JP2926630B2 - Interprocess communication method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inter-process communication system for performing communication between processes.

[0002]

2. Description of the Related Art Conventionally, when data is asynchronously transferred from a plurality of processes to a certain process and processing is requested, as shown in FIG. 7, a message queue for connecting messages in a shared space and a data to be processed are stored in a shared space. A buffer for writing and passing is provided, and each process asynchronously writes data to the buffer and connects a message to a message queue to request processing. The process that performs processing repeats taking out a message from the head of the message queue, reading data from the corresponding buffer, and performing processing. Hereinafter, the configuration and operation of FIG. 7 will be briefly described.

FIG. 7 shows an explanatory diagram of the prior art. In FIG. 7, processes A, B, and C are processes in the spaces A, B, and C that request data processing asynchronously.

[0004] Buffers A, B, and C are buffers provided in the shared space and assigned by processes A, B, and C for writing data. The processes A, B, and C asynchronously overwrite the buffers A, B, and C with the latest data, respectively.

A process D is for reading out data requested to be processed by the processes A, B, and C from the buffers A, B, and C, and performing a process (for example, a display process). It is.

The message queues are processes A, B, C
Are connected to a message in which the contents of the processing request and the head addresses of the buffers A, B, and C for writing the data are connected, and the processing is requested to the process D, and is provided in the shared space. The process D sequentially retrieves messages from the head of the message queue and performs processing.

The buffers A, B, and C are processes A, B,
C is an area for overwriting data, and is provided in the shared space. Next, the operation will be described.

(1) The process A writes data requested to be processed to the buffer A, and writes a process request in which the start address of the process A and the buffer A are set to a message and connects the message to a message queue asynchronously. Similarly, the other processes B and C also write data into the buffers B and C and write a processing request in which the start addresses of the own processes B and C and the buffers B and C are respectively set to a message and connect them to the message queue. Respectively.

(2) The process D removes one message from the head of the message queue, extracts data from any of the buffers A, B, and C at the head address specified by the message, and performs processing specified by the message (for example, Display processing) is repeated.

As described above, processes A, B, and C write data asynchronously to buffers A, B, and C,
Has been designed to sequentially extract data from buffers A, B, and C and perform processing (eg, display processing).

[0011]

The processes A, B, and C according to the configuration shown in FIG. 7 described above asynchronously write data to the buffers A, B, and C, and the process D takes out the data in order to perform the processing. If the data processing of the process D is delayed for some reason (for example, if the processing is delayed due to waiting for access from an external I / O or the like), it is delayed to take out the message connected to the message queue and perform the processing. There has been a problem that the data on the buffers A, B, and C sent asynchronously from the processes A, B, and C cannot be processed in real time, for example, the data at the current time cannot be displayed on the screen in real time. In addition, if the process D is once delayed and many messages are accumulated in the message queue, the number of messages connected to the message queue does not readily decrease, and the load of the process D is large and a long time continues. As a result, other processing cannot be performed, and a lot of time is required before the processing can be performed in real time.

The present invention has been developed to solve these problems.
Each client process writes the data and serial number to the buffer, sets the serial number for the message, connects to the message queue, requests processing, and the serial number of the message retrieved from the message queue by the server process is equal to the serial number of the data on the buffer. Perform processing only in the case, stop processing when they are not the same, process only the latest data, process the requested data in real time, and even if many messages stay in the message queue for some reason It is also intended to stop useless processing and quickly return to a state where data is processed in real time.

[0013]

Means for solving the problem will be described with reference to FIG. In FIG. 1, a client process 1 requests data processing.

The buffer 2 is provided in a shared space, and is an area where each client process 1 writes data. The message 31 sets the start address of the data to be processed on the buffer 2 and the serial number of the data.

The message queue 3 connects the message 31 and requests the server process 4 for processing. The server process 4 sequentially retrieves the message 31 from the head of the message queue 3 and performs processing only when the serial number set in the message 31 is equal to the serial number of the data of the buffer 2 at the set head address. It is.

[0016]

According to the present invention, as shown in FIG. 1, each client process 1 writes data and a serial number of the data in a buffer 2 and sends a message 31 in which a head address of the buffer 2 and a serial number of the data are set to a message queue. 3, the server process 4 sequentially retrieves the message 31 from the head of the message queue 3, and only when the serial number in the retrieved message 31 is equal to the serial number of the data in the buffer 2 at the head address, the data is read from the buffer 2. Is taken out and the process is performed. If the values are not equal, the process is stopped and the process proceeds to the next process.

When the start address of the buffer 2 is fixed, the client process 1 connects the message 31 to which the serial number has been set to the message queue 3, and the server process 4 extracts the serial number extracted from the message 31 and the fixed start address. Only when the serial number of the data in the buffer 2 is equal, the data is extracted from the buffer 2 and the processing is performed. When the serial numbers are not equal, the processing is stopped and the processing proceeds to the next processing.

A plurality of processes are provided as the client process 1, and each of these processes has its own process ID.
, And a message 31 in which a start address is set if necessary is connected to the message queue 3.

