Real-time distributed data base locking manager
AssigneeThe United States of America as represented by the Secretary of the Navy
InventorsCarlos M. Tavares, Durval M. Tavares
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Abstract
A method of data sharing between processors on the same network utilizes en migration for providing a data locking mechanism. A token migrates between the processors for each original data item and its replicas. Only the processor having possession of the token can perform certain operations such as updating and transmitting this updated information to the other processors. Two different queuing arrangements are described for giving up or retaining possession of the token when a processor, not in possession of the token makes a request for the token.
Claims16
A method of managing the power of individual processors to perform processes including managing data sharing between processors on a network by a locking and unlocking of data items, utilizing a migrating token, where the processors has at least one data item, each of said at least one data item being an original or replicated data item, comprising the steps of:
- forming the following series of operational states within each processor, with each processor being in one of said operational states and transitioning from one state to another upon certain happenings, a token being the sole entitlement for each of said processors to transmit data on said network, and said token migrates among each of said processors, the states being:
- (A) the absence of said token, (B) the token being at the processor but not in use, (C) requesting the token from another processor, (D) the token being assigned to a process at the processor but no other requests are pending, (E) the token having at least one request pending and the token being in the processor;
- controlling the transitioning from one state to another such that all except one processor is in one of states (A) and (C), and said one processor is in one of states (B), (D), and (E);
- controlling the transitioning from one state to another such that each processor in state (A) can transition to state (C) upon requesting and not receiving said token, so that a plurality Of processors can be in state (C) at the same time;
- and
- said processors in each of states (A), (B), (C), (D), and (E) can read verify a data item without changing states.
Dependencies are inferred from the claim text.