Computer file system providing looped file structure for post-occurrence data collection of asynchronous events

• US 6,035,367 A
• Filed: 04/03/1997
• Issued: 03/07/2000
• Est. Priority Date: 04/04/1997
• Status: Expired due to Term

• Current Assignee: Avid Technology Incorporated
• Original Assignee: Avid Technology Incorporated
• Inventors: Laws, Richard
• Primary Examiner(s): Chan, Eddie P.
• Assistant Examiner(s): Encarnacion, Yamir
• Application Number:
  US08/835,104
• Time in Patent Office: 1,069 Days
• Field of Search: 360/54, 360/7, 360/8, 711/110, 711/100, 707/100, 707/200, 707/205, 369/60, 369/7, 386/52, 386/124, 348/714
• US Class Current: 711/100
• CPC Class Codes: G06F 16/182 Distributed file systems
• CPC Class Codes: G11B 2220/20 Disc-shaped record carriers
• CPC Class Codes: G11B 27/034 on discs G11B27/036, G11B27/038 take precedence
• CPC Class Codes: Y10S 707/99953 Recoverability
• CPC Class Codes: Y10S 707/99956 File allocation

Abstract

An operating system has a file system which supports writing data to a file in a logical loop of clusters of storage locations. Writing can be performed in looped or unlooped modes, and a transition between looping and non-looped recording may be supported. Recording prior to occurrence of an asynchronous event is performed in a looped mode. After occurrence of the asynchronous event, the data collected in the looped portion is seamlessly merged with subsequently collected data by manipulation of pointers to the clusters by the operating system. By providing such a general structure for use in a file system of a computer, a substantially larger amount of memory is available for looped recording. In fact, several minutes of full motion broadcast quality video may be captured. In addition, by using the file system to handle the storage of data, an application does not need to arrange recorded information on a physical recording medium. Such a file system may be used in any application which collects data for the purpose of capturing the occurrence of an asynchronous event. Such applications include, but are not limited to, motion video recording, surveillance, test data collection, and other types of systems that need to record events that precede some arbitrary "trigger" condition and which may require a large amount of storage.

Claims

1. An operating system for a computer system having a memory system having a plurality of logic blocks of memory storage locations, the operating system providing a file system through which at least one file containing data is made accessible to at least one application program, the operating system comprising:

means for mapping a first file of the at least one file to a first two or more loop blocks of a plurality of blocks;

means for enabling a loop mode of writing to the first file wherein data is written in a continuous loop of the first loop blocks;

means for detecting one or more triggering events;

means for disabling the loop mode in response to a first triggering event;

means for enabling a linear sequence mode of writing to the first file, wherein the means for enabling the linear sequence mode is evoked responsive to the first triggering event; and

means for constructing the first file into a linear sequence of blocks when the loop mode is disabled.

2. The operating system of claim 1, wherein:

the data comprises media data.

3. The operating system of claim 1, wherein:

the first loop blocks have a total actual loop length, and

the operating system further comprises;

means for receiving a requested loop length, and

means for providing that the total actual loop length is at least as great as the requested loop length.

4. The operating system of claim 3, wherein:

the requested loop length is user-selected.

5. The operating system of claim 1, in combination with a motion video recorder.

6. An operating system for a computer system having a memory system having a plurality of logic blocks of memory storage locations, the operating system providing a file system through which at least one file containing data is made accessible to at least one application program, the operating system comprising:

means for mapping a first file of the at least one file to a first two or more loop blocks of a plurality of blocks;

means for enabling a loop mode of writing to the first file wherein data is written in a continuous loop of the first loop blocks;

means for detecting one or more triggering events;

means for disabling the loop mode in response to a first triggering event; and

means for enabling a linear sequence mode of writing to the first file, wherein the means for enabling the linear sequence mode is evoked responsive to the first triggering event; and

means for constructing the first file into a linear sequence of blocks when the loop mode is disabled and the linear sequence mode is enabled.