Therefore, each client process 1 writes the data and the serial number in the buffer 2 and the message 31
The server process 4 performs processing only when the serial number of the message 31 retrieved from the message queue 3 and the serial number of the data in the buffer 2 are equal. If there is no message, the processing of the requested data is performed in real time by canceling the processing and processing only the latest data, and even if many messages 31 stay in the message queue 3 for some reason, the processing is useless. Can be stopped and the data can be immediately returned to a state where it is processed in real time.

[0020]

Next, the structure and operation of an embodiment of the present invention will be sequentially described in detail with reference to FIGS.

FIG. 1 shows a system configuration diagram of the present invention.
In FIG. 1, a client process 1 asynchronously requests data processing to a server process 4, and here, for example, includes processes A, B, and C as shown in FIG. It exists in a space different from the space B, the space C, and the like. The process A, the process B, and the process C that are the client processes 1 each include a transmission process 11 and the like.

The transmission processing 11 writes data and a serial number of the data into the buffer 2 or writes a new serial number into the buffer 2 irrespective of data change, and sets a data serial number and a head address of the buffer 2. The message 31 is connected to the message queue 3 or the like.

The buffer 2 is provided in the shared space, and is used by the processes A, B, and C as the client processes 1 to write data and serial numbers. Here, buffers A, B, and C having fixed start addresses are provided as buffers 2 for processes A, B, and C. As shown in the figure, the serial numbers and data are overwritten in the buffers A, B, and C, and the latest serial numbers and data are always written.

The message queue 3 manages the processing order by asynchronously connecting the message 31 in which the start address and serial number of the buffer 2 are set. The server process 4 sends the message 31 from the top of the message queue 3
Are sequentially extracted and the processing is performed, and includes a reception processing 41 and the like.

The receiving process 41 extracts the message 31 from the head of the message queue 3 and only when the serial number set in the extracted message 31 is equal to the serial number of the data of the buffer 2 of the set head address. Processing (for example, processing for displaying data on a screen) is performed. Therefore, regardless of whether the data in the buffer 2 is overwritten, the latest data having the same serial number is taken out from the buffer 2 and processed.

The details will be sequentially described below. FIG. 2 shows a flowchart of the transmission process of the client process of the present invention. In FIG. 2, S1 sets data in the buffer 2. This is because, for example, the transmission process 11 of the process A, which is the client process 1 in FIG. 1, overwrites (sets) the data to be processed by the server process 4 in the buffer A for the process A in the buffer 2. ).

In step S2, a data serial number is set in the buffer 2. This is because, in S1, for example, after the transmission processing 11 of the process A sets data in the buffer A,
The serial number of data is overwritten (set) in the buffer A.

In step S3, a message is created (data processing request). This is because, for example, the process A is performed as shown in FIG.
As shown in the message 31, the message 31 in which the data processing request (type), A (source process ID), the head address of the buffer, and the serial number of the data are set.

In step S4, a message is transmitted (connected to the message queue 3). This connects (enqueues) the message 31 created in S3 to the end of the message queue 3. Thus, the transmission of the message 31 is requested.

As described above, in the client process 1, after the transmission process 11 overwrites the data to be processed and the serial number of the data in the buffer 2, the head address of the buffer 2 and the serial number of the data are set in the message 31. To the end of the message queue 3 to request transmission. As a result, the buffer 2 always overwrites the latest data and the serial number of the data, and the message queue 3 stores the message 3
1 are sequentially connected to the end of the message queue 3 to request transmission.

FIG. 3 shows an example of the buffer contents of the present invention.
This is an example of the buffer 2 provided in the shared space of FIG. Here, an area of a predetermined size L from the start address a is an area of the buffer A (buffer 2 for the process A), and the data serial number a and the data are overwritten as shown in the figure. Similarly, a predetermined size L from the start addresses b and c
Are areas of buffers B and C (buffer 2 for processes B and C), and data serial numbers b and c as shown in the figure.
And data are overwritten respectively. Where size L
May be set arbitrarily.

FIG. 4 shows an example of message contents according to the present invention. This is an example of the message 31 connected to the message queue 3 provided in the shared space of FIG. Here, the following information shown in the figure is set.

• Type: For example, “Processing request”, “Status notification” • Source process ID: For example, “A” for process A • Start address of buffer: For example, for process A, start address a ( (See FIG. 3).

Data serial number: for example, a sequential number for each process (1, 2, 3,...) FIG. 5 is a flowchart showing the receiving process of the server process of the present invention.

In FIG. 5, S11 receives a message. This is the reception process 4 of the server process 4 in FIG.
1 is the message 31 from the top of the message queue 3
Take out one.

At S12, the serial number X of the data in the message 31 is obtained. This acquires the serial number X of the data in the message 31 extracted in S11 (see FIG. 4). S
13 obtains the serial number of the data in the buffer 2 specified by the message 31. That is, the data serial number Y is obtained from the position of the buffer 2 at the head address set in the message 31 extracted in S11.

