JPH03266148A - File update system - Google Patents

Abstract

PURPOSE:To shorten the time up to the return of control to an application program by performing garbage collection by an asynchronous program and returning the control to the application program simultaneously with update. CONSTITUTION:A data operation instruction analyzing means 2 receives a request to update a record from the application program 1 and analyzes the request to update and a record updating means 13 updates the record according to the analytic result. A garbage collection detecting means 4 judges the necessity of the garbage collection after the record is updated and a system lock means 6 in a system program 5 other than the application program which makes the request to update inhibits the object block of the garbage collection from being updated by other programs. Then a garbage collecting means 7 performs the garbage collection of the object block and a system opening means 8 unlocks the block after the garbage collection is completed. Consequently, the time up to the return of the control to the application program is shortened.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a file update method in a file control system of an electronic computer, and in particular, a block can have a plurality of variable length records managed by line offsets. Concerning files.

C. Prior Art] As one method of storing records, there is a method of deleting unnecessary information in the record, compressing the record, and handling it as a variable length record. It is superior in terms of storage efficiency.

FIG. 4 (al shows an example of a block containing a variable length record, and a plurality of these blocks are collected to form a file.

In FIG. 4 tMl, the block 10 is composed of a block header section 11, a record section 12, and a line offset section 13. Block header section 11 is block 1
A plurality of variable-length records 14a to tte are stored in the record section 12, which is located at the beginning of 0 and has a certain fixed length, and the record itself has information about the length of the record. The starting position of each record 148 to 14e is the corresponding line offset 168 to 168 of the line offset section 13.
16e. That is, line offset 16a indicates the start position of record 14a, and record 1
Line offset 16b indicates the start position of record 14b, line offset 16c indicates the start position of record 14c, and line offset 16 indicates the start position of record 14d.
d, and a line offset 16e indicates the start position of the record 14e. Also, the shaded part 15
A to 15C are free areas.

FIG. 3 shows the configuration of a conventional system in which an application program 1 updates a file 9 having blocks 10 having the above-described structure.

First, application programs 1 to 4 (al.
If an update request is issued to, for example, the record 14c of the block 10 in the state of
(not shown).

If the length of the record 14C does not change or becomes shorter as a result of the update, it is stored at the original position of block 100.

Furthermore, if the length of the record 14C becomes longer as a result of the update, it cannot be stored in the original position, so a free area after the last record in the block 10 is searched.

Therefore, it is determined whether the updated record 14C can be stored in the free area 15C after the record 14e, and assuming that the free area 15C has enough free space to store the record 14c, the record 14C is stored in the free area 15C, and the line offset 16C corresponding to the record 14C is updated to point to the head position of the free area 15c where the updated record 14c is stored. The area remaining after storing the record 14c becomes a new free area 15C, and the area occupied by the record 14C before the update is released and becomes a new free area 15d. This state is shown in Figure 4 (mountain).

Next, the application cage program 1 to 4-)
If an update request is issued to, for example, record 14b of block 10 in the state of Updated.

If the length of record 14b does not change or becomes shorter as a result of the update, it is stored in the original position of block 10, but if the length of record 14b becomes longer, it cannot be stored in the original position. , the free space after the last record in block IO is searched.

Here, it is determined whether record b can be stored in the free area 15C after the record 14c.
Assuming that C does not have enough free space to store the record 14b, the record 14b cannot be stored in the block 10 as it is, so the garbage collection means 4'' is activated.

Therefore, the block 10 is the garbage collection means 4
゛ It is determined whether garbage collection is possible or not, and if it is determined that garbage collection is possible, garbage collection is performed. Garbage collection is the process of repacking records to free up free space within a block.
This is done when the total free space within the block is sufficient to store the updated record. Furthermore, if it is impossible to store the data even if garbage collection is performed, the data is not stored in the block, and the process moves to storing the data in another block.

In the current example, assuming that it is possible to store the updated record 14b by summing up the free area 15a, free area 15d, free area 15b, and free area 15c in the block 10, garbage collection It will be done.

During garbage collection, the work area 5 corresponding to the block 10 is cleared by the garbage collection means 4''.
° is prepared and the block header section 11 is placed on the working area 5'.
After the records 14a are created, the records 14a are updated in the order of line offsets 168 to 16e, except for the record 14b that is subject to update.

Record 14C, record 14d, and record 14e are stored, and line offset 16a and line offset 1 are stored.
6C, line offset 16d, line offset 16
e is newly set, and one free area 15a is created. This state is shown in FIG. 4fcl.

When the garbage collection is completed, the record updating means 3 stores the record 14b in the free area 15a, the corresponding line offset 16b is also updated, and the updating process regarding the record 14b is completed. This state is shown in FIG. 4 Fdl.

