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ConstantSpeculativeExecutionPolicy.java
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ConstantSpeculativeExecutionPolicy.java
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/*
* Copyright DataStax, Inc.
*
* Licensed 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 com.datastax.oss.driver.internal.core.specex;
import com.datastax.oss.driver.api.core.CqlIdentifier;
import com.datastax.oss.driver.api.core.config.DefaultDriverOption;
import com.datastax.oss.driver.api.core.config.DriverConfigProfile;
import com.datastax.oss.driver.api.core.context.DriverContext;
import com.datastax.oss.driver.api.core.metadata.Node;
import com.datastax.oss.driver.api.core.session.Request;
import com.datastax.oss.driver.api.core.specex.SpeculativeExecutionPolicy;
import net.jcip.annotations.ThreadSafe;
/**
* A policy that schedules a configurable number of speculative executions, separated by a fixed
* delay.
*
* <p>See the (commented) sample configuration in {@code reference.conf} for detailed explanations
* about each option.
*/
@ThreadSafe
public class ConstantSpeculativeExecutionPolicy implements SpeculativeExecutionPolicy {
private final int maxExecutions;
private final long constantDelayMillis;
public ConstantSpeculativeExecutionPolicy(DriverContext context, String profileName) {
DriverConfigProfile config = context.config().getProfile(profileName);
this.maxExecutions = config.getInt(DefaultDriverOption.SPECULATIVE_EXECUTION_MAX);
if (this.maxExecutions < 1) {
throw new IllegalArgumentException("Max must be at least 1");
}
this.constantDelayMillis =
config.getDuration(DefaultDriverOption.SPECULATIVE_EXECUTION_DELAY).toMillis();
if (this.constantDelayMillis < 0) {
throw new IllegalArgumentException("Delay must be positive or 0");
}
}
@Override
public long nextExecution(
@SuppressWarnings("unused") Node node,
@SuppressWarnings("unused") CqlIdentifier keyspace,
@SuppressWarnings("unused") Request request,
int runningExecutions) {
assert runningExecutions >= 1;
return (runningExecutions < maxExecutions) ? constantDelayMillis : -1;
}
@Override
public void close() {
// nothing to do
}
}