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using System;
using NGit;
using NGit.Errors;
using NGit.Revwalk;
using NGit.Storage.File;
using NGit.Storage.Pack;
using NGit.Util;
using NGit.Util.IO;
using Sharpen;

namespace NGit.Storage.File
{
	[NUnit.Framework.TestFixture]
	public class ConcurrentRepackTest : RepositoryTestCase
	{
		/// <exception cref="System.Exception"></exception>
		[NUnit.Framework.SetUp]
		public override void SetUp()
		{
			WindowCacheConfig windowCacheConfig = new WindowCacheConfig();
			windowCacheConfig.SetPackedGitOpenFiles(1);
			WindowCache.Reconfigure(windowCacheConfig);
			base.SetUp();
		}

		/// <exception cref="System.Exception"></exception>
		[NUnit.Framework.TearDown]
		public override void TearDown()
		{
			base.TearDown();
			WindowCacheConfig windowCacheConfig = new WindowCacheConfig();
			WindowCache.Reconfigure(windowCacheConfig);
		}

		/// <exception cref="NGit.Errors.IncorrectObjectTypeException"></exception>
		/// <exception cref="System.IO.IOException"></exception>
		[NUnit.Framework.Test]
		public virtual void TestObjectInNewPack()
		{
			// Create a new object in a new pack, and test that it is present.
			//
			Repository eden = CreateBareRepository();
			RevObject o1 = WriteBlob(eden, "o1");
			Pack(eden, o1);
			NUnit.Framework.Assert.AreEqual(o1.Name, Parse(o1).Name);
		}

		/// <exception cref="NGit.Errors.IncorrectObjectTypeException"></exception>
		/// <exception cref="System.IO.IOException"></exception>
		[NUnit.Framework.Test]
		public virtual void TestObjectMovedToNewPack1()
		{
			// Create an object and pack it. Then remove that pack and put the
			// object into a different pack file, with some other object. We
			// still should be able to access the objects.
			//
			Repository eden = CreateBareRepository();
			RevObject o1 = WriteBlob(eden, "o1");
			FilePath[] out1 = Pack(eden, o1);
			NUnit.Framework.Assert.AreEqual(o1.Name, Parse(o1).Name);
			RevObject o2 = WriteBlob(eden, "o2");
			Pack(eden, o2, o1);
			// Force close, and then delete, the old pack.
			//
			WhackCache();
			Delete(out1);
			// Now here is the interesting thing. Will git figure the new
			// object exists in the new pack, and not the old one.
			//
			NUnit.Framework.Assert.AreEqual(o2.Name, Parse(o2).Name);
			NUnit.Framework.Assert.AreEqual(o1.Name, Parse(o1).Name);
		}

		/// <exception cref="NGit.Errors.IncorrectObjectTypeException"></exception>
		/// <exception cref="System.IO.IOException"></exception>
		[NUnit.Framework.Test]
		public virtual void TestObjectMovedWithinPack()
		{
			// Create an object and pack it.
			//
			Repository eden = CreateBareRepository();
			RevObject o1 = WriteBlob(eden, "o1");
			FilePath[] out1 = Pack(eden, o1);
			NUnit.Framework.Assert.AreEqual(o1.Name, Parse(o1).Name);
			// Force close the old pack.
			//
			WhackCache();
			// Now overwrite the old pack in place. This method of creating a
			// different pack under the same file name is partially broken. We
			// should also have a different file name because the list of objects
			// within the pack has been modified.
			//
			RevObject o2 = WriteBlob(eden, "o2");
			PackWriter pw = new PackWriter(eden);
			pw.AddObject(o2);
			pw.AddObject(o1);
			Write(out1, pw);
			pw.Release();
			// Try the old name, then the new name. The old name should cause the
			// pack to reload when it opens and the index and pack mismatch.
			//
			NUnit.Framework.Assert.AreEqual(o1.Name, Parse(o1).Name);
			NUnit.Framework.Assert.AreEqual(o2.Name, Parse(o2).Name);
		}