[Problem to be solved by the invention]

As mentioned above, garbage collection must be taken into consideration for files that use variable-length records.
In the conventional file update method, garbage collection that occurs when a record is updated is performed as an extension of the application program that issued the record update request, and this garbage collection moves all records in the block. Since this is a highly loaded part of the file control system, it has the disadvantage that it takes a very long time before control is returned to the application program. In particular, in online transaction systems that involve file updates within transactions,
A major problem is that the responsiveness to the terminal deteriorates, making it impossible to improve the number of transactions per second.

The present invention has been proposed in view of the above points, and its purpose is to provide a file control system for files that can have multiple variable-length records managed by line offsets within a block. To provide a file update method that can eliminate the burden of garbage collection on an application program, shorten the time until control is returned to the application program, and improve service to users.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a file control system for files that can have multiple variable-length records managed by line offsets within a block, which accepts record update requests from application programs. A data manipulation command analysis means for analyzing an update request, a record update means for updating a record based on an analysis result of an update request, a garbage collection detection means for determining the necessity of garbage collection after updating a record, and a garbage collection detection means for issuing an update request. A system lock means that is included in a system program that is separate from the application cage-type program and that prevents other programs from updating blocks that perform garbage collection; The system includes a garbage collection means that performs collection, and a system lock release means that is included in the system program and releases a lock on a block for which garbage collection has been completed.

[Effect]

In the file update method of the present invention, the data manipulation command analysis means receives a record update request from an application program and analyzes the update request, the record update means updates the record based on the analysis result of the update request,
A garbage collection detection means determines the necessity of garbage collection after a record is updated, and a system locking means included in a system program separate from the application program that issued the update request prevents the blocks to be garbage collected from being blocked by other programs. Updates are prohibited, a garbage collection means included in the system program performs garbage collection on the target block, and a system lock release means included in the system program unlocks the block for which garbage collection has been completed.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the file update method of the present invention. In FIG. 1, the present embodiment includes a file 9 including a block 10 in which a plurality of variable-length records are managed and stored using line offsets, and an application program 1 that issues an update request regarding the records of the file 9 based on an update command. , a data manipulation command analysis means 2 that receives a record update request from the application program 1 and analyzes the update request; a record update means 3 that updates the record based on the analysis result of the update request by the data manipulation command analysis means 2; A garbage collection detection means 4 that determines the necessity of garbage collection after a record is updated by the update means 3, and a block 10 that is included in a system program 5 that is separate from the application program 1 that issued the update request and that performs garbage collection. On the other hand, there is a system locking means 6 that prohibits updates from other programs, and a garbage collection 9 of the target block 10 that is included in the system program 5.
The system comprises a garbage collection means 7 that performs garbage collection, and a system lock release means 8 that is included in the system program 5 and releases the lock on the block 10 for which garbage collection has been completed.

FIG. 2 specifically shows the contents of block 10, and FIG. 2 1al is similar to FIG.
It has a similar configuration. That is, in FIG. 2 1a), a block 10 is composed of a block header section 11, a record section 12, and a line offset section 13, and the block header section 11 is located at the beginning of the block 10 and has a certain length. A plurality of variable-length records 148 to 14e are stored in the record section 12, the record length information is owned and held by the record itself, and the starting position of each record 14a to 14e is determined by the line offset section 130.
It is stored in the corresponding line offsets 16a to 16e. That is, line offset 16a indicates the start position of record 14a, line offset 16b indicates the start position of record 14b, line offset 16c indicates the start position of record 14C, and line offset 16c indicates the start position of record 14C, and line offset 16c indicates the start position of record 14C.
A line offset 16d indicates the start position of the record 14e, and a line offset 16e indicates the start position of the record 14e. Furthermore, the shaded portions 158 to 15c are empty areas.

The operation of the embodiment shown in FIG. 1 will be explained below.

First, from application program 1 to Fig. 2 ta)
If an update request is issued to, for example, record 14C of block 10 in the state of
(not shown).

If the length of the record 14c does not change or becomes shorter as a result of the update, it is stored in the original position.

Furthermore, if the length of the record 14C becomes longer as a result of the update, it cannot be stored in the original position, so a free area after the last record in the block 10 is searched.

Therefore, it is determined whether the updated record 14c can be stored in the free area 15c after the record 14e, and assuming that the free area 15C has enough free space to store the record 14c, the record 14C is stored in the free area 15C, and the line offset 16C corresponding to the record 14C is updated to point to the head position of the free area 15c where the updated record 14C is stored. The area remaining after storing the record 14C becomes a new free area 15C, and the area occupied by the record 14C before the update is released and becomes a new free area 15d. This state is shown in Figure 2 (bl
It is. Note that when storing the record 14C in the fat shown in FIG. 2, if the updated record 14C cannot be stored in the rear free area 15C, processing moves to storing it in another block, etc.

