US5745674A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Management of units of work on a computer system log
Assignee: International Business Machines Corp
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Filing: 1996-06-04
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Granted: 1998-04-28
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Expires: 2016-06-04
Abstract
Abstract A method of moving records, stored on a recovery log, which are associated with units of work which have waited for a long time is described. Units of work which have waited for a long time, such as those which are in-doubt have their records copied from a recovery log to a secondary log. When the earliest-written record for this in-doubt unit of work has been copied, a new record called a fork record is written on to the recovery log which has two effects: to subtract the log records currently on the recovery log for this unit of work from the recovery log and to refer to the copied records written on the secondary log. The new record achieves this using two pointers, a pointer to point to the most-recently written record on the recovery log for this unit of work and a pointer to point to the most-recently written record on the secondary log for this unit of work.
Inventors
- 👤 Peter James Lupton
- 👤 Robert Frank Buxton
- 👤 Ian Hunter
- 👤 Handel Glasnant Price
- 👤 Adam Richards
- 👤 John Simon Tilling
- 👤 Dennis Jack Zimmer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 02:19
CPC Classifications
G; G06; G06F; G06F11/00; G06F11/07; G06F11/14; G06F11/1471
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
161 words
A method of managing records, associated with units of work, on a recovery log, the method comprising the steps of: for each unit of work having records stored on the recovery log, checking whether that unit of work is in an in-doubt state; for each of said units of work which is in an in-doubt state, scanning the recovery log for records associated with said in-doubt unit of work; on finding a record associated with said in-doubt unit of work, copying said record to a secondary recovery log; on finding the earliest-written record for said in-doubt unit of work, writing a further record on to the recovery log, associated with said in-doubt unit of work, the record having the effects of subtracting the log records currently on the recovery log associated with the indoubt unit of work from the recovery log and of referring to the copied log records associated with the in-doubt unit of work written on the secondary log.
Claim 2
Independent Claim
161 words
A method of managing records, associated with units of work, on a recovery log, the method comprising the steps of: for each unit of work having records stored on the recovery log, checking whether that unit of work is in an in-doubt state; for each of said units of work which is in an in-doubt state, scanning the recovery log for records associated with said in-doubt unit of work; on finding a record associated with said in-doubt unit of work, copying said record to a secondary recovery log; on finding the earliest-written record for said in-doubt unit of work, writing a further record on to the recovery log, associated with said in-doubt unit of work, the record having the effects of subtracting the log records currently on the recovery log associated with the indoubt unit of work from the recovery log and of referring to the copied log records associated with the in-doubt unit of work written on the secondary log.
Claim 3
Dependent Claim
28 words
A method as claimed in claim 1 wherein the log records currently on the recovery log associated with the in-doubt unit of work remain on the recovery log.
Claim 4
Dependent Claim
33 words
A method as claimed in claim 1 wherein a unit of work has suffered a backout failure, due to non-availability of one of a plurality of resources requiring updates to be backed out.
Claim 5
Dependent Claim
37 words
A method as claimed in claim 1 wherein said step of checking whether a unit of work is in an in-doubt state comprises checking that the most-recently written record on the recovery log is a prepare record.
Claim 6
Dependent Claim
19 words
A method as claimed in claim 1 wherein the earliest-written record is indicated by a flag within said record.
Claim 7
Dependent Claim
43 words
A method as claimed in claim 1 wherein said records for each unit of work stored on the recovery log, comprise information concerning updates made to stored data by said unit of work and information concerning the status of said unit of work.
Claim 8
Dependent Claim
60 words
A method as claimed in claim 1 wherein said step of scanning for records associated with said in-doubt unit of work comprises reading each record in sequence on the recovery log, from the most-recently written record and checking the unit of work identification to see if it corresponds to the in-doubt unit of work whose records are being scanned for.
Claim 9
Dependent Claim
69 words
A method as claimed in claim 1 wherein: the effect of subtracting the log records is by means of a pointer to the most-recently written record associated with said in-doubt unit of work on said recovery log; and the effect of referring to the copied log records is by means of a pointer to the most-recently written record associated with said in-doubt unit of work on said secondary log.
