Method and apparatus for coordination of client/server processes

• US 7,233,972 B2
• Filed: 05/28/2002
• Issued: 06/19/2007
• Est. Priority Date: 09/25/1998
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Minow, Martin A.
• Primary Examiner(s): WINDER, PATRICE L
• Application Number:
  US10/157,764
• Publication Number:
  US 20030074483A1
• Time in Patent Office: 1,848 Days
• Field of Search: 709/203, 709/227, 709/224, 719/315, 719/318
• US Class Current: 709/203
• CPC Class Codes: G06F 9/466 Transaction processing
• CPC Class Codes: H04L 67/01 Protocols

Abstract

The invention provides for the coordination of client/server processes. One or more embodiments provide a completion object comprised of various states of completion of a client request. The completion object may be manipulated to transition from one state to another by both the client and server. The following states of completion may be provided: idle, ready, active, completing, completed, and acknowledged. In the idle state, the completion object is obtained by the client (by constructing a new object or retrieving an existing object that has been recycled). In the ready state, the request has been initialized but not yet issued to the server or I/O device. In the active state, the server processes the I/O request. In the completing state, the server has completed the I/O operations requested but has not yet stored the results. In the completed state, the server stores the results to be returned to the client and notifies the client. At the acknowledged state, the client examines the results, performs additional operations and frees up the completion object for use by another client request. Depending on the state of the completion object, a request to cancel the I/O operations may require varying actions. The completion object provides the ability to easily and quickly determine where in the completion process an I/O request is. Further, when a client request is canceled, the completion object provides the ability to easily identify the actions necessary to properly cancel the request.

Claims

1. A system comprising:

one or more processors;

a memory coupled to said one or more processors;

one or more sequences of instructions which, when executed by said one or more processors, cause said one or more processors to perform the steps of;

obtaining a completion object associated with a first request from at least one client to at least one server, wherein said completion object indicates a state of completion of said first request;

transitioning said completion object from indicating a first state of completion of said first request to indicating a second state of completion of said first request in response to a message from said at least one client; and

transitioning said completion object from indicating a third state of completion of said first request to indicating a fourth state of completion of said first request in response to a message from said at least one server;

wherein said second state of completion and said third state of completion are the same state of completion.

2. The system of claim 1, said instructions including instructions for causing said one or more processors to perform the step of:

notifying a computer process when said first request is complete.

3. The system of claim 1, wherein said instructions for obtaining said completion object comprises instructions for obtaining a reference to an existing completion object.

4. The system of claim 1, said instructions including instructions for causing said one or more processors to perform the steps of:

determining if said first request conflicts with a second request; and

deleting one or more references to said completion object if a conflict exists.

6. The system of claim 1, wherein said instructions including instructions for causing said one or more processors to perform the step of:

querying said completion object to determine said status of said particular operation as indicated by said completion object'"'"'s state.

7. The computer-readable medium of claim 6, said instructions including instructions for causing said one or more processors to perform the step of:

notifying a computer process when said first request is complete.

8. The computer-readable medium of claim 6 wherein said instructions for obtaining said object comprises instructions for obtaining a reference to an existing object.

9. The computer-readable medium of claim 6, said instructions including instructions for causing said one or more processors to perform the steps of:

determining if said first request conflicts with a second request; and

deleting one or more references to said object if a conflict exists.

10. The computer-readable medium of claim 6, wherein said first request is a client request for a specific function, action, or resource of a server.

11. The computer-readable medium of claim 6, wherein said first state of completion is an idle state and said second state of completion is a ready state.

12. The computer-readable medium of claim 11, wherein said third state of completion is a ready state and said fourth state of completion is an active state.

13. The computer-readable medium of claim 11, wherein said third state of completion is a ready state and said fourth state of completion is a completing state.

14. The computer-readable medium of claim 6, wherein said third state of completion is an active state and said fourth state of completion is a completing state.

15. The computer-readable medium of claim 14, wherein said third state of completion is a completing state and said fourth state of completion is a completed state.

39. The computer-readable medium of claim 6, wherein said first request is an I/O request from said at least one client to said at least one server.

5. A computer-readable medium bearing one or more sequences of instructions for coordinating computer processes, said instructions which, when executed by one or more processors, cause said one or more processors to perform the steps of:

obtaining an object associated with a first request from at least one client to at least one server, wherein said object indicates a state of completion of said first request;

transitioning said completion object from indicating a first state of completion of said first request to indicating a second state of completion of said first request in response to a message from said at least one client; and

transitioning said completion object from indicating a third state of completion of said first request to indicating a fourth state of completion of said first request in response to a message from said at least one server;

wherein said second state of completion and said third state of completion are the same state of completion.

