FILE SYSTEM HAVING TRANSACTION RECORD COALESCING

• US 20110072060A1
• Filed: 11/29/2010
• Published: 03/24/2011
• Est. Priority Date: 07/01/2005
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: QNX Software Systems Company (Blackberry Limited)
• Inventors: Dodge, Dan
• Granted Patent: US 8,412,752 B2
• Time in Patent Office: Days
• US Class Current: 707/826
• CPC Class Codes: G06F 16/50 of still image data

Abstract

An electronic data system comprises memory storage having stored data, file system software, and a transaction file. The transaction file is maintained by the file system software, and includes a plurality of transaction records corresponding to transactions that have been or are to be executed on one or more files and/or the or more directories of the file system. The file system software operates to organize and maintain the stored data in the files and directories and also to coalesce multiple transaction records meeting one or more criteria into fewer coalesced transaction records. The physical memory space required by the transaction file is reduced by the transaction record coalescing. The coalesced transaction records may be constructed so that they represent a logical result of applying each transaction record of a transaction record set in chronological order. Once the coalesced transaction records have been committed in the file system, the physical memory used by the original transaction records in the set may be reclaimed for further use (e.g., to store further transaction records) or may be otherwise removed from further use (e.g., when the physical memory is located in a block of memory in a flash-like memory device that has reached its maximum number of write and/or erase cycles).

Claims

1. An electronic data system comprising:

a memory comprising stored data;

a file system code executable to organize and maintain the stored data in a plurality of files and a plurality of directories;

a transaction file maintained by the file system code in the memory, the transaction file comprising a plurality of transaction records stored on the memory, where the transaction records correspond to a plurality of transactions on at least one of the files and the directories, where each transaction record of the transaction records comprises a header section and a data section, where the header section of each respective one of the transaction records identifies at least one of a file and a directory associated with the data section of the respective one of the transaction records, and the file and the directory are included in at the least one of the files and the directories; and

where the file system code coalesces the transaction records stored on the memory by;

scanning the header section of each transaction record of the transaction records for identification of a first subset of the transaction records directed to a same file, a second subset of the transaction records directed to a same logical portion of one of the files, and a third subset of the transaction records directed to a same directory; and

at least one of;

combining the first subset of the transaction records identified during the scanning as directed to the same file into one or more first coalesced transaction records and releasing one or more transaction records of the first subset of the transaction records identified as directed to the same file as free memory thereby reducing an amount of the memory used by the transaction file,

combining the second subset of the transaction records identified during the scanning as directed to the same logical portion of the file into one or more second coalesced transaction records and releasing one or more transaction records of the second subset of the transaction records identified as directed to the same logical portion of the file as free memory thereby reducing the amount of the memory used by the transaction file, and

combining the third subset of the transaction records identified during the scanning as directed to the same directory into one or more third coalesced transaction records and releasing one or more transaction records of the third subset of the transaction records identified as directed to the same directory as free memory thereby reducing the amount of the memory used by the transaction file;

where the header section of each respective one of the transaction records further comprises a first field from which the file system code determines a starting address at which the data section is to be written into the at least one of the file and the directory identified in the header section, and a second field from which the file system code determines an amount of the at least one of the file and the directory that is to be overwritten.

2. The electronic data system of claim 1 where the file system code is executable to assign one or more transaction identifiers to the one or more first coalesced transaction records, the one or more second coalesced transaction records and the one or more third coalesced transaction records.

3. The electronic data system of claim 1 where the file system code further coalesces the transaction records stored on the memory by:

generating a first transaction record set comprising the first subset of the transaction records directed to the same file,

generating a second transaction record set comprising the second subset of the transaction records directed to the same logical portion of the file, and

generating a third transaction record set comprising the third subset of the transaction records directed to the same directory pursuant to coalescing the transaction records.

4. The electronic data system of claim 3 where the first, the second, and the third transaction record sets comprise a plurality of pointers to a plurality of locations in the transaction file of the first, the second, and the third subset of the transaction records, respectively.

