Asynchronous Cache Refresh for Systems with a Heavy Load

• US 20110060881A1
• Filed: 09/10/2009
• Published: 03/10/2011
• Est. Priority Date: 09/10/2009
• Status: Active Grant

• Current Assignee: Red Hat, Inc. (International Business Machines Corporation)
• Original Assignee: Red Hat, Inc. (International Business Machines Corporation)
• Inventors: Gallagher, Stephen J.
• Granted Patent: US 8,539,160 B2
• Time in Patent Office: Days
• US Class Current: 711/133
• CPC Class Codes: G06F 16/9574 of access to content, e.g. by caching

Abstract

A method and system to refresh a data entry in a cache before the data entry expires. The system includes a client computing system coupled to a server via a network connection. In response to a request for data access, the client computing system locates a data entry in a cache and determines whether the data entry in the cache has exceeded a refresh timeout since a last update of the data entry. If the data entry in the cache has exceeded the refresh timeout, the client computing system retrieves the data entry found in the cache in response to the request without waiting for the data entry to be refreshed, and requests a refresh of the data entry from the server via the network connection.

Claims

1. A method, implemented by a client computing system programmed to perform the following, comprising:

locating, by the client computing system locally coupled to a cache, a data entry in the cache in response to a request to access the data entry;

determining, by the client computing system, whether the data entry has exceeded a refresh timeout since a last update of the data entry in the cache; and

in response to a determination that the data entry has exceeded the refresh timeout, returning, by the client computing system, the data entry located in the cache in response to the request without waiting for the data entry to be refreshed, and requesting a refresh of the data entry from a central server via a network connection.

2. The method of claim 1, wherein the client computing system is a Web server that receives a user'"'"'s request to access a Web page.

3. The method of claim 1, wherein the refresh timeout is less than an expiration timeout, which is a value indicating when the data entry in the cache expires.

4. The method of claim 1, further comprising:

indicating to an application requesting the data entry that the requesting application can begin processing a next request such that the next request is not blocked by the request to access the data entry.

5. The method of claim 1, further comprising:

in response to a determination that the data entry is not in the cache or is expired since the last update, retrieving data from the central server to update the data entry in the cache.

6. The method of claim 1, further comprising:

queuing only one refresh request out of multiple refresh requests of a same data entry; and

attaching information to the one refresh request to indicate which requesting applications are requesting the same data entry.

7. The method of claim 1, wherein the central server is one of the following:

a Lightweight Directory Access Protocol (LDAP) server, an NIS server, an NIS+ server, or an SQL database server.

8. A computer readable storage medium including instructions that, when executed by a processing system, cause the processing system to perform a method comprising:

locating a data entry in a cache in response to a request to access the data entry;

determining whether the data entry has exceeded a refresh timeout since a last update of the data entry in the cache; and

in response to a determination that the data entry has exceeded the refresh timeout, returning the data entry located in the cache in response to the request without waiting for the data entry to be refreshed, and requesting a refresh of the data entry from a central server via a network connection.

9. The computer readable storage medium of claim 8, wherein the cache is locally coupled to a Web server that locates the data entry in the cache.

10. The computer readable storage medium of claim 8, wherein the refresh timeout is less than an expiration timeout, which is a value indicating when the data entry in the cache expires.

11. The computer readable storage medium of claim 8, further comprising:

indicating to an application requesting the data entry that the requesting application can begin processing a next request such that the next request is not blocked by the request to access the data entry.

12. The computer readable storage medium of claim 8, further comprising:

in response to a determination that the data entry is not in the cache or is expired since the last update, retrieval data from the central server to update the data entry in the cache.

13. The computer readable storage medium of claim 8, further comprising:

queuing only one refresh request out of multiple refresh requests of a same data entry; and

attaching information to the one refresh request to indicate which requesting applications are requesting the same data entry.

14. The computer readable storage medium of claim 8, wherein the central server is one of the following:

a Lightweight Directory Access Protocol (LDAP) server, an NIS server, an NIS+ server, or an SQL database server.

15. A system comprising:

a client computing system coupled to a central server via a network connection; and

a cache locally coupled to the client computing system,

wherein the client computing system comprises a data manager to;

locate a data entry in the cache in response to a request to access the data entry,

determine whether the data entry has exceeded a refresh timeout since a last update of the data entry in the cache; and

in response to a determination that the data entry has exceeded the refresh timeout, return the data entry located in the cache in response to the request without waiting for the data entry to be refreshed, and request a refresh of the data entry from the central server via the network connection.

16. The system of claim 15, wherein the client computing system is a Web server that receives a user'"'"'s request to access a Web page.

17. The system of claim 15, wherein the refresh timeout is less than an expiration timeout, which is a value that indicates when the data entry in the cache expires.

18. The system of claim 15, wherein the central server is one of the following:

a Lightweight Directory Access Protocol (LDAP) server, an NIS server, an NIS+ server, or an SQL database server.

19. The system of claim 15, further comprises:

a refresh request queue, in which the request for refresh of the data entry is queued with other refresh requests to be scheduled for delivery to the central server, wherein the refresh request queue enqueues only one refresh request out of multiple refresh requests of a same data entry.

20. The system of claim 15, wherein the refresh timeout for different categories of data entries are configured to different values.