JPS5837586B2 - Data file control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data file control method used in a so-called file share system in which two or more data processing devices share the same data file.

In a file sharing system, between the time a certain processing device reads and updates data in a file and before writing it, another data processing device reads the data,
There is a possibility that the data may be updated and written.

In this case, the other processing devices must process the updated data, but end up processing the old data before the update, causing a contradiction in data processing.

One of the conventional techniques to avoid this contradiction is to use a program to control the process of updating data in a file so that the processing device performing the update has exclusive access to the file from the time the data is read until the time it is written. It is.

Specifically, a macro instruction for instructing exclusive use of a file and a macro instruction for instructing release of exclusive use of a file are provided, and the program issues a macro instruction for exclusive use of the file before updating data in the file. Then, the file is exclusively owned, the data is updated, and then a macro command to release the exclusive use of the file is issued to release the exclusive use of the file.

However, in the method of exclusive use of a file through program processing, the exclusive use of the file is achieved by a combination of instructions, so the exclusive use time of the file inevitably becomes longer than necessary, and during that exclusive time, other The probability that the processing device is forced to wait while trying to use the file increases, and this may lead to a decrease in the processing capacity of the system.

SUMMARY OF THE INVENTION An object of the present invention is to provide a data file control method that reduces the time that a data processing device uses a file as much as possible and maintains a high system throughput.

Next, one embodiment of the present invention will be illustrated in the drawings.

Two configuration examples of file sharing systems are shown in Figures 1 and 2.
As shown in the figure.

FIG. 1 shows a configuration in which two data processing devices CPU are connected to a file control device FC via the same channel control device CH and share a data file device F.

In FIG. 2, two data processing devices CPU are each connected to a channel control device CH corresponding to the device, and the two channel control devices CH share a data file device F via the same file control device FC. This shows the configuration.

An actual file sharing system will likely have a complicated structure, and a combination of the structure shown in FIG. 1 and the structure shown in FIG. 2 is also conceivable.

FIG. 3 shows an example of the structure of the file control device FC.

When a startup instruction is given, a processing device number line 1 indicating the number of the instructed processing device is input to a processing device number holding circuit 2 and a comparison circuit 3.

A command signal line 5 is input to a command decoder 6, and a decode signal line 7 for a command instructing interlock is input to an interlock state holding circuit 8.

The activation signal 9 is based on the state of the ink clock state holding circuit 8,
Depending on the state of the output signal line 4 of the comparison circuit 3, a startup response signal 11 or an in-use response signal 10 is output.

The operation will be explained based on the above configuration.

The command that interlocks the file control device is, for example, a "test and set" command.

When a certain processing device updates data in a data file device, it reads the data at the first point, updates the data, and then performs "test and set" at the second point where the updated data is prepared. The command is used to instruct the data to be read again.

When this instruction is received, the processing device number 1 and the "test and set" command 5 are sent together with the activation signal 9 from the channel control device.

The "Test and Set" command has the same operation as a normal read command in terms of data transfer, but at the same time the command starts executing, the file control device is placed in an interlock state and the "Test and Set" command is transferred from a processing device other than the one that issued the "Test and Set" command. It is characterized in that it responds that it is in use when it is activated.

When execution of the "test and set" command is started, the interlock state is held in the holding circuit 8 and the processing device number is held in the holding circuit 2.

The interlock state is maintained even after the execution of the "test and set" command is completed, and when the start signal 9 is sent from the processing device in this state, the processing device number 1 is compared with the value held in the holding circuit 2. .

If the comparison results do not match, the activation is from a different processing device than the one that previously issued the "test and set" command, so the in-use response signal 10 is returned, for example, and execution of the command is suppressed.

If they match as a result of comparing the processing device numbers, the command is from the processing device that previously issued the "Test and Set" command, so the startup response signal 11 is returned and execution of the command is started, and the startup control circuit 12 Holding circuit 2 through
At the same time, the interlock state held in the holding circuit 8 is released.

However, if the subsequent command is "test and set", the interlock state will be established again.

In the above example, a format was shown in which the interlock is in progress and the in-use response is responded to activation from another processing device, but in order to make the processing in the program more clear, a means for reporting the interlock state was created. , a format that responds as an interlock state is also conceivable.

Now, when the data is read by the "Test and Set" command, it is compared with the data read at the first point, and at the third point when it is confirmed that there is a match, a command is issued to write the updated data. Issue.

With the control method described above, if another processing device has updated the data between the first time point and the second time point, a discrepancy will be discovered by data comparison, so it is possible to prevent a discrepancy. Further, from the second time point to the third time point, the interlock of the "test and set" command ensures that access from other processing devices is impossible.

According to the present invention, there is an effect that the exclusive time for a file is reduced compared to the conventional method.

[Brief explanation of the drawing]

1 and 2 are diagrams showing the configuration of a system that is an embodiment of the present invention, and FIG. 3 is a block diagram showing details of the file control device. Explanation of symbols, CPU...Data processing device, CH
...Channel control device, FC...File control device, F...Data file device, 1
...Processing device number line, 2...Processing device number holding circuit, 3...Comparison circuit, 4...
・Comparison match signal line, 5...Command signal line, 6
...Command decoder, 7...Command decode signal line, 8...Interlock state holding circuit, 9...Start signal, 10... In-use response signal, 11... Startup response signal, 12... Startup stage control circuit.

Claims (1)

[Claims] 1. In a data file control method for a system in which two or more data processing devices share the same data file, when a certain data processing device updates data in a data file, it first extracts the data to be updated from the data file. reading the data that was read and then updated from the data file again, and prohibiting access from other processing devices to the data file;
A data file control method characterized in that if the first and second read data are equal to each other, updated data of the read data is written to the data file.