modules/core/src/main/java/org/apache/ignite/internal/processors/datastructures/GridCacheQueueHeader.java

/*
 * 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.datastructures;

import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.util.HashSet;
import java.util.Set;
import org.apache.ignite.internal.processors.cache.GridCacheInternal;
import org.apache.ignite.internal.util.tostring.GridToStringInclude;
import org.apache.ignite.internal.util.typedef.F;
import org.apache.ignite.internal.util.typedef.internal.S;
import org.apache.ignite.internal.util.typedef.internal.U;
import org.apache.ignite.lang.IgniteUuid;
import org.jetbrains.annotations.Nullable;

/**
 * Queue header.
 */
public class GridCacheQueueHeader implements GridCacheInternal, Externalizable {
    /** */
    private static final long serialVersionUID = 0L;

    /** */
    private IgniteUuid id;

    /** */
    private long head;

    /** */
    private long tail;

    /** */
    private int cap;

    /** */
    private boolean collocated;

    /** */
    @GridToStringInclude
    private Set<Long> rmvIdxs;

    /**
     * Required by {@link Externalizable}.
     */
    public GridCacheQueueHeader() {
        // No-op.
    }

    /**
     * @param id Queue unique ID.
     * @param cap Capacity.
     * @param collocated Collocation flag.
     * @param head Queue head index.
     * @param tail Queue tail index.
     * @param rmvIdxs Indexes of removed items.
     */
    public GridCacheQueueHeader(IgniteUuid id, int cap, boolean collocated, long head, long tail,
        @Nullable Set<Long> rmvIdxs) {
        assert id != null;
        assert head <= tail;

        this.id = id;
        this.cap = cap;
        this.collocated = collocated;
        this.head = head;
        this.tail = tail;
        this.rmvIdxs = rmvIdxs;
    }

    /**
     * @return Queue unique ID.
     */
    public IgniteUuid id() {
        return id;
    }

    /**
     * @return Capacity.
     */
    public int capacity() {
        return cap;
    }

    /**
     * @return Queue collocation flag.
     */
    public boolean collocated() {
        return collocated;
    }

    /**
     * @return Head index.
     */
    public long head() {
        return head;
    }

    /**
     * @return Tail index.
     */
    public long tail() {
        return tail;
    }

    /**
     * @return {@code True} if queue is bounded.
     */
    public boolean bounded() {
        return cap < Integer.MAX_VALUE;
    }

    /**
     * @return {@code True} if queue is empty.
     */
    public boolean empty() {
        return head == tail;
    }

    /**
     * @return {@code True} if queue is full.
     */
    public boolean full() {
        return bounded() && size() == capacity();
    }

    /**
     * @return Queue size.
     */
    public int size() {
        int rmvSize = F.isEmpty(removedIndexes()) ? 0 : removedIndexes().size();

        int size = (int)(tail() - head() - rmvSize);

        assert size >= 0 : size;

        return size;
    }

    /**
     * @return Indexes of removed items.
     */
    @Nullable public Set<Long> removedIndexes() {
        return rmvIdxs;
    }

    /** {@inheritDoc} */
    @Override public void writeExternal(ObjectOutput out) throws IOException {
        U.writeGridUuid(out, id);
        out.writeInt(cap);
        out.writeBoolean(collocated);
        out.writeLong(head);
        out.writeLong(tail);
        out.writeBoolean(rmvIdxs != null);

        if (rmvIdxs != null) {
            out.writeInt(rmvIdxs.size());

            for (Long idx : rmvIdxs)
                out.writeLong(idx);
        }
    }

    /** {@inheritDoc} */
    @Override public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
        id = U.readGridUuid(in);
        cap = in.readInt();
        collocated = in.readBoolean();
        head = in.readLong();
        tail = in.readLong();

        if (in.readBoolean()) {
            int size = in.readInt();

            rmvIdxs = new HashSet<>();

            for (int i = 0; i < size; i++)
                rmvIdxs.add(in.readLong());
        }
    }

    /** {@inheritDoc} */
    @Override public String toString() {
        return S.toString(GridCacheQueueHeader.class, this);
    }
}