Lightweight time change detection

• US 20080282103A1
• Filed: 05/09/2007
• Published: 11/13/2008
• Est. Priority Date: 05/09/2007
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Li, Eric, Sambotin, Dragos C., Earhart, Robert
• Granted Patent: US 8,219,845 B2
• Time in Patent Office: Days
• US Class Current: 713/500
• CPC Class Codes: G06F 1/14 Time supervision arrangements, e.g. real time clock

Abstract

A timer service uses a single timer function to perform timing services for both relative and absolute timers. The first timers from a sorted array of absolute timers and relative timers are used in a function that will return when the earliest absolute timer expires or will timeout when the earliest relative timer expires. The timer function may be interrupted when a new timer is added to one of the arrays. The function will operate in a predictable and consistent manner, even when a system clock is adjusted.

Claims

1. A method comprising:

receiving a timer request;

determining that said timer request is either an absolute or relative timer;

storing said timer request in either a first array comprising absolute timers or a second array comprising relative timers; and

starting a timer function adapted to return based on an earliest of said absolute timers and an earliest of said relative timers.

2. The method of claim 1, said timer request comprising a work item to execute.

3. The method of claim 2, said timer request further comprising a context to pass to said work item.

4. The method of claim 1, said timer request being periodic.

5. The method of claim 1 further comprising:

sorting said first array to determine said earliest absolute timer; and

sorting said second array to determine said earliest relative timer.

6. The method of claim 1, said timer function comprising a timeout function using said earliest relative timer.

7. The method of claim 1 further comprising:

interrupting said timer function when a new timer request is received.

8. The method of claim 1 further comprising:

interrupting said timer function when a new timer request is stored.

9. A computer readable media comprising computer executable instructions adapted to perform the method of claim 1.

10. A timer service comprising:

a first array comprising absolute timers;

a second array comprising relative timers;

an input function adapted to receive a timer request and store said timer request in either said first array or said second array; and

a timer function comprising an earliest absolute timer and an earliest relative timer, said timer function being adapted to return when the earliest of said earliest absolute timer or said earliest relative timer occurs.

11. The timer service of claim 10, said timer request comprising a work item to execute.

12. The timer service of claim 11, said timer request further comprising a context to pass to said work item.

13. The timer service of claim 10, said timer request being periodic.

14. The timer service of claim 10, said first array being a sorted array and said second array being a sorted array.

15. The timer service of claim 10, said timer function further comprising a timeout function using said earliest relative timer.

16. The timer service of claim 10 further comprising:

an interruption function adapted to interrupt said timer function after a new timer request is received.

17. A system comprising:

a system clock; and

a timer service adapted to;

receiving a timer request;

determining that said timer request is either an absolute or relative timer;

storing said timer request in either a first array comprising absolute timers or a second array comprising relative timers; and

starting a timer function adapted to return based on an earliest of said absolute timers and an earliest of said relative timers.

18. The system of claim 17, said timer request comprising a work item to execute and a context to pass to said work item.

19. The system of claim 17, said timer function comprising a timeout function using said earliest relative timer.

20. The system of claim 17 said timer service further adapted to:

interrupting said timer function after a new timer request is received.