io.nosqlbench.engine.api.scoping.ScopedSupplier Maven / Gradle / Ivy

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The engine API for nosqlbench; Provides the interfaces needed to build internal modules for the nosqlbench core engine

There is a newer version: 5.17.0

package io.nosqlbench.engine.api.scoping;

import java.util.function.Supplier;

/**
 * Helper class to consolidate the notions of scoping items over different
 * NB layers of execution.
 */
public enum ScopedSupplier {

    /**
     * Once a supplier is instantiated for singleton scope, it should provide only one instance of
     * the supplied element for that instance. Multiple instances (separately constructed)
     * of the supplier can each provide their own distinct supplied instance.
     */
    singleton,
    /**
     * Once a supplier is instantiated for thread scope, it should provide a unique instance of
     * the supplied element for each thread, according to the inner supplier's semantics.
     */
    thread,
    /**
     * When a supplier is instantiated for caller scope, each time the supplier is accessed,
     * it returns a new instance according to the inner supplier's semantics.
     */
    caller;

    public  Supplier supplier(Supplier supplier) {

        switch (this) {
            case singleton:
                T got = supplier.get();
                return () -> got;
            case thread:
                ThreadLocal tlsupplier = ThreadLocal.withInitial(supplier);
                return tlsupplier::get;
            case caller:
                return supplier;
            default:
                throw new RuntimeException("Unknown scope type:" + this);
        }
    }

}