    25  
    26  	return openFile(f)
    27  
    28  }
    29  
    30  func OpenMmap(filePath string) (*Mmap, error) {
    31  	// := os.Open(filePath)
    32  	f, err := os.OpenFile(filePath, os.O_RDWR, 0644)
    33  	// f, err := os.Open("../../../dump.shm")
    34  	if err != nil {
    35  		return nil, fmt.Errorf("open error: %w", err)
    36  	}
    37  	return openFile(f)
    38  }
    39  
    40  func openFile(f *os.File) (*Mmap, error) {
    41  
    42  	fd := int(f.Fd())
    43  	// fmt.Println("fd:", fd)
    44  
    45  	stat, err := f.Stat()
    46  	if err != nil {
    47  		// fmt.Println("stat error", err)
    48  		return nil, fmt.Errorf("stat error: %w", err)
    49  	}
    50  
    51  	size := int(stat.Size())
    52  	// fmt.Println("size", size)
    53  
    54  	b, err := openMmap(fd, size)
    55  	if err != nil {
    56  		fmt.Println("mmap error", err)
    57  		return nil, fmt.Errorf("mmap error: %v", err)
    58  	}
    59  
    60  	ret := Mmap{
    61  		file: f,
    62  		buf:  b,
    63  	}
    64  
    65  	// For GC
    66  	runtime.SetFinalizer(&ret, (*Mmap).Close)
    67  	return &ret, nil
    68  }
    69  
    70  func (m *Mmap) Bytes() []byte {
    71  	return m.buf
    72  }
    73  
    74  func (m *Mmap) Close() error {
    75  	err := closeMmap(m.buf)
    76  
    77  	m.file.Close()
    78  
    79  	// release GC setting
    80  	runtime.SetFinalizer(m, nil)
    81  	return err
    82  
    83  }
    84  
    85  func RemoveMmap(filePath string) error {
    86  	return os.Remove(filePath)
    87  }