JPS6195450A - Exclusive control system of record - Google Patents

Abstract

PURPOSE:To improve the reliability of data by reading data again immediately before the update of the data and comparing the read data with the contents obtained before change. CONSTITUTION:Data are read from an external storage device 24 to an I/O buffer 22 and transferred to a record storing area 21. After changing the data, the changed data are transferred from a keyboard on a CRT26 to a changed data storing area 23. The same record is read again from the device 24 to the buffer 22 and the contents of the area 21 are compared with that of the buffer 22. When both the contents coincide with each other, the data stored in the area 23 are transferred to the buffer 22. Consequently, the contents of the buffer 22 are written in the device 24. When both the contents are inconsistent, data in the device 24 have been already changed by another program, so that the data in the buffer 22 are not written in the device 24. A message indicating the completion of change is displayed on the screen of the CRT26 to make the operator select the stop of the processing or the continuation of the processing.

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a record exclusive control method, and particularly in a computer system in which multiple programs can simultaneously process the same record on the same file, the present invention relates to a record exclusive control method, and particularly in a computer system where multiple programs can simultaneously process the same record on the same file. The present invention relates to a record exclusive control method that detects whether or not the data being updated has already been updated by another program.

(Prior art) Conventionally, in a computer system where multiple programs can simultaneously process the same record on the same file, when a program reads a specific record from an external storage device onto the main storage device (main memory), , lock the record so that it cannot be referenced by other programs (L-OCK), or do not lock it if it is okay for it to be referenced by other programs (UNLOCK)
You can do it like this. It is well known that when a program locks and reads a record, there is a high possibility of deadlock occurring, especially when multiple programs process the same file at the same time.

On the other hand, if a program reads records unlocked, there is no possibility of deadlock. Therefore, in most application systems in which multiple programs process all of the same file at the same time, each program uses a system in which each program reads records in an unlocked manner.

However, if another program changes the contents of that record and outputs it to an external storage device while the own program reads a particular record in an unlocked state and processes all of the records, then the own program When the contents of a record are changed and output, not only the contents (information) previously changed by other programs are lost, but also the data contents of other files related to the record are adversely affected.

For example, in the conventional record exclusive control method, as shown in FIG. related file of file 15a). First, the program 11 reads a specific record of the file 15a in an unlocked manner.

While changing the contents from the keyboard of the CRT 16a, the program 12 reads the same record with a lock, changes the key value t-"1" to 2" in the file 15b from the keyboard of the CRT 16b, and writes it to the file 15a. At this time, it is assumed that the record with the key value "2" in the file 15b has been modified by the program 12.Finally, when the program 11 writes back to the file 15a, the contents of the record in the file 15a are modified. File 1
The key value of 5b will return from 12'' to 1''. If a record with a key value of 121 in file 15b is not chained to any record in file 15a, the program 12 will not know that it has been changed.

As described above, the conventional record exclusive control method has the drawback that the authenticity of data becomes clearly questionable.

(Objective of the Invention) The present invention eliminates the drawbacks of the conventional record exclusive control method, saves the data before the change, and immediately before outputting the changed data to the external storage device, reads the data again into the main memory and saves it. Record exclusive control that improves the reliability of data by comparing it with the data before the change, indicating if there is a difference, and outputting the changed data to an external storage device if it is exactly the same. It is possible to provide a method.

(Structure of the Invention) According to the present invention, in a computer system in which a plurality of programs can run simultaneously, when the plurality of programs simultaneously update data on the same file existing in the same external storage device, the own program While referring to the contents of a specific record, determine whether the contents of the same record have been changed by another program, and if the contents have not been changed, the program itself changes the record and stores it on the external storage device. A record exclusive control system can be obtained which has a means to completely indicate to the own program that the contents of the record have already been changed by another program if the contents of the record have been output and changed.

(Example) Next, embodiments of the present invention will be described with reference to the drawings.

Referring to FIG. 1, one embodiment of the present invention is a computer system in which a plurality of programs can run simultaneously. Main storage device 25
and a CRT display for displaying each message.

The main storage device 25 has a record storage area 21, a record I10 buffer 22, a modified data storage area 23, and a function to import all data from the external storage device 24, and conversely write it to the external storage device 24. Furthermore, it has a function of transferring data on the main storage device 25.

FIG. 2 is a flowchart showing the operation of this embodiment. The operation will be explained with reference to this flowchart. First, data is read from the external storage device 24 into the record 110717-22. The record I10 buffer 22 transfers data to the record storage area 21. Next, the data is changed by changing the data from the keyboard of the CRT 26 in the data storage area 23.
Transfer to.

The same record is transferred again from the external storage device 24 to record I1.
0 buffer 22. The contents of the record storage area 21 and the contents of the record I10 buffer 22 are compared, and if they are exactly the same, the data stored in the changed data storage area 23 is transferred to the record I10 buffer 22. From this K, the contents of the record I10 buffer 22 are written to the external storage device 24.

If the contents of record storage area 21 and record I10
If the contents of the buffer 22 do not match when compared, the data on the external storage device 24 has already been changed by another program, so the record I/Q buffer 22
The data is not written to the external storage device 24 and is
The message ``The data has already been changed by another program'' is displayed on the screen of T26, and the operator is asked to choose whether to abort the process or continue the process.

As described above, in this embodiment, the KL is provided with a function of entrusting the operator with subsequent treatment of data changed by another program, thereby providing credibility to the data.

(Effects of the Invention) As described above, the present invention is more effective in preventing damage to the reliability of data by re-reading the data immediately before updating the data and comparing it with the contents before the change.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of one embodiment of the present invention, FIG. 2 is a flow chart showing the operation of one embodiment of the present invention, and FIG. 3 is a diagram showing a conventional system. 10... Main memory, 11... Program, 12... Program, 15a, 15b...
...File, 21...Record storage area, 22...Record I/. Buffer, 23...Change data storage area, 2
4... External storage device, 25... Main storage device, 26... CRT display.

Claims (1)

[Claims] In a computer system where multiple programs can run simultaneously, when multiple programs simultaneously update data on the same file that exists in the same external storage device,
While your own program is referencing the contents of a specific record, determine whether the contents of the same record have been changed by another program, and if the contents have not been changed, your own program will change that record and store it on the external storage device. Output to
A record exclusive control system characterized by having means for displaying a message on the own program side to the effect that the contents of the record have already been changed by another program if the contents of the record have been changed.