Automatic Reallocation of Structured External Storage Structures

• US 20110302377A1
• Filed: 06/07/2010
• Published: 12/08/2011
• Est. Priority Date: 06/07/2010
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Elko, David A., Palmer, Stewart L.
• Granted Patent: US 8,341,368 B2
• Time in Patent Office: Days
• US Class Current: 711/152
• CPC Class Codes: G06F 9/5016 the resource being the memory
• CPC Class Codes: G06F 9/5022 Mechanisms to release resources

Abstract

A mechanism for automatic reallocation of shared external storage structures is provided. The shared external storage divides the dynamically allocable storage into fixed sized blocks referred to as allocation units. To create an object of a specific type, the shared external storage uses some number of allocation units. If the object will fit in one allocation unit, then it is placed in one allocation unit. If the object is larger than one allocation unit, then the appropriate number of allocation units is obtained and chained together to contain all of the information of the required object. When an object so allocated is no longer needed, the shared external storage breaks the object down to a set of one or more fixed sized allocation units. The shared external storage then returns the allocation units to the pool of available objects.

Claims

1. A method, in a shared external storage device, for automatic allocation of shared external storage structures, the method comprising:

receiving a request from a client, wherein the request requires allocation of one or more objects of one or more of a set of predetermined object types;

automatically allocating a portion of the shared external storage structures within the shared external storage device for the one or more objects; and

creating the one or more objects from the portion of the shared external storage structures.

2. The method of claim 1, further comprising:

dividing dynamically allocable storage within the shared external storage device into a plurality of fixed sized allocation units; and

generating a free list of the allocation units.

3. The method of claim 2, wherein the one or more objects comprise first object of a first type and a second object of a second type and wherein automatically allocating the portion of the shared external storage structures and creating the one or more objects comprise:

removing an allocation unit from the free list and converting the allocation unit into the first object of the first type; and

removing two or more allocation units from the free list and converting the two or more allocation units into the second object of the second type.

4. The method of claim 3, wherein the request comprises a request for a lock and wherein the first object is a lock entry for the lock, the method further comprising:

recording lock information for the lock in the lock entry.

5. The method of claim 4, further comprising:

responsive to a determination that the lock entry is no longer needed, converting the lock entry into an allocation unit and returning the allocation unit to the free list.

6. The method of claim 4, wherein the second object is a client entry for the client, the method further comprising:

recording, in the client entry, client interest in the lock.

7. The method of claim 6, wherein removing two or more allocation units from the free list and converting the two or more allocation units into an object of the second type comprises:

removing two allocation units from the free list and converting the two allocation units into a single client entry object.

8. The method of claim 6, wherein removing two or more allocation units from the free list and converting the two or more allocation units into an object of the second type comprises:

removing two allocation units from the free list and converting the two allocation units into a client entry object and a client history object, wherein the client entry object and the client history object point to each other.

9. The method of claim 6, further comprising:

modifying the lock entry to point to the client entry.

10. The method of claim 6, further comprising:

responsive to a determination that the client entry is no longer needed, converting the client entry into two allocation units and returning the two allocation units to the free list.

11. A computer program product comprising a computer readable storage medium having a computer readable program stored therein, wherein the computer readable program, when executed on a shared external storage device, causes the shared external storage device to:

receive a request from a client of the shared external storage device, wherein the request requires allocation of one or more objects of one or more of a set of predetermined object types;

automatically allocate a portion of shared external storage structures within the shared external storage device for the one or more objects; and

create the one or more objects from the portion of the shared external storage structures.

12. The computer program product of claim 11, wherein the computer readable program further causes the shared external storage device to:

divide dynamically allocable storage within the shared external storage device into a plurality of fixed sized allocation units; and

generate a free list of the allocation units.

13. The computer program product of claim 12, wherein the one or more objects comprise a first object of a first type and a second object of a second type and wherein automatically allocating the portion of the shared external storage structures and creating the one or more objects comprise:

removing an allocation unit from the free list and converting the allocation unit into the first object of the first type; and

removing two or more allocation units from the free list and converting the two or more allocation units into the second object of the second type.

14. The computer program product of claim 13, wherein the request comprises a request for a lock and wherein the first object is a lock entry for the lock and wherein the computer readable program further causes the shared external storage device to:

record lock information for the lock in the lock entry.

15. The computer program product of claim 14, wherein the second object is a client entry for the client, the method further comprising:

recording, in the client entry, client interest in the lock.

16. The computer program product of claim 15, wherein removing two or more allocation units from the free list and converting the two or more allocation units into an object of the second type comprises:

removing two allocation units from the free list and converting the two allocation units into a single client entry object.

17. The computer program product of claim 15, wherein removing two or more allocation units from the free list and converting the two or more allocation units into an object of the second type comprises:

removing two allocation units from the free list and converting the two allocation units into a client entry object and a client history object, wherein the client entry object and the client history object point to each other.

18. The computer program product of claim 15, further comprising:

modifying the lock entry to point to the client entry.

19. A shared external storage device, comprising:

a processor; and

a memory coupled to the processor, wherein the memory comprises instructions which, when executed by the processor, cause the processor to;

receive a request from a client of the shared external storage device, wherein the request requires allocation of one or more objects of one or more of a set of predetermined object types;

automatically allocate a portion of shared external storage structures within the shared external storage device for the one or more objects; and

create the one or more objects from the portion of the shared external storage structures.

20. The shared external storage device of claim 19, wherein the instructions further cause the processor to:

divide dynamically allocable storage within the shared external storage device into a plurality of fixed sized allocation units; and

generate a free list of the allocation units,

wherein the one or more objects comprise a first object of a first type and a second object of a second type and wherein automatically allocating the portion of the shared external storage structures and creating the one or more objects comprise;

removing an allocation unit from the free list and converting the allocation unit into the first object of the first type; and

removing two or more allocation units from the free list and converting the two or more allocation units into the second object of the second type.