Claim 10
Dependent Claim
28 words
A method as claimed in claim 8 wherein the log records currently on the recovery log associated with the in-doubt unit of work remain on the recovery log.
Claim 11
Dependent Claim
33 words
A method as claimed in claim 8 wherein a unit of work has suffered a backout failure, due to non-availability of one of a plurality of resources requiring updates to be backed out.
Claim 12
Dependent Claim
37 words
A method as claimed in claim 8 wherein said step of checking whether a unit of work is in an in-doubt state comprises checking that the most-recently written record on the recovery log is a prepare record.
Claim 13
Dependent Claim
60 words
A method as claimed in claim 8 wherein said step of scanning for records associated with said in-doubt unit of work comprises reading each record in sequence on the recovery log, from the most-recently written record and checking the unit of work identification to see if it corresponds to the in-doubt unit of work whose records are being scanned for.
Claim 14
Dependent Claim
19 words
A method as claimed in claim 8 wherein the earliest-written record is indicated by a flag within said record.
Claim 15
Dependent Claim
43 words
A method as claimed in claim 8 wherein said records for each unit of work stored on the recovery log, comprise information concerning updates made to stored data by said unit of work and information concerning the status of said unit of work.
Claim 16
Dependent Claim
171 words
Data processing apparatus for managing records, stored on a recovery log, the apparatus comprising: a recovery log for storing records, the records being associated with a unit of work; means for checking which units of work are in an in-doubt state; means, responsive to the checking means, for processing records associated with units of work which are in an in-doubt state, the means for processing comprising; means for scanning the recovery log for records associated with said in-doubt unit of work; means, responsive to said scanning means, for copying said record to a secondary recovery log; means for finding the earliest-written record for said in-doubt unit of work; means, responsive to said finding means, for writing a further record on to the recovery log, associated with said in-doubt unit of work, the record having a pointer to a most-recently written record associated with said in-doubt unit of work on said recovery log and a pointer to a most-recently written record associated with said in-doubt unit of work on said secondary log.
Claim 17
Dependent Claim
171 words
Data processing apparatus for managing records, stored on a recovery log, the apparatus comprising: a recovery log for storing records, the records being associated with a unit of work; means for checking which units of work are in an in-doubt state; means, responsive to the checking means, for processing records associated with units of work which are in an in-doubt state, the means for processing comprising; means for scanning the recovery log for records associated with said in-doubt unit of work; means, responsive to said scanning means, for copying said record to a secondary recovery log; means for finding the earliest-written record for said in-doubt unit of work; means, responsive to said finding means, for writing a further record on to the recovery log, associated with said in-doubt unit of work, the record having a pointer to a most-recently written record associated with said in-doubt unit of work on said recovery log and a pointer to a most-recently written record associated with said in-doubt unit of work on said secondary log.
Claim 18
Dependent Claim
96 words
Data processing apparatus as claimed in claim 15 wherein said further record written comprises entries representing the length of the record, an indication that this is a record having pointers to the most-recently written records on the recovery log and on the secondary recovery log, a timestamp, an identification of the unit of work with which it is associated, a pointer to a most-recently written record associated with said in-doubt unit of work on said recovery log and a pointer to a most-recently written record associated with said in-doubt unit of work on said secondary log.
Claim 19
Dependent Claim
65 words
Data processing apparatus as claimed in claim 15 wherein said means for scanning for records associated with said in-doubt unit of work comprises means for reading each record in sequence on the recovery log, from the most-recently written record and means for checking the unit of work identification to see if it corresponds to the in-doubt unit of work whose records are being scanned for.
Claim 20
Dependent Claim
96 words
Data processing apparatus as claimed in claim 17 wherein said further record written comprises entries representing the length of the record, an indication that this is a record having pointers to the most-recently written records on the recovery log and on the secondary recovery log, a timestamp, an identification of the unit of work with which it is associated, a pointer to a most-recently written record associated with said in-doubt unit of work on said recovery log and a pointer to a most-recently written record associated with said in-doubt unit of work on said secondary log.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-04-27 | 2001-10-27 | 2002-04-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-04-27 | 2005-10-27 | 2006-04-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-04-27 | 2009-10-27 | 2010-04-28 | $7700.00 | Window Closed / Lapsed |