Closing Channels in COBOL

IDENTIFICATION DIVISION.
PROGRAM-ID. CLOSING-CHANNELS.

ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.

DATA DIVISION.
FILE SECTION.
WORKING-STORAGE SECTION.
01 WS-JOB PIC 9(5).
01 WS-MORE PIC X VALUE 'Y'.
01 WS-DONE PIC X VALUE 'N'.

PROCEDURE DIVISION.
MAIN-PROCEDURE.
    PERFORM INITIALIZE-CHANNELS
    PERFORM START-WORKER
    PERFORM SEND-JOBS
    PERFORM WAIT-FOR-COMPLETION
    PERFORM CHECK-CHANNEL-STATUS
    STOP RUN.

INITIALIZE-CHANNELS.
    *> In COBOL, we don't have channels. We'll use variables instead.
    MOVE 0 TO WS-JOB.
    MOVE 'N' TO WS-DONE.

START-WORKER.
    *> In COBOL, we don't have goroutines. We'll simulate the worker
    *> behavior in the main program.
    DISPLAY "Worker started".

SEND-JOBS.
    PERFORM VARYING WS-JOB FROM 1 BY 1 UNTIL WS-JOB > 3
        DISPLAY "sent job " WS-JOB
        PERFORM PROCESS-JOB
    END-PERFORM.
    MOVE 'N' TO WS-MORE.
    DISPLAY "sent all jobs".

PROCESS-JOB.
    *> This simulates the worker receiving and processing a job
    DISPLAY "received job " WS-JOB.

WAIT-FOR-COMPLETION.
    *> Simulate waiting for the worker to complete
    DISPLAY "received all jobs".
    MOVE 'Y' TO WS-DONE.

CHECK-CHANNEL-STATUS.
    *> Simulate checking if the channel is closed
    IF WS-MORE = 'N'
        DISPLAY "received more jobs: false"
    ELSE
        DISPLAY "received more jobs: true"
    END-IF.

This COBOL program simulates the behavior of the original Go program that demonstrates closing channels. Here’s an explanation of the key parts:

We use variables WS-JOB, WS-MORE, and WS-DONE to simulate the behavior of channels.
The MAIN-PROCEDURE orchestrates the program flow, similar to the main() function in the original Go code.
INITIALIZE-CHANNELS sets up our variables, analogous to creating channels in Go.
START-WORKER simulates starting a worker. In COBOL, we don’t have goroutines, so we just display a message.
SEND-JOBS sends jobs (numbers 1 to 3) and processes them immediately. This simulates sending jobs to a channel and having a worker process them.
PROCESS-JOB simulates the worker receiving and processing a job.
WAIT-FOR-COMPLETION simulates waiting for the worker to finish all jobs.
CHECK-CHANNEL-STATUS checks if there are more jobs, simulating checking a closed channel in Go.

To run this COBOL program, you would typically compile it and then execute the resulting binary. The exact commands may vary depending on your COBOL compiler, but it might look something like this:

$ cobc -x closing-channels.cob
$ ./closing-channels

This would produce output similar to:

Worker started
sent job 00001
received job 00001
sent job 00002
received job 00002
sent job 00003
received job 00003
sent all jobs
received all jobs
received more jobs: false

Note that COBOL doesn’t have built-in support for concurrent programming features like Go’s channels and goroutines. This example demonstrates a sequential approximation of the Go program’s behavior.

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Closing Channels in COBOL