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/*
* Copyright 2016 The Netty Project
*
* The Netty Project licenses this file to you under the Apache License,
* version 2.0 (the "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
package io.netty.channel;
import io.netty.util.IntSupplier;
/**
* Select strategy interface.
*
* Provides the ability to control the behavior of the select loop. For example a blocking select
* operation can be delayed or skipped entirely if there are events to process immediately.
*/
public interface SelectStrategy {
/**
* Indicates a blocking select should follow.
*/
int SELECT = -1;
/**
* Indicates the IO loop should be retried, no blocking select to follow directly.
*/
int CONTINUE = -2;
/**
* Indicates the IO loop to poll for new events without blocking.
*/
int BUSY_WAIT = -3;
/**
* The {@link SelectStrategy} can be used to steer the outcome of a potential select
* call.
*
* @param selectSupplier The supplier with the result of a select result.
* @param hasTasks true if tasks are waiting to be processed.
* @return {@link #SELECT} if the next step should be blocking select {@link #CONTINUE} if
* the next step should be to not select but rather jump back to the IO loop and try
* again. Any value >= 0 is treated as an indicator that work needs to be done.
*/
int calculateStrategy(IntSupplier selectSupplier, boolean hasTasks) throws Exception;
}