16. A system comprising:

one or more processors;

a memory coupled to said one or more processors; and

one or more sequences of instructions which, when executed by said one or more processors, cause said one or more processors to perform the steps of;

specifying a level of completion of a particular operation in a completion object associated with said particular operation; and

transitioning said completion object between a plurality of states of completion, said completion object'"'"'s state of completion indicating a status of said particular operation;

wherein said transitioning includes

transitioning said completion object from a first state of completion to a second state of completion in response to a message from a first entity of a plurality of entities involved in said operation,

transitioning said completion object from a third state of completion to a fourth state of completion in response to a message from a second entity of the plurality of entities involved in said operation, and

wherein said second state of completion and said third state of completion are the same state of completion.

17. The system of claim 16, said instructions including instructions for causing said one or more processors to perform the step of:

said second entity completing said particular operation without information about said at first entity.

18. The system of claim 16, said instructions including instructions for causing said one or more processors to perform the step of:

notifying a computer process when said particular operation is complete.

19. The system of claim 16, wherein said particular operation may be terminated in a first state and a second state.

20. The system of claim 16, wherein said instructions for specifying said level of completion in said completion object comprises instructions for obtaining a reference to said completion object.

21. The system of claim 16, said instructions including instructions for causing said one or more processors to perform the steps of:

determining if said particular operation conflicts with a second operation; and

deleting one or more references to said completion object if a conflict exists.

22. The system of claim 16, wherein said particular operation is an I/O request from a client to a server.

23. A method of providing completion status for a client request, comprising:

a client obtaining a completion object, said completion object indicating a first completion state of a plurality of completion states;

said client associating said first completion state with a current status of a client request;

said client transitioning said first completion state to a second completion state when said client request is ready to be sent to a server;

said client providing said client request and said completion object to said server; and

said server transitioning said completion state from a third completion state to one of a subset of said plurality of completion states when processing of said client request by said server enters one or more phases corresponding to said subset of said plurality of completion states, wherein said second completion state and said third completion state are the same completion state.

24. The method of claim 23, wherein obtaining said completion object comprises obtaining a reference to an available completion object in an idle state.

25. The method of claim 23, wherein obtaining said completion object comprises obtaining a new instance of a completion object class.

26. The method of claim 23, wherein associating said completion state with said current status of said client request comprises:

associating said client request with said completion object; and

initializing said completion state.

27. The method of claim 23, further comprising said server returning said completion object and any results of said client request to said client.

28. The method of claim 23, further comprising said client polling said completion object to determine said current status.

29. The method of claim 23, further comprising notifying said client when processing of said client request is completed.

30. The method of claim 23, further comprising said client freeing said completion object.

31. The method of claim 30, wherein freeing said completion object comprises transitioning said completion object into an idle state for re-use.

32. The method of claim 23, further comprising at least one of said client and said server querying said completion object to determine said current status of said client request.

33. The method of claim 23, further comprising said completion object initiating one or more steps to cancel said client request at response to invocation of a cancellation method of said completion object, said one or more steps being dependent on said completion state.

34. The method of claim 23, further comprising said completion object returning an error when one of said client and said server attempts an invalid transition between said plurality of completion states.

35. The method of claim 23, further comprising:

receiving a second request;

determining that said second request conflicts with said client request; and

deleting said second request.

36. A method for coordinating computer processes, the method comprising:

obtaining an object associated with a first request from at least one client to at least one server, wherein said object indicates a state of completion of said first request;

transitioning said completion object from indicating a first state of completion of said first request to indicating a second state of completion of said first request in response to a message from said at least one client; and

transitioning said completion object from indicating a third state of completion of said first request to indicating a fourth state of completion of said first request in response to a message from said at least one server;

wherein said second state of completion and said third state of completion are the same state of completion.

37. A computer-readable storage medium storing one or more sequences of instructions which, when executed by one or more processors, cause said one or more processors to perform the steps of:

specifying a level of completion of a particular operation in a completion object associated with said particular operation; and

transitioning said completion object between a plurality of states of completion, said completion object'"'"'s state of completion indicating a status of said particular operation;

wherein said transitioning includes

transitioning said completion object from a first state of completion to a second state of completion in response to a message from a first entity of a plurality of entities involved in said operation,

transitioning said completion object from the third state of completion to a fourth state of completion in response to a message from a second entity of the plurality of entities involved in said operation, and

wherein said second state of completion and said third state of completion are the same state of completion.

38. A computer-readable storage medium storing one or more sequences of instructions for providing completion status for a client request, said instructions which, when executed by one or more processors, cause said one or more processors to perform the steps of:

in response to a client message, initializing a completion object to indicate a first completion state of a plurality of completion states;

in response to a client message, associating said first completion state with a current status of a client request;

in response to a client message, transitioning said frost completion state to a second completion state when said client request is ready to be sent to a server; and

in response to a server message, transitioning said completion from a third completion state to one of a subset of said plurality of completion states when processing of said client request by said server enters one or more phases corresponding to said subset of said plurality of completion states, wherein said second completion state and said third completion state are the same completion state.