JP3236152B2 - File compression processor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a file compression processing apparatus, and more particularly, to a file for compressing and recording image data and text data on a file recording medium such as a magneto-optical disk (MO) or a hard disk. The present invention relates to a compression processing device.

[0002]

2. Description of the Related Art In recent years, a database is constructed by recording text data, binary data (programs and image data) and the like on a large-capacity recording medium such as a magneto-optical disk (MO) or a hard disk. An online information search service that accesses a corresponding database via a communication line or the like as necessary so that a user can search for data requested by the user is becoming widespread. In this case, the information in the database has a very large amount of information. Therefore, various data compression techniques are used as a data recording method on the recording medium, and the apparent capacity of the recording file is reduced. It is increasing.

An example of a data file compression technique in such a system is disclosed in, for example, Japanese Patent Application Laid-Open No. 63-26657.
9 and JP-A-64-2152. In these techniques, data compression is performed on all of the recorded data files using a predetermined data compression, and when the user uses this file, the data expansion / reproduction processing of the file is automatically performed. .

[0004]

In such a conventional data file compression system, since all the files are subjected to data compression processing and stored in a file device such as a disk, an empty file is stored in the file device. Even if the capacity is sufficient, the file is compressed, and when using the file, it is necessary to always perform the file expansion / reproduction processing, and there is a disadvantage that the reproduction processing is reduced.

Also, there is only one compression method for data compression, and depending on the access frequency and the type of file obtained from the last access date and time and the number of accesses of the file to be compressed, the compression, decompression speed and compression ratio are not so large. Despite some that are not required, it is not possible to select a compression method.

The present invention has been made to solve the above-mentioned drawbacks of the prior art. A first object of the present invention is to reproduce a file at high speed without compressing the file if the free space of the file device is large. It is another object of the present invention to provide a file compression processing apparatus that enables a file to be efficiently used by appropriately selecting a compression method according to a file access frequency and a type. A second object of the present invention is to expand and reproduce a frequently accessed compressed file among expanded files when the free file capacity is increased, thereby making it possible to use a file compression that can use the file without performing expansion generation as much as possible. An object of the present invention is to provide a processing device.

In order to achieve the above object, in the file compression processing apparatus of the present invention, a current free space value on a file device for recording a file is compared with a threshold value preset as an upper limit of the free space value. File status monitoring means; file compression means for performing compression processing of a file on the file device when the current free space value is determined to be smaller than a threshold value by the file status monitoring means; Based on the management information of the file attribute management unit that stores management information including the last access date and time and the number of times of access for each file recorded, information on whether or not compressed, and data type information, and the file attribute management unit, Uncompressed files are searched in ascending order of access frequency obtained from the number of accesses, and compressed by the compression means. And file retrieval means for selecting a compressed file to be, based on the management information of said file attribute management unit, obtains the data type and the access frequency of the file that performs a compression process in the compression means, the
For files with frequently accessed stages , the extended playback time
Short compression scheme, low stage of the frequently accessed files
The yl select highly compressed file compression method, characterized in that it comprises a compression method selection means for instructing the compression process by the compression method selected for the compression means.

[0008] The file compression processing apparatus of the present invention according to claim 2
Then, the compressed file recorded in the file device
A file that expands and plays back the compressed file in response to an access request.
File reproducing means .

[0009]

[0010]

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram of a file processing system using a file compression processing device according to a first embodiment of the present invention. 1, this file processing system includes a file compression processing device 100, a user program 120, and a file device 130.

The file compression processing apparatus 100 performs automatic file compression and decompression reproduction processing on each disk 131 of the file apparatus 130 asynchronously with the user program 120. The user program 120 accesses a file recorded in the file device 130 via the file compression processing device 100 and uses the file. The file device 130 is a magneto-optical disk (MO)
131 as a recording medium such as a hard disk or a hard disk
And a file attribute management unit 132 that manages management information of files recorded on each disk 131.

As shown, the file compression processing apparatus 100 comprises a file status monitoring means 101, a file search means 102, a file compression method selection means 104, a file compression means 105, and a file reproduction means 106. The file status monitoring unit 101 manages the file device 130 managed in the file attribute management unit 132.
It is determined whether or not the above current file free space value exceeds or falls below a predetermined threshold value (a free file space value to be secured in the file device 130).

