JPH0696033A - Preread control system for file in client-server system - Google Patents

Abstract

PURPOSE:To improve the throughput of a read of plural records as to the file preread control system in the client-server system of an information processor. CONSTITUTION:When a one-record read request is received from an application program 1, a client function part 2 requests a server to read one record and then requests it to read plural following records. A server function part 3 reads one corresponding record according to the one-record read request from the client and informs the client function part 2 of the record, and then reads plural corresponding records at the successively generated plural-record read request and informs the client function part 2 of them. The client function part 2 informs the application program 1 of the requested one record without waiting for the following records.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a file prefetch control system in a client / server system.

In recent years, a client / server system has been used in a system composed of computers such as a plurality of workstations. In response to a request from an application (program), the client side requests the server to read a file record, reads the data requested by the server, and notifies the client.
In reading such a file, it is desired to efficiently read a plurality of records.

[0003]

2. Description of the Related Art In a client / server system, there are generally two methods for reading a file that is input / output in record units, as shown in FIGS.

FIG. 5 is an operation explanatory diagram when reading one conventional record, and FIG. 6 is an operational explanatory diagram when reading a plurality of conventional records. In both figures, 50 is a client of one workstation and 51 is a client. An application (meaning an application program, represented by APL) of the client 50, 52 is a client function unit. Reference numeral 53 is a server provided in the other workstation connected by the network, and 54 is a server function unit.

In the case of FIG. 5, one record is read by one request, and the procedure is as follows. An application (hereinafter referred to as APL) 51 requests the client function unit 52 to read one record.

The client function unit 52 issues a read request for the record requested by the APL 51 to the server function unit 54 of the server 53. The server function unit 54 notifies the client function unit 52 of the record requested to be read.

Upon receiving the record notification from the server function unit 54, the client function unit 52 notifies the APL 51 of the record. In the method of FIG. 5, since one record is notified,
When a request to read multiple records occurs, the throughput of the entire system was not good.

As a method of solving this, a method of reading a plurality of records by one request shown in FIG. 6 has been used. This will be explained below. The APL 51 issues a record read request.

The client function unit 52 has an APL 51
Requests the server function unit 54 to read a plurality of records including a record subsequent to the record for which the read request has been issued. When the client function unit 52 receives a plurality of records from the server function unit 54, the client function unit 52 stores the records in a buffer and
Notifies the APL only of the record for which the reading request has been issued.

Next, when the APL 51 issues a read request for a record subsequent to the previously read record, the client function unit 52 notifies the APL 51 of the contents of the buffer.

When there are no records in the buffer, the AP
When the L51 issues a read request for the subsequent record, the client function unit 52 issues a read request for a plurality of records to the server 53 (same as).

[0012]

According to the conventional method shown in FIG. 6, since the record requested by the APL to be read and a plurality of subsequent records are collectively notified to the server,
There is a problem in that the read time is increased by the number of records to be read in advance, and therefore it takes time until the record is notified to the client function unit 52 and the application.

An object of the present invention is to provide a file read-ahead control method in a client / server method that can improve the throughput of reading a plurality of records.

[0014]

FIG. 1 is a block diagram showing the principle of the present invention. Reference numerals 1 and 2 are provided on the client side, 1 is an application, 2 is a client function unit, 2a is a 1-record read request generation means, 2b is a subsequent plural-record read request generation means, 2c is a record notification means, and 2d is plural records. A buffer for storing, 2e is a record read notifying means. Reference numeral 3 is a server function unit provided on the server side, 3a is one record reading means, and 3b.
Is a subsequent plural record reading means, 3c is a one-record notifying means, and 3d is a plural-record notifying means.

According to the present invention, when a client makes a read request for one record in response to a request from an application, it also makes a read request for a plurality of succeeding records.
When receiving a notification of reading one record from the server, the application is notified of the one record, and when receiving a notification of reading a plurality of subsequent records from the server, it is stored in the buffer. When a read request from the application occurs, one record at a time It is read from the buffer.

[0016]

When the application 1 issues a 1-record read request, the 1-record read request generation means 2a of the client function unit 2 is driven, and the server function unit 3 is set to 1
A request for reading a record is generated, and subsequently, the plurality of subsequent record reading means 3b is driven to generate a request for reading a plurality of subsequent records to the server function unit 3. The one-record reading means 3a of the server function unit 3 is the client function unit 2
1 record of the corresponding file is read in response to the 1 record read request first received from, and when the reading of 1 record is completed, the 1 record notifying means 3c is driven. The one-record notifying unit 3c notifies the client function unit 2 of the read one record.

When the server function unit 3 receives the request for reading the subsequent plural records after the request for reading the one record, the subsequent plural record reading means 3b is driven, and the plural records succeeding the one record of the file which has been previously read. Is read, and a plurality of records are notified from the plurality of record notification means 3d to the client function unit 2. The client function unit 2 stores the plurality of records in the buffer 2d.
To store. The plurality of records stored in the buffer 2d are read one by one and notified to the application each time the application 1 issues a request to read a subsequent record.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is a processing flow of an embodiment in a client function unit, and FIGS. 3 and 4 are examples (No. 1) and (No. 2) of operation sequences of prefetch control in a client and a server.

