JPH064372A - Block use control system - Google Patents

Abstract

PURPOSE:To effectively utilize a block by efficiently storing a new record in an unused area or an erased area in the block. CONSTITUTION:This system is provided with low-order block managing tables 21, 22-24 to divide data blocks and to manage them corresponding to the maximum unused area lengths of respective data blocks 31-36 in a file, and a high- order block managing table 1 to store the maximum used area lengths and the addresses of the correspondent low-order block managing tables 21-24. Then, the data block having the unused area of a length corresponding to the desired record to be stored is found from the high-order/low-order block managing tables 1 and 21, 22,... and the record is stored in the unused area of the found block. After the storage, the high-order/low-order block managing tables 1 and 21, 22,... are updated.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a block use control system,
In particular, the present invention relates to a block use control method for storing records in a block of a file set in a randomly accessible storage device including a plurality of blocks having a plurality of record storage areas.

[0002]

2. Description of the Related Art Conventionally, in this type of block use control method, all record storage areas in a block are unused, or all record storage areas in a block can be reused by deleting records. When the state, that is, the block becomes empty, the block is reused. If there is no free block, if there is an unused area that is large enough to store the target record and has never been used, the record is stored in that area. If additional storage is performed and there is no unused area, a new block is secured and the target record is stored in the unused area.

[0003]

In the conventional block use control method described above, the records are stored even once and the used blocks are reused only when all the records in the blocks are deleted and become empty. Is possible,
If it is used even a little, it cannot be used until it becomes empty.
Therefore, when there is no free space to store the target record in the last block at the time of newly storing a record, it has an unused area large enough to store another record to be stored. Even if there is a block, the unused area in that block is not used. As a result, the record to be stored is stored in the empty new block. Especially in a file with a large record storage area, it can be reused even though the unused record storage area increases due to the deletion of records in the update process in which records are deleted and stored randomly. However, the number of blocks used increases only when new records are stored, and the record storage area in the blocks cannot be used effectively.

[0004]

According to the block use control method of the present invention, a record is stored in a block of a file set in a randomly accessible storage device composed of a plurality of blocks having a plurality of record storage areas. In the block usage control method for managing blocks, a block management table that manages blocks by the length of the maximum unused area of consecutive unused areas in each block, and that record is stored when a new record is stored. Block selecting means for selecting a block having an unused area of a possible size from the block management table,
The block selected by the block selection means is read, an unused area of a size capable of storing the record is searched, and a record storage means for storing the record, and the record storage means stores the record Table updating means for updating the block management table in accordance with the length of the new largest unused area in the block when the length of the unused area changes.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a relational diagram of a table used in an embodiment of the present invention, showing a relation between a management table and a data block used for one file. In the embodiment of FIG. 1, the upper block management table 1 and the maximum of 25
5 lower block management tables 21, 22, and 24;
A plurality of data blocks 31, 32, to 36 having the same capacity are shown.

The upper block management table 1 has 255 entries such as entries 11, 12, ...
Each entry is associated with the record length coefficient of the maximum unused area length in the block by the relative position from the beginning, and each entry stores the address of the lower block management table. Each of the lower block management tables 21, 22 to 24 has a data block 3 having the same maximum unused area length in the block.
It is an aggregate of block numbers 1, 32 to 36. The record length coefficient is a coefficient indicating a ratio of the entire length of the data block, and 255 types of 1 to 255 are represented by 1 byte. That is, for example, the data block length is 1000 bytes,
Assuming that the maximum unused area in a block is 100 bytes, the record length coefficient is 100 / (1000/25
5) ≈ 25 (cut off after the decimal point). In FIG. 1, the lower block management table 23 has a plurality of entries 231, 232 and the like divided into 4-byte units, and stores the block numbers of blocks A and B, respectively.
Since it is the lower block management table of the address pointed to by the entry at the relative position 64 of the upper block management table 1, the blocks A and B have the maximum unused area length in the block = 250 bytes (100 ÷ 255 × 64). It indicates that

FIG. 2 is a structural diagram of the data block shown in FIG. 1, and shows the data block 33 of FIG. 1 as an example.
The data block 33 is a used area 33 in which a record is stored.
1 and 333, unused areas 332 and 334 in which no record is stored, and an area information table 335. The area information table 335 has entries corresponding to each used area and unused area in the data block 33, and is sequentially generated from the end of the data block 33. Entries 51, 52, 53, and 54 are used area 331, unused area 332, and used area 33, respectively.
3 and unused area 334. Each entry of the area information table 335 stores area storage information 501 and area length 502. The area storage information consists of 16 bits. The first 1st bit is used information indicating whether the target area is in use or is empty, and the other 15 bits are the target area. It is used as a storage position indicating a relative position from the beginning in the block. The area length 502 is the length of the target area and is represented by the above-mentioned record coefficient.

