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Groovy example source code file (AbstractConcurrentMapBase.java)

This example Groovy source code file (AbstractConcurrentMapBase.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Groovy tags/keywords

abstractconcurrentmapbase, entry, entry, k, lockableobject, max_segments, maximum_capacity, maximum_capacity, object, object, retries_before_lock, segment, segment, v

The Groovy AbstractConcurrentMapBase.java source code

/*
 * Copyright 2003-2010 the original author or authors.
 *
 * 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 org.codehaus.groovy.util;

public abstract class AbstractConcurrentMapBase {
    protected static final int MAXIMUM_CAPACITY = 1 << 30;
    static final int MAX_SEGMENTS = 1 << 16;
    static final int RETRIES_BEFORE_LOCK = 2;
    final int segmentMask;
    final int segmentShift;
    protected final Segment[] segments;

    public AbstractConcurrentMapBase(Object segmentInfo) {
        int sshift = 0;
        int ssize = 1;
        while (ssize < 16) {
            ++sshift;
            ssize <<= 1;
        }
        segmentShift = 32 - sshift;
        segmentMask = ssize - 1;
        this.segments = new Segment[ssize];

        int c = 512 / ssize;
        if (c * ssize < 512)
            ++c;
        int cap = 1;
        while (cap < c)
            cap <<= 1;

        for (int i = 0; i < this.segments.length; ++i)
            this.segments[i] = createSegment(segmentInfo, cap);
    }

    protected abstract Segment createSegment(Object segmentInfo, int cap);

    protected static <K> int hash(K key) {
        int h = System.identityHashCode(key);
        h += ~(h << 9);
        h ^=  (h >>> 14);
        h +=  (h << 4);
        h ^=  (h >>> 10);
        return h;
    }

    public Segment segmentFor(int hash) {
        return segments[(hash >>> segmentShift) & segmentMask];
    }

    public int fullSize() {
        int count = 0;
        for (int i = 0; i < segments.length; i++) {
            segments[i].lock();
            try {
                for (int j = 0; j < segments[i].table.length; j++) {
                    Object o = segments[i].table [j];
                    if (o != null) {
                        if (o instanceof Entry) {
                            count++;
                        }
                        else {
                            Object arr [] = (Object[]) o;
                            count += arr.length;
                        }
                    }
                }
            }
            finally {
                segments[i].unlock();
            }
        }
        return count;
    }

    public int size() {
        int count = 0;
        for (int i = 0; i < segments.length; i++) {
            segments[i].lock();
            try {
                for (int j = 0; j < segments[i].table.length; j++) {
                    Object o = segments[i].table [j];
                    if (o != null) {
                        if (o instanceof Entry) {
                            Entry e = (Entry) o;
                            if (e.isValid())
                              count++;
                        }
                        else {
                            Object arr [] = (Object[]) o;
                            for (int k = 0; k < arr.length; k++) {
                                Entry info = (Entry) arr[k];
                                if (info != null && info.isValid())
                                    count++;
                            }
                        }
                    }
                }
            }
            finally {
                segments[i].unlock();
            }
        }
        return count;
    }

    public static class Segment extends LockableObject {
        volatile int count;

        int threshold;

        protected volatile Object[] table;

        protected Segment(int initialCapacity) {
            setTable(new Object[initialCapacity]);
        }

        void setTable(Object[] newTable) {
            threshold = (int) (newTable.length * 0.75f);
            table = newTable;
        }

        void removeEntry (Entry e) {
            lock ();
            int newCount = count;
            try {
                Object [] tab = table;
                int index = e.getHash() & (tab.length-1);
                Object o = tab[index];
                if (o != null) {
                    if (o instanceof Entry) {
                        if (o == e) {
                            tab [index] = null;
                            newCount--;
                        }
                    }
                    else {
                        Object arr [] = (Object[]) o;
                        Object res = null;
                        for (int i = 0; i < arr.length; i++) {
                            Entry info = (Entry) arr[i];
                            if (info != null) {
                                if(info != e) {
                                  if (info.isValid()) {
                                     res = put(info, res);
                                  }
                                  else {
                                      newCount--;
                                  }
                                }
                                else {
                                  newCount--;
                                }
                            }
                        }
                        tab [index] = res;
                    }
                    count = newCount;
                }
            }
            finally {
                unlock();
            }
        }

        void rehash() {
            Object[] oldTable = table;
            int oldCapacity = oldTable.length;
            if (oldCapacity >= MAXIMUM_CAPACITY)
                return;

            int newCount = 0;
            for (int i = 0; i < oldCapacity ; i++) {
                Object o = oldTable [i];
                if (o != null) {
                    if (o instanceof Entry) {
                        Entry e = (Entry) o;
                        if (e.isValid()) {
                            newCount++;
                        }
                        else {
                            oldTable[i] = null;
                        }
                    }
                    else {
                        Object arr [] = (Object[]) o;
                        int localCount = 0;
                        for (int index = 0; index < arr.length; index++) {
                            Entry e = (Entry) arr[index];
                            if (e != null && e.isValid()) {
                                localCount++;
                            }
                            else {
                                arr [index] = null;
                            }
                        }
                        if (localCount == 0)
                          oldTable[i] = null;
                        else
                          newCount += localCount;
                    }
                }
            }

            Object[] newTable = new Object[newCount+1 < threshold ? oldCapacity : oldCapacity << 1];
            int sizeMask = newTable.length - 1;
            newCount = 0;
            for (int i = 0; i < oldCapacity ; i++) {
                Object o = oldTable[i];
                if (o != null) {
                    if (o instanceof Entry) {
                        Entry e = (Entry) o;
                        if (e.isValid()) {
                            int index = e.getHash() & sizeMask;
                            put(e, index, newTable);
                            newCount++;
                        }
                    }
                    else {
                        Object arr [] = (Object[]) o;
                        for (int j = 0; j < arr.length; j++) {
                            Entry e = (Entry) arr[j];
                            if (e != null && e.isValid()) {
                                int index = e.getHash() & sizeMask;
                                put(e, index, newTable);
                                newCount++;
                            }
                        }
                    }
                }
            }

            threshold = (int)(newTable.length * 0.75f);

            table = newTable;
            count = newCount;
        }

        private void put(Entry ee, int index, Object[] tab) {
            Object o = tab[index];
            if (o != null) {
                if (o instanceof Entry) {
                    Object arr [] = new Object [2];
                    arr [0] = ee;
                    arr [1] = (Entry) o;
                    tab[index] = arr;
                    return;
                }
                else {
                    Object arr [] = (Object[]) o;
                    Object newArr [] = new Object[arr.length+1];
                    newArr [0] = ee;
                    System.arraycopy(arr, 0, newArr, 1, arr.length);
                    tab [index] = newArr;
                    return;
                }
            }
            tab[index] = ee;
        }

        private Object put(Entry ee, Object o) {
            if (o != null) {
                if (o instanceof Entry) {
                    Object arr [] = new Object [2];
                    arr [0] = ee;
                    arr [1] = (Entry) o;
                    return arr;
                }
                else {
                    Object arr [] = (Object[]) o;
                    Object newArr [] = new Object[arr.length+1];
                    newArr [0] = ee;
                    System.arraycopy(arr, 0, newArr, 1, arr.length);
                    return newArr;
                }
            }
            return ee;
        }
    }

    public interface Entry<V> {
        V getValue();

        void setValue(V value);

        int getHash();

        boolean isValid();
    }
}

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