BRIEF DESCRIPTION OF DRAWINGS
The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will be understood best by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:
FIG. 1 is an exemplary computer network;
FIG. 2 describes programs and files in a memory on a computer;
FIG. 3 is a flowchart of a Configuration Component;
FIG. 4 is a flowchart of a Table Entry Component;
FIG. 5 is a flowchart of a Sort Component;
FIG. 6 is a flowchart of a Eviction Component; and
FIG. 7 is an example of tables used by the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The principles of the present invention are applicable to a variety of computer hardware and software configurations. The term “computer hardware” or “hardware,” as used herein, refers to any machine or apparatus that is capable of accepting, performing logic operations on, storing, or displaying data, and includes without limitation processors and memory. The term “computer software” or “software,” refers to any set of instructions operable to cause computer hardware to perform an operation. A “computer,” as that term is used herein, includes without limitation any useful combination of hardware and software, and a “computer program” or “program ” includes without limitation any software operable to cause computer hardware to accept, perform logic operations on, store, or display data. A computer program may, and often is, comprised of a plurality of smaller programming units, including without limitation subroutines, modules, functions, methods, and procedures. Thus, the functions of the present invention may be distributed among a plurality of computers and computer programs. The invention is described best, though, as a single computer program that configures and enables one or more general-purpose computers to implement the novel aspects of the invention. For illustrative purposes, the inventive computer program will be referred to as the Eviction Candidate Sorting Tool” (ECST).
Additionally, the ECST is described below with reference to an exemplary network of hardware devices, as depicted in FIG. 1. A “network” comprises any number of hardware devices coupled to and in communication with each other through a communications medium, such as the Internet. A “communications medium” includes without limitation any physical, optical, electromagnetic, or other medium through which hardware or software can transmit data. For descriptive purposes, exemplary network 100 has only a limited number of nodes, including workstation computer 105, workstation computer 110, server computer 115, and persistent storage 120. Network connection 125 comprises all hardware, software, and communications media necessary to enable communication between network nodes 105-120. Unless otherwise indicated in context below, all network nodes use publicly available protocols or messaging services to communicate with each other through network connection 125.
ECST 200 typically is stored in a memory, represented schematically as memory 220 in FIG. 2. The term “memory,” as used herein, includes without limitation any volatile or persistent medium, such as an electrical circuit, magnetic disk, or optical disk, in which a computer can store data or software for any duration. A single memory may encompass and be distributed across a plurality of media. Further ECST 200 may reside in more than one memory distributed across different computers, servers, logical partitions or other hardware devices. The elements depicted in memory 220 may be located in or distributed across separate memories in any combination, and ECST 200 may be adapted to identify, locate and access any of the elements and coordinate actions, if any, by the distributed elements. Thus, FIG. 2 is included merely as a descriptive expedient and does not necessarily reflect any particular physical embodiment of memory 220. As depicted in FIG. 2, though, memory 220 may include additional data and programs. Of particular import ECST 200, memory 220 may include eviction mechanism 230, objects in cache 240, configuration file 250, evict entry table 260 and disk location table 270 with which ECST 200 interacts. ECST 200 has four components: configuration component 300, table entry component 400, sort component 500 and eviction component 600. Eviction mechanism 230 exists in the art, and is not disclosed here. Eviction mechanism 230 includes without limitation known database tracking eviction programs, algorithms, routines or subroutines. Eviction mechanism 230 is adapted to communicate with the various components of ECST 200, particularly by asking eviction component 600 to identify candidate objects 240 to remove from cache.
FIG. 3 shows configuration component 300 started by a computer system administrator (310). Configuration component 300 provides prompts for the administrator to made changes (321). The prompts may be text in a data file or may include graphical representations such as radio buttons or drop down menus. If the administrator wants to change the settings of evict entry table 260 (314), classes are added or removed from the table (316) and the changes are saved to configuration file 250 (318). Classes fields in a database table, in this case a class corresponds to specific object metadata attribute. Classes selected for evict entry table 260 should only include those object metadata attributes necessary to identify candidates for eviction. If the administrator wants to change the settings of disk location table 270 (320), classes are added or removed from the table (322) and the changes are save to configuration file 250 (324). Classes selected for disk location table 270 should only include those object metadata attributes necessary to locate identified candidates for eviction. If the administrator wants to change the sort criteria (326), classes are added, removed or reordered (328) and the changes are save to configuration file 250 (330). Classes and sort order selected for the sort criteria should match as close as possible the eviction algorithm used by eviction mechanism 230. If the administrator is finished making configuration changes (332), configuration component 300 stops (334). An embodiment of configuration component 300 automatically configures itself based on the settings used by eviction mechanism 230.
