JPH0256035A - Write/read control system for sequential file - Google Patents

Abstract

PURPOSE:To constitute the title system so that exact EOF information can always be obtained, and a record can be referred to in the course of addition processing of the record by providing an EOF managing mechanism separately from a file and inquiring of this mechanism about an EOF position. CONSTITUTION:The system can execute a utilization in which a WRITE processing and a READ processing at the time when a record is added to the same sequential file, that is, when a file is opened are mixed. EOF information is managed separately from the file in accordance with an EOF managing process 2 of an EOF managing mechanism. This EOF managing mechanism has a function for updating a pointer of an EOF by adding the record, a function for informing an EOF pointer in the case of referring to the record, and a waiting control mechanism of a reference processing of the record. By inquiring of the EOF managing mechanism about an EOF position by these functions, exact EOF information can always be obtained.

Description

[Detailed Description of the Invention] [Summary] Regarding a write/read control method when opening a file in a usage mode in which record addition and reference to the same sequential file are mixed, record addition and reference to the same sequential file are mixed. The purpose of the present invention is to provide a sequential file write/read control method that allows for sequential file read/write control, and a file means that allows records to be added to and referenced from an opened file, as well as En(I Of
This is a mechanism for managing File (EOF) information separately from the file means, and it is a mechanism that manages the EOF information separately from the file means, and it is a mechanism for
Receives the old EOF that is given to the AD process means and causes the READ process means to perform READ processing of the sequential file, checks whether or not a record is added by the WRITE process means during the READ processing, and performs the WRIT
If there is an E process, the E generated after additional processing
The new EOF and old EOF obtained by importing the OF pointer
If they do not match, the EOF management process means that always manages the position of the EOF pointer by sending a new EOF to the READ process means, and the EOF management process means that opens a sequential file and requests the EOF pointer from the EOF management process means. After acquiring the EOF pointer, access the file means, and after reading the records of the sequential file,
A READ process means that requests the EOF management process means to determine whether or not the EOF is to be taken again, and if there is a retake of the EOF, continues the READ processing up to the new EOF, and a READ process means that opens a sequential file and writes records in the sequential file. After adding, the EOF management process means
After requesting an update of the F pointer and receiving a message of completion for updating the EOF from the EOF management process means,
W to decide whether to continue adding records
It consists of a RITE process means and is configured to mix record addition and record reference to the same sequential file.

[Industrial application field]

The present invention relates to a sequential file control method, and more particularly to a write/read control method when opening a file in a usage mode in which record addition and reference to the same sequential file are mixed.

2. Description of the Related Art With the development of an advanced information processing society, advanced forms of use of information processing devices that read information from files, process it, and then store it again have become increasingly important. In a file system, each file is a collection of records, and records are frequently added and referenced in the same sequential file. In record addition processing, the current E OF (End Of File) is opened after opening the file.
) is detected, and record information is added in order from the EOF position.

This is the WRITE process when a sequential file is opened in EXTEND mode. Further, the record reference process is a process of sequentially reading information up to the current EOF after opening a file, and this is a READ process when a sequential file is opened in INPUT mode. Generally, record references are written directly on the file medium.
When 'F is detected, the process ends. On the other hand, when adding a record, the record is overwritten on the existing EOF, and after the record addition is completed, a new EOF is written on the medium.

Recently, in order to make advanced use of file systems, there has been a demand for access to two files at the same time.
The demand for simultaneously adding records and referencing records to a single file has increased significantly.

[Conventional technology]

Conventionally, only a method has been adopted in which the strength of exclusive processing for files is strengthened at the time of file allocation so that multiple application programs can share multiple files.

[Problem to be solved by the invention]

This type of conventional method has a problem in that it is not possible to mix record addition and record reference to the same file. When record addition and record reference are mixed for the same sequential file, when record reference detects an EOF written directly on the medium, the process ends; After the record is overwritten and the record addition is completed, a new EOF is written on the medium, so the file EOF does not exist while the record is being added. Φ Therefore, in the record reference process, the EOF
cannot be detected, and record reference processing may overtake record addition processing. In the conventional method, it is not possible to perform control such that record reference processing does not overtake record addition processing, and it is difficult to implement the following record reference wait control, for example.

