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Metered concurrency: Difference between revisions
→{{header|Groovy}}: new solution
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Line 733:
studied.Done() // signal done
}</lang>
=={{header|Groovy}}==
Solution:
<lang groovy>class CountingSemaphore {
private int count = 0
private final int max
CountingSemaphore(int max) { this.max = max }
synchronized int acquire() {
while (count >= max) { wait() }
++count
}
synchronized int release() {
if (count) { count--; notifyAll() }
count
}
synchronized int getCount() { count }
}</lang>
Test:
<lang groovy>def cs = new CountingSemaphore(4)
(1..12).each { threadID ->
Thread.start {
def id = "Thread #${(threadID as String).padLeft(2,'0')}"
try {
def sCount = cs.acquire()
println("${id} has acquired Semaphore at count = ${sCount}")
sleep(2000)
} finally {
println("${id} is releasing Semaphore at count = ${cs.count}")
cs.release()
}
}
}</lang>
Output:
<pre style="height:30ex;overflow:scroll;">Thread #03 has acquired Semaphore at count = 4
Thread #07 has acquired Semaphore at count = 2
Thread #02 has acquired Semaphore at count = 1
Thread #09 has acquired Semaphore at count = 3
Thread #03 is releasing Semaphore at count = 4
Thread #02 is releasing Semaphore at count = 4
Thread #09 is releasing Semaphore at count = 4
Thread #07 is releasing Semaphore at count = 4
Thread #12 has acquired Semaphore at count = 4
Thread #05 has acquired Semaphore at count = 3
Thread #06 has acquired Semaphore at count = 4
Thread #08 has acquired Semaphore at count = 2
Thread #12 is releasing Semaphore at count = 4
Thread #06 is releasing Semaphore at count = 4
Thread #05 is releasing Semaphore at count = 4
Thread #10 has acquired Semaphore at count = 4
Thread #11 has acquired Semaphore at count = 4
Thread #08 is releasing Semaphore at count = 3
Thread #01 has acquired Semaphore at count = 4
Thread #04 has acquired Semaphore at count = 4
Thread #11 is releasing Semaphore at count = 4
Thread #10 is releasing Semaphore at count = 4
Thread #04 is releasing Semaphore at count = 2
Thread #01 is releasing Semaphore at count = 2</pre>
=={{header|Haskell}}==
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