When the file status monitoring means 101 determines that the current file free space value is lower than the threshold value, the file search means 102 determines whether the file to be compressed (the file to be compressed Of all files except those designated as not to be accessed), the uncompressed files are searched in ascending order of access frequency. The search for the compression target file is performed with reference to the file management information of the file attribute management unit 132.

The file management information of the file attribute management unit 132 includes a list of file names and directory names, the last access date and time and the number of accesses for each file. File access frequency depends on the access
It is determined based on the number of times and divided into high, medium, low, etc. stages. The criteria for determining the level of the access frequency is set in the file search means 102. The user can also set the reference and the stage.

The file compressing means 105 is for actually compressing the retrieved compression target file and recording it on the disk 131 of the file device 130. The file compression means 105 includes attributes such as the access frequency of the compression target file and the type of the file. Accordingly, a compression process is performed by appropriately selecting a data compression method. In this case, when selecting a method for compressing a file to be compressed by the data compression means 105, the file compression method selection means 104 selects the method. The file compression method selection unit 104 includes a file attribute management unit 132
A data compression method suitable for the file is selected in consideration of data attributes such as text data and binary data (program, image data, etc.) and access frequency among the management information on each file.

The data attribute of a file is used when selecting a data compression method having a higher compression rate that matches the data attribute, and the frequency of file access is determined when selecting a data compression method having a short data compression / decompression time. Used for The data compression method selection means 104 selects one of several data compression methods selected based on the data attribute.
For a file with a high access frequency, a data compression method with a shorter data compression / decompression time is selected, and for a file with a low access frequency, a data compression method with a higher compression rate is selected.

As described above, the file attribute management unit 132 of the file device 130 stores the file free space value information of the file device 130, the file name and directory name of each file, and the difference between the file size before and after the file is compressed. Maximum and minimum values, file names with those maximum and minimum values, file size of each file, data attributes (text data file, program file, image data file, etc.), whether the file is not a file to be compressed Whether the identifier, file compression /
Uncompressed, compression method, last access date and time, number of accesses,
In the case of a compressed file, file management information on the file size and the like after compression is managed. Here, an identifier indicating whether or not the file is not a file to be compressed is added to a file designated by the user as not to be compressed.

In FIG. 1, the file attribute management unit 13
2 is physically provided separately from the disk 131, but each file actually has a file control information area for recording the file management information separately from the data area. The file attribute management unit 132 manages the file management information of the area.

The file reproducing means 106 performs a decompression / reproduction process of the file in response to a file use request from the user program 120, and refers to a data compression method which is one of the management information of the file. Then, the reverse extension reproduction is performed. However, as a result of checking the file compression / non-compression information of the file in the file attribute management unit 132, if the file is an uncompressed file, no decompression / reproduction is performed, and a process of simply reading the file from the file device 130 is performed. Become.

FIG. 2 is a flowchart showing the operation of the apparatus shown in FIG. Asynchronous with the user program 120, the file status monitoring means 101 causes the file device 130
The current free file capacity in the server is monitored (step 2
10). The free space and free file area information on the file device 130 are stored as file management information in the file attribute management unit 132 on the file device 130, and this information is managed by the file management of the operating system. When the free file area information and the free space information are changed, the file attribute management unit 132
File management information has been updated,
When deletion, expansion, or reduction occurs, it is changed by management of the operating system.

Then, the file status monitoring means 101 compares the current file free space value of the file device 130 with the threshold value (step 211). Since there is enough space, the data compression process is not performed. in this case,
Since data compression is not performed, when using files,
The file access processing can be performed immediately without performing the data decompression / reproduction processing, and the speed can be increased.

If the free space value is below the threshold,
Therefore, file compression processing is performed for the first time. Therefore, a file to be compressed is searched based on the file management information of the file attribute management unit 132 (step 22).
0). At the time of retrieval, the file is retrieved from files that have not been compressed yet and that have a low access frequency among files other than files for which compression is prohibited by the user. If there is no file to be compressed, the process returns to step 210. At step 221, it is determined whether or not there is a "file to be compressed". The "file to be compressed" means a file to be compressed before reaching a file free space equal to or larger than a set threshold value. I'm pointing.

