Negating initiative for select entries from a shared, strictly FIFO initiative queue

• US 8,793,699 B2
• Filed: 03/19/2008
• Issued: 07/29/2014
• Est. Priority Date: 02/25/2008
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Errickson, Richard K., Crew, Geoffrey A., Haileselaissie, Welela, Whalen, Robert M. Jr.
• Primary Examiner(s): Fennema, Robert
• Assistant Examiner(s): LINDLOF, JOHN M
• Application Number:
  US12/051,628
• Publication Number:
  US 20090217270A1
• Time in Patent Office: 2,323 Days
• Field of Search: None
• US Class Current: 718/107
• CPC Class Codes: G06F 2209/548 Queue
• CPC Class Codes: G06F 9/546 Message passing systems or structures, e.g. queues

Abstract

A computer program product, apparatus and method for negating initiative for select entries from a shared, strictly FIFO initiative queue in a multi-tasking multi-processor environment. An exemplary embodiment includes a computer program product for negating initiative for select entries from a shared initiative queue in a multi-tasking multi-processor environment, the computer program product including a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method including identifying an element within the environment that has failed and recovered, not removing the element from the shared initiative queue and entering a boundary element entry into the shared initiative queue.

Claims

1. A computer program product for negating initiative for select entries from a shared initiative first-in first-out (FIFO) queue in a multi-tasking multi-processor environment, the computer program product comprising:

a non-transitory storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising;

maintaining a plurality of entries in the shared initiative FIFO queue including a first entry corresponding to an element in the environment;

determining that the element within the environment has failed and recovered;

maintaining a location of the first entry corresponding to the element in the shared initiative FIFO queue;

inserting a distinct boundary element entry comprising a notation as an additional entry into the shared initiative FIFO queue based on determining that the element has failed and recovered;

inserting a second entry corresponding to the element in the shared initiative FIFO queue;

setting the notation in a notation area, the notation indicating that the first entry is to be discarded;

processing the plurality of entries in the shared initiative FIFO queue on a first-in, first-out basis;

based on the first entry being advanced to an output of the shared initiative FIFO queue, discarding the first entry while the notation is set in the notation area;

in response to the boundary element entry advancing to the output of the shared initiative FIFO queue, resetting the notation in the notation area; and

processing the second entry based on the second entry advancing to the output of the shared initiative FIFO queue.

2. The computer program product as claimed in claim 1 further comprising setting a boundary element token equal to a notation token.

3. The computer program product as claimed in claim 2 wherein the method further comprises resetting a notation area in the shared initiative queue.

4. The computer program product as claimed in claim 1 wherein the method further comprises, in response to the boundary element entry advancing to the output of the shared initiative FIFO queue, determining whether a boundary element token is equal to a notation token;

and

resetting the notation in the notation area based on determining that the boundary element token is equal to the notation token.

5. The computer program product as claimed in claim 1, further comprising:

determining whether an entry advanced to the output of the shared initiative FIFO queue is the boundary element; and

based on determining that the entry advanced to the output of the shared initiative FIFO queue is not the boundary element, determining whether the entry includes a notation for the boundary element.

6. The computer program product as claimed in claim 5 wherein the method further comprises in response to an identification of the notation for the boundary element in the entry, discarding the entry.

7. The computer program product as claimed in claim 6 wherein the method further comprises in response to an absence of the notation for the boundary element, processing the element.

8. A system for negating initiative for select entries from a shared initiative queue in a multi-tasking multi-processor environment, the system comprising:

a processor;

a strictly first-in, first-out (FIFO) shared initiative queue comprising a plurality of entries including a first entry corresponding to an element within the environment;

a process residing in the processor and configured for recovering a failed element within the strictly FIFO initiative queue, the process comprising;

determining that the element within the environment that has failed and recovered;

maintaining a position of the first entry corresponding to the element in the strictly FIFO shared initiative queue;

inserting a distinct boundary element entry comprising a notation as an additional entry into the strictly FIFO shared initiative queue, at an input end of the strictly FIFO shared initiative queue, responsive to determining that the element has failed and recovered;

setting the notation in a notation area, the notation indicating that work entries associated with the boundary element entry are to be discarded;

inserting a second entry corresponding to the element in the shared initiative FIFO queue at the input end of the strictly FIFO shared initiative queue;

processing the plurality of entries in the strictly FIFO shared initiative queue from the output end of the strictly FIFO shared initiative queue, and discarding the work entries, including the first entry, while the notation is set in the notation area;

in response to encountering the boundary element entry, resetting the notation in the notation area; and

processing work entries in the strictly FIFO shared initiative queue encountered subsequent to the boundary element entry.

9. The system as claimed in claim 8 wherein the process further performs:

setting a boundary element token equal to a notation token;

resetting a notation area in the shared initiative queue; and

discarding the element.

10. The system as claimed in claim 8 wherein the process further performs:

in response to identifying a boundary element entry in the shared initiative queue setting a boundary element token equal to a notation token and discarding the failed element;

in response to the lack of a boundary element in the shared initiative queue, identifying a notation for the boundary element; and

in response to an identification of a notation for the boundary element, discarding the element.

11. A method for negating initiative for select entries from a shared initiative queue in a multi-tasking multi-processor environment, the method comprising:

maintaining a plurality of entries in the shared initiative queue including a first entry corresponding to an element in the environment;

determining that the element within the environment has failed and recovered;

maintaining a position of the first entry corresponding to the element in the shared initiative queue;

inserting a distinct boundary element entry comprising a notation as an additional entry into the shared initiative queue responsive to determining that the element has failed and recovered;

setting the notation in a notation area, the notation indicating that work entries associated with the boundary element entry are to be discarded;

inserting a second entry corresponding to the element into the shared initiative queue;

discarding the work entries, including the first entry, based on the notation being set in the notation area;

in response to encountering the boundary element entry, resetting the notation in the notation area; and

processing work entries, including the second entry, encountered subsequent to the boundary element entry.

12. The method as claimed in claim 11 further comprising setting a boundary element token equal to a notation token.

13. The method as claimed in claim 12 further comprising:

resetting a notation area in the shared initiative queue; and

discarding the element.

14. The method as claimed in claim 11 further comprising in response to identifying a boundary element entry in the shared initiative queue setting a boundary element token equal to a notation token and discarding the failed element.

15. The method as claimed in claim 14 further comprising in response to the lack of a boundary element in the shared initiative queue, identifying a notation for the boundary element.

16. The method as claimed in claim 15 further comprising in response to an identification of a notation for the boundary element, discarding the element.

17. The method as claimed in claim 16 further comprising in response to an absence of a notation for the boundary element, processing the element.