From f231175d97338fef850723ab324b76c914008f42 Mon Sep 17 00:00:00 2001 From: Aravinth Manivannan Date: Sat, 13 Apr 2024 16:31:56 +0530 Subject: [PATCH] fix: update tests to reflect new permanent linking scheme --- tests/7158b1cdd50c.html | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/tests/7158b1cdd50c.html b/tests/7158b1cdd50c.html index 1e0f305..17eb63d 100644 --- a/tests/7158b1cdd50c.html +++ b/tests/7158b1cdd50c.html @@ -149,7 +149,7 @@ rel="noreferrer"> Open post in medium.com 
8	atomicLock = int32(0)Permanant linkHighlight
9	locked = int32(1)Permanant linkHighlight
10	unlocked = int32(0)Permanant linkHighlight
13// lock spins in the loop until it can "acquire" the lockPermanant linkHighlight
14// by atomically changing the atomicLock variable from Permanant linkHighlight
15// unlocked to locked. Our CPU will guarantee that Permanant linkHighlight
16// only one thread/goroutine will succeed if multiplePermanant linkHighlight
17// try to lock at the same time, and the others willPermanant linkHighlight
18// block in the for loop until atomicLock is set toPermanant linkHighlight
21	pointer := &atomicLockPermanant linkHighlight
25		// spin until we successfully change thePermanant linkHighlight
26		// atomicLock from unlocked to lockedPermanant linkHighlight
27		if atomic.CompareAndSwapInt32(pointer, old, new) {Permanant linkHighlight
34	atomic.StoreInt32(&atomicLock, unlocked)Permanant linkHighlight
40	// do some exclusive shit	Permanant linkHighlight
}
+ }
8	atomicLock = int32(0)Permanant linkHighlight
9	locked = int32(1)Permanant linkHighlight
10	unlocked = int32(0)Permanant linkHighlight
13// lock spins in the loop until it can "acquire" the lockPermanant linkHighlight
14// by atomically changing the atomicLock variable from Permanant linkHighlight
15// unlocked to locked. Our CPU will guarantee that Permanant linkHighlight
16// only one thread/goroutine will succeed if multiplePermanant linkHighlight
17// try to lock at the same time, and the others willPermanant linkHighlight
18// block in the for loop until atomicLock is set toPermanant linkHighlight
21	pointer := &atomicLockPermanant linkHighlight
25		// spin until we successfully change thePermanant linkHighlight
26		// atomicLock from unlocked to lockedPermanant linkHighlight
27		if atomic.CompareAndSwapInt32(pointer, old, new) {Permanant linkHighlight
34	atomic.StoreInt32(&atomicLock, unlocked)Permanant linkHighlight
40	// do some exclusive shit	Permanant linkHighlight
}
See gist on GitHub

Even though a spinlock is burning power in a tight loop until it succeeds, it actually is sometimes preferred over a traditional mutex. Traditional mutexes put a thread to sleep when they block, increasing the minimum latency for acquiring them from another thread. Modern mutexes are often a hybrid approach between a spinlock and a traditional mutex. Hybrid mutexes will attempt to acquire the lock quickly in userspace using atomic operations, without giving away their kernel-scheduled appointment on the CPU core. If the gambit didn’t pan out, the hybrid mutex will put the thread to sleep with a blocking syscall.

@@ -177,7 +177,7 @@ rel="noreferrer"> Open post in medium.com 
1import java.util.concurrent.atomic.*;Permanant linkHighlight
3import net.jcip.annotations.*;Permanant linkHighlight
6 * ConcurrentStackPermanant linkHighlight
8 * retrieved from https://en.wikipedia.org/wiki/Treiber_StackPermanant linkHighlight
10 * Nonblocking stack using Treiber's algorithmPermanant linkHighlight
12 * @author Brian Goetz and Tim PeierlsPermanant linkHighlight
15public class ConcurrentStack <E> {Permanant linkHighlight
16    AtomicReference<Node<E>> top = new AtomicReference<Node<E>>();Permanant linkHighlight
18    public void push(E item) {Permanant linkHighlight
19        Node<E> newHead = new Node<E>(item);Permanant linkHighlight
20        Node<E> oldHead;Permanant linkHighlight
22            oldHead = top.get();Permanant linkHighlight
23            newHead.next = oldHead;Permanant linkHighlight
24        } while (!top.compareAndSet(oldHead, newHead));Permanant linkHighlight
27    public E pop() {Permanant linkHighlight
28        Node<E> oldHead;Permanant linkHighlight
29        Node<E> newHead;Permanant linkHighlight
31            oldHead = top.get();Permanant linkHighlight
32            if (oldHead == null)Permanant linkHighlight
34            newHead = oldHead.next;Permanant linkHighlight
35        } while (!top.compareAndSet(oldHead, newHead));Permanant linkHighlight
36        return oldHead.item;Permanant linkHighlight
39    private static class Node <E> {Permanant linkHighlight
40        public final E item;Permanant linkHighlight
41        public Node<E> next;Permanant linkHighlight
43        public Node(E item) {Permanant linkHighlight
44            this.item = item;Permanant linkHighlight
}
+ }
1import java.util.concurrent.atomic.*;Permanant linkHighlight
3import net.jcip.annotations.*;Permanant linkHighlight
6 * ConcurrentStackPermanant linkHighlight
8 * retrieved from https://en.wikipedia.org/wiki/Treiber_StackPermanant linkHighlight
10 * Nonblocking stack using Treiber's algorithmPermanant linkHighlight
12 * @author Brian Goetz and Tim PeierlsPermanant linkHighlight
15public class ConcurrentStack <E> {Permanant linkHighlight
16    AtomicReference<Node<E>> top = new AtomicReference<Node<E>>();Permanant linkHighlight
18    public void push(E item) {Permanant linkHighlight
19        Node<E> newHead = new Node<E>(item);Permanant linkHighlight
20        Node<E> oldHead;Permanant linkHighlight
22            oldHead = top.get();Permanant linkHighlight
23            newHead.next = oldHead;Permanant linkHighlight
24        } while (!top.compareAndSet(oldHead, newHead));Permanant linkHighlight
27    public E pop() {Permanant linkHighlight
28        Node<E> oldHead;Permanant linkHighlight
29        Node<E> newHead;Permanant linkHighlight
31            oldHead = top.get();Permanant linkHighlight
32            if (oldHead == null)Permanant linkHighlight
34            newHead = oldHead.next;Permanant linkHighlight
35        } while (!top.compareAndSet(oldHead, newHead));Permanant linkHighlight
36        return oldHead.item;Permanant linkHighlight
39    private static class Node <E> {Permanant linkHighlight
40        public final E item;Permanant linkHighlight
41        public Node<E> next;Permanant linkHighlight
43        public Node(E item) {Permanant linkHighlight
44            this.item = item;Permanant linkHighlight
}
See gist on GitHub

Spin Spin Spin