com.datastax.oss.driver.api.core.specex.SpeculativeExecutionPolicy Maven / Gradle / Ivy
The newest version!
/*
* 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.api.core.specex;
import com.datastax.oss.driver.api.core.CqlIdentifier;
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.session.SessionBuilder;
import edu.umd.cs.findbugs.annotations.NonNull;
import edu.umd.cs.findbugs.annotations.Nullable;
/**
* The policy that decides if the driver will send speculative queries to the next nodes when the
* current node takes too long to respond.
*/
public interface SpeculativeExecutionPolicy extends AutoCloseable {
/**
* @param node the node that caused the speculative execution (that is, the node that was queried
* previously but was too slow to answer)
* @param keyspace the CQL keyspace currently associated to the session. This is set either
* through the configuration, by calling {@link SessionBuilder#withKeyspace(CqlIdentifier)},
* or by manually executing a {@code USE} CQL statement. It can be {@code null} if the session
* has no keyspace.
* @param request the request to execute.
* @param runningExecutions the number of executions that are already running (including the
* initial, non-speculative request). For example, if this is 2 it means the initial attempt
* was sent, then the driver scheduled a first speculative execution, and it is now asking for
* the delay until the second speculative execution.
* @return the time (in milliseconds) until a speculative request is sent to the next node, or 0
* to send it immediately, or a negative value to stop sending requests.
*/
long nextExecution(
@NonNull Node node,
@Nullable CqlIdentifier keyspace,
@NonNull Request request,
int runningExecutions);
/** Called when the cluster that this policy is associated with closes. */
@Override
void close();
}