In S14, it is determined whether X = Y. In the case of YES, the serial number X in the message 31 and the serial number Y of the data in the buffer 2 are equal, and it is determined that the message 31 is for the latest data. Therefore, the data in the buffer 2 is obtained in S15, and the obtained data is obtained in S16. The data is processed (for example, displayed on a screen as shown in FIG. 6 described later). On the other hand, in the case of NO in S14, it is determined that the message is not the message 31 for the latest data, so the process returns to S11, retrieves the next message 31 from the message queue 3, and repeats S12 and subsequent steps.

As described above, the reception process 41 in the server process 4 starts from the top of the message queue 3
1 is taken out, the serial number set in the message 31 is compared with the serial number of the data in the buffer 2 of the set start address, and when they match, it is determined that the data is the latest data. On the other hand, when they do not match, it is determined that the data is old, so the data processing is stopped and the process proceeds to the reception processing of the next message 31. As a result, the processing of the old message 31 is stopped, the processing of the next message 31 is proceeded, only the latest data is processed, and the real-time performance of the data processing can be greatly improved.

FIG. 6 shows an application example of the present invention. this is,
The client process 1 asynchronously buffers the data in which the number or the number of objects changes with the passage of time.
And a process request to the server process 4 by using the message queue 3 and the server process 4 displaying the number and the number of people on the screen. The horizontal axis is the time axis.

FIG. 6A shows actual data. This indicates a change in the number or number of objects detected by the client process 1 in FIG. Here, the following data is detected: time t1: 10, time t2: 15, time t3: 20. When such data is detected, the data is immediately overwritten in the buffer 2 and a serial number is set. And the message 31 in which the head address of the buffer 2 is set is connected to the message queue 3 and the transmission is sequentially requested.

FIG. 6B shows the real time. this is,
The actual times at which the actual data of FIG.
2, t3. FIG. 6C shows conventional processing (processing by the process D in FIG. 7). In the conventional process D of FIG. 7, the data “1” at time t1
Since “0” is the first time, it can be displayed as “10” at the same time as the real time.However, for data “15” at time t2, the processing of the other messages 31 connected to the message queue 3 is not performed. Since the operation has been performed, the “15” can be displayed as shown in the figure with a delay of Δt 2. Further, as for the data “20” at the time t3,
Other messages 3 connected to message queue 3
Since the processing of No. 1 has been performed, "20" is displayed as shown in the figure, which is significantly delayed from Δt3. In particular, the data "20" at time t3 cannot be said to be displayed in real time. .

FIG. 6D shows the processing of the present invention (processing by the server process 4). In the processing by the server process 4 of the present invention, since the data “10” at the time t1 is the first, the “1” at the same time as the real time
0 ". When the processing of the other message 31 is completed and the message 31 at the time t2 is taken out of the message queue 3 a little after the time t3, the data and the serial number in the buffer 2 are changed to the time t3. Since the data "1" has been overwritten, the data "1"
5 "is stopped, and the process proceeds to the next process. When the message 31 at the time t3 is taken out from the message queue 3, the data and the serial number in the buffer 2 are changed to the time t.
3 and coincide with each other, the display processing of the data “20” at the time t3 is performed, and the real-time processing (display) can be performed as shown in FIG.

The objects include the number of visitors, traffic volume,
There are reservation status, temperature, and others (things that can be monitored by numbers etc.), and the quantity and number of these objects are displayed in real time.

[0044]

As described above, according to the present invention,
Each client process 1 writes data and a serial number in the buffer 2, sets a serial number in the message 31, connects to the message queue 3 and requests processing, and the server process 4 retrieves the message 3 from the message queue 3.
Since the processing is performed only when the serial number of No. 1 and the serial number of the data on the buffer 2 are equal, and when the serial numbers are not equal, the processing is stopped and only the latest data is processed.
The requested data is processed in real time, and even if many messages 31 stay in the message queue 3 for some reason, useless processing can be stopped and the data can be promptly returned to the real time processing state. .

[Brief description of the drawings]

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

FIG. 2 is a transmission flowchart of a client process of the present invention.

FIG. 3 is an example of buffer contents according to the present invention.

FIG. 4 is an example of a message content according to the present invention.

FIG. 5 is a reception processing flowchart of a server process of the present invention.

FIG. 6 is an application example of the present invention.

FIG. 7 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 1: client process 11: transmission process 2: buffer 3: message queue 31: message 4: server process 41: reception process

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Claims (3)

(57) [Claims] An inter-process communication method for performing communication between processes, wherein a buffer provided for each client process in which each client process requesting processing overwrites data and sets a serial number changed each time the data is overwritten. And a message queue for connecting the head address of the data overwritten in this buffer and the message set with the serial number in the shared space, and the server process performing the requested processing sets the serial number of the message extracted from the head of the message queue. performs processing retrieves the data from the buffer only if equal and serial number of the data in the buffer start address has been set, the main treated discontinued when unequal
An inter-process communication method, wherein a next top message is retrieved from a message queue . 2. The inter-process communication method according to claim 1, wherein the message set with the serial number is connected to a message queue when the head address of the buffer is fixed. 3. The method according to claim 1, wherein the client process comprises a plurality of processes, each of which is connected to the message queue with a message having its own process ID, a serial number, and, if necessary, a head address set. The inter-process communication method according to claim 1 or 2, wherein