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/*
* Copyright (c) 2008-2016, Hazelcast, Inc. All Rights Reserved.
*
* 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.hazelcast.config;
import com.hazelcast.spi.annotation.Beta;
import com.hazelcast.topic.TopicOverloadPolicy;
import java.util.LinkedList;
import java.util.List;
import java.util.concurrent.Executor;
import static com.hazelcast.topic.TopicOverloadPolicy.BLOCK;
import static com.hazelcast.util.Preconditions.checkNotNull;
import static com.hazelcast.util.Preconditions.checkPositive;
/**
* Configuration for a reliable {@link com.hazelcast.core.ITopic}.
*
* The reliable topic makes use of the {@link com.hazelcast.ringbuffer.Ringbuffer} to store the actual messages.
*
* To configure the ringbuffer for a reliable topic, define a ringbuffer in the config with exactly the same name. It is very
* unlikely that you want to run with the default settings.
*
* When a ReliableTopic starts, it will always start from the tail+1 item from the RingBuffer. It will not chew its way through
* all available events but it will wait for the next item being published.
*
* In the reliable topic, global order is always maintained, so all listeners will observe exactly the same order of sequence of
* messages.
*/
@Beta
public class ReliableTopicConfig {
/**
* The default read batch size.
*/
public static final int DEFAULT_READ_BATCH_SIZE = 10;
/**
* The default slow consumer policy.
*/
public static final TopicOverloadPolicy DEFAULT_TOPIC_OVERLOAD_POLICY = BLOCK;
/**
* Default value for statistics enabled.
*/
public static final boolean DEFAULT_STATISTICS_ENABLED = true;
private Executor executor;
private int readBatchSize = DEFAULT_READ_BATCH_SIZE;
private String name;
private boolean statisticsEnabled = DEFAULT_STATISTICS_ENABLED;
private List listenerConfigs = new LinkedList();
private TopicOverloadPolicy topicOverloadPolicy = DEFAULT_TOPIC_OVERLOAD_POLICY;
/**
* Creates a new ReliableTopicConfig with default settings.
*/
public ReliableTopicConfig(String name) {
this.name = checkNotNull(name, "name");
}
/**
* Creates a new ReliableTopicConfig by cloning an existing one.
*
* @param config the ReliableTopicConfig to clone.
*/
ReliableTopicConfig(ReliableTopicConfig config) {
this.name = config.name;
this.statisticsEnabled = config.statisticsEnabled;
this.readBatchSize = config.readBatchSize;
this.executor = config.executor;
this.topicOverloadPolicy = config.topicOverloadPolicy;
this.listenerConfigs = config.listenerConfigs;
}
ReliableTopicConfig(ReliableTopicConfig config, String name) {
this(config);
this.name = name;
}
/**
* Gets the name of the reliable topic.
*
* @return the name of the reliable topic.
*/
public String getName() {
return name;
}
/**
* Gets the TopicOverloadPolicy for this reliable topic.
*
* @return the TopicOverloadPolicy.
*/
public TopicOverloadPolicy getTopicOverloadPolicy() {
return topicOverloadPolicy;
}
/**
* Sets the TopicOverloadPolicy for this reliable topic. Check the {@link TopicOverloadPolicy} for more details about
* this setting.
*
* @param topicOverloadPolicy the new TopicOverloadPolicy.
* @return the updated reliable topic config.
* @throws IllegalArgumentException if topicOverloadPolicy is null.
*/
public ReliableTopicConfig setTopicOverloadPolicy(TopicOverloadPolicy topicOverloadPolicy) {
this.topicOverloadPolicy = checkNotNull(topicOverloadPolicy, "topicOverloadPolicy can't be null");
return this;
}
/**
* Gets the Executor that is going to process the events.
*
* If no Executor is selected, then the {@link com.hazelcast.spi.ExecutionService#ASYNC_EXECUTOR} is used.
*
* @return the Executor used to process events.
* @see #setExecutor(java.util.concurrent.Executor)
*/
public Executor getExecutor() {
return executor;
}
/**
* Sets the Executor that is going to process the event.
*
* In some cases it is desirable to set a specific Executor. For example, you may want to isolate a certain topic from other
* topics because it contains long running messages or very high priority messages.
*
* A single Executor can be shared between multiple Reliable topics, although it could take more time to process a message.
* If a single Executor is not shared with other reliable topics, then the Executor only needs to have a single thread.
*
* @param executor the Executor. if the executor is null, the {@link com.hazelcast.spi.ExecutionService#ASYNC_EXECUTOR} will
* be used to process the event.
* @return the updated config.
