Timeouts in D Programming Language

Timeouts are important for programs that connect to external resources or that otherwise need to bound execution time. Implementing timeouts in D is straightforward using threads and message passing.

import std.stdio;
import std.concurrency;
import core.thread;
import core.time;

void main()
{
    // For our example, suppose we're executing an external
    // call that returns its result on a Tid after 2s.
    auto tid1 = spawn({
        Thread.sleep(dur!"seconds"(2));
        ownerTid.send("result 1");
    });

    // Here's the receive implementing a timeout.
    // receiveTimeout awaits the result for a specified duration.
    // If no message is received within the timeout, it returns false.
    auto result = receiveTimeout(dur!"seconds"(1),
        (string msg) {
            writeln(msg);
            return true;
        }
    );

    if (!result)
        writeln("timeout 1");

    // If we allow a longer timeout of 3s, then the receive
    // will succeed and we'll print the result.
    auto tid2 = spawn({
        Thread.sleep(dur!"seconds"(2));
        ownerTid.send("result 2");
    });

    result = receiveTimeout(dur!"seconds"(3),
        (string msg) {
            writeln(msg);
            return true;
        }
    );

    if (!result)
        writeln("timeout 2");
}

Running this program shows the first operation timing out and the second succeeding.

$ dmd -run timeouts.d
timeout 1
result 2

In this D version:

We use std.concurrency for message passing between threads, which is similar to Go’s channel concept.
Instead of goroutines, we use D’s spawn function to create new threads.
The select statement with timeout in Go is replaced by D’s receiveTimeout function, which allows us to specify a duration to wait for a message.
We use Thread.sleep to simulate time-consuming operations, similar to time.Sleep in Go.
The buffered channels in Go are not directly translated, as D’s message passing model is different. However, the spawn function creates a new thread, which serves a similar purpose of non-blocking execution.

This example demonstrates how to implement timeouts in D, providing a way to bound execution time for operations that might take too long.

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Timeouts in D Programming Language