org.apache.flink.runtime.state.ttl.TtlMapState Maven / Gradle / Ivy

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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.flink.runtime.state.ttl;

import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.api.common.typeutils.base.MapSerializer;
import org.apache.flink.runtime.state.internal.InternalMapState;
import org.apache.flink.util.FlinkRuntimeException;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;

import java.util.AbstractMap;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.function.Function;

/**
 * This class wraps map state with TTL logic.
 *
 * @param  The type of key the state is associated to
 * @param  The type of the namespace
 * @param  Type of the user entry key of state with TTL
 * @param  Type of the user entry value of state with TTL
 */
class TtlMapState
        extends AbstractTtlState<
                K, N, Map, Map>, InternalMapState>>
        implements InternalMapState {
    TtlMapState(
            TtlStateContext>, Map>
                    ttlStateContext) {
        super(ttlStateContext);
    }

    @Override
    public UV get(UK key) throws Exception {
        TtlValue ttlValue = getWrapped(key);
        return ttlValue == null ? null : ttlValue.getUserValue();
    }

    private TtlValue getWrapped(UK key) throws Exception {
        accessCallback.run();
        return getWrappedWithTtlCheckAndUpdate(
                () -> original.get(key), v -> original.put(key, v), () -> original.remove(key));
    }

    @Override
    public void put(UK key, UV value) throws Exception {
        accessCallback.run();
        original.put(key, wrapWithTs(value));
    }

    @Override
    public void putAll(Map map) throws Exception {
        accessCallback.run();
        if (map == null) {
            return;
        }
        Map> ttlMap = new HashMap<>(map.size());
        long currentTimestamp = timeProvider.currentTimestamp();
        for (Map.Entry entry : map.entrySet()) {
            UK key = entry.getKey();
            ttlMap.put(key, TtlUtils.wrapWithTs(entry.getValue(), currentTimestamp));
        }
        original.putAll(ttlMap);
    }

    @Override
    public void remove(UK key) throws Exception {
        accessCallback.run();
        original.remove(key);
    }

    @Override
    public boolean contains(UK key) throws Exception {
        TtlValue ttlValue = getWrapped(key);
        return ttlValue != null;
    }

    @Override
    public Iterable> entries() throws Exception {
        return entries(e -> e);
    }

    private  Iterable entries(Function, R> resultMapper) throws Exception {
        accessCallback.run();
        Iterable>> withTs = original.entries();
        return () ->
                new EntriesIterator<>(
                        withTs == null ? Collections.emptyList() : withTs, resultMapper);
    }

    @Override
    public Iterable keys() throws Exception {
        return entries(Map.Entry::getKey);
    }

    @Override
    public Iterable values() throws Exception {
        return entries(Map.Entry::getValue);
    }

    @Override
    public Iterator> iterator() throws Exception {
        return entries().iterator();
    }

    @Override
    public boolean isEmpty() throws Exception {
        accessCallback.run();
        return original.isEmpty();
    }

    @Nullable
    @Override
    public Map> getUnexpiredOrNull(@Nonnull Map> ttlValue) {
        // the remove operation will clear the whole state if the map becomes empty after init
        if (ttlValue.isEmpty()) {
            return ttlValue;
        }
        Map> unexpired = new HashMap<>();
        TypeSerializer> valueSerializer =
                ((MapSerializer>) original.getValueSerializer())
                        .getValueSerializer();
        for (Map.Entry> e : ttlValue.entrySet()) {
            if (!expired(e.getValue())) {
                // we have to do the defensive copy to update the value
                unexpired.put(e.getKey(), valueSerializer.copy(e.getValue()));
            }
        }
        if (!unexpired.isEmpty()) {
            return unexpired;
        } else {
            // map is not empty but all values expired
            return null;
        }
    }

    @Override
    public void clear() {
        original.clear();
    }

    private class EntriesIterator implements Iterator {
        private final Iterator>> originalIterator;
        private final Function, R> resultMapper;
        private Map.Entry nextUnexpired = null;
        private boolean rightAfterNextIsCalled = false;

        private EntriesIterator(
                @Nonnull Iterable>> withTs,
                @Nonnull Function, R> resultMapper) {
            this.originalIterator = withTs.iterator();
            this.resultMapper = resultMapper;
        }

        @Override
        public boolean hasNext() {
            rightAfterNextIsCalled = false;
            while (nextUnexpired == null && originalIterator.hasNext()) {
                nextUnexpired = getUnexpiredAndUpdateOrCleanup(originalIterator.next());
            }
            return nextUnexpired != null;
        }

        @Override
        public R next() {
            if (hasNext()) {
                rightAfterNextIsCalled = true;
                R result = resultMapper.apply(nextUnexpired);
                nextUnexpired = null;
                return result;
            }
            throw new NoSuchElementException();
        }

        @Override
        public void remove() {
            if (rightAfterNextIsCalled) {
                originalIterator.remove();
            } else {
                throw new IllegalStateException(
                        "next() has not been called or hasNext() has been called afterwards,"
                                + " remove() is supported only right after calling next()");
            }
        }

        private Map.Entry getUnexpiredAndUpdateOrCleanup(Map.Entry> e) {
            TtlValue unexpiredValue;
            try {
                unexpiredValue =
                        getWrappedWithTtlCheckAndUpdate(
                                e::getValue,
                                v -> original.put(e.getKey(), v),
                                originalIterator::remove);
            } catch (Exception ex) {
                throw new FlinkRuntimeException(ex);
            }
            return unexpiredValue == null
                    ? null
                    : new AbstractMap.SimpleEntry<>(e.getKey(), unexpiredValue.getUserValue());
        }
    }
}