*/
public ReliableTopicConfig setExecutor(Executor executor) {
this.executor = executor;
return this;
}
/**
* Gets the maximum number of items to read in a batch. Returned value will always be equal or larger than 1.
*
* @return the read batch size.
*/
public int getReadBatchSize() {
return readBatchSize;
}
/**
* Sets the read batch size.
*
* The ReliableTopic tries to read a batch of messages from the ringbuffer. It will get at least one, but
* if there are more available, then it will try to get more to increase throughput. The minimal read
* batch size can be influenced using the read batch size.
*
* Apart from influencing the number of messages to download, the readBatchSize also determines how many
* messages will be processed by the thread running the MessageListener before it returns back to the pool
* to look for other MessageListeners that need to be processed. The problem with returning to the pool and
* looking for new work is that interacting with an Executor is quite expensive due to contention on the
* work-queue. The more work that can be done without retuning to the pool, the smaller the overhead.
*
* If the readBatchSize is 10 and there are 50 messages available, 10 items are retrieved and processed
* consecutively before the thread goes back to the pool and helps out with the processing of other messages.
*
* If the readBatchSize is 10 and there are 2 items available, 2 items are retrieved and processed consecutively.
*
* If the readBatchSize is an issue because a thread will be busy too long with processing a single MessageListener
* and it can't help out other MessageListeners, increase the size of the threadpool so the other MessageListeners don't
* need to wait for a thread, but can be processed in parallel.
*
* @param readBatchSize the maximum number of items to read in a batch.
* @return the updated reliable topic config.
* @throws IllegalArgumentException if readBatchSize is smaller than 1.
*/
public ReliableTopicConfig setReadBatchSize(int readBatchSize) {
this.readBatchSize = checkPositive(readBatchSize, "readBatchSize should be positive");
return this;
}
/**
* Checks if statistics are enabled for this reliable topic.
*
* @return true if enabled, false otherwise.
*/
public boolean isStatisticsEnabled() {
return statisticsEnabled;
}
/**
* Enables or disables statistics for this reliable topic..
*
* @param statisticsEnabled true to enable statistics, false to disable.
* @return the updated reliable topic config.
*/
public ReliableTopicConfig setStatisticsEnabled(boolean statisticsEnabled) {
this.statisticsEnabled = statisticsEnabled;
return this;
}
/**
* Gets the list of message listeners (listens for when messages are added or removed) for this reliable topic.
*
* @return list of MessageListener configurations.
*/
public List getMessageListenerConfigs() {
return listenerConfigs;
}
/**
* Adds a message listener (listens for when messages are added or removed) to this reliable topic.
*
* @param listenerConfig the ListenerConfig to add.
* @return the updated config.
* @throws NullPointerException if listenerConfig is null.
*/
public ReliableTopicConfig addMessageListenerConfig(ListenerConfig listenerConfig) {
checkNotNull(listenerConfig, "listenerConfig can't be null");
listenerConfigs.add(listenerConfig);
return this;
}
/**
* Returns a readonly version of the ReliableTopicConfig.
*
* @return a readonly version of this reliable topic config.
*/
public ReliableTopicConfig getAsReadOnly() {
return new ReliableTopicConfigReadOnly(this);
}
@Override
public String toString() {
return "ReliableTopicConfig{"
+ "name='" + name + '\''
+ ", topicOverloadPolicy=" + topicOverloadPolicy
+ ", executor=" + executor
+ ", readBatchSize=" + readBatchSize
+ ", statisticsEnabled=" + statisticsEnabled
+ ", listenerConfigs=" + listenerConfigs
+ '}';
}
static class ReliableTopicConfigReadOnly extends ReliableTopicConfig {
public ReliableTopicConfigReadOnly(ReliableTopicConfig config) {
super(config);
}
@Override
public ReliableTopicConfig setExecutor(Executor executor) {
throw new UnsupportedOperationException("This config is read-only");
}
@Override
public ReliableTopicConfig setReadBatchSize(int readBatchSize) {
throw new UnsupportedOperationException("This config is read-only");
}
@Override
public ReliableTopicConfig setStatisticsEnabled(boolean statisticsEnabled) {
throw new UnsupportedOperationException("This config is read-only");
}
@Override
public ReliableTopicConfig addMessageListenerConfig(ListenerConfig listenerConfig) {
throw new UnsupportedOperationException("This config is read-only");
}
@Override
public ReliableTopicConfig setTopicOverloadPolicy(TopicOverloadPolicy topicOverloadPolicy) {
throw new UnsupportedOperationException("This config is read-only");
}
}
}
