Recoverable spin lock system

DC
  • US 5,991,845 A
  • Filed: 10/21/1996
  • Issued: 11/23/1999
  • Est. Priority Date: 10/21/1996
  • Status: Expired due to Term
First Claim
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1. A method for recovering spin locks in a system having one or more processes capable of accessing a shared resource, the system providing a lock indicating exclusive access of the shared resource by a single process and enabling one or more processes to repeatedly attempt to gain ownership of the lock when exclusive access to the shared resource is desired, said method for recovering spin locks comprising the steps of:

  • generating a queue structure including a process currently having exclusive access to the lock and adding processes that desire ownership of the lock to said queue structure;

    setting a first status flag indicating a desire of one of said processes to be added to said queue structure;

    setting a second status flag indicating that said one process is currently modifying the queue structure;

    monitoring a third status flag indicating whether said queue structure is being restored and not attempting to modify said queue structure if said queue structure is being restored;

    conducting a cleanup process if one or more of said processes indicated by said first status flag set have terminated, said cleanup process removing said one or more of said terminated processes from said queue structure, setting said third status flag to indicate that recovery of said queue structure is in process, and recovering said queue structure after all modification activity on said queue structure has finished; and

    resetting said third status flag after completion of said cleanup process to indicate that said recovery process has completed.

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