Github user ejwhite922 commented on a diff in the pull request:
https://github.com/apache/incubator-rya/pull/272#discussion_r167240341
--- Diff:
extras/rya.streams/query-manager/src/main/java/org/apache/rya/streams/querymanager/QueryManager.java
---
@@ -0,0 +1,884 @@
+/**
+ * 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 org.apache.rya.streams.querymanager;
+
+import static java.util.Objects.requireNonNull;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.Set;
+import java.util.UUID;
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.RejectedExecutionException;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import org.apache.rya.streams.api.entity.StreamsQuery;
+import org.apache.rya.streams.api.queries.ChangeLogEntry;
+import org.apache.rya.streams.api.queries.InMemoryQueryRepository;
+import org.apache.rya.streams.api.queries.QueryChange;
+import org.apache.rya.streams.api.queries.QueryChangeLog;
+import org.apache.rya.streams.api.queries.QueryChangeLogListener;
+import org.apache.rya.streams.api.queries.QueryRepository;
+import
org.apache.rya.streams.querymanager.QueryChangeLogSource.SourceListener;
+import
org.apache.rya.streams.querymanager.QueryExecutor.QueryExecutorException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.common.base.Preconditions;
+import
com.google.common.util.concurrent.AbstractScheduledService.Scheduler;
+import com.google.common.util.concurrent.AbstractService;
+import com.google.common.util.concurrent.UncheckedExecutionException;
+
+import edu.umd.cs.findbugs.annotations.DefaultAnnotation;
+import edu.umd.cs.findbugs.annotations.NonNull;
+
+/**
+ * A service for managing {@link StreamsQuery} running on a Rya Streams
system.
+ * <p>
+ * Only one QueryManager needs to be running to manage any number of rya
+ * instances/rya streams instances.
+ */
+@DefaultAnnotation(NonNull.class)
+public class QueryManager extends AbstractService {
+ private static final Logger log =
LoggerFactory.getLogger(QueryManager.class);
+
+ /**
+ * The source of {@link QueryChangeLog}s. Each log discovered is bound
to a specific
+ * Rya instnace.
+ */
+ private final QueryChangeLogSource changeLogSource;
+
+ /**
+ * The engine that is responsible for executing {@link StreamsQuery}s.
+ */
+ private final QueryExecutor queryExecutor;
+
+ /**
+ * How long blocking operations will be attempted before potentially
trying again.
+ */
+ private final long blockingValue;
+
+ /**
+ * The units for {@link #blockingValue}.
+ */
+ private final TimeUnit blockingUnits;
+
+ /**
+ * Used to inform threads that the application is shutting down, so
they must stop work.
+ */
+ private final AtomicBoolean shutdownSignal = new AtomicBoolean(false);
+
+ /**
+ * This thread pool manages the two thread used to work the {@link
LogEvent}s
+ * and the {@link QueryEvent}s.
+ */
+ private final ExecutorService executor =
Executors.newFixedThreadPool(2);
+
+ /**
+ * Creates a new {@link QueryManager}.
+ *
+ * @param queryExecutor - Runs the active {@link StreamsQuery}s. (not
null)
+ * @param source - The {@link QueryChangeLogSource} of
QueryChangeLogs. (not null)
+ * @param blockingValue - How long blocking operations will try before
looping. (> 0)
+ * @param blockingUnits - The units of the {@code blockingValue}. (not
null)
+ */
+ public QueryManager(
+ final QueryExecutor queryExecutor,
+ final QueryChangeLogSource source,
+ final long blockingValue,
+ final TimeUnit blockingUnits) {
+ this.changeLogSource = requireNonNull(source);
+ this.queryExecutor = requireNonNull(queryExecutor);
+ Preconditions.checkArgument(blockingValue > 0, "The blocking value
must be > 0. Was: " + blockingValue);
+ this.blockingValue = blockingValue;
+ this.blockingUnits = requireNonNull(blockingUnits);
+ }
+
+ @Override
+ protected void doStart() {
+ log.info("Starting a QueryManager.");
+
+ // A work queue of discovered Query Change Logs that need to be
handled.