After the record 14c is stored in the block 10, control is passed to the garbage collection detection means 4, and the garbage collection detection means 4 further stores the record 14c in the free area 15c after the record 14c just stored in the block 10. It is determined whether the data can be stored, and if it can be stored, it is determined that there is no need for garbage collection, and if it cannot be stored, it is determined that garbage collection is necessary. That is, the necessity of garbage collection replacement is determined based on the length of the latest record and whether there is a free space that can store a record of the same length.

If it is determined that garbage collection is not necessary, control is immediately returned to the application program l, but if it is determined that garbage collection is necessary, control is returned from the garbage collector detection means 4 to the system program 5. A communication is made to instruct block 10 to be garbage collected. This ends the update process, and control is returned to the application program l, which continues the process.

The system program 5, which has received a notification from the garbage collection detecting means 4 about the execution of garbage collection, locks the block 10 to be garbage collected in order to wait for references, updates, etc. from other programs. Locking is performed by 6. Here, since the system program 5 takes over and locks the block 10 from the application program 1, the system program 5 can refer to and update the block 10, and the block 10 can be referenced and updated from the application program 1. If so, a meeting will occur.

Next, in the system program 5, the garbage collection means 7 performs garbage collection of the block 10. Note that in this embodiment, unlike the conventional example,
No special work area is used for garbage collection. That is, records 14a, record 14b, record 14d, record 14e, and record 14C are stored in the order in which they are physically located at the front in the block 10, filling up the free space, and the corresponding line-off cellar) 1
6a, line offset 16b, line offset 16d, line offset 16e, line offset 1
6C is newly set and one free area 15a is created. This state is shown in FIG. 2 (10).

When the garbage collection by the garbage collection means 7 is completed, the system lock release means 8
The lock on block 10 is released, and requests for reference, update, etc. to block 10 from other programs are permitted.

Next, the application program 1 to FIG. 2 (C
If an update request is issued to, for example, the record 14b of the block 10 in the state 1, the update request is analyzed by the data manipulation command analysis means 2, and based on the update result, the record 14b is updated by the record update means 3. updated on the buffer.

If the length of record 14b does not change or becomes shorter as a result of the update, it is stored in the original position of block 10, but if the length of record 14b becomes longer, it cannot be stored in the original position. , the free space after the last record in block 10 is searched.

Here, it is determined whether the record 14b can be stored in the free area 15a after the record 14C, and
Assuming that a has enough free space to store the record 14b, the record 14b is stored in the free space 15a, and the line offset 16b corresponding to the record 14b is the free space where the updated record 14b is stored. It is updated to point to the beginning position of 15a.

The area remaining after storing the record 14b becomes the new free area 15a, and the area remaining after storing the record 14b becomes the new free area 15a.
The area occupied by 4b is released, and a new free area 15
It becomes b. This state is shown in FIG. 2 (dl).

After storing the record 14b, control is passed to the garbage collection detection means 4, and the garbage collection detection means 4 detects the record 14 in the block 10 that has just been stored.
It is determined whether the record 14b can be further stored in the free area 15a after the record 14b, and if it is determined that the record 14b can be stored sufficiently, it is determined that there is no need for garbage collection, and control is returned to the application program 1.

〔Effect of the invention〕

As explained above, in the file update method of the present invention, garbage collection is performed on an asynchronous system program that is separate from the application program, and control is returned to the application program as soon as the update is completed. This has the effect of shortening the time it takes for control to be returned to the application program and significantly improving service to users. In particular, in an online transaction system that involves file updates within a transaction, responsiveness to terminals is improved and the number of transactions per second can be improved.

[Brief Description of the Drawings] 1rEJ is a configuration diagram showing an embodiment of the file update method of the present invention, FIG. 2 is an explanatory diagram of its operation, FIG. 3 is a configuration diagram of a conventional example, and FIG. 4 is its It is an operation explanatory diagram. In the figure, 1...Application program 2...
... Data manipulation command analysis means 3 ... Record updating means 4 ... Garbage collection detection means 5 ...
...System program 6 ...System lock means 7 ...Garbage collection means 8 ...
・System lock release means 9...File 10...Block

Claims (2)

[Claims] (1) In a file control system for files that can have multiple variable-length records managed by line offsets within a block, data manipulation instructions accept record update requests from application programs and analyze the update requests. an analysis means, a record update means for updating a record based on the analysis results of an update request, a garbage collection detection means for determining the necessity of garbage collection after updating a record, and a system separate from the application program that issued the update request. A system lock means that prohibits updates from other programs to blocks that are included in the program and that are subject to garbage collection; a garbage collection means that is included in the system program that performs garbage collection of the target blocks; and a system lock release means for releasing a lock on a block for which garbage collection has been completed. (2) The file according to claim 1, wherein the garbage collection detection means determines the necessity of garbage collection based on whether the record stored by updating can be further stored in a free area at the rear end of the same block. Update method.