When a file to be compressed is searched, a data compression process is performed on the file (step 2).
50). At this time, a data compression method with an appropriate compression rate and compression / decompression speed is selected by the file compression method selection means 104 according to the access frequency and data attribute of the file.

When selecting a data compression method, the file compression method selection means 104 selects a data compression method suitable for the data attribute according to the data attribute of the file attribute management unit 132. Next, access of the file attribute management unit 132
The access frequency is obtained from the number of times, and a file compression method with a short decompression / reproduction time is selected for a file with a high access frequency, and a file compression method with a high compression rate is selected for a file with a low access frequency. As the data compression method, a known data compression method is used. For example, in the present embodiment, the following data compression methods are used.

Data compression methods for text files include Huffman coding, arithmetic coding, Lempel-Ziv coding, and the like. The Huffman coding method is a method of changing the number of bits representing a character according to the frequency of appearance of the character. The Huffman coding scheme creates a tree-structured code table, and there are fixed and variable code tables. The former is called static Huffman coding, and the latter is called dynamic Huffman coding.

The arithmetic coding method is a method in which Huffman coding is applied to each section in consideration of the probability that a character appears in a certain section. The Lempel-Ziv coding method focuses on repetition of a character string, and performs compression by deleting redundant portions of the character string. Generally, in the Lempel-Ziv coding method, the Huffman coding method has a lower compression rate than the arithmetic coding method, but has a higher compression / decompression reproduction processing speed. The file compression method selection unit 104 selects a Lempel-Ziv coding method for a file having a high access frequency and a Huffman coding method or an arithmetic coding method for a file having a low access frequency.

As a data compression method for a binary file (image data), there are a run-length encoding method, a differential mapping method, and the like. In the former, the same continuous data is represented by the number, and the number of pixels on the image is represented by the number, so that a larger number of bits can be saved as compared with the image element column, but the processing speed is inferior. The difference mapping method is a method in which an image is expressed not as a brightness value itself but as an array of differences between the brightness of adjacent pixels. File compression method selection means 1
For example, in the case of image data, a difference mapping method is selected for a file having a high access frequency, and a run-length coding method is selected for a file having a low access frequency.

The details of these data compression methods are disclosed in the following documents. In other words, bit separate volume “ACM Computing Survey '8
7 Computer Science "" Data Compression "(P.1
65-P. 195), C Magazine 199
January / January "Introduction to Data Compression Algorithm" (P.44)
~ P. 58, Interface 1992, August, "Data compression algorithm and its substance" (P.88 to P.1)
23) and the like.

The file is compressed according to the selected data compression method (step 260). When the file compression process ends, the process returns to step 210 again and the above operations are repeated. This file compression process is repeated until the free file capacity value exceeds the threshold. If it is determined in step 211 that the free file capacity value exceeds the threshold value, the compression processing of the next file becomes unnecessary and is not performed. Thereafter, when the free file capacity value becomes smaller than the threshold value due to addition of a new file or the like, the compression process is performed again.

FIG. 3 is a flowchart showing a process when the user program 120 uses a file on the file device 130. First, the file reproducing means 10
6, the file compression /
It is determined whether the file is compressed based on the uncompressed information (step 310). If the data is not compressed, the file is read as it is. If the data is compressed, the data compression method is determined based on the file attribute information (step 320), and the decompression / reproduction processing corresponding to the method is performed (step 320). 311).

FIG. 4 is a block diagram showing a file compression processing apparatus according to a second embodiment of the present invention.
The same components as those of the embodiment are denoted by the same reference numerals. Second
The file compression processing apparatus according to the embodiment includes a threshold value changing unit 103 in addition to the configuration of the first embodiment. The threshold value changing means 103 is provided for the file status monitoring means 10.
1 controls to increase or decrease the threshold value to be compared with the file free space value.

The file search means 102 is provided with a function of searching for a file having a high access frequency among already compressed files. In this apparatus, when the file status monitoring means 101 determines that the threshold value is the initial value and the free space value of the file exceeds the threshold value, the file search means 102 Among them, a file having a high access frequency is searched, and the file is expanded and reproduced by the file reproducing means 106. The other configuration is the same as that of the first embodiment, and the description is omitted.

