Method and apparatus for accelerating the expiration of resource records in a local cache

• US 20050044355A1
• Filed: 09/30/2003
• Published: 02/24/2005
• Est. Priority Date: 08/20/2003
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Cheshire, Stuart D.
• Granted Patent: US 8,949,304 B2
• Time in Patent Office: Days
• US Class Current: 713/163
• CPC Class Codes: G06F 16/24552 Database cache management
• CPC Class Codes: H04L 67/5682 Policies or rules for updating, deleting or replacing the stored data
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]

Abstract

One embodiment of the present invention provides a system that facilitates reconfirmation of resource records in a cache. The system starts by retrieving the resource record at a client and attempting to establish communication using the data in that resource record. In the event that communication is not successful, the system responds by issuing one or more queries for the resource record in question. The system then waits for a response to the query. If the response to the query is not received in a predetermined amount of time, the system invalidates the resource record. The response from the device is a multicast response, thereby allowing other clients to update corresponding resource records in their local caches without querying the device, and thus saving network bandwidth.

Claims

1. method for validating a resource record in a cache, comprising:

retrieving the resource record at a client;

issuing one or more queries for the resource record;

waiting for a response to the query; and

if the response to the query is not received in a pre-determined amount of time, invalidating the resource record.

2. The method of claim 1, wherein the response to the query is a multicast response, thereby allowing other clients to update corresponding copies of the resource records without querying the device, thus saving network bandwidth.

3. The method of claim 1, further comprising:

receiving a multicast message from a second client querying a second device;

locating a second resource record associated with the second device;

waiting for a multicast response to the multicast query; and

if after a pre-determined number of queries the multicast response to the multicast query is not received in the pre-determined amount of time, invalidating the second resource record.

4. The method of claim 1, wherein invalidating the resource record further comprises invalidating a child record of the resource record.

5. The method of claim 1, wherein if the response to the query is not received in a pre-determined amount of time, the method further comprises:

retrieving a parent record of the resource record at the client, wherein the parent record refers to the resource record;

issuing a query for the parent record;

waiting for a response to the query from the device; and

if the response to the query is not received in a pre-determined amount of time, invalidating the parent record, and then repeating the above process by applying it recursively to any records that refer to the now-invalidated parent record.

6. The method of claim 1, wherein if the response to the query is not received in a pre-determined amount of time, the method further comprises:

retrieving a parent record of the resource record at the client, wherein the parent record refers to the resource record;

issuing a query for the parent record;

receiving a response to the query from the device, wherein the response includes information for updating the resource record; and

updating the resource record with the information received in the response.

7. The method of claim 6, wherein the method further comprises updating the parent record with the information received in the response.

8. The method of claim 1, wherein the method is invoked at a pre-specified time interval.

9. A computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method for validating a resource record in a cache, the method comprising:

retrieving the resource record at a client;

issuing one or more queries for the resource record;

waiting for a response to the query; and

if the response to the query is not received in a pre-determined amount of time, invalidating the resource record.

10. The computer-readable storage medium of claim 9, wherein the response to the query is a multicast response, thereby allowing other clients to update corresponding copies of the resource records without querying the device, thus saving network bandwidth.

11. The computer-readable storage medium of claim 9, wherein the method further comprises:

receiving a multicast message from a second client querying a second device;

locating a second resource record associated with the second device;

waiting for a multicast response to the multicast query; and

if after a pre-determined number of queries the multicast response to the multicast query is not received in the pre-determined amount of time, invalidating the second resource record.

12. The computer-readable storage medium of claim 9, wherein invalidating the resource record further comprises invalidating a child record of the resource record.

13. The computer-readable storage medium of claim 9, wherein if the response to the query is not received in a pre-determined amount of time, the method further comprises:

retrieving a parent record of the resource record at the client, wherein the parent record refers to the resource record;

issuing a query for the parent record;

waiting for a response to the query from the device; and

if the response to the query is not received in a pre-determined amount of time, invalidating the parent record, and then repeating the above process by applying it recursively to any records that refer to the now-invalidated parent record.

14. The computer-readable storage medium of claim 9, wherein if the response to the query is not received in a pre-determined amount of time, the method further comprises:

retrieving a parent record of the resource record at the client, wherein the parent record refers to the resource record;

issuing a query for the parent record;

receiving a response to the query from the device, wherein the response includes information for updating the resource record; and

updating the resource record with the information received in the response.

15. The computer-readable storage medium of claim 14, wherein the method further comprises updating the parent record with the information received in the response.

16. The computer-readable storage medium of claim 9, wherein the method is invoked at a pre-specified time interval.

17. An apparatus that validates a resource record in a cache, comprising:

a retrieval mechanism at a client configured to retrieve the resource record; and

an invalidation mechanism configured to,

issue one or more queries for the resource record,

wait for a response to the query, and

if the response to the query is not received in a pre-determined amount of time, to invalidate the resource record.

18. The apparatus of claim 17, wherein the response to the query is a multicast response, thereby allowing other clients to update corresponding copies of the resource records without querying the device, thus saving network bandwidth.

19. The apparatus of claim 17, wherein the invalidation mechanism is configured to:

receive a multicast message from a second client querying a second device;

locate a second resource record associated with the second device;

wait for a multicast response to the multicast query; and

if after a pre-determined number of queries the multicast response to the multicast query is not received in the pre-determined amount of time, to invalidate the second resource record.

20. The apparatus of claim 17, wherein invalidating the resource record further comprises invalidating a child record of the resource record.

21. The apparatus of claim 17, wherein if the response to the query is not received in a pre-determined amount of time, the invalidation mechanism is additionally configured to:

retrieve a parent record of the resource record at the client, wherein the parent record refers to the resource record;

issue a query for the parent record;

wait for a response to the query from the device; and

if the response to the query is not received in a pre-determined amount of time, to invalidate the parent record, and to then repeat the above process by applying it recursively to any records that refer to the now-invalidated parent record.

22. The apparatus of claim 17, further comprising an updating mechanism, wherein if the response to the query is not received in a pre-determined amount of time, the updating mechanism is configured to:

retrieve a parent record of the resource record at the client, wherein the parent record refers to the resource record;

issue a query for the parent record;

receive a response to the query from the device, wherein the response includes information for updating the resource record; and

to

update the resource record with the information received in the response.

23. The apparatus of claim 22, wherein the updating mechanism is additionally configured to update the parent record with the information received in the response.

24. The apparatus of claim 17, wherein the apparatus is invoked at a pre-specified time interval.