FIG. 2 shows a processing flow when the client function unit (FIG. 1) is implemented by a program. When the processing of the read request starts, it is determined whether there is a read request from the APL (application) (S in FIG. 2).
1) When there is a read request, it is determined whether random reading (reading of a record number that is out of order with respect to the previous reading number), change of the read position (file), or change of the search key ( Same S2). At this time, if any of the random reading, the change of the read position, or the change of the search key is performed, the data stored in the buffer (2d in FIG. 1) is discarded (at step S3). To the server to determine if multiple requests have been made (S
4).

In this case, assuming that a read request from the APL is first received, a request for a plurality of records has not yet been issued to the server, so NO is determined, and then it is determined whether or not there is data in the buffer. S6). In this case as well, since there is no data in the buffer yet, a read request for one record is issued to the server (at step S8), and a read request for subsequent multiple records is issued to the server (at step S9). Further, one record is received and notified to APL (S10 of the same), S1
Return to.

Returning to S1, through S2 and S3, when it is determined in S3 whether a request for a plurality of records is issued to the server, it is determined YES in S4 when a request for a plurality of records is issued. The process of receiving from the server and storing it in the buffer is performed.
5). Further, when it is determined in S6 whether there is data in the buffer, the data is stored in the buffer in S5, so YES is determined and the data in the buffer is A
A process of notifying the PL is performed (S7).

The processes of S2 and S3 are continued to the first record if there is random reading or a change in the reading position after the plural records are received from the server and stored in the buffer by the process of S5. It is executed to discard the data in the buffer because it will be useless to read multiple records.

Next, FIGS. 3 and 4 show an operation sequence of prefetch control of the client and the server in the case of reading a record according to a certain detection key. In the following, the processing operations (1) to (16) of the client function unit corresponding to the APL requests a to g of the client will be mainly described along with the processes A to F of the server function unit of the server in order. To do. In the following explanation, the client function part,
The server function units are abbreviated as “client” and “server”, respectively.

(1) Since the record read request a has been received from the client APL, the record read request is transmitted to the server. The server reads the requested record and notifies the client (A).

(2) APL sends a read request for n records following the record requested to be read by the APL to the server. The server reads the requested n records and notifies the client (B).

(3) Since the record requested by the APL is notified from the server, the record is notified to the APL. (4) Since the record read request b has been received from the APL, the notification (B) of the n records requested to be read by the server is received and the result is stored in the buffer.

(5) In response to the reception of the request b from the APL, read the n records or the first record from the stored buffer and notify the APL. Below, AP
The request from L, the reading from the buffer to the APL, and the notification are repeated.

(6) Since the record read request c from the nth APL has been received, the nth record is read from the buffer and notified to the APL. (7) In FIG. 4, a record read request d from the APL
Is received and there is no record in the buffer, so a read request for that record is issued to the server. The server reads the record and notifies the client (C).

(8) Issue a read request for n records following the record requested by the APL. Below, (9), (10), (1
In 1), the same processing as in (3), (4), and (5) above is performed.

(12) When the search key is changed f in the APL, the record in the buffer is discarded. (13) A record read request g from the APL is accepted, and since there is no record in the buffer, a read request for that record is sent to the server. In response to this request, the server reads the record and notifies the client (E).

(14) The APL sends a read request for n records following the record requested to be read by the APL to the server. Thereafter, the processing of (15), (16) ... Is executed in the same manner as the above (3), (4) ...

[0032]

According to the read-ahead control of the present invention, in a client-server system, it is possible to speed up the sequential reading of files in record units, so that the system throughput can be improved.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is a processing flow of an embodiment in a client function unit.

FIG. 3 is an example (part 1) of an operation sequence of prefetch control in a client and a server.

FIG. 4 is an example (No. 2) of the operation sequence of prefetch control in the client and the server.

FIG. 5 is an operation explanatory diagram when reading one record of the related art.

FIG. 6 is an operation explanatory diagram when reading a plurality of conventional records.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 application (APL) 2 client function part 2a 1 record read request generation means 2b subsequent plural record read request generation means 2c record notification means 2d buffer 2e record read notification means 3 server function part 3a 1 record read means 3b subsequent plural record read means 3c 1 record notifying means 3d multiple record notifying means

Claims (3)

[Claims] 1. In a file read-ahead control method in a client / server method of an information processing apparatus, when a 1-record read request is received from an application, a client function unit requests the server to read a 1-record, and subsequently A request to read multiple records is issued, the server function unit reads the corresponding one record in response to a request to read one record from the client, notifies the client function unit of the one record, and the subsequent multiple records that occur Read the corresponding multiple records according to the request to read, and notify the client function part,
A client read function is a file read-ahead control method characterized by notifying the application of one requested record without waiting for the server to notify of the subsequent records. 2. The client function unit according to claim 1, upon receiving a read notification of a plurality of subsequent records from the server, stores the plurality of records in a buffer, and the plurality of records stored in the buffer is a successor from an application. Each time a record read request is received, the application is notified one record at a time from the buffer. 3. The client function unit according to claim 2, wherein when a plurality of records are stored in the buffer and an application changes a reading position or an order or a search key is changed, the records stored in the buffer are stored. A read-ahead control method for files that is characterized by erasing.