FIGS. 5, 6, and 7 are flow charts showing the operation of the second embodiment. The same steps as those in the flowchart shown in FIG. 2 are denoted by the same reference numerals. In step 221, the "file to be compressed"
If there is no, it is determined in step 222 whether the threshold value changing means 103 can reduce the threshold value by a predetermined adjustment value. The threshold value changing unit 103 determines that the threshold value after being reduced by the predetermined adjustment value is the difference between the file size before compression and the file size after compression among all files managed by the file attribute management unit 132. If it is larger than the maximum value, it is determined that the adjustment is possible, and the currently set threshold value is reduced by a predetermined adjustment value (step 240). FIG. 8 shows steps 222 and 24.
The state when the threshold value at 0 is decreased is shown. Here, the predetermined adjustment value is X, and the maximum value of the difference between the file size before compression and the file size after compression is M.

As described above, when the adjusted threshold value is larger than the maximum value of the difference between the file sizes before and after compression, the threshold value is reduced, so that the file size of all the files before compression and the file size after compression are reduced. A free file capacity equal to or greater than the maximum value of the file size difference is maintained. Thus, even if the file having the maximum difference in the file size before and after the compression is expanded and reproduced, the expanded and reproduced file can be created on the file device 130. Further, by decreasing the threshold value by the predetermined adjustment value, “NO” is determined in the step 211, and the process proceeds to the next step 230 (see FIG. 6). The predetermined adjustment value of the threshold value is set in the threshold value changing unit 103 in advance.

The operation shown in FIG. 6 (steps 230 to 23)
4) When the file on the file device 130 is deleted or reduced by the file management of the operating system, the free file capacity increases. Therefore, the threshold value is set to the initial value (the free file capacity value to be originally secured). ) Must be reset and returned, and the flow of the processing is shown.

The threshold value changing means 103 determines whether the file free space value exceeds the initial threshold value (step 230) and determines whether the current threshold value is the initial value (step 230). 231) If the condition is satisfied, the current threshold value is returned to the initial value (step 232). Then, the process returns to step 210 again to monitor the state of the free space value. FIG. 9 shows a state where the threshold value is reset to the initial value.

If it is determined in step 230 that the file free space value is smaller than the initial threshold value, it is determined whether the difference α between the free space value and the current threshold value is larger than a predetermined adjustment value X. Is performed (step 233). If it is determined to be larger, the difference α between the free space value and the current threshold value is divided by the predetermined adjustment value X, and the obtained integer value and the predetermined adjustment value X
Is multiplied by the current threshold value (step 2
34). Then, the process returns to step 210, and the file free space value is monitored. FIG. 10 shows the state of the process of increasing the threshold value.

As described above, when the file free space increases due to deletion or reduction of a file, step 240
By returning the threshold value to the initial value in step 234, or by increasing the threshold value in step 234 so as to approach the initial value, the file free space to be secured is always kept constant. Further, the threshold value does not become larger than the initial value.

FIG. 7 shows that the free space increases due to file deletion or file reduction by file management of the operating system and exceeds the initial threshold value (step 230), and the threshold value is increased in step 231 in FIG. This shows a process of decompressing and reproducing a compressed file with a high access frequency when it is determined to be the initial value.

As shown in FIG . 7, the file search means 10
2 indicates that the free file capacity exceeds the initial threshold value.
(Step 235), the "compressed file"
A search is performed (step 236). Here, a search for “compressed file” is performed, and the “compressed file” corresponds to a file that is a compressed file and has a high access frequency. For access frequency,
As described above, the determination is made based on the file management information of the file attribute management unit 132. Empty at step 235
If the file size does not exceed the initial threshold value
Then, the process returns to step 210 to monitor the state of the free space value.

As a result of the search, if "compressed file" exists (step 237), the file is expanded and reproduced by the file reproducing means 106 (step 238). If "compressed file" does not exist,
Returning to step 210, the state of the free space value is monitored. FIG. 11 shows the state of the “compressed file” expansion / reproduction processing from step 235 to step 238.

If the "compressed file" does not exist in step 236 in FIG. 7, all the files have been expanded and reproduced, and the file reproducing means 106 does not perform the expansion and reproduction of the file. In addition, files other than compressed and frequently accessed files are not treated as “compressed files”. As a result, when the file is decompressed and played back as a “compressed file”, the decompressed file has a high access frequency. Therefore, when the free space is reduced by adding the file, the file is immediately replaced with the “compression target file” in steps 220 to 260 Is less likely to be compressed.

