Event-driven serialization of access to shared resources

• US 6,295,602 B1
• Filed: 12/20/1999
• Issued: 09/25/2001
• Est. Priority Date: 12/30/1998
• Status: Expired due to Term

• Current Assignee: SPEX Technologies, Inc.
• Original Assignee: Spyrus, Inc.
• Inventors: Dalcher, Gregory W., Weissman, Gregg D.
• Primary Examiner(s): BUTLER, DENNIS
• Application Number:
  US09/468,028
• Time in Patent Office: 645 Days
• Field of Search: 713/1, 713/100, 709/102, 709/103, 709/104, 709/105
• US Class Current: 713/1
• CPC Class Codes: G06F 9/4812 by interrupt, e.g. masked
• CPC Class Codes: G06F 9/52 Program synchronisation; Mutual exclusion, e.g. by means of semaphores

Abstract

The invention mediates use of a computer resource by multiple events that seek to use the computer resource at the same time. In particular, the invention mediates such use by events that seek to use the computer resource at times that are not known until access to the computer resource is sought. Advantageously, the invention enables mediation of the use of a computer resource when typical operating system functionality provided for that purpose is ineffective. The invention allows work initiated by an event granted access to a resource to be completed by a different, interrupting event.

Claims

1. A method for mediating the use of a computer resource by a series of events that seek access to the computer resource at times that are not known until access is sought, comprising the steps of:

identifying that a current event seeks to use the computer resource;

disabling interrupts to the method;

checking a resource usage status indicator associated with a resource to be used by the current event to determine whether the resource is being used by another event;

if the step of checking a resource usage status indicator indicates that the resource is being used, performing the following steps, then returning to the step of disabling;

enabling interrupts to the method;

checking the operation indicator to determine whether an operation is being performed by the resource, the step of checking the operation indicator being repetitively performed until the operation indicator indicates that the resource is no longer performing operations;

disabling interrupts to the method;

setting the value of the resource usage status indicator to indicate that the resource is not being used; and

enabling interrupts to the method; and

if the step of checking a resource usage status indicator indicates that the resource is not being used, performing the steps of;

setting the value of the resource usage status indicator to indicate that the resource is being used;

storing the memory address of a set of computer instructions for checking the status of a resource;

storing the memory address of a set of computer instructions for monitoring completion of use of a resource by an event;

setting an operation indicator to indicate that an operation is being performed by the resource;

enabling interrupts to the method;

checking the operation indicator to determine whether an operation is being performed by the resource, the step of checking the operation indicator being repetitively performed until the operation indicator indicates that the resource is no longer performing operations;

disabling interrupts to the method;

setting the value of the resource usage status indicator to indicate that the resource is not being used; and

enabling interrupts to the method.