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Sridhar Nanjundeswaran
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CSHARP-714 : AscendingGuidGenerator and tests
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‎MongoDB.Bson/MongoDB.Bson.csproj‎

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<Compile Include="Serialization\CreatorMapDelegateCompiler.cs" />
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<Compile Include="Serialization\ExpressionVisitor.cs" />
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<Compile Include="Serialization\ICreatorSelector.cs" />
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<Compile Include="Serialization\IdGenerators\AscendingGuidGenerator.cs" />
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<Compile Include="Serialization\IdGenerators\BsonBinaryDataGuidGenerator.cs" />
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<Compile Include="Serialization\IdGenerators\BsonObjectIdGenerator.cs" />
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<Compile Include="Serialization\IdGenerators\CombGuidGenerator.cs" />

‎MongoDB.Bson/Serialization/IdGenerators/AscendingGuidGenerator.cs‎

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/* Copyright 2010-2013 10gen Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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using System;
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using System.Diagnostics;
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using System.Runtime.CompilerServices;
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using System.Security;
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using System.Security.Cryptography;
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using System.Text;
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using System.Threading;
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namespace MongoDB.Bson.Serialization.IdGenerators
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{
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/// <summary>
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/// A GUID generator that generates GUIDs in ascending order. To enable
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/// an index to make use of the ascending nature make sure to use
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/// <see cref="GuidRepresentation.Standard">GuidRepresentation.Standard</see>
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/// as the storage representation.
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/// Internally the GUID is of the form
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/// 8 bytes: Ticks from DateTime.UtcNow.Ticks
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/// 3 bytes: hash of machine name
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/// 2 bytes: low order bytes of process Id
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/// 3 bytes: increment
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/// </summary>
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public class AscendingGuidGenerator : IIdGenerator
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{
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// private static fields
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private static readonly AscendingGuidGenerator __instance = new AscendingGuidGenerator();
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private static readonly byte[] __machineProcessId;
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private static int __increment;
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// static constructor
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static AscendingGuidGenerator()
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{
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var machineHash = GetMachineHash();
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short processId;
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try
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{
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// use low order two bytes only
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processId = (short)GetCurrentProcessId();
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}
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catch (SecurityException)
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{
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processId = 0;
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}
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__machineProcessId = new byte[5]
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{
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machineHash[0],
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machineHash[1],
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machineHash[2],
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(byte)(processId >> 8),
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(byte)(processId)
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};
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}
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// public static properties
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/// <summary>
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/// Gets an instance of AscendingGuidGenerator.
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/// </summary>
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public static AscendingGuidGenerator Instance
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{
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get { return __instance; }
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}
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// public methods
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/// <summary>
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/// Generates an ascending Guid for a document. Consecutive invocations
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/// should generate Guids that are ascending from a MongoDB perspective
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/// </summary>
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/// <param name="container">The container of the document (will be a
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/// MongoCollection when called from the driver). </param>
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/// <param name="document">The document it was generated for.</param>
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/// <returns>A Guid.</returns>
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public object GenerateId(object container, object document)
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{
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var increment = Interlocked.Increment(ref __increment) & 0x00ffffff;
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return GenerateId(DateTime.UtcNow.Ticks, __machineProcessId, increment);
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}
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/// <summary>
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/// Generates a Guid for a document. Note - this is purely used for
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/// unit testing
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/// </summary>
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/// <param name="tickCount">The time portion of the Guid</param>
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/// <param name="machineProcessId">A 5 byte array with the first 3 bytes
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/// representing a machine id and the next 2 representing a process
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/// id</param>
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/// <param name="increment">The increment portion of the Guid. Used
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/// to distinguish between 2 Guids that have the timestamp. Note
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/// only the least significant 3 bytes are used.</param>
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/// <returns>A Guid.</returns>
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public object GenerateId(
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long tickCount,
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byte[] machineProcessId,
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int increment)
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{
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var a = (int)(tickCount >> 32);
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var b = (short)(tickCount >> 16);
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var c = (short)(tickCount);
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var d = new byte[8];
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Array.Copy(machineProcessId, d, 5);
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d[5] = (byte)(increment >> 16);
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d[6] = (byte)(increment >> 8);
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d[7] = (byte)(increment);
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return new Guid (a, b, c, d);
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}
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/// <summary>
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/// Tests whether an id is empty.
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/// </summary>
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/// <param name="id">The id to test.</param>
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/// <returns>True if the Id is empty. False otherwise</returns>
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public bool IsEmpty(object id)
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{
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return id == null || (Guid)id == Guid.Empty;
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}
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// private static methods
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/// <summary>
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/// Gets the current process id. This method exists because of how
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/// CAS operates on the call stack, checking for permissions before
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/// executing the method. Hence, if we inlined this call, the calling
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/// method would not execute before throwing an exception requiring the
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/// try/catch at an even higher level that we don't necessarily control.
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/// </summary>
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[MethodImpl(MethodImplOptions.NoInlining)]
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private static int GetCurrentProcessId()
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{
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return Process.GetCurrentProcess().Id;
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}
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private static byte[] GetMachineHash()
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{
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// use instead of Dns.HostName so it will work offline
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var hostName = Environment.MachineName;
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var sha1 = SHA1.Create();
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return sha1.ComputeHash(Encoding.UTF8.GetBytes(hostName));
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}
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}
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}

