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  1. // Copyright (c) 2017 Couchbase, Inc.
  2. //
  3. // Licensed under the Apache License, Version 2.0 (the "License");
  4. // you may not use this file except in compliance with the License.
  5. // You may obtain a copy of the License at
  6. //
  7. // http://www.apache.org/licenses/LICENSE-2.0
  8. //
  9. // Unless required by applicable law or agreed to in writing, software
  10. // distributed under the License is distributed on an "AS IS" BASIS,
  11. // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12. // See the License for the specific language governing permissions and
  13. // limitations under the License.
  14. // +build !nommap
  15. package vellum
  16. import (
  17. "os"
  18. mmap "github.com/edsrzf/mmap-go"
  19. )
  20. type mmapWrapper struct {
  21. f *os.File
  22. mm mmap.MMap
  23. }
  24. func (m *mmapWrapper) Close() (err error) {
  25. if m.mm != nil {
  26. err = m.mm.Unmap()
  27. }
  28. // try to close file even if unmap failed
  29. if m.f != nil {
  30. err2 := m.f.Close()
  31. if err == nil {
  32. // try to return first error
  33. err = err2
  34. }
  35. }
  36. return
  37. }
  38. func open(path string) (*FST, error) {
  39. f, err := os.Open(path)
  40. if err != nil {
  41. return nil, err
  42. }
  43. mm, err := mmap.Map(f, mmap.RDONLY, 0)
  44. if err != nil {
  45. // mmap failed, try to close the file
  46. _ = f.Close()
  47. return nil, err
  48. }
  49. return new(mm, &mmapWrapper{
  50. f: f,
  51. mm: mm,
  52. })
  53. }
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