ACCUMULATOR FOR PREFETCH ABORT

• US 20100088369A1
• Filed: 11/16/2009
• Published: 04/08/2010
• Est. Priority Date: 07/12/2007
• Status: Active Grant

• Current Assignee: ViaSat Incorporated
• Original Assignee: ViaSat Incorporated
• Inventors: Sebastian, William B., Newman, Dan
• Granted Patent: US 8,171,135 B2
• Time in Patent Office: Days
• US Class Current: 709/203
• CPC Class Codes: G06F 16/00 Information retrieval; Database structures therefor; File system structures therefor
• CPC Class Codes: G06F 16/9574 of access to content, e.g. by caching
• CPC Class Codes: H04L 67/55 Push-based network services
• CPC Class Codes: H04L 67/5681 Pre-fetching or pre-delivering data based on network characteristics
• CPC Class Codes: H04L 69/00 Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass networks security protocols H04L9/40; wireless communication networks H04W
• CPC Class Codes: H04L 69/04 Protocols for data compression, e.g. ROHC
• CPC Class Codes: H04L 69/40 for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection management of faults, events, alarms or notifications in data switching networks H04L41/06

Abstract

The present invention relates to systems, apparatus, and methods of determining whether to abort a prefetch operation. Embodiments include accumulator functionality for accumulating object data prior to making an abort determination. Certain embodiments compress the accumulated data to more accurately reflect the cost of pushing the data to the client as part of the prefetch operation. Accumulation and/or compression of the data may provide sufficient data relating to the size of the object to make a useful prefetch abort determination, even where the size of the object cannot be otherwise determined (e.g., from the object data header). Other embodiments store accumulated data (e.g., in compressed or uncompressed form) for use in further optimizing prefetch operations. For example, if an accumulated prefetch is aborted before the object is forwarded to the client, and the client later requests the object, the object may be pushed to the client from server-side storage, rather than retrieving (e.g., and compressing) the object from the content server redundantly.

Claims

1. A method for handling object data as part of a prefetch operation in a communications system, the method comprising:

commencing downloading of object data of a prefetch object from a content server using a prefetch server communicatively coupled with the content server;

accumulating the object data in an accumulator at the prefetch server;

checking an accumulated size of the accumulated object data;

determining, at the prefetch server and as a function of the accumulated size of the accumulated object data, whether the cost of pushing the object data to a client over a communication link of the communications system exceeds the benefit of pushing the object data to the client over the communication link of the communications system; and

when the cost of pushing the object data to the client exceeds the benefit of pushing the object data to the client, aborting the prefetch operation.

2. The method of claim 1, further comprising:

when the cost of pushing the object data to the client does not exceed the benefit of pushing the object data to the client, pushing the object data to the client.

3. The method of claim 1, further comprising:

when the cost of pushing the object data to the client exceeds the benefit of pushing the object data to the client, pushing the object data to an output data store.

4. The method of claim 3, further comprising:

receiving a request for the prefetch object from the client at the prefetch server subsequent to pushing the object data to the output data store; and

satisfying the request by pushing the object data from the output data store to the client.

5. The method of claim 1, further comprising:

compressing the object data into compressed object data at the accumulator.

6. The method of claim 5, wherein checking the accumulated size of the accumulated object data comprises checking the accumulated size of the compressed object data.

7. The method of claim 5, further comprising:

when the cost of pushing the object data to the client exceeds the benefit of pushing the object data to the client, pushing the compressed object data to an output data store.

8. The method of claim 5, further comprising:

when the cost of pushing the object data to the client exceeds the benefit of pushing the object data to the client;

accumulating additional object data in the accumulator at the prefetch server, wherein compressing the object data comprises compressing the additional object data into the compressed object data at the accumulator; and

pushing the compressed object data to an output data store.

9. The method of claim 1, further comprising:

determining, at the prefetch server, a threshold value indicating a threshold size of the prefetch object, such that the cost of pushing the object data to the client is substantially equal to the benefit of pushing the object data to the client when the accumulated size of the accumulated data is substantially equal to the threshold size.

10. The method of claim 9, wherein determining whether the cost of pushing the object data to the client exceeds the benefit of pushing the object data to the client comprises:

determining whether the accumulated size of the accumulated object data exceeds the threshold value.

