/*
* Aerospike Client - Java Library
*
* Copyright 2012 by Aerospike, Inc. All rights reserved.
*
* Availability of this source code to partners and customers includes
* redistribution rights covered by individual contract. Please check your
* contract for exact rights and responsibilities.
*/
package com.aerospike.client.query;
import com.aerospike.client.AerospikeException;
import com.aerospike.client.cluster.Node;
import com.aerospike.client.policy.QueryPolicy;
public abstract class QueryExecutor {
private final QueryPolicy policy;
protected final Statement statement;
private QueryThread[] threads;
private volatile int nextThread;
protected volatile Exception exception;
public QueryExecutor(QueryPolicy policy, Statement statement) {
this.policy = policy;
this.policy.maxRetries = 0; // Retry policy must be one-shot for queries.
this.statement = statement;
}
protected final void startThreads(Node[] nodes) {
// Initialize threads.
threads = new QueryThread[nodes.length];
for (int i = 0; i < nodes.length; i++) {
QueryCommand command = createCommand(nodes[i]);
threads[i] = new QueryThread(command);
}
// Initialize maximum number of nodes to query in parallel.
nextThread = (policy.maxConcurrentNodes == 0 || policy.maxConcurrentNodes >= threads.length)? threads.length : policy.maxConcurrentNodes;
// Start threads. Use separate max because threadCompleted() may modify nextThread in parallel.
int max = nextThread;
for (int i = 0; i < max; i++) {
threads[i].start();
}
}
private final void threadCompleted() {
int index = -1;
// Determine if a new thread needs to be started.
synchronized (threads) {
if (nextThread < threads.length) {
index = nextThread++;
}
}
if (index >= 0) {
// Start new thread.
threads[index].start();
}
else {
// All threads have been started. Check status.
for (QueryThread thread : threads) {
if (! thread.complete) {
// Some threads have not finished. Do nothing.
return;
}
}
// All threads complete. Tell RecordSet thread to return complete to user.
sendCompleted();
}
}
protected final void stopThreads(Exception cause) {
// Exception may be null, so can't synchronize on it.
// Use statement instead.
synchronized (statement) {
if (exception != null) {
return;
}
exception = cause;
}
if (threads != null) {
for (QueryThread thread : threads) {
try {
thread.stopThread();
thread.interrupt();
}
catch (Exception e) {
}
}
}
sendCompleted();
}
protected final void checkForException() throws AerospikeException {
// Throw an exception if an error occurred.
if (exception != null) {
if (exception instanceof AerospikeException) {
throw (AerospikeException)exception;
}
else {
throw new AerospikeException(exception);
}
}
}
private final class QueryThread extends Thread {
private final QueryCommand command;
private boolean complete;
public QueryThread(QueryCommand command) {
this.command = command;
}
public void run() {
try {
command.resetSendBuffer();
command.query(policy, statement);
}
catch (Exception e) {
// Terminate other query threads.
stopThreads(e);
}
complete = true;
if (exception == null) {
threadCompleted();
}
}
public void stopThread() {
command.stop();
}
}
protected abstract QueryCommand createCommand(Node node);
protected abstract void sendCompleted();
}