Table entry component 400, shown in FIG. 4, starts whenever an object 240 is saved to cache (410). Table entry component 400 references the class settings for evict entry table 260 and disk location table 270 from Configuration file 250 (412). Table entry component 400, extracts the relevant attributes such as a hashed identifier, file size or last access time from the metadata of object 240 (414) and enters the attributes as classes in evict entry table 260 (416) and disk location table 270 (418). A set of objects sharing the same attributes can be included in the same class in evict entry table 260. The entry from disk location table 270 is mapped to the entry of evict entry table 260 (420) using a disk location identifier. After initiating sort component 500 (422), table entry component 400 stops (424).
Referring to FIG. 5, Sort component 500 starts when initiated by table entry component 400 or eviction component 600 (510). Sort component 500 may also start when initiated by eviction mechanism 230. Sort component 500 references the sort criteria saved in configuration file 250 (512), reorders the entries in evict entry table 260 based on the sort criteria (514) then stops (516).
Referring to FIG. 6, eviction component 600 starts when eviction mechanism 230 indicates a need for the identity of candidates to delete from cache (610). Eviction component 600 identifies a candidate for eviction by selecting the first entry in a previously sorted evict entry table 260 (612). Eviction component 600 references the mapped entry to disk location table 270 (614) to locate the object 240 in the cache (616). Eviction component 600 compares metadata attributes of the object in object cache 240 to the eviction criteria used by eviction mechanism 230 (618). If the eviction criteria is not met (620), eviction component 600 determines if another object in disk that shares the same set of attributes as object 240 (622) and repeats the process of verifying whether the other object meets the eviction criteria (614-620). If at step 622, another object does not share the same set of attributes, eviction component 600 initiates sort component 500 (624) and repeats the process of identifying and verifying a new eviction candidate (612-620). If the eviction criteria is met by object 240 in cache, the identity of the object is sent to eviction mechanism 230 for deletion (626). Eviction component 600 confirms eviction of the candidate (628) and removes the corresponding entries from evict entry table 260 and disk location table 270 (630). Eviction component 600 initiates sort component 500 (632) to reorder the remaining entries, and then stops (634).
FIG. 7 depicts an example of ECST 200 interacting with evict entry table 260 and disk location table 270. Object metadata 710 is an example of metadata associated with an object in cache 240. First arrow 720 represents table entry component 400 extracting certain classes of attributes from object metadata 710, and the extracted attributes are shown as evict entry 730. The extracted attributes include the creation time “CT5,” expiration time “ET5,” size “1.20 MB” and file type “.wav.” Object in cache 240 is assigned to disk location identifier “DLI5.” Second arrow 725 represents table entry component 400 extracting physical location attributes from object metadata 710, shown in FIG. 7 as disk entry 735. Third arrow 740 represents table entry component 400 placing evict entry 730 into evict entry table 750 as Entry 5. Evict entry table 750 contains previously placed entries (Entry 1-Entry 4) with extracted attributes corresponding to other cached objects. Fourth arrow 745 represents table entry component 400 placing disk entry 735 into disk location table 790. Disk location table 790 contains previously placed entries describing the location of other cached objects. Fifth arrow 760 represents sort component 500 reordering the entries in evict entry table 750 based on file size. The reordered table is shown as evict entry table 770. Sixth arrow 780 represents eviction component 600 referencing the physical location of object in cache 240 in disk location table 790. ECST 200 passes the identity of object in cache 240 to eviction mechanism 230 for deletion.
A preferred form of the invention has been shown in the drawings and described above, but variations in the preferred form will be apparent to those skilled in the art. The preceding description is for illustration purposes only, and the invention should not be construed as limited to the specific form shown and described. The scope of the invention should be limited only by the language of the following claims.
Patent Application
20080071992
