Alachisoft.NCache.Common.Locking.LockManager Maven / Gradle / Ivy

Go to download
package Alachisoft.NCache.Common.Locking;


import com.alachisoft.ncache.runtime.util.NCDateTime;
import com.alachisoft.ncache.serialization.core.io.ICompactSerializable;
import com.alachisoft.ncache.serialization.core.io.NCacheObjectInput;
import com.alachisoft.ncache.serialization.core.io.NCacheObjectOutput;

import java.io.IOException;
import java.util.Calendar;
import java.util.UUID;

//C# TO JAVA CONVERTER TODO TASK: There is no preprocessor in Java:
//#if !EXPRESS || (EXPRESS && PROFESSIONAL)
//#else
//#endif

/**
 * LockManager is responsible for maintaining locks for cache items.
 */
public class LockManager implements ICompactSerializable {

//C# TO JAVA CONVERTER TODO TASK: There is no preprocessor in Java:
    ///#region /                       --- LockHandle (Inner Class)---                 /

    private java.util.ArrayList _readerLocks = new java.util.ArrayList();

//C# TO JAVA CONVERTER TODO TASK: There is no preprocessor in Java:
    ///#endregion
    private LockHandle _writerLock;
    private LockMode _lockMode = LockMode.None;

    private String GenerateLockId() {

        return UUID.randomUUID().toString() +
                new NCDateTime(Calendar.getInstance().getTimeInMillis()).getTicks();
    }

    /**
     * Gets the current locking mode.
     */
    public final LockMode getMode() {
        return _lockMode;
    }

    /**
     * Acquires the reader lock for a cache item. Reader lock is assigned
     * only if no writer lock exists. Multiple reader locks can be acquired.
     *
     * @return Unique lock id
     */
    public final boolean AcquireReaderLock(String lockHandle) {
        synchronized (this) {
            if (_lockMode == LockMode.None || _lockMode == LockMode.Reader) {
                _readerLocks.add(new LockHandle(lockHandle));
                _lockMode = LockMode.Reader;
                return true;
            }
        }
        return false;
    }

    /**
     * Releases a reader lock on a cache item.
     *
     * @param lockId
     */
    public final void ReleaseReaderLock(String lockId) {
        if (lockId == null) {
            return;
        }
        synchronized (this) {
            if (_lockMode == LockMode.Reader) {
                if (_readerLocks.contains(new LockHandle(lockId))) {
                    _readerLocks.remove(new LockHandle(lockId));
                    if (_readerLocks.isEmpty()) {
                        _lockMode = LockMode.None;
                    }
                }
            }
        }
    }

    /**
     * Acquires the writer lock on a cache item. Writer lock is acquired only if
     * no reader or wirter lock exists on the item.
     *
     * @return Lockid against which lock is acquired.
     */
    public final boolean AcquireWriterLock(String lockHandle) {
        synchronized (this) {
            if (_lockMode == LockMode.None) {
                _writerLock = new LockHandle(lockHandle);
                _lockMode = LockMode.Write;
                return true;
            }
        }
        return false;
    }

    /**
     * Releases a writer lock on the cache item.
     *
     * @param lockId
     */
    public final void ReleaseWriterLock(String lockId) {
        synchronized (this) {
            if (_lockMode == LockMode.Write) {
                if (_writerLock.equals(lockId)) {
                    _writerLock = null;
                    _lockMode = LockMode.None;
                }
            }
        }
    }

    /**
     * Validates whether a valid lock is acquired by a lock holder.
     *
     * @param mode   Locking mode.
     * @param lockId LockId for which lock is to be validated.
     * @return Returns true if a lock holder still holds lock on the item.
     */
    public final boolean ValidateLock(LockMode mode, String lockId) {
        if (lockId == null && mode != LockMode.None) {
            return false;
        }

        synchronized (this) {
            switch (mode) {
                case Reader:
                    return _readerLocks.contains(new LockHandle(lockId));

                case Write:
                    return _writerLock.equals(lockId);

                case None:
                    return true;
            }
        }
        return false;
    }

    public final boolean ValidateLock(String lockId) {
        return ValidateLock(_lockMode, lockId);
    }

    @Override
    public final void deserialize(NCacheObjectInput reader) throws ClassNotFoundException, IOException {
        _lockMode = LockMode.forValue(reader.readByte());
        Object tempVar = reader.readObject();
        String writerLockId = (String) ((tempVar instanceof String) ? tempVar : null);
        if (!tangible.DotNetToJavaStringHelper.isNullOrEmpty(writerLockId)) {
            _writerLock = new LockHandle(writerLockId);
        }

        int readLockCount = reader.readInt();
        _readerLocks = new java.util.ArrayList();
        Object tempVar2 = null;
        for (int i = 0; i < readLockCount; i++) {
            tempVar2 = reader.readObject();
            _readerLocks.add(new LockHandle((String) ((tempVar2 instanceof String) ? tempVar2 : null)));
        }
    }


//C# TO JAVA CONVERTER TODO TASK: There is no preprocessor in Java:
    ///#region ICompactSerializable Members

    @Override
    public final void serialize(NCacheObjectOutput writer) throws IOException {
//C# TO JAVA CONVERTER WARNING: Unsigned integer types have no direct equivalent in Java:
//ORIGINAL LINE: writer.Write((byte)_lockMode);
        writer.write((byte) _lockMode.getValue());

        if (_writerLock != null) {
            writer.writeObject(_writerLock.getLockId());
        } else {
            writer.writeObject(null);
        }

        writer.writeInt(_readerLocks.size());
        for (LockHandle handle : _readerLocks) {
            writer.writeObject(handle.getLockId());
        }
    }

    private static class LockHandle implements ICompactSerializable {
        private String _lockId;
        private java.util.Date _lockTime = new java.util.Date(0);

        public LockHandle(String lockId) {
            _lockId = lockId;
            _lockTime = new java.util.Date();
        }

        public final String getLockId() {
            return _lockId;
        }

        public final java.util.Date getLockTime() {
            return _lockTime;
        }

        @Override
        public boolean equals(Object obj) {
            LockHandle other = (LockHandle) ((obj instanceof LockHandle) ? obj : null);
            if (other != null && other._lockId.equals(_lockId)) {
                return true;
            } else if (obj instanceof String) {
                return _lockId.equals((String) obj);
            } else {
                return false;
            }
        }


//C# TO JAVA CONVERTER TODO TASK: There is no preprocessor in Java:
        ///#region ICompactSerializable Members

        @Override
        public final void deserialize(NCacheObjectInput reader) throws ClassNotFoundException, IOException {
            Object tempVar = reader.readObject();
            _lockId = (String) ((tempVar instanceof String) ? tempVar : null);
        }

        @Override
        public final void serialize(NCacheObjectOutput writer) throws IOException {
            writer.writeObject(_lockId);
        }

//C# TO JAVA CONVERTER TODO TASK: There is no preprocessor in Java:
        ///#endregion
    }

//C# TO JAVA CONVERTER TODO TASK: There is no preprocessor in Java:
    ///#endregion
}