		/// <exception cref="NGit.Errors.IncorrectObjectTypeException"></exception>
		/// <exception cref="System.IO.IOException"></exception>
		[NUnit.Framework.Test]
		public virtual void TestObjectMovedToNewPack2()
		{
			// Create an object and pack it. Then remove that pack and put the
			// object into a different pack file, with some other object. We
			// still should be able to access the objects.
			//
			Repository eden = CreateBareRepository();
			RevObject o1 = WriteBlob(eden, "o1");
			FilePath[] out1 = Pack(eden, o1);
			NUnit.Framework.Assert.AreEqual(o1.Name, Parse(o1).Name);
			ObjectLoader load1 = db.Open(o1, Constants.OBJ_BLOB);
			NUnit.Framework.Assert.IsNotNull(load1);
			RevObject o2 = WriteBlob(eden, "o2");
			Pack(eden, o2, o1);
			// Force close, and then delete, the old pack.
			//
			WhackCache();
			Delete(out1);
			// Now here is the interesting thing... can the loader we made
			// earlier still resolve the object, even though its underlying
			// pack is gone, but the object still exists.
			//
			ObjectLoader load2 = db.Open(o1, Constants.OBJ_BLOB);
			NUnit.Framework.Assert.IsNotNull(load2);
			NUnit.Framework.Assert.AreNotSame(load1, load2);
			byte[] data2 = load2.GetCachedBytes();
			byte[] data1 = load1.GetCachedBytes();
			NUnit.Framework.Assert.IsNotNull(data2);
			NUnit.Framework.Assert.IsNotNull(data1);
			NUnit.Framework.Assert.AreNotSame(data1, data2);
			// cache should be per-pack, not per object
			NUnit.Framework.Assert.IsTrue(Arrays.Equals(data1, data2));
			NUnit.Framework.Assert.AreEqual(load2.GetType(), load1.GetType());
		}

		private static void WhackCache()
		{
			WindowCacheConfig config = new WindowCacheConfig();
			config.SetPackedGitOpenFiles(1);
			WindowCache.Reconfigure(config);
		}

		/// <exception cref="NGit.Errors.MissingObjectException"></exception>
		/// <exception cref="System.IO.IOException"></exception>
		private RevObject Parse(AnyObjectId id)
		{
			return new RevWalk(db).ParseAny(id);
		}

		/// <exception cref="System.IO.IOException"></exception>
		private FilePath[] Pack(Repository src, params RevObject[] list)
		{
			PackWriter pw = new PackWriter(src);
			foreach (RevObject o in list)
			{
				pw.AddObject(o);
			}
			ObjectId name = pw.ComputeName();
			FilePath packFile = FullPackFileName(name, ".pack");
			FilePath idxFile = FullPackFileName(name, ".idx");
			FilePath[] files = new FilePath[] { packFile, idxFile };
			Write(files, pw);
			pw.Release();
			return files;
		}

		/// <exception cref="System.IO.IOException"></exception>
		private static void Write(FilePath[] files, PackWriter pw)
		{
			long begin = files[0].GetParentFile().LastModified();
			NullProgressMonitor m = NullProgressMonitor.INSTANCE;
			OutputStream @out;
			@out = new SafeBufferedOutputStream(new FileOutputStream(files[0]));
			try
			{
				pw.WritePack(m, m, @out);
			}
			finally
			{
				@out.Close();
			}
			@out = new SafeBufferedOutputStream(new FileOutputStream(files[1]));
			try
			{
				pw.WriteIndex(@out);
			}
			finally
			{
				@out.Close();
			}
			Touch(begin, files[0].GetParentFile());
		}

		/// <exception cref="System.IO.IOException"></exception>
		private static void Delete(FilePath[] list)
		{
			long begin = list[0].GetParentFile().LastModified();
			foreach (FilePath f in list)
			{
				FileUtils.Delete(f);
				NUnit.Framework.Assert.IsFalse(f.Exists(), f + " was removed");
			}
			Touch(begin, list[0].GetParentFile());
		}

		private static void Touch(long begin, FilePath dir)
		{
			while (begin >= dir.LastModified())
			{
				try
				{
					Sharpen.Thread.Sleep(25);
				}
				catch (Exception)
				{
				}
				//
				dir.SetLastModified(Runtime.CurrentTimeMillis());
			}
		}

		private FilePath FullPackFileName(ObjectId name, string suffix)
		{
			FilePath packdir = new FilePath(((ObjectDirectory)db.ObjectDatabase).GetDirectory
				(), "pack");
			return new FilePath(packdir, "pack-" + name.Name + suffix);
		}

		/// <exception cref="System.IO.IOException"></exception>
		private RevObject WriteBlob(Repository repo, string data)
		{
			RevWalk revWalk = new RevWalk(repo);
			byte[] bytes = Constants.Encode(data);
			ObjectInserter inserter = repo.NewObjectInserter();
			ObjectId id;
			try
			{
				id = inserter.Insert(Constants.OBJ_BLOB, bytes);
				inserter.Flush();
			}
			finally
			{
				inserter.Release();
			}
			try
			{
				Parse(id);
				NUnit.Framework.Assert.Fail("Object " + id.Name + " should not exist in test repository"
					);
			}
			catch (MissingObjectException)
			{
			}
			// Ok
			return revWalk.LookupBlob(id);
		}
	}
}