‎MongoDB.BsonUnitTests/MongoDB.BsonUnitTests.csproj‎

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<Compile Include="Serialization\Conventions\PropertyFinderConventionsTests.cs" />
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<Compile Include="Serialization\Conventions\ReadWriteMemberFinderConventionsTests.cs" />
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<Compile Include="Serialization\Conventions\StringObjectIdGeneratorConventionsTests.cs" />
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<Compile Include="Serialization\IdGenerators\AscendingGuidGeneratorTests.cs" />
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<Compile Include="Serialization\LegacyBsonClassMapTests.cs" />
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<Compile Include="Serialization\Serializers\ExtraElementsTests.cs" />
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<Compile Include="Serialization\Options\RepresentationSerializationOptionsTests.cs" />

‎MongoDB.BsonUnitTests/Serialization/IdGenerators/AscendingGuidGeneratorTests.cs‎

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/* Copyright 2010-2013 10gen Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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using System;
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using System.Linq;
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using MongoDB.Bson.Serialization.IdGenerators;
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using NUnit.Framework;
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namespace MongoDB.BsonUnitTests.Serialization
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{
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[TestFixture]
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public class AscendingGuidGeneratorTests
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{
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private AscendingGuidGenerator _generator = new AscendingGuidGenerator();
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[Test]
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public void TestIsEmpty()
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{
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Assert.IsTrue(_generator.IsEmpty(null));
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Assert.IsTrue(_generator.IsEmpty(Guid.Empty));
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var guid = _generator.GenerateId(null, null);
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Assert.IsFalse(_generator.IsEmpty(guid));
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}
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[Test]
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public void TestGuid()
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{
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var expectedTicks = DateTime.Now.Ticks;
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var expectedIncrement = 1000;
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var expectedMachineProcessId = new byte[] { 1, 32, 64, 128, 255 };
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var guid = (Guid)_generator.GenerateId(expectedTicks, expectedMachineProcessId, expectedIncrement);
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var bytes = guid.ToByteArray();
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var actualTicks = GetTicks(bytes);
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var actualMachineProcessId = GetMachineProcessId(bytes);
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var actualIncrement = GetIncrement(bytes);
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Assert.AreEqual(expectedTicks, actualTicks);
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Assert.IsTrue(expectedMachineProcessId.SequenceEqual(actualMachineProcessId));
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Assert.AreEqual(expectedIncrement, actualIncrement);
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}
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[Test]
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public void TestGuidWithSpecifiedTicks()
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{
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var expectedTicks = 0x8000L;
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var expectedIncrement = 32;
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var expectedMachineProcessId = new byte[] { 1, 32, 64, 128, 255 };
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var guid = (Guid)_generator.GenerateId(expectedTicks, expectedMachineProcessId, expectedIncrement);
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var bytes = guid.ToByteArray();
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var actualTicks = GetTicks(bytes);
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var actualMachineProcessId = GetMachineProcessId(bytes);
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var actualIncrement = GetIncrement(bytes);
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Assert.AreEqual(expectedTicks, actualTicks);
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Assert.IsTrue(expectedMachineProcessId.SequenceEqual(actualMachineProcessId));
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Assert.AreEqual(expectedIncrement, actualIncrement);
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}
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private long GetTicks(byte[] bytes)
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{
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var a = (ulong)BitConverter.ToUInt32(bytes, 0);
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var b = (ulong)BitConverter.ToUInt16(bytes, 4);
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var c = (ulong)BitConverter.ToUInt16(bytes, 6);
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return (long)((a << 32) | (b << 16) | c);
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}
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private byte[] GetMachineProcessId(byte[] bytes)
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{
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var result = new byte[5];
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Array.Copy(bytes, 8, result, 0, 5);
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return result;
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}
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private int GetIncrement(byte[] bytes)
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{
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var increment = (bytes[13] << 16) + (bytes[14] << 8) + bytes[15];
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return increment;
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}
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}
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}

‎MongoDB.DriverUnitTests/Jira/CSharp714Tests.cs‎

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/* Copyright 2010-2013 10gen Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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using System;