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Virtual Memory Management of APL Packaged Workspaces

IP.com Disclosure Number: IPCOM000034956D
Original Publication Date: 1989-May-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Brown, JA: AUTHOR [+3]

Abstract

This invention relates to a method for virtual memory management in which packaged workspaces (PWSs) actuable by an APL2 interpretive processor may be located in APL freespace (unallocated memory outside the APL workspace) or in a discontiguous VM-shared segment. It is an object to locate APL PWSs into such VM segments where their contents may be accessed by multiple users. However, such VM segments are in demand. The method presumes that each APL PWS contains a signature and a unique token which allows it to be identified and distinguished from other PWSs. When a PWS is first accessed, its unique token is copied into the active APL workspace (WS). At that time, the tokens for any other existing PWSs are validated by comparing the copy in the active WS to the expected copy in the PWS.

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Virtual Memory Management of APL Packaged Workspaces

This invention relates to a method for virtual memory management in which packaged workspaces (PWSs) actuable by an APL2 interpretive processor may be located in APL freespace (unallocated memory outside the APL workspace) or in a discontiguous VM-shared segment. It is an object to locate APL PWSs into such VM segments where their contents may be accessed by multiple users. However, such VM segments are in demand. The method presumes that each APL PWS contains a signature and a unique token which allows it to be identified and distinguished from other PWSs. When a PWS is first accessed, its unique token is copied into the active APL workspace (WS). At that time, the tokens for any other existing PWSs are validated by comparing the copy in the active WS to the expected copy in the PWS. If the token is found to be invalid in the PWS, the PWS is marked "not loaded" in the active WS. Later, during execution of APL expressions, if a "not loaded" PWS is encountered, the APL interpreter is recalled to automatically reload it. This procedure may cause other PWSs to be marked "not loaded". When execution completes in the PWS and control is returned to the name scope, the APL interpreter ensures that the necessary PWS is reloaded. Reloading a PWS, after it has been designated "not loaded" subsequent to an initial loading, requires only making a call to a resident VM manager to request that the necessary VM segment contai...