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added IterableQueue implementation

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Sebastian Sdorra
2013-03-01 17:20:48 +01:00
parent 457e562b2b
commit 4299d9f64d
3 changed files with 371 additions and 0 deletions
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204
scm-core/src/main/java/sonia/scm/collect/IterableQueue.java Normal file
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/**
* Copyright (c) 2010, Sebastian Sdorra
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* 3. Neither the name of SCM-Manager; nor the names of its
* contributors may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* http://bitbucket.org/sdorra/scm-manager
*
*/
package sonia.scm.collect;
//~--- non-JDK imports --------------------------------------------------------
import com.google.common.collect.Iterators;
import com.google.common.collect.Lists;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
//~--- JDK imports ------------------------------------------------------------
import java.util.Iterator;
import java.util.List;
/**
* A iterable queue. The queue can have multiple consumer {@link Iterator},
* which can iterate over all items of the queue until the end of the queue is
* reached. The end of the queue if reached, if a producer call the method
* {@link #endReached()} and the iterator has consumed all items of the backend
* list.
*
* @author Sebastian Sdorra
*
* @since 1.29
* @param <T> type of the queued items
*/
public final class IterableQueue<T> implements Iterable<T>
{
/**
* the logger for IterableQueue
*/
private static final Logger logger =
LoggerFactory.getLogger(IterableQueue.class);
//~--- constructors ---------------------------------------------------------
/**
* Constructs a new {@link IterableQueue} with the default implementation
* of the backing list.
*
*/
public IterableQueue()
{
list = Lists.newArrayList();
}
/**
* Constructs a new {@link IterableQueue} with the given backing list.
*
*
* @param list backend list for the queue
*/
public IterableQueue(List<T> list)
{
this.list = list;
}
//~--- methods --------------------------------------------------------------
/**
* Mark that the end of the queue is reached and notify all consuming
* iterators.
*
* @throws IllegalStateException if the end of the queue if already reached
*/
public synchronized void endReached()
{
if (endReached)
{
throw new IllegalStateException(
"the end of the queue is already reached");
}
endReached = true;
notifyAll();
}
/**
* Returns a new consuming iterator for the queue. The methods
* {@link Iterator#hasNext()} and {@link Iterator#next()} of the
* {@link Iterator} will block until the next item is pushed to the queue, if
* the queue is empty and the end is not reached. The
* {@link Iterator#remove()} method of the {@link Iterator} is not implemented
* and will throw a {@link UnsupportedOperationException}.
*
*
* @return new consuming iterator
*/
@Override
public Iterator<T> iterator()
{
Iterator<T> iterator;
if (endReached)
{
logger.trace("create list iterator");
iterator = Iterators.unmodifiableIterator(list.iterator());
}
else
{
logger.trace("create queue iterator");
iterator = new QueueIterator<T>(this);
}
return iterator;
}
/**
* Push a new item to the queue and notify all consuming iterators.
*
* @throws IllegalStateException if the end of the queue is already reached
* @param item item to push to the queue
*/
public synchronized void push(T item)
{
if (endReached)
{
throw new IllegalStateException(
"the end of the queue is already reached");
}
list.add(item);
notifyAll();
}
/**
* Returns the current size of the queue.
*
*
* @return current size
*/
int size()
{
return list.size();
}
//~--- get methods ----------------------------------------------------------
/**
* Returns the item at the specified index in this queue.
*
*
* @param index index of the item in the queue
*
* @return item at the current index
*/
T get(int index)
{
return list.get(index);
}
/**
* Returns true if the end of the queue is reached.
*
*
* @return true if the end is reached
*/
boolean isEndReached()
{
return endReached;
}
//~--- fields ---------------------------------------------------------------
/** marker for the end of the queue */
private boolean endReached = false;
/** backend list of the queue */
private List<T> list;
}

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scm-core/src/main/java/sonia/scm/collect/QueueIterator.java Normal file
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/**
* Copyright (c) 2010, Sebastian Sdorra
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* 3. Neither the name of SCM-Manager; nor the names of its
* contributors may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* http://bitbucket.org/sdorra/scm-manager
*
*/
package sonia.scm.collect;
//~--- JDK imports ------------------------------------------------------------
import com.google.common.collect.UnmodifiableIterator;
import java.util.NoSuchElementException;
import java.util.concurrent.TimeUnit;
/**
* Iterator for the {@link IterableQueue}. The {@link QueueIterator} should
* only be created from the {@link IterableQueue} by calling the
* {@link IterableQueue#iterator()}.
*
* @author Sebastian Sdorra
*
* @since 1.29
* @param <T> type of the queued items
*/
public final class QueueIterator<T> extends UnmodifiableIterator<T>
{
/**
* Constructs a new {@link QueueIterator} for the given {@link IterableQueue}.
*
*
* @param queue backend queue
*/
QueueIterator(IterableQueue<T> queue)
{
this.queue = queue;
}
//~--- methods --------------------------------------------------------------
/**
* Returns the next item in the queue. This method will block until the next
* item is pushed to the queue, if the queue is empty and the end is not
* reached.
*
* @throws NoSuchElementException if the iteration has no more elements
*
* @return the next item in the queue
*/
@Override
public T next()
{
if ( ! hasNext() ){
throw new NoSuchElementException("no more items in the queue");
}
return queue.get(index++);
}
//~--- get methods ----------------------------------------------------------
/**
* Returns {@code true} {@code true} if the queue has more items.
* This method will block until the next item is pushed to the queue, if the
* queue is empty and the end is not
* reached.
*
*
* @return {@code true} {@code true} if the queue has more items
*/
@Override
public boolean hasNext()
{
boolean result = false;
if (index < queue.size())
{
result = true;
}
else if (!queue.isEndReached())
{
synchronized (queue)
{
try
{
queue.wait(TimeUnit.SECONDS.toMillis(10));
result = index < queue.size();
}
catch (InterruptedException ex)
{
throw new RuntimeException(ex);
}
}
}
return result;
}
//~--- fields ---------------------------------------------------------------
/** queue for the iterator */
private final IterableQueue<T> queue;
/** current index */
private int index = 0;
}

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scm-core/src/main/java/sonia/scm/collect/package-info.java Normal file
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/**
* Copyright (c) 2010, Sebastian Sdorra
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* 3. Neither the name of SCM-Manager; nor the names of its
* contributors may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* http://bitbucket.org/sdorra/scm-manager
*
*/
/** Collection classes for SCM-Manager */
package sonia.scm.collect;