co.elastic.apm.agent.sdk.weakmap.WeakMapSupplier Maven / Gradle / Ivy

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 * Elastic APM Java agent
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package co.elastic.apm.agent.sdk.weakmap;

import co.elastic.apm.agent.shaded.weaklockfree.WeakConcurrentMap;
import co.elastic.apm.agent.shaded.weaklockfree.WeakConcurrentSet;

/**
 * The canonical place to get a new instance of a {@link WeakConcurrentMap}.
 * Do not instantiate a {@link WeakConcurrentMap} directly to benefit from the global cleanup of stale entries.
 */
public class WeakMapSupplier {
    private static final WeakConcurrentSet> registeredMaps = new WeakConcurrentSet<>(WeakConcurrentSet.Cleaner.INLINE);
    private static final WeakConcurrentSet> registeredSets = new WeakConcurrentSet<>(WeakConcurrentSet.Cleaner.INLINE);

    public static  WeakConcurrentMap createMap() {
        WeakConcurrentMap result = new NullSafeWeakConcurrentMap<>(false);
        registeredMaps.add(result);
        return result;
    }

    public static  WeakConcurrentSet createSet() {
        WeakConcurrentSet weakSet = new NullSafeWeakConcurrentSet<>(WeakConcurrentSet.Cleaner.MANUAL);
        registeredSets.add(weakSet);
        return weakSet;
    }

    /**
     * Calls {@link WeakConcurrentMap#expungeStaleEntries()} on all registered maps,
     * causing the entries of already collected keys to be removed.
     * Avoids that the maps take unnecessary space for the {@link java.util.Map.Entry}, the {@link java.lang.ref.WeakReference} and the value.
     * Failing to call this does not mean the keys cannot be collected.
     */
    public static void expungeStaleEntries() {
        for (WeakConcurrentMap weakMap : registeredMaps) {
            weakMap.expungeStaleEntries();
        }
        for (WeakConcurrentSet weakSet : registeredSets) {
            weakSet.expungeStaleEntries();
        }
    }
}