Marcosrico commented on code in PR #2515:
URL: https://github.com/apache/helix/pull/2515#discussion_r1228631420
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meta-client/src/main/java/org/apache/helix/metaclient/recipes/lock/DistributedSemaphore.java:
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@@ -75,8 +133,19 @@ public Permit acquire() {
* @param count number of permits to acquire
* @return a collection of permits
*/
- public Collection<Permit> acquire(int count) {
- throw new NotImplementedException("Not implemented yet.");
+ public synchronized Collection<Permit> acquire(int count) {
+ if (getRemainingCapacity() < count) {
+ LOG.warn("No sufficient permits available. Attempt to acquire {}
permits, but only {} permits available", count,
+ getRemainingCapacity());
+ return null;
+ } else {
+ updateAcquirePermit(count);
Review Comment:
After an offline discussion we agreed that it was necessary to implement
some sort of anti race condition that prevents two clients from modifying a
semaphore at the same time / in between processes. We came up with multiple
solutions but ultimately agreed that we would check for the available capacity
in the update call rather than having it separately.
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