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package memory_map
import (
"os"
"time"
)
var (
// _ backend.BackendStorageFile = &MemoryMappedFile{} // remove this to break import cycle
)
type MemoryMappedFile struct {
mm *MemoryMap
}
func NewMemoryMappedFile(f *os.File, memoryMapSizeMB uint32) *MemoryMappedFile {
mmf := &MemoryMappedFile{
mm: new(MemoryMap),
}
mmf.mm.CreateMemoryMap(f, 1024*1024*uint64(memoryMapSizeMB))
return mmf
}
func (mmf *MemoryMappedFile) ReadAt(p []byte, off int64) (n int, err error) {
readBytes, e := mmf.mm.ReadMemory(uint64(off), uint64(len(p)))
if e != nil {
return 0, e
}
// TODO avoid the extra copy
copy(p, readBytes)
return len(readBytes), nil
}
func (mmf *MemoryMappedFile) WriteAt(p []byte, off int64) (n int, err error) {
mmf.mm.WriteMemory(uint64(off), uint64(len(p)), p)
return len(p), nil
}
func (mmf *MemoryMappedFile) Truncate(off int64) error {
return nil
}
func (mmf *MemoryMappedFile) Close() error {
mmf.mm.DeleteFileAndMemoryMap()
return nil
}
func (mmf *MemoryMappedFile) GetStat() (datSize int64, modTime time.Time, err error) {
stat, e := mmf.mm.File.Stat()
if e == nil {
return mmf.mm.End_of_file + 1, stat.ModTime(), nil
}
return 0, time.Time{}, err
}
func (mmf *MemoryMappedFile) Name() string {
return mmf.mm.File.Name()
}
func (mm *MemoryMappedFile) Sync() error {
return nil
}
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