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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 org.apache.ignite.internal.processors.metastorage;
import java.io.Serializable;
import java.util.Collection;
import java.util.function.BiConsumer;
import java.util.function.Predicate;
import org.apache.ignite.IgniteCheckedException;
import org.apache.ignite.cluster.ClusterNode;
import org.apache.ignite.internal.GridKernalContext;
import org.apache.ignite.internal.IgniteFeatures;
import org.apache.ignite.internal.managers.discovery.IgniteDiscoverySpi;
import org.apache.ignite.spi.discovery.DiscoverySpi;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;
import static org.apache.ignite.internal.IgniteFeatures.DISTRIBUTED_METASTORAGE;
/**
* API for distributed data storage. Gives the ability to store configuration data (or any other data)
* consistently and cluster-wide. It is guaranteed that every read value is the same on every node in the cluster
* all the time.
*/
public interface ReadableDistributedMetaStorage {
/**
* @return {@code True} if all nodes in the cluster support discributed metastorage feature.
* @see IgniteFeatures#DISTRIBUTED_METASTORAGE
*/
public static boolean isSupported(GridKernalContext ctx) {
DiscoverySpi discoSpi = ctx.config().getDiscoverySpi();
if (discoSpi instanceof IgniteDiscoverySpi)
return ((IgniteDiscoverySpi)discoSpi).allNodesSupport(DISTRIBUTED_METASTORAGE);
else {
Collection<ClusterNode> nodes = discoSpi.getRemoteNodes();
return IgniteFeatures.allNodesSupports(nodes, DISTRIBUTED_METASTORAGE);
}
}
/**
* Get the total number of updates (write/remove) that metastorage ever had.
*/
long getUpdatesCount();
/**
* Get value by the key. Should be consistent for all nodes.
*
* @param key The key.
* @return Value associated with the key.
* @throws IgniteCheckedException If reading or unmarshalling failed.
*/
@Nullable <T extends Serializable> T read(@NotNull String key) throws IgniteCheckedException;
/**
* Iterate over all values corresponding to the keys with given prefix. It is guaranteed that iteration will be
* executed in ascending keys order.
*
* @param keyPrefix Prefix for the keys that will be iterated.
* @param cb Callback that will be applied to all {@code <key, value>} pairs.
* @throws IgniteCheckedException If reading or unmarshalling failed.
*/
void iterate(
@NotNull String keyPrefix,
@NotNull BiConsumer<String, ? super Serializable> cb
) throws IgniteCheckedException;
/**
* Add listener on data updates. Updates happens it two cases:
* <ul>
* <li>
* Some node invoked write or remove. Listeners are invoked after update update operation is
* already completed.
* </li>
* <li>
* Node is just started and not ready for write yet. In this case listeners are invoked for every
* key with new value (retrieved from the clueter) or already existing value if there was no updates
* for given key. This guarantees that all listeners are invoked for all updates in case of failover.
* </li>
* </ul>
*
* @param keyPred Predicate to check whether this listener should be invoked on given key update or not.
* @param lsnr Listener object.
* @see DistributedMetaStorageListener
*/
void listen(@NotNull Predicate<String> keyPred, DistributedMetaStorageListener<?> lsnr);
}