METHOD FOR COORDINATING UPDATES TO DATABASE AND IN-MEMORY CACHE

• US 20090300286A1
• Filed: 05/28/2008
• Published: 12/03/2009
• Est. Priority Date: 05/28/2008
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Synge, James M.
• Granted Patent: US 8,131,698 B2
• Time in Patent Office: Days
• US Class Current: 711/118
• CPC Class Codes: G06F 16/24539 using cached or materialised query results
• CPC Class Codes: G06F 16/24552 Database cache management

Abstract

A computer method and system of caching. In a multi-threaded application, different threads execute respective transactions accessing a data store (e.g. database) from a single server. The method and system represent status of datastore transactions using respective certain (e.g. Future) parameters.

Results of the said transactions are cached based on transaction status as represented by the certain parameters and on data store determination of a subject transaction. The caching employs a two stage commit and effectively forms a two level cache. One levels maps from datastore keys to entries in the cache. Each entry stores a respective last known commit value. The second level provides an optional mapping from a respective transaction as represented by the corresponding certain parameter to an updated value.

Claims

1. A computer method of caching comprising:

executing a multi-threaded application, different threads executing respective transactions accessing a data store from a single server;

representing status of said transactions;

caching results of said transactions based on transaction status and on data store determination of transaction, such that said caching is accomplished in a two stage commit and effectively forms a two level cache.

2. A method as claimed in claim 1, wherein the data store is a database.

3. A method as claimed in claim 1 wherein the step of representing status of said transactions includes:

for each transaction, using a Future parameter having a Boolean value of true for succeeded/committed and false for failed/rolled back.

4. A method as claimed in claim 3, wherein the two level cache includes:

a mapping from keys to entries in the cache, each entry storing a respective last known commit value; and

an optional mapping from a respective transaction as represented by the corresponding Future parameter to an updated value.

5. The method as claimed in claim 3, wherein the step of caching results of said transactions includes:

for a given transaction, using a flag with the Future parameter, the flag recording transition from performing the given transaction to committing the given transaction and effectively stalling other transactions awaiting conclusion of the given transaction.

6. A method as claimed in claim 5, wherein the flag is a latch.

7. A method as claimed in claim 1, wherein the two level cache is in-memory relative to the multi-threaded application.

8. A computer caching system comprising:

a data store supporting a multi-threaded application, different threads executing respective transactions accessing the data store from a single server;

transaction status indicators representing status of said transactions; and

a cache storing results of the transactions based on transaction status indicators and on data store determinations of transactions, such that said cache employs a 2 phase commit and two level storage.

9. A caching system as claimed in claim 8, wherein the data store is a database.

10. A caching system as claimed in claim 8, wherein the transaction status indicators include:

for each transaction, a Future parameter having a Boolean value of true for succeeded/committed and false for failed/rolled back.

11. A caching system as claimed in claim 10, wherein the two level storage includes:

a mapping from keys to entries in the cache, each entry storing a respective last known commit value; and

an optional mapping from a respective transaction as represented by the corresponding Future parameter to an updated value.

12. A caching system as claimed in claim 10, wherein the cache stores results of the transactions by:

for a given transaction, using a flag with the Future parameter, the flag recording transition from performing the given transaction to committing the given transaction and effectively stalling other transactions awaiting conclusion of the given transaction.

13. A caching system as claimed in claim 12, wherein the flag is a latch.

14. A caching system as claimed in claim 8, wherein the transaction status indicators represent results of computations being performed by the transactions.

15. A caching system as claimed in claim 8, wherein the cache is in-memory relative to the multi-threaded application.

16. An in-memory computer cache comprising:

given a multi-threaded application, different threads executing respective transactions accessing a data store from a single server, a transaction cache storing results of the transactions and having;

a two level storage, one level mapping from data store keys to entries in the cache; and

a second level optionally mapping from a respective transaction to an updated value;

wherein each respective transaction is represented by a corresponding value indicative of computations being preferred by the transaction and the cache employs a two phase commit.

17. A computer cache as claimed in claim 16, wherein the data store is a database.

18. A computer cache as claimed in claim 16, wherein the corresponding value is a Boolean value of true for succeeded/committed and false for failed/rolled back.

19. A computer cache as claimed in claim 16, further comprising:

for a given transaction, a flag operably coupled to the second level, the flag recording transition from performing the given transaction to committing the given transaction and effectively stalling other transactions awaiting conclusion of the given transaction.

20. A computer program product for caching results of database transactions, the computer program product comprising:

a computer usable medium having computer usable program code embodied therewith, the computer usable program code comprising;

computer useable code configured to implement a cache having a two stage commit and two levels such that each database transaction sees its produced updated value on top of an effectively shared store of known commit values,

the database transactions accessing a database from a single server.