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This code is derived from jgit (http://eclipse.org/jgit).
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Copyright owners are documented in jgit's IP log.
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This program and the accompanying materials are made available
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under the terms of the Eclipse Distribution License v1.0 which
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accompanies this distribution, is reproduced below, and is
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available at http://www.eclipse.org/org/documents/edl-v10.php
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Redistribution and use in source and binary forms, with or
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without modification, are permitted provided that the following
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- Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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- Redistributions in binary form must reproduce the above
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copyright notice, this list of conditions and the following
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disclaimer in the documentation and/or other materials provided
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with the distribution.
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- Neither the name of the Eclipse Foundation, Inc. nor the
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names of its contributors may be used to endorse or promote
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products derived from this software without specific prior
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
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CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
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INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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using NGit.Storage.Pack;
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namespace NGit.Storage.Pack
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internal class DeltaCache
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private readonly long size;
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private readonly int entryLimit;
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private readonly ReferenceQueue<byte[]> queue;
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internal DeltaCache(PackConfig pc)
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size = pc.GetDeltaCacheSize();
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entryLimit = pc.GetDeltaCacheLimit();
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queue = new ReferenceQueue<byte[]>();
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internal virtual bool CanCache(int length, ObjectToPack src, ObjectToPack res)
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// If the cache would overflow, don't store.
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if (0 < size && size < used + length)
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CheckForGarbageCollectedObjects();
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if (0 < size && size < used + length)
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if (length < entryLimit)
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// If the combined source files are multiple megabytes but the delta
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// is on the order of a kilobyte or two, this was likely costly to
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// construct. Cache it anyway, even though its over the limit.
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if (length >> 10 < (src.GetWeight() >> 20) + (res.GetWeight() >> 21))
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internal virtual void Credit(int reservedSize)
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internal virtual DeltaCache.Ref Cache(byte[] data, int actLen, int reservedSize)
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// The caller may have had to allocate more space than is
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// required. If we are about to waste anything, shrink it.
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data = Resize(data, actLen);
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// When we reserved space for this item we did it for the
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// inflated size of the delta, but we were just given the
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// compressed version. Adjust the cache cost to match.
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if (reservedSize != data.Length)
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used -= reservedSize;
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return new DeltaCache.Ref(data, queue);
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internal virtual byte[] Resize(byte[] data, int actLen)
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if (data.Length != actLen)
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byte[] nbuf = new byte[actLen];
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System.Array.Copy(data, 0, nbuf, 0, actLen);
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private void CheckForGarbageCollectedObjects()
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while ((r = (DeltaCache.Ref)queue.Poll()) != null)
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internal class Ref : SoftReference<byte[]>
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internal readonly int cost;
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internal Ref(byte[] array, ReferenceQueue<byte[]> queue) : base(array, queue)