■Reference records up to EOF when the file is opened.

(2) If the EOF has been updated by adding records, refer to the records up to the updated EOF.

(2) If the EOF has not been updated (no record has been added yet), wait until the record is referenced until the EOF is updated by adding a record.

That is, the conventional method has a problem in that, for example, it is not possible to perform a monitoring process in which data written to a sequential file is directly output to a console device. Therefore, a usage pattern in which record addition and reference are mixed is not used to a high degree, and a problem arises in that the usage pattern is limited to the sharing of a file by a plurality of application programs.

SUMMARY OF THE INVENTION An object of the present invention is to provide a sequential file write/read control method that allows record addition and reference to the same sequential file to be mixed.

[Means to solve the problem]

FIG. 1 is a functional block diagram of the present invention.

The information processing system includes a file means 1' that is capable of at least adding records to and referencing records in an opened file. And End Of Fi
A mechanism for managing le (EOF) information separately from the file means 1, which uses the EOF pointer requested when opening a sequential file in READ processing.
It has a mechanism to receive the old EOF which is given to the D process means 3 and which gives the termination after the read process of the sequential file in the READ process means 3 is completed, and the record is added by the WRITE process means 4 during the READ process. If there is a WRITE process, the new EOF pointer generated after the additional processing is fetched, and if the acquired new EOF and old EOF have not lost, the new EOF pointer is sent to the READ process means 3.
An EOF management process means 2 is provided to transmit the EOF pointer and always manage the position of the EOF pointer. Then, when a sequential file is opened, an EOF pointer is requested from the EOF management process means 2, and after acquiring the EOF pointer, the file means 1 is accessed, a record of the sequential file is read, and after reading is completed, whether the EOF is to be retrieved again. If the EOF management process means 2 needs to be re-taken, the RE is sent to the new EOF.
The READ process means 3 continues AD processing, opens a sequential file, adds a record to the sequential file, requests the EOF management process means 2 to update the EOF pointer, and updates the EOF from the EOF management process means 2. After receiving the completion message for the WRITE process, the WRITE process means 4 decides whether to continue the record addition process.

[For production]

In the present invention, instead of having the EOF information of a file in the medium within the file, an EOF management mechanism is provided that manages the EOF separately from the file, and by querying the EOF management mechanism for the EOF position, the EOF information is always accurate. Information can be obtained.

This makes it possible to refer to the record during record addition processing without destroying the EOF information due to record addition.

〔Example〕

Next, the present invention will be described in detail with reference to the drawings.

FIG. 2 is a functional block diagram of the process of the present invention. In the figure, the same things as in Figure 1 are indicated by the same symbols, and 4 is a W that executes record addition to the sequential file.
A RITE process, 3 a READ process that executes record reference for a sequential file, 2 an EOF management process that manages an EOF pointer, and ■ a sequential file medium.

The present invention enables the addition of records to the same sequential file, that is, the sequential file in the EXTEND mode.
A usage mode is realized in which WRITE processing when opened and READ processing when a record is referenced, that is, a sequential file is opened in the implant (INPtJT) mode. Therefore, in the present invention, the EOF information is
It is managed independently from files according to the EOF management process 2 of the OF management mechanism. That is, the EOF information is not directly written on the file medium, but is managed by the EOF management mechanism. This EOF management mechanism has a function of updating an EOF pointer by adding a record, a function of notifying the EOF pointer when a record is referenced, and a function of waiting control for record reference processing. With these features,
By querying the EOF management mechanism for the EOF position, operations are always performed to obtain accurate EOF information, and the EOF information is not destroyed by adding records.
Records can be referenced during record addition processing. Such an operation will be explained below.