11. The method of claim 9, wherein the threshold value is determined as a function of at least one of:

a probability of use of the prefetch object by the client;

a communication time relating to communication of the prefetch object between the content server and the prefetch server;

or

a communication time relating to communication of the prefetch object between the prefetch server and the client.

12. The method of claim 9, wherein the threshold value is determined such that:

S=[P*(T_RT+T_PF)*B]/(1−

P),

wherein S indicates the threshold value, P indicates a probability of use of the prefetch object by the client, B indicates a bandwidth of the communication link of the communications system between the prefetch server and the client, T_RT indicates a round-trip time for communicating the prefetch between the prefetch server and the client, and T_PF indicates a prefetch time for downloading the prefetch object from the content server to the prefetch server.

13. The method of claim 1, wherein:

the proxy server is in communication with the content server over a first communication link;

the proxy server is in communication with the client over a second communication link; and

latency of the first communication link is substantially low relative to latency of the second communication link.

14. A system for handling object data as part of a prefetch operation in a communications system, the system comprising:

a proxy server located at a server-side node of the communications system, the proxy server being communicatively coupled with a content server and with a client located at a client-side node of the communications system, the proxy server comprising;

an accumulator configured to accumulate object data of a prefetch object; and

a prefetch server, communicatively coupled with the accumulator and configured to;

download the object data from the content server to the accumulator;

check an accumulated size of the accumulated object data;

determine, as a function of the accumulated size of the accumulated object data, whether the cost of pushing the object data to the client over a communication link of the communications system exceeds the benefit of pushing the object data to the client over the communication link of the communications system; and

when the cost of pushing the object data to the client exceeds the benefit of pushing the object data to the client, aborting the prefetch operation.

15. The system of claim 14, the prefetch server being further configured to:

push the object data to the client when the cost of pushing the object data to the client does not exceed the benefit of pushing the object data to the client.

16. The system of claim 14, further comprising:

an output data store, communicatively coupled with the proxy server,

wherein the prefetch server is further configured to push the object data to the output data store when the cost of pushing the object data to the client exceeds the benefit of pushing the object data to the client.

17. The system of claim 16, the prefetch server being further configured to:

receive a request for the prefetch object from the client subsequent to pushing the object data to the output data store;

retrieve the object data from the output data store; and

push the object data from the output data store to the client in response to the request.

18. The system of claim 14, further comprising:

a prefetch compressor, communicatively coupled with the accumulator and configured to compress the object data into compressed object data at the accumulator.

19. The system of claim 14, the prefetch server being further configured to:

determine a threshold value indicating a threshold size of the prefetch object, such that the cost of pushing the object data to the client exceeds the benefit of pushing the object data to the client when the accumulated size of the accumulated data exceeds the threshold size.

20. A machine-readable medium for handling object data as part of a prefetch operation in a communications system, the machine-readable medium having instructions stored thereon which, when executed by a machine, cause the machine to perform steps comprising:

commencing downloading of object data of the prefetch object from a content server communicatively coupled with the machine;

accumulating the object data in an accumulator;

checking an accumulated size of the accumulated object data;

determining, as a function of the accumulated size of the accumulated object data, whether the cost of pushing the object data to a client communicatively coupled with the machine over a communication link of the communications system exceeds the benefit of pushing the object data to the client over the communication link of the communications system; and

when the cost of pushing the object data to the client exceeds the benefit of pushing the object data to the client, aborting the prefetch operation.

21. The machine-readable medium of claim 20, the instructions stored thereon, when executed by the machine, causing the machine to perform steps further comprising:

when the cost of pushing the object data to the client does not exceed the benefit of pushing the object data to the client, pushing the object data to the client.

22. The machine-readable medium of claim 20, the instructions stored thereon, when executed by the machine, causing the machine to perform steps further comprising:

when the cost of pushing the object data to the client exceeds the benefit of pushing the object data to the client, pushing the object data to an output data store communicatively coupled with the machine.

23. The machine-readable medium of claim 20, the instructions stored thereon, when executed by the machine, causing the machine to perform steps further comprising:

compressing the object data into compressed object data at the accumulator.

24. The machine-readable medium of claim 20, the instructions stored thereon, when executed by the machine, causing the machine to perform steps further comprising:

determining a threshold value indicating a threshold size of the prefetch object, such that the cost of pushing the object data to the client exceeds the benefit of pushing the object data to the client when the accumulated size of the accumulated data exceeds the threshold size.