3 and 4 are flow charts of an embodiment of the present invention. FIG. 1, FIG. 2, FIG. 3, and FIG.
With reference to FIG. In the following explanation, 10
It is assumed that a record having a record length of 250 bytes (record coefficient 64, hexadecimal "40") is stored in a file having a plurality of data blocks of 00 bytes. First, using the record length as a key, an entry in the upper block management table 1 is selected (step 101). In the example of FIG. 1, the entry 13 is selected. At this time, the entry in the upper block management table 1 has not been completed (step 10
2) Reference the value of the selected entry 13 (step 103). It is checked whether or not a value is stored in the referred entry (step 104). If the value is stored, the entry in the lower block management table of the address of that value is referred to (step 106). If there is no value in the entry referred to in step 104, the next entry in the upper block management table 1 is selected (step 105) and the process returns to step 102. In the example of FIG. 1, in step 106, the block number A is referred to as the value of the first entry of the lower block management table 23. Next, the data block of this block number is read (step 107). The value of the usage information of the entry of the area information table 335 in the read data block is "1", and the one whose area length is equal to or larger than the record length to be stored is extracted (steps 108 and 10).
9, 110, 111). In the example of FIG. 2, since the area length of the entry 52 is “40” in hexadecimal, which is equal to the record length to be stored, the unused area 332 is determined as the storage destination unused area. Here, the value of the area length of this entry is stored in the storage area (step 112). Next, change the usage information of this entry to "0" meaning that it is in use, change the size of the record that stores the value of the area length, and add a new entry corresponding to the remaining unused area. Create (step 113). Then, the record is stored in the unused area at the storage position of the entry of the area table to be stored (step 114). In the example of FIG. 2, the record is stored in the unused area 332 from the storage position of the entry 52. Next, in order to check whether the upper / lower block management table needs to be updated, the value of the storage area in step 112 is compared with the maximum unused record length of this data block (step 115). The value obtained from the relative position of the upper block management table 1 is used for this record length. Therefore, if the record length is large, the process ends immediately, but if the record length is large, the value of the maximum unused area length is selected from the entry of the area information table 335 in the target data block (step 116). ). In the example of FIG. 2, the storage area value “40” stored in step 115 is equal to the record length “40”, and the entry having the maximum unused area length from the entries in the area information table 335 in step 116. The area length "38" of 54 is selected. Next, the selected area length is compared with the record length used in step 115 (step 117), and if they are the same, the process immediately ends, and if they are not the same, that is, the record length is "40" as in the example of FIG. If the area length is as small as "38", the target entry of the lower block management table is deleted and the entry of the upper block management table 1 is updated (step 118). As a result of scanning the upper block management table 1 in step 102, if a data block having an unused area with a size capable of storing a record cannot be found, the maximum unused block number + 1 unused The block number is generated, and an entry having this block number is newly added to the upper and lower block management tables (step 119). Next, the data block set in step 119 is read (step 120), the first entry is stored in the area information table in the read data block (step 121), and the process proceeds to step 111. The area length 502 in this entry is set to one entry length of the data block length-area information table, unused "1" is set to the usage information, and "0" is set to the storage position.

[0010]

As described above, the present invention intends to provide and store a block management table which manages by dividing into blocks according to the length of the maximum unused area of the unused areas in each block. Since a block having an unused area of the record length of a record is selected by this block management table, it is not necessary to use a data block in which all the records in the data block have been deleted as in the conventional case, and the unused area is There are advantages that the number of opportunities to be assigned to a new record is increased, the efficiency of use of the unused area is improved, and inefficient data blocks are not increased.

[Brief description of drawings]

FIG. 1 is a related diagram of a table used in an embodiment of the present invention.

FIG. 2 is a structural diagram of a data block shown in FIG.

FIG. 3 is part of a flow chart of one embodiment of the present invention.

4 is a part of the flowchart of one embodiment of the present invention, which follows the flowchart of FIG.

[Explanation of symbols]

1 Upper block management table 11, 12, ~ 14, 51, 52, ~ 54, 231, 2
32 entries 21,22 to 24 lower block management table 31,32, to 36 data blocks 331,333 used area 332,334 unused area 335 area information table 501 area storage information 502 area length

Claims (1)

[Claims] 1. In a block use control method for storing records in a block of a file set in a randomly accessible storage device composed of a plurality of blocks having a plurality of record storage areas, in each block, The block management table that manages blocks according to the maximum unused area length of continuous unused areas, and the block that has an unused area of a size that can store the record when a new record is stored are described above. A block selecting means for selecting from the block management table, a record storing means for reading the block selected by the block selecting means, searching for an unused area having a size capable of storing the record, and storing the record, and the record storing means. By storing records by A block use control method comprising: a table updating unit that updates the block management table according to a new maximum unused area length of a block when the length of a large unused area changes.