Data transmission over the internet using a cache memory file system

• US 5,950,205 A
• Filed: 09/25/1997
• Issued: 09/07/1999
• Est. Priority Date: 09/25/1997
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Aviani, James A. Jr.
• Primary Examiner(s): Lintz, Paul R.
• Assistant Examiner(s): Colbert, Ella
• Application Number:
  US08/937,966
• Time in Patent Office: 712 Days
• Field of Search: 707/103, 707/205, 710/5, 710/36, 711/129, 711/162, 711/134, 711/135, 345/502, 348/7, 395/670, 395/674, 395/675, 395/200.49, 395/200.61
• US Class Current: 1/1
• CPC Class Codes: G06F 12/123 with age lists, e.g. queue, most recently used [MRU] list or least recently used [LRU] list
• CPC Class Codes: G06F 16/316 Indexing structures
• CPC Class Codes: Y10S 707/99944 Object-oriented database structure
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

A method for storing a plurality of multimedia objects in a cache memory is described. First ones of the multimedia objects are written into the cache memory sequentially from the beginning of the cache memory in the order in which they are received. When a first memory amount from a most recently stored one of the first multimedia objects to the end of the cache memory is insufficient to accommodate a new multimedia object, the new multimedia object is written from the beginning of the cache memory, thereby writing over a previously stored one of the first multimedia objects. Second ones of the multimedia objects are then written into the cache memory sequentially following the new multimedia object in the order in which they are received, thereby writing over the first ones of the multimedia objects. This cycle is repeated, thereby maintaining a substantially full cache memory.

Claims

1. A method for storing a first object in a cache memory using a write pointer to indicate a most recently allocated memory portion, and a flush pointer to indicate a most recently flushed object, the method comprising:

(A) determining a size of the first object;

(B) determining a first memory amount available for writing the first object with reference to the write and flush pointers;

(C) where the first memory amount is insufficient to accommodate the first object, moving the flush pointer to the end of a next flushed object immediately following the most recently flushed object, the next flushed object then becoming the most recently flushed object;

(D) performing (B) and (C) until the first memory amount is sufficient to accommodate the first object;

(E) where the first memory amount is sufficient to accommodate the first object, moving the write pointer to allocate a second memory amount corresponding to a first portion of the cache memory, the second memory amount being smaller than the first memory amount and also being sufficient to accommodate the first object; and

(F) writing the first object in the first portion of the cache memory.

2. The method of claim 1 wherein determining the first memory amount comprises determining first available memory between the write and flush pointers.

3. The method of claim 2 wherein the cache memory comprises a beginning and an end, and determining the first memory amount comprises determining second available memory between the write pointer and the end of the cache memory.

4. The method of claim 3 further comprising, where the first memory amount is determined to be insufficient to accommodate the first object based on the second available memory, writing the first object at the beginning of the cache memory.

5. The method of claim 1 further comprising:

determining whether a copy of the first object already exists in the cache memory; and

where the copy exists in the cache memory, preventing subsequent access to the copy.

6. The method of claim 5 wherein determining whether the copy exists in the cache memory comprises referring to a directory of objects which are stored in the cache memory.

7. The method of claim 6 wherein the directory is stored in volatile memory separate from the cache memory.

8. The method of claim 6 wherein preventing subsequent access to the copy comprises deleting a reference to the copy from the directory.

9. The method of claim 6 wherein preventing subsequent access to the copy comprises altering a data field in the cache memory associated with the copy thereby making the copy inaccessible.

10. A cache memory system for storing a first object in a cache memory using a write pointer to indicate a most recently allocated memory portion, and a flush pointer to indicate a most recently flushed object, the cache memory system comprising:

the cache memory; and

a controller which is operable to;

(A) determine a size of the first object;

(B) determine a first memory amount available for writing the first object with reference to the write and flush pointers;

(C) where the first memory amount is insufficient to accommodate the first object, move the flush pointer to the end of a next flushed object immediately following the most recently flushed object, the next flushed object then becoming the most recently flushed object;

(D) perform (B) and (C) until the first memory amount is sufficient to accommodate the first object;

(E) where the first memory amount is sufficient to accommodate the first object, move the write pointer to allocate a second memory amount corresponding to a first portion of the cache memory, the second memory amount being smaller than the first memory amount and also being sufficient to accommodate the first object; and

(F) write the first object in the first portion of the cache memory.

11. A method for storing a plurality of multimedia objects in a cache memory, the cache memory having a beginning and an end, the method comprising:

(A) writing first ones of the multimedia objects into the cache memory sequentially from the beginning of the cache memory in the order in which the first ones of the multimedia objects are received;

(B) when a first memory amount from a most recently stored one of the first multimedia objects to the end of the cache memory is insufficient to accommodate a new multimedia object, writing the new multimedia object from the beginning of the cache memory, thereby writing over one of the first ones of the multimedia objects;

(C) writing second ones of the multimedia objects into the cache memory sequentially following the new multimedia object in the order in which the second ones of the multimedia objects are received, thereby writing over the first ones of the multimedia objects; and

(D) repeating (B) and (C).

