com.datastax.oss.driver.internal.core.specex.ConstantSpeculativeExecutionPolicy Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF 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 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.DriverExecutionProfile;
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 edu.umd.cs.findbugs.annotations.NonNull;
import edu.umd.cs.findbugs.annotations.Nullable;
import net.jcip.annotations.ThreadSafe;
/**
* A policy that schedules a configurable number of speculative executions, separated by a fixed
* delay.
*
* To activate this policy, modify the {@code advanced.speculative-execution-policy} section in
* the driver configuration, for example:
*
*
* datastax-java-driver {
* advanced.speculative-execution-policy {
* class = ConstantSpeculativeExecutionPolicy
* max-executions = 3
* delay = 100 milliseconds
* }
* }
*
*
* See {@code reference.conf} (in the manual or core driver JAR) for more details.
*/
@ThreadSafe
public class ConstantSpeculativeExecutionPolicy implements SpeculativeExecutionPolicy {
private final int maxExecutions;
private final long constantDelayMillis;
public ConstantSpeculativeExecutionPolicy(DriverContext context, String profileName) {
DriverExecutionProfile config = context.getConfig().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(
@NonNull @SuppressWarnings("unused") Node node,
@Nullable @SuppressWarnings("unused") CqlIdentifier keyspace,
@NonNull @SuppressWarnings("unused") Request request,
int runningExecutions) {
assert runningExecutions >= 1;
return (runningExecutions < maxExecutions) ? constantDelayMillis : -1;
}
@Override
public void close() {
// nothing to do
}
}