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Computer Storage Cleanup Mechanism

IP.com Disclosure Number: IPCOM000048854D
Original Publication Date: 1982-Mar-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 3 page(s) / 28K

Publishing Venue

IBM

Related People

Anderson, MJ: AUTHOR [+6]

Abstract

A method is provided for the verification and correction of linkages between pieces of data in an object-oriented architecture. These linkages are system defined and required for user manipulation of the data. The function performing this is referred to as the Reclaim Storage function.

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Computer Storage Cleanup Mechanism

A method is provided for the verification and correction of linkages between pieces of data in an object-oriented architecture. These linkages are system defined and required for user manipulation of the data. The function performing this is referred to as the Reclaim Storage function.

Four underlying concepts are necessary to understand the description of the implementation. The first of these is the concept of a physical object. A physical object is a related collection of data, against which a predefined set of system functions operates. Each object is presented as a single entity above the machine interface and is accessed through pointers.

The second concept is that of authorization and ownership. To keep track of authorization and ownership, special objects called user profiles are defined in the system. When any object is created, a profile, associated with the process in which it is created, is given ownership of the object. This ownership provides unique authorization to the object and may be transferred by machine instructions. In addition, authorization may be explicitly granted to other profiles. This provides processes associated with other user profiles' rights to use objects.

The third concept is that of symbolic addressability. Object references by a user are made by object type and symbolic name. The system then maps the type and name to physical addresses in memory. This mapping information is stored in specialized objects called contexts. The location of all contexts defined in the system is maintained by the hardware. by the hardware.

The fourth concept is that of user-defined objects which are created, used, and deleted through system-provided commands. User-defined objects are related to physical objects in that they consist of either a single physical object called a simple object or a group of functionally related physical objects referred to as a composite object. User defined objects are addressed symbolically through a context. For composites, only one object, the primary, needs to be addressed through a context. The remaining objects, secondary pieces, are located through pointers in the primary. Unless the primary can be found in a context, the secondaries cannot be accessed or deleted through system commands. An example of a composite object that is properly addressable is shown in the diagram on the next page.

The Reclaim Storage function provides the mechanism by which objects that are improperly owned or have improper context addressability can be corrected or deleted from the system.

In order to verify that all objects are properly addressable and owned, each object on the system is processed by the Reclaim Storage function. Initially, a machine instruction is executed which returns a list of any unowned objects. Unowned objects occur when the profile that owns them is destroyed or some system failure such as a crash occurs during an object creation. Unowned obje...