/hudson-core/src/main/java/hudson/CopyOnWrite.java

http://github.com/hudson/hudson · Java · 54 lines · 11 code · 2 blank · 41 comment · 0 complexity · b376503885cbcae2b70dde6c3e7d8105 MD5 · raw file

  1. /*
  2. * The MIT License
  3. *
  4. * Copyright (c) 2004-2009, Sun Microsystems, Inc., Kohsuke Kawaguchi
  5. *
  6. * Permission is hereby granted, free of charge, to any person obtaining a copy
  7. * of this software and associated documentation files (the "Software"), to deal
  8. * in the Software without restriction, including without limitation the rights
  9. * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10. * copies of the Software, and to permit persons to whom the Software is
  11. * furnished to do so, subject to the following conditions:
  12. *
  13. * The above copyright notice and this permission notice shall be included in
  14. * all copies or substantial portions of the Software.
  15. *
  16. * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17. * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18. * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  19. * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20. * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21. * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22. * THE SOFTWARE.
  23. */
  24. package hudson;
  25. import java.lang.annotation.Documented;
  26. import static java.lang.annotation.ElementType.FIELD;
  27. import java.lang.annotation.Retention;
  28. import static java.lang.annotation.RetentionPolicy.SOURCE;
  29. import java.lang.annotation.Target;
  30. /**
  31. * Represents fields that are protected for concurrency by the copy-on-write semantics.
  32. *
  33. * <p>
  34. * Fields marked by this annotation always holds on to an immutable collection.
  35. * A change to the collection must be done by first creating a new collection
  36. * object, making changes, then replacing the reference atomically.
  37. *
  38. * <p>
  39. * This allows code to access the field without synchronization, and
  40. * greatly reduces the risk of dead-lock bugs.
  41. *
  42. * <p>
  43. * The field marked with this annotation usually needs to be marked as
  44. * <tt>volatile</tt>.
  45. *
  46. * @author Kohsuke Kawaguchi
  47. */
  48. @Retention(SOURCE)
  49. @Documented
  50. @Target(FIELD)
  51. public @interface CopyOnWrite {
  52. }