7. The operating system of claim 6, wherein:

the means for reconstructing comprises

means for determining a last loop block that is the last of the first loop blocks into which data is written prior to disabling the loop mode,

means for determining a first non-loop block that is the first block into which data is written subsequent to enabling the linear sequence mode and that is not a loop block, and

means for mapping the first file to the last loop block and the first non-loop block so that, in the first file, data in the first non-loop block logically sequentially follow immediately after data in the last loop block.

8. The operating system of claim 7, wherein:

the means for reconstructing further comprises

means for mapping the first file to each of the first loop blocks so that, in the first file, data in the first loop blocks logically sequentially follow according to an order in which data was written to the first loop blocks, and

means for mapping the first file to one or more sequential non-loop blocks, if any, into which data is written subsequent to the writing of data to the first non-loop block so that, in the first file, data in the one or more sequential non-loop blocks logically sequentially follow according to an order in which data was written to them.

9. The operating system of claim 8, further comprising:

means for disabling the linear sequential mode in response to a second triggering event;

means for mapping the first file to a second two or more loop blocks of the plurality of blocks not already mapped to the first file; and

means for re-enabling the loop mode of writing to the first file wherein, responsive to the second triggering event, data is written in a continuous loop of the second loop blocks.

10. A method for providing looped and unlooped writing to at least one file of a file system provided by a computer operating system operating on a computer system having a memory system having a plurality of logic blocks of memory storage locations, the at least one file containing data and being accessible to at least one application program, the method comprising the steps of:

mapping a first file of the at least one file to a first two or more loop blocks of the plurality of blocks;

enabling the loop mode of writing to the first file wherein data is written in a continuous loop of the first blocks;

detecting one or more triggering events;

disabling the loop mode in response to a first triggering event;

enabling a linear sequence mode of writing to the first file; and

reconstructing the first file into a linear sequence of blocks when the loop mode is disabled.

11. The method of claim 10, wherein:

the data comprises media data.

12. The method of claim 10, wherein:

the first loop blocks have a total actual loop length, and

the method further comprises the steps of;

receiving a requested loop length, and

providing that the total actual loop length is at least as great as the requested loop length.

13. The method of claim 10, wherein:

the step of enabling a linear sequence mode is taken response to the first triggering event.

14. A method for providing looped and unlooped writing to at least one file of a file system provided by a computer operating system operating on a computer system having a memory system having a plurality of logic blocks of memory storage locations, the at least one file containing data and being accessible to at least one application program, the method comprising the steps of:

mapping a first file of the at least one file to a first two or more loop blocks of the plurality of blocks;

enabling the loop mode of writing to the first file wherein data is written in a continuous loop of the first blocks;

detecting one or more triggering events;

disabling the loop mode in response to a first triggering event;

enabling a linear sequence mode of writing to the first file; and

reconstructing the first file into a linear sequence of blocks when the loop mode is disabled and the linear sequence mode is enabled.

15. The method of claim 14, wherein:

the step of reconstructing comprises the steps of

determining a last loop block that is the last of the first loop blocks into which data is written prior to disabling the loop mode,

determining a first non-loop block that is the first block into which data is written subsequent to enabling the linear sequence mode and that is not a loop block, and

mapping the first file to the last loop block and the first non-loop block so that, in the first file, data in the first non-loop block logically sequentially follow immediately after data in the last loop block.

16. The method of claim 15, wherein:

the step of reconstructing further comprises the steps of

mapping the first file to each of the first loop blocks so that, in the first file, data in the first loop blocks logically sequentially follow according to an order in which data was written to the first loop blocks, and

mapping the first file to one or more sequential non-loop blocks, if any, into which data is written subsequent to the writing of data to the first non-loop block so that, in the first file, data in the one or more sequential non-loop blocks logically sequentially follow according to an order in which data was written to them.

17. The method of claim 16, further comprising the steps of:

disabling the linear sequential mode in response to a second triggering event;

mapping the first file to a second two or more loop blocks of the plurality of blocks not already mapped to the first file; and

re-enabling the loop mode of writing to the first file wherein, responsive to the second triggering event, data is written in a continuous loop of the second loop blocks.

