Multi-part aggregated variable in structured external storage

摘要

A mechanism is provided for multi-part aggregated variables in structured external storage. The shared external storage provides a serialized, aggregated structure update capability. The shared external storage identifies each local value for which a group value is needed by name. Each time a member writes out its value, the member specifies the name of the object, the member's current value, and the type of aggregate function to apply (e.g., minimum, maximum, etc.). The structured external storage in one atomic operation updates the member's value, recalculates the aggregate of all of the individual values, and returns the aggregate to the member. The advantage of this approach is that it requires only one write operation to the structured external storage. The update operation does not require locking, because the operation is atomic.

主权项

1. A method, in a shared external storage device, for multi-part aggregate variables in shared external storage structures, the method comprising:
receiving, by the shared external storage device, a request to write a value to a multi-part aggregate variable from a first member client; creating, by the shared external storage device, a first entry, wherein the first entry comprises a primary key identifying the multi-part aggregate variable, a member identifier identifying the first member client, an identification of an aggregate function for the multi-part aggregate variable, and the value being written by the first member client; determining, by the shared external storage device, an aggregate value for the multi-part aggregate variable based on the aggregate function for the multi-part aggregate variable; writing, by the shared external storage device, the aggregate value for the multi-part aggregate variable in a predetermined entry for the multi-part aggregate variable; and returning the aggregate value to the first member client.