NioEventLoop之SelectStrategy

​DefaultSelectStrategyFactory 默认Select策略工厂​

public final class DefaultSelectStrategyFactory implements SelectStrategyFactory {
    public static final SelectStrategyFactory INSTANCE = new DefaultSelectStrategyFactory();

    private DefaultSelectStrategyFactory() { }

    @Override
    public SelectStrategy newSelectStrategy() {
        return DefaultSelectStrategy.INSTANCE; //默认Select策略
    }
}

​DefaultSelectStrategy 默认Select策略​

/**
 * Default select strategy.
 */
final class DefaultSelectStrategy implements SelectStrategy {
    static final SelectStrategy INSTANCE = new DefaultSelectStrategy();

    private DefaultSelectStrategy() { }

    @Override
    public int calculateStrategy(IntSupplier selectSupplier, boolean hasTasks) throws Exception {
        return hasTasks ? selectSupplier.get() : SelectStrategy.SELECT;
    }
}

​IntSupplier​

//IntSupplier
private final IntSupplier selectNowSupplier = new IntSupplier() {
        @Override
        public int get() throws Exception {
            return selectNow();
        }
 };


int selectNow() throws IOException {
        try {
            return selector.selectNow(); //jdk原生Selector的selectNow函数
        } finally {
            // restore wakeup state if needed
            if (wakenUp.get()) {
                selector.wakeup();
            }
        }
    }