Network Object Cache Engine

• US 20070050662A1
• Filed: 07/31/2006
• Published: 03/01/2007
• Est. Priority Date: 06/08/1998
• Status: Active Grant

• Current Assignee: CA, Inc. (d/b/a CA Technologies) (Broadcom, Inc.)
• Original Assignee: Blue Coat Systems Incorporated (Gen Digital Inc.)
• Inventors: Malcolm, Michael, Zarnke, Robert
• Granted Patent: US 7,539,818 B2
• Time in Patent Office: Days
• US Class Current: 714/4
• CPC Class Codes: G06F 11/1435 using file system or storage system metadata
• CPC Class Codes: G06F 12/0813 with a network or matrix configuration
• CPC Class Codes: G06F 16/9574 of access to content, e.g. by caching

Abstract

The invention provides a method and system for caching information objects transmitted using a computer network. A cache engine determines directly when and where to store those objects in a memory (such as RAM) and mass storage (such as one or more disk drives), so as to optimally write those objects to mass storage and later read them from mass storage, without having to maintain them persistently. The cache engine actively allocates those objects to memory or to disk, determines where on disk to store those objects, retrieves those objects in response to their network identifiers (such as their URLs), and determines which objects to remove from the cache so as to maintain sufficient operating space. The cache engine collects information to be written to disk in write episodes, so as to maximize efficiency when writing information to disk and so as to maximize efficiency when later reading that information from disk. The cache engine performs write episodes so as to atomically commit changes to disk during each write episode, so the cache engine does not fail in response to loss of power or storage, or other intermediate failure of portions of the cache. The cache engine also stores key system objects on each one of a plurality of disks, so as to maintain the cache holographic in the sense that loss of any subset of the disks merely decreases the amount of available cache. The cache engine also collects information to be deleted from disk in delete episodes, so as to maximize efficiency when deleting information from disk and so as to maximize efficiency when later writing to those areas having former deleted information. The cache engine responds to the addition or deletion of disks as the expansion or contraction of the amount of available cache.

Claims

1. A cache engine, comprising a processor communicatively coupled to a cache having a memory and a mass storage unit, the processor operable under the control of computer-readable instructions to maintain a plurality of network objects in the cache such that at least some of the network objects are written from the memory to the mass storage unit on occasion.

2. The cache engine of claim 1, wherein the processor is operable under the control of the computer-readable instructions to maintain the plurality of network objects in the cache such that at least some of the network objects are written from the memory to the mass storage unit on occasion so as to maintain more frequently accessed ones of the network objects in the memory.

3. An apparatus for maintaining a set of network objects comprising a processor for controlling a cache mechanism configured to cache a plurality of objects including said set of network objects, said processor in communication with a network and configured to send at least one of said set of network objects over said network;

a mass storage associated with said cache mechanism, in communication with said processor;

a memory, associated with said cache mechanism, in communication with said processor and said mass storage;

a hash mechanism configured to locate any of said plurality of objects in said cache mechanism, responsive to an object identifier; and

an object storage mechanism, responsive to said hash mechanism, configured to transfer one or more of said plurality of objects between said memory and said mass storage.

4. The apparatus of claim 3, wherein said cache mechanism is organized into a plurality of blocks and the hash mechanism returns a block pointer to access any of said plurality of objects stored in said cache mechanism.

5. The apparatus of claim 4, wherein said plurality of blocks of the mass storage are directly accessed independently of any filesystem imposed on the mass storage.

6. The apparatus of claim 3, wherein the object storage mechanism further includes a delayed write means for performing an atomic write episode to write a plurality of blocks containing one ore more of said plurality of objects to said mass storage.

7. The apparatus of claim 4, wherein the object storage mechanism further includes an optimization means for minimizing the time required to transfer said plurality of blocks.

8. The apparatus of claim 3, wherein the mass storage includes a plurality of disk drives and each of said plurality of disk drives is associated with a corresponding disk set descriptor object, each of said corresponding disk set descriptor objects referenced by a disk set object.

9. The apparatus of claim 8, further including a dynamic mass storage configuration means for updating said disk set object and creating or modifying said corresponding disk set descriptor object responsive to the addition, removal, failure or replacement of one or more of said plurality of disk drives while said apparatus continues to operate.

10. A computer controlled method for maintaining a set of network objects, comprising controlling a cache mechanism configured to cache a plurality of objects including said set of network objects;

locating any of said plurality of objects in said cache mechanism, responsive to an object identifier;

atomically transferring, responsive to the step of locating, one or more of said plurality of objects between a memory and a mass storage; and

sending at least one of said set of network objects over said network.

11. The computer controlled method of claims 10, wherein said cache mechanism is organized into a plurality of blocks and a hash mechanism returns a block pointer to access any of said plurality of objects stored in said cache mechanism.

12. The computer controlled method of claim 10, further including performing an atomic write episode to write a plurality of blocks containing one or more of said plurality of objects to said mass storage.

13. The computer controlled method of claim 10, further including minimizing the time required to transfer said plurality of blocks