18. A computer system comprising:

a central processing unit;

an operating system that provides a file system having at least one file; and

at least one memory stored system having stored therein a set of application instructions for execution of an application program by the central processing unit in cooperation with the operating system, the memory system also having a plurality of logical blocks of memory storage locations;

wherein;

the file system supports writing data to at least one file and a continuous logical loop of a first plurality of loop blocks of the plurality of logical blocks having a first loop length, wherein the data is accessible to the application program; and

wherein the file system further supports writing data to the at least one file in a logical linear sequence of one or more of a first set of non-loop blocks of a plurality of logical blocks comprised of blocks that are now loop blocks, wherein the data in the first set of non-loop blocks is accessible to the application program;

wherein prior to occurrence of the first synchronous event, the file system provides that data is written to the first plurality of loop blocks, and

responsive to occurrence of the first asynchronous event, the file system provides that data is written to the first set of non-loop blocks and further provides that the data written to the first plurality of loop blocks is logically sequentially linked with data written to the first set of non-loop blocks in an order in which the data was written so that those of the first plurality of loop blocks into which data was written, and those of the first set of non-loop blocks into which data was written, are reconstructed into a linear sequence of blocks accessible to the application program by accessing the file.

19. The computer system of claim 18, wherein:

the file system provides the sequential linking by manipulation of pointers to at least one of the first plurality of loop blocks and at least one of the first set of non-loop blocks.

20. The computer system of claim 18, wherein:

responsive to an occurrence of a second asynchronous event, the file system provides that data is written to a second plurality of loop blocks of the plurality of logical blocks or memory storage locations that do not comprise any of the first plurality of loop blocks into which data has been written or any of the first set of one or more non-loop blocks into which data has been written.

21. The computer system of claim 20, wherein:

responsive to an occurrence of a third asynchronous event, the file system provides that data is written to a second set of one or more non-loop blocks that do not comprise any of the first or second pluralities of loop blocks into which data has been written or any of the first set of one or more non-loop blocks into which data has been written.

22. The computer system of claim 18, wherein:

the data comprises media data.

23. The computer system of claim 18, wherein the computer system is integrated in a motion video recorder.

24. A computer program product for use with a computing system having an operating system that provides a file system having at least one file containing data and being accessible to at least one application program, the computing system further having at least one memory storage system having a plurality of logical blocks of memory storage locations, the computer program product comprising a computer usable medium having embedded therein computer readable program code method steps comprising:

mapping a first file of the at least one file to a first two or more loop blocks of the plurality of blocks;

enabling a loop mode of writing to the first file wherein data is written in a continuous loop of the first loop blocks;

detecting one or more triggering events;

disabling the loop mode in response to a first triggering event;

enabling a linear sequence mode of writing to the first file; and

reconstructing the first file into a linear sequence of blocks when the loop mode is disabled.

25. The computer program product of claim 24, wherein:

the data comprises media data.

26. The computer program product of claim 24, wherein:

the step of enabling a linear sequence mode is taken responsive to the first triggering event.

27. The computer program product of claim 24, wherein the computer program product is used by a motion video camera.

28. A method for providing looped and unlooped writing to at least one file of a file system provided by a computer operating system having an I/O system, the operating system operating on a computer system having a central processing unit (CPU) and a memory system having a plurality of logical blocks of memory storage locations, the memory system having stored therein a set of application instructions for execution of an application program by the CPU in cooperation with the operating system, the at least one file containing data and being accessible to the application program, the method comprising:

initializing a loop control data structure comprising

a first value indicating a user-requested length of the first loop, and

a second value indicating an actual length of the first loop determined to be at least as great as the user-requested length;

opening the at least one file;

determining a first block of the at least one file that is a first write location;

implementing an I/O system control function comprising passing the first and second values of the loop control data structure to the I/O system; and

activating a loop control function of the file system that, based on the first write location and the loop control data structure, enables writing to the first loop.