5. The electronic data system of claim 3 where the first, the second, and the third transaction record sets are formatted in a same manner as a manner in which a corresponding transaction record of the transaction records is formatted in the transaction file.

6. The electronic data system of claim 3 where the file system code is further executable to:

apply, pursuant to generating the first transaction record set, the first subset of the transaction records directed to the same file in a first chronological sequence corresponding to a first time order in which each transaction record of the first subset of the transaction records directed to the same file originally occurred;

apply, pursuant to generating the second transaction record set, the second subset of the transaction records directed to the same logical portion of a file in a second chronological sequence corresponding to a second time order in which each transaction record of the second subset of the transaction records directed to the same logical portion of the file occurred; and

apply, pursuant to generating the third transaction record set, the third subset of the transaction records directed to the same directory in a third chronological sequence corresponding to a third time order in which each transaction record of the second subset of the transaction records directed to the same directory occurred.

7. The electronic data system of claim 3 where file system code is executable to:

combine the transaction records of the first transaction record set to reduce a first number of transaction records directed to the same file;

combine the transaction records of the second transaction record set to reduce a second number of transaction records directed to the same logical portion of a file; and

combine the transaction records of the third transaction record set to reduce a third number of transaction records directed to the same directory.

8. The electronic data system of claim 1 where the file system code is executable to reclaim a residual physical storage space that results from coalescing the transaction records for use in storing additional transaction records.

9. The electronic data system of claim 1 where each header section of each transaction record of the transaction records further comprises a status field which is indicative of whether each transaction record of the transaction records has been committed.

10. A method comprising:

providing a plurality of files and a plurality of directories stored on a memory device;

providing, on the memory device, a transaction file comprising a plurality of transaction records, where each respective one of the transaction records comprises a header section and a data section, where the header section of each respective one of the transaction records identifies at least one of the files and the directories that is associated with the data section of the respective one of the transaction records;

coalescing the transaction records stored on the memory device with a processor by;

scanning the header section of each of the transaction records for identification of a first subset of the transaction records directed to a same file;

combining the first subset of the transaction records identified during the scanning as directed to the same file into one or more first coalesced transaction records; and

releasing one or more transaction records of the first subset of the transaction records identified as directed to the same file for a reduction in an amount of memory used by the transaction file,

where the header section of each respective one of the transaction records further comprises a first field indicating a starting address at which the data section is to be written into the at least one of the file and the directory, and where the header section of each respective one of the transaction records further comprises a second field indicating an amount of the at least one of the file and the directory that is to be overwritten.

11. The method of claim 10, wherein coalescing further comprises:

scanning the header section of each of the transaction records for identification of a second subset of the transaction records directed to a same logical portion of one of the files;

combining the second subset of the transaction records identified during the scanning as directed to the same logical portion of the file into one or more second coalesced transaction records; and

releasing one or more transaction records of the second subset of the transaction records identified as directed to the same logical portion of the file for a further reduction in the amount of memory used by the transaction file.

12. The method of claim 10, wherein coalescing further comprises:

scanning the header section of each of the transaction records for identification of a second subset of the transaction records directed to a same directory;

combining the second subset of the transaction records identified during the scanning as directed to the same directory into one or more second coalesced transaction records; and

releasing one or more transaction records of the second subset of the transaction records identified as directed to the same directory for a further reduction in the amount of memory used by the transaction file.

13. The method of claim 11, wherein coalescing further comprises:

generating a first transaction record set from the first subset of transaction records directed to the same file; and

generating a second transaction record set from the second subset of the transaction records directed to the same logical portion of the file.

14. The method of claim 12, wherein coalescing further comprises:

generating a first transaction record set from the first subset of transaction records directed to the same file; and

generating a second transaction record set from the second subset of the transaction records directed to the same directory.

15. The method of claim 13 where:

combining the transaction records of the first transaction record comprises combining the transaction records of the first transaction record set into a first single record directed to the same file; and

combining the transaction records of the second transaction record set comprises combining the transaction records of the second transaction record set into a second single record directed to the same logical portion of the file.