Re: A little of coordination for Rosettacode

[bearophile]

This D1 entry needs an update:
http://rosettacode.org/wiki/Metered_concurrency#D
Is someone willing to update it?


import std.stdio, core.thread, std.c.time;

class Semaphore {
    private int lockCnt, maxCnt;

    this(in int count) {
        maxCnt = lockCnt = count;
    }

    void acquire() {
        if (lockCnt < 0 || maxCnt <= 0)
            throw new Exception("Negative Lock or Zero init. 
Lock");
        while(lockCnt == 0)
            Thread.getThis.yield; // Let other threads release 
lock.
        synchronized lockCnt--;
    }

    void release() {
        synchronized
            if (lockCnt < maxCnt)
                lockCnt++;
            else
                throw new Exception("Release lock before 
acquire");
    }

    int getCnt() {
        synchronized return lockCnt;
    }
}

class Worker : Thread {
    private static int id = 0;
    private Semaphore lock;
    private int myId;

    this (Semaphore l) {
        super();
        lock = l;
        myId = id++;
    }

    int run() {
        lock.acquire;
        writefln("Worker %d got a lock(%d left).", myId, 
lock.getCnt);
        msleep(2_000); // Wait 2.0 seconds.
        lock.release;
        writefln("Worker %d released a lock(%d left).",
                 myId, lock.getCnt);
        return 0;
    }
}

void main() {
    Worker[10] crew;
    Semaphore lock = new Semaphore(4);

    foreach (ref c; crew)
        (c = new Worker(lock)).start;
    foreach (ref c; crew)
        c.wait;
}


Bye,
bearophile