As described above, when the free space of a file is increased by deleting a file or reducing the size of a file, the “compressed file” is expanded and reproduced until the free file capacity approaches the initial threshold value. When a file on the file device 130 is used by the user program 120, the file access processing can be performed as much as possible without performing the decompression reproduction processing by the file reproduction means 106.

The file search means 102 outputs the currently available file.
If the file capacity does not exceed the initial threshold value
Does not perform the file expansion / reproduction processing by the file reproduction means 106 even when there is a “compressed file”. This means that the current file size will
This is because if the file is not expanded and the file is expanded and reproduced, the file free space value becomes smaller than the threshold value.

As described above, the free space of the file is monitored, the necessity of the file compression processing is determined according to the size of the free space and the threshold, and the access frequency and the data attribute of the file are determined at the time of the compression processing. Since an appropriate compression method is selected in accordance with this, compared to compressing all the files collectively with a fixed compression method, the reproduction process at the time of using the file is speeded up, and the file can be effectively used. Although the present invention has been described with reference to the preferred embodiments, the present invention is not necessarily limited to the above embodiments.

[0047]

As described above, according to the file compression processing apparatus of the present invention, if the free space of the file device is large, the file can be reproduced at high speed without compressing the file. It is possible to provide a file compression processing apparatus that enables efficient use of a file by appropriately selecting a compression method according to the type.

Further, when the free file capacity increases.
Of compressed files that are frequently accessed
By performing extension reproduction, extension generation is performed as little as possible
The file can be used, and the playback process when using the file
Processing speed is increased.

[Brief description of the drawings]

FIG. 1 is a block diagram of a file compression processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation of a file compression process of the file compression processing apparatus according to the first embodiment.

FIG. 3 is a flowchart showing an access operation by a user program according to the first embodiment;

FIG. 4 is a block diagram of a file compression processing apparatus according to a second embodiment of the present invention.

FIG. 5 is a flowchart showing the operation of the file compression processing apparatus according to the second embodiment.

FIG. 6 is a flowchart showing the operation of the file compression processing apparatus according to the second embodiment.

FIG. 7 is a flowchart illustrating the operation of the file compression processing apparatus according to the second embodiment.

FIG. 8 is a view for explaining a state in which the threshold value in FIG. 5 is reduced.

9 is a view for explaining a reset state of a threshold value in FIG. 6 to an initial value.

FIG. 10 is a view for explaining a state of a threshold value increasing process in FIG. 6;

FIG. 11 is an exemplary view for explaining the state of decompression reproduction processing of “compressed file” in FIG. 7;

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 file compression processing device 101 file state monitoring means 102 file search means 103 threshold value change means 104 file compression method selection means 105 file compression means 106 file reproduction means 120 user program 130 file device 131 disk 132 file attribute management unit

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-4-151746 (JP, A) JP-A-4-91558 (JP, A) JP-A-3-157021 (JP, A) JP-A-4-151 191939 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G06F 12/00 511 G06F 12/00 501

Claims (2)

(57) [Claims] 1. A file status monitor for comparing a current free space value on a file device for recording a file with a threshold value set in advance as an upper limit of the free space value. File compression means for performing compression processing of a file on the file device when it is determined that the free space value of the file device is smaller than the threshold value; a last access date and time and the number of times of access for each file recorded on the file device; A file attribute management unit that stores management information including information as to whether or not compressed, data type information, and, based on management information of the file attribute management unit, uncompressed data in ascending order of access frequency obtained by the access count. File search means for searching a file and selecting it as a compression target file to be compressed by the compression means If, on the basis of the management information of the file attribute management unit, obtains the data type and the access frequency of the file that performs a compression process in the compression means, the access frequent steps fa
To yl, short compression method of extension and reproduction time, the access
High compression file pressures for infrequently staged files
Select a reduced manner, file compression processing device comprising: a compression method selection means for instructing the compression process by the compression method selected for the compression means. 2. The file compression processing apparatus according to claim 1, further comprising a file playback unit that expands and plays back the compressed file in response to an access request for the compressed file recorded in the file device.