+ // This queue exists so that the source notifying thread may be
released
+ // immediately instead of calling into blocking functions.
+ final BlockingQueue<LogEvent> logEvents = new
ArrayBlockingQueue<>(1024);
+
+ // A work queue of discovered Query Changes from the monitored
Query Change Logs
+ // that need to be handled. This queue exists so that the Query
Repository notifying
+ // thread may be released immediately instead of calling into
blocking functions.
+ final BlockingQueue<QueryEvent> queryEvents = new
ArrayBlockingQueue<>(1024);
+
+ try {
+ // Start up a LogEventWorker using the executor service.
+ executor.submit(new LogEventWorker(logEvents, queryEvents,
blockingValue, blockingUnits, shutdownSignal));
+
+ // Start up a QueryEvent Worker using the executor service.
+ executor.submit(new QueryEventWorker(queryEvents,
queryExecutor, blockingValue, blockingUnits, shutdownSignal));
+
+ // Start up the query execution framework.
+ queryExecutor.startAndWait();
+
+ // Startup the source that discovers new Query Change Logs.
+ changeLogSource.startAndWait();
+
+ // Subscribe the source a listener that writes to the
LogEventWorker's work queue.
+ changeLogSource.subscribe(new LogEventWorkGenerator(logEvents,
blockingValue, blockingUnits, shutdownSignal));
+ } catch(final RejectedExecutionException |
UncheckedExecutionException e) {
+ log.error("Could not start up a QueryManager.", e);
+ notifyFailed(e);
+ }
+
+ // Notify the service was successfully started.
+ notifyStarted();
+
+ log.info("QueryManager has finished starting.");
+ }
+
+ @Override
+ protected void doStop() {
+ log.info("Stopping a QueryManager.");
+
+ // Set the shutdown flag so that all components that rely on that
signal will stop processing.
+ shutdownSignal.set(true);
+
+ // Stop the workers and wait for them to die.
+ executor.shutdownNow();
+ try {
+ if(!executor.awaitTermination(10, TimeUnit.SECONDS)) {
+ log.warn("Waited 10 seconds for the worker threads to die,
but they are still running.");
+ }
+ } catch (final InterruptedException e) {
+ log.warn("Waited 10 seconds for the worker threads to die, but
they are still running.");
+ }
+
+ // Stop the source of new Change Logs.
+ try {
+ changeLogSource.stopAndWait();
+ } catch(final UncheckedExecutionException e) {
+ log.warn("Could not stop the Change Log Source.", e);
+ }
+
+ // Stop the query execution framework.
+ try {
+ queryExecutor.stopAndWait();
+ } catch(final UncheckedExecutionException e) {
+ log.warn("Could not stop the Query Executor", e);
+ }
+
+ // Notify the service was successfully stopped.
+ notifyStopped();
+
+ log.info("QueryManager has finished stopping.");
+ }
+
+ /**
+ * Offer a unit of work to a blocking queue until it is either
accepted, or the
+ * shutdown signal is set.
+ *
+ * @param workQueue - The blocking work queue to write to. (not null)
+ * @param event - The event that will be offered to the work queue.
(not null)
+ * @param offerValue - How long to wait when offering new work.
+ * @param offerUnits - The unit for the {@code offerValue}. (not null)
+ * @param shutdownSignal - Used to signal application shutdown has
started, so
+ * this method may terminate without ever placing the event on the
queue. (not null)
+ * @return {@code true} if the evet nwas added to the queue, otherwise
false.
+ */
+ private static <T> boolean offerUntilAcceptedOrShutdown(
+ final BlockingQueue<T> workQueue,
+ final T event, final
+ long offerValue,
--- End diff --
final and long are on separate lines
---