12. The method of claim 11 further comprising creating a corresponding entry in a directory for each of the multimedia objects written into the cache memory.

13. The method of claim 12 wherein the directory is stored in volatile memory separate from the cache memory.

14. The method of claim 11 further comprising deleting a corresponding entry from a directory for each of the plurality of multimedia objects which are written over.

15. The method of claim 11 further comprising:

indicating an allocated portion of the cache memory with a write pointer;

indicating a flushed multimedia object with a flush pointer; and

for each particular multimedia object written into the cache memory,

moving the flush pointer past at least one previously stored multimedia object thereby flushing the at least one multimedia object; and

moving the write pointer to allocate memory for the particular multimedia object.

16. A cache memory system for storing a plurality of multimedia objects comprising:

a cache memory having a beginning and an end;

a controller which is operable to;

(A) write first ones of the multimedia objects into the cache memory sequentially from the beginning of the cache memory in the order in which the first ones of the multimedia objects are received;

(B) when a first memory amount from a most recently stored one of the first multimedia objects to the end of the cache memory is insufficient to accommodate a new multimedia object, write the new multimedia object from the beginning of the cache memory, thereby writing over a previously stored one of the first multimedia objects;

(C) write second ones of the multimedia objects into the cache memory sequentially following the new multimedia object in the order in which the second ones of the multimedia objects are received, thereby writing over the first ones of the multimedia objects; and

(D) repeat (B) and (C).

17. A method for accessing multimedia objects stored in a cache memory comprising:

in volatile memory associated with and separate from the cache memory, providing a directory of the multimedia objects comprising data stored with the multimedia objects in the cache memory; and

accessing the multimedia objects using the directory.

18. The method of claim 17 further comprising, where the directory is lost from the volatile memory, subsequently rebuilding the directory in the volatile memory from the data in the cache memory.

19. The method of claim 18 wherein the data comprises a plurality of data fields each of which is stored with an associated one of the multimedia objects.

20. The method of claim 19 wherein rebuilding the directory comprises sequentially reading the data fields associated with the multimedia objects and constructing the directory from information stored therein.

21. A cache memory system for storing multimedia objects comprising:

a cache memory for storing the multimedia objects in a sequential manner in the order in which the multimedia objects are received, later stored ones of the multimedia objects being written over earlier stored ones of the multimedia objects; and

volatile memory associated with and separate from the cache memory for storing a directory for facilitating access to the multimedia objects stored in the cache memory.

22. A method for storing a first object in a cache memory using a write pointer to indicate a most recently allocated memory portion, and a flush pointer to indicate a most recently flushed object, the method comprising:

(A) determining a size of the first object;

(B) determining a first memory amount available for writing the first object with reference to the write and flush pointers;

(C) where the first memory amount is insufficient to accommodate the first object, moving the flush pointer to the end of a next flushed object immediately following the most recently flushed object, the next flushed object then becoming the most recently flushed object;

(D) performing (B) and (C) until the first memory amount is sufficient to accommodate the first object;

(E) where the first memory amount is sufficient to accommodate the first object, moving the write pointer to allocate a second memory amount corresponding to a first portion of the cache memory, the second memory amount being smaller than the first memory amount and also being sufficient to accommodate the first object; and

(F) writing the first object in the first portion of the cache memory.

23. At least one computer readable medium containing program instructions for storing a plurality of multimedia objects in a cache memory, the cache memory having a beginning and an end, said at least one computer readable medium comprising:

computer readable code for writing first ones of the multimedia objects into the cache memory sequentially from the beginning of the cache memory in the order in which the first ones of the multimedia objects are received;

computer readable code for, when a first memory amount from a most recently stored one of the first multimedia objects to the end of the cache memory is insufficient to accommodate a new multimedia object, writing the new multimedia object from the beginning of the cache memory, thereby writing over one of the first ones of the multimedia objects; and

computer readable code for writing second ones of the multimedia objects into the cache memory sequentially following the new multimedia object in the order in which the second ones of the multimedia objects are received, thereby writing over the first ones of the multimedia objects.

24. At least one computer readable medium containing program instructions for storing a first object in a cache memory using a write pointer to indicate a most recently allocated memory portion, and a flush pointer to indicate a most recently flushed object, said at least one computer readable medium comprising:

computer readable code for determining a size of the first object;

computer readable code for determining a first memory amount available for writing the first object with reference to the write and flush pointers;

computer readable code for, where the first memory amount is insufficient to accommodate the first object, moving the flush pointer to the end of a next flushed object immediately following the most recently flushed object, the next flushed object then becoming the most recently flushed object;

computer readable code for determining the first memory amount and moving the flush pointer until the first memory amount is sufficient to accommodate the first object;

computer readable code for, where the first memory amount is sufficient to accommodate the first object, moving the write pointer to allocate a second memory amount corresponding to a first portion of the cache memory, the second memory amount being smaller than the first memory amount and also being sufficient to accommodate the first object; and

computer readable code for writing the first object in the first portion of the cache memory.