In READ process 3, in step R1,
When opening a sequential file, that is, in implant mode, an EOF boiling request is made to the EOF management process 2. In step R2, the EOF pointer is acquired from the EOF management process 2.

A READ process is performed in step R3 using the acquired EOF pointer. If the EOF at this time is the old EOF, the READ process in step R3 reads the record from the first address of the sequential file to this old EOF,
In step R4, it is determined whether the pointer has reached the EOF.

If it is not EOF, step R3 is repeated, the next record is read, and this process is performed one after another.

In step R4, the pointer is the EOF acquired in R2.
If this happens, the READ process ends.

That is, it is checked whether the record has been read up to the EOF position of the sequential file, and if the record has been read up to the EOF position, the process moves to the next step R5. In step R5, EO
Retake the F pointer, i.e. a new E to replace the old EOF.
Check if OF exists. Therefore, EOF
The message requesting the same is reported to the EOF management process 2 again.

At this time, the value of the EOF pointer held by the READ process 3, that is, the old EOF, and the identifier of the READ process 3 that sent the message, that is, the address for the reply message, are transferred to the EOF management process 2. This identifier is set in the EOF management process 2 as the return address and the old EOF value is also sent. That is, the EOF management process 2 stores the EOF pointer and return address sent from the READ process in a control table within the EOF management process. In the EOF management process 2, the READ process 3 is waiting for a message, so it reads the reply message to the message from the READ process 3.
Send to process 3.

Upon receiving a message from the EOF management process 2 in step R6, the READ process 3 decodes the contents of this message. Then, it is checked whether the EOF pointer is an updated EOF pointer different from the EOF obtained in step R2, and further it is determined whether it is a record reference end notification. That is, in step R7, it is checked whether the content of the received message is a new EOF or the end of record reference, and if it is the end of record reference, the series of record reference processing is ended. If it is a new EOF,
Execute the next step R8. In step R8, the read record is processed, and the new EOF is used to perform the READ process in step R3. Like this R
In the EAD process 3, since the EOF management mechanism is constantly inquired about the EOF position, accurate EOF information can be obtained.

The process of changing from old EOF to new EOF is WRITE
This is process 4. The WRITE process 4 also has a function of notifying the EOF management process 2 of the update when the EOF pointer is updated by adding a record. In step Wl of the WRITE process 4, the sequential file is opened in the expansion mode, and the EOF management process 2 is notified that the sequential file has been opened. Step W2
Access similar files and add records. In this case, the EOF will be deleted and a record will be added. Then, record addition is repeated until a logical processing break is reached. In step W3, after the record addition is completed, the EOF management process 2 is notified as a message that a new EOF pointer has been updated. W4
In step EOF management process 4 is certainly the new EO
Receives an EOF update completion message indicating that F has been received. After receiving the EOF update completion message, if the process of adding records is to be continued, the process returns to step W2 and performs the same process. If no record has been added and the record addition process has been completed, the file is closed and the process moves to the next step W5. In step W5, when the file is closed, the EOF management process is notified of the closing.

The EOF management process 2 manages EOF information independently of files.

FIG. 3 is a functional block diagram of the management process of the EOF management mechanism of the present invention. The EOF management process 2 always performs processing for the message from the READ process 3 and processing 2 for the WRITE process 4 at the same time.

The right diagram in FIG. 3 shows the process of processing a function for a READ message, and the left diagram shows a process of processing a function for a WRITE message. In step 5 of processing for the READ message, a message from the READ process 3 is waited for, and if there is no message, the state is always in a waiting state, but if a message is received, the return address of the READ process and the old EOF notified from the READ process are returned. is stored and the process goes to step 6.

Then, the currently stored EOF is WRITE process 4
Update on request from or READ process 3
EOF
Lock pointer. And in step 7, READ
The old EOF at the time when the READ process has already been completed is received from the process 3, and the new EOF is received from the WtTE process 4 and stored. Then, in step 8, unlock EOF, and in step 9, WRIT
It is checked whether the new EOF obtained from the E process 4 and the old EOF received from the READ process 3 match. If the new EOF and old EOF do not match, RE to the old EOF for which READ processing has already been completed, and then use that as the starting address to the new new EOF.
Performs control for AD. Therefore, in step 1o, the new EOF of the update method is sent to the READ process 3, and the process returns to step 5 to wait for a message from the READ process 3. Also, if the new EOF and old EOF match, the READ process ends and the EOF is changed to WRI.
Since it can be confirmed that it has not been updated by TE process 4, the process moves to step 11. In step 11, it is checked whether there is any WRITE process 4 that is opening a file in extended mode, and if there is, the READ process 3 is notified of its termination. If the file is opened in extended mode, WRI
Step 1 if at least one TE process 4 exists
2, the new EOF is received from the WRITE process 4, so it enters a waiting state. Furthermore, in step 12, the R
It is also in a waiting state for processing a message from the EAD process 3, and at this time, the READ process 3 is also in a waiting state. In step 12, the EOF is
If updated by TE process 4, step 6.7
．． Returning to step 8, the EOF pointer is locked, and after acquiring the EOF pointer, the lock is released. And the new E
Give the OF pointer to the READ process 3.

The left diagram in FIG. 3 shows processing for WRITE messages. If the message from WRITE process 4 is waited for in step 13 and the message from WRITE process 4 is received in step 14, then in step 15
The OF pointer is locked, the EOF pointer is updated in step 16, and the EOF pointer is unlocked in step 17. After updating the new EOF, in step 18, resume the READ message that was being prayed in the first year of junior high school. That is, the processing of the message of the READ process 3 in the waiting state is restarted, and if there are multiple processes in the waiting state, all of them are restarted. Thereafter, the process returns to step 13 and waits for a message from the WRITE process 4.

In addition, the EOF management process 2 manages the number of WRITE processes 4 that have opened any sequential file,
It also manages whether the READ process 3 is opening this sequential file.

Furthermore, when all the WRITE processes 4 that have opened a certain sequential file are gone, all the READ processes 3 that have opened that sequential file are notified of the end of the record reference process.

〔Effect of the invention〕

In the present invention, EOF information is managed by an EOF management mechanism separate from files, so it is possible to accurately obtain the EOF position, record references do not overtake record addition processing, and in extended mode It is possible to mix adding records within an open file and referencing records in the same sequential file opened by an input mote. Therefore, monitoring processing and the like for sequential files to which records are being added can be accurately executed.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram of the present invention, FIG. 2 is a functional block diagram of the process processing of the present invention, and FIG. 3 is a functional block diagram of the management process of the EOF management mechanism of the present invention. 1... File means, 2... EOF management process means, 3... READ process means, 4... WRITE process means,

Claims (1)

[Claims] File means (1) capable of adding and referencing records to an opened file, and a mechanism that manages End Of File (EOF) information separately from the file means (1). EOF requested when opening a sequential file during READ processing.
Give the pointer to the READ process means (3) and
Receives the old EOF that provides READ processing for the sequential file in the D process means (3), checks whether or not a record is added by the WRITE process means (4) during the READ processing, and writes the WR
If there is an ITE process, it takes the new EOF pointer generated after the additional processing, opens a sequential file, requests the EOF pointer from the EOF management process means (2), and after acquiring the EOF pointer, the file means (1) READ which requests the EOF management process means (2) whether or not the EOF is to be retaken again after reading the records of the sequential file, and if the EOF is to be retaken, continues the READ process up to the new EOF. A process means (3) opens a sequential file, adds a record to the sequential file, requests the EOF management process means (2) to update the EOF pointer, and updates the EOF from the EOF management process means (2). A sequence comprising a WRITE process means (4) for determining whether or not to continue the record addition process after receiving a completion message for the sequence, and characterized in that record addition and record reference to the same sequential file are mixed. File write/read control method.