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Locking and unlocking mechanism for controlling concurrent access to objects

  • US 6,247,025 B1
  • Filed: 09/22/1997
  • Issued: 06/12/2001
  • Est. Priority Date: 07/17/1997
  • Status: Expired due to Term
First Claim
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1. A method for controlling concurrent access to an object in a multi-threaded computer processing system, the method comprising the steps of:

  • storing in memory a lock that is associated with said object, said lock comprising a thread identifier field and a flag field;

    wherein, when said object is not locked by any thread, a portion of said lock is set to a predetermined value that indicates that the object is not locked by any thread;

    wherein, when an object is locked by a particular thread, said thread identifier field is set to a value that identifies the particular thread, if no other threads are waiting to lock the object, said flag field is set to a predetermined value that indicates that no other threads are waiting to lock the object, and if other threads are waiting to lock the object, said flag field is set to a predetermined value which indicates that there is a non-empty queue of waiting threads associated with the object.

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