com.sequoiadb.datasource.ConnectionItemMgr Maven / Gradle / Ivy

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Java client driver for SequoiaDB
There is a newer version: 5.10
/*
 * Copyright 2018 SequoiaDB Inc.
 *
 * 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.sequoiadb.datasource;

import java.util.Iterator;
import java.util.List;
import java.util.TreeSet;
import java.util.concurrent.locks.ReentrantLock;


class ConnItem implements Comparable {
    private String _addr;
    private long _sequenceNumber;

    public ConnItem(String addr, long sequenceNumber) {
        _addr = addr;
        _sequenceNumber = sequenceNumber;
    }

    public String getAddr() {
        return _addr;
    }

    public void setAddr(String addr) {
        _addr = addr;
    }

    public long getSequenceNumber() {
        return _sequenceNumber;
    }

    public void setSequenceNumber(long sequenceNumber) {
        _sequenceNumber = sequenceNumber;
    }

    @Override
    public int compareTo(ConnItem other) {
        if (_sequenceNumber != other._sequenceNumber)
            return (int) (_sequenceNumber - other._sequenceNumber);
        else
            return _addr.compareTo(other._addr);
    }
}

class ConnectionItemMgr {
    private int _capacity;
    private static long _sequenceNumber = -1;
    private TreeSet _idleItem = null;
    private TreeSet _usedItem = null;

    public ConnectionItemMgr(int capacity, List usedItems) {
        _capacity = capacity;
        _idleItem = new TreeSet();
        _usedItem = new TreeSet();
        int initNum = 0;
        if (usedItems != null) {
            Iterator itr = usedItems.iterator();
            while (itr.hasNext()) {
                _usedItem.add(itr.next());
            }
            initNum = (capacity > _usedItem.size()) ? (capacity - _usedItem.size()) : 0;
        } else {
            initNum = capacity;
        }
        for (int i = 0; i < initNum; i++) {
            // we must give a sequence number to the instance of ConnItem,
            // for _idleItem is TreeSet, it won't save two instances with
            // the same content
            _idleItem.add(new ConnItem("", ++_sequenceNumber));
        }
    }

    public synchronized long getCurrentSequenceNumber() {
        return _sequenceNumber;
    }

    public synchronized int getCapacity() {
        return _capacity;
    }

    public synchronized int getIdleItemNum() {
        return _idleItem.size();
    }

    public synchronized int getUsedItemNum() {
        return _usedItem.size();
    }

    public synchronized void resetCapacity(int capacity) {
        if (_capacity < capacity) {
            // increase items
            for (int i = _capacity; i < capacity; i++) {
                _idleItem.add(new ConnItem("", ++_sequenceNumber));
            }
        } else {
            // decrease items
            int deltaNum = _capacity - capacity;
            while (deltaNum-- != 0) {
                ConnItem connItem = _idleItem.pollFirst();
                if (connItem == null) {
                    break;
                }
            }
        }
        _capacity = capacity;
    }

    public synchronized ConnItem getItem() {
        ConnItem connItem = _idleItem.pollFirst();
        // reset sequence number
        if (connItem != null) {
            connItem.setSequenceNumber(++_sequenceNumber);
            _usedItem.add(connItem);
        }
        return connItem;
    }

    public synchronized void releaseItem(ConnItem item) {
        _usedItem.remove(item);
        // _usedItem has remove one, so we must use "<" here
        if (_usedItem.size() + _idleItem.size() < _capacity) {
            item.setAddr("");
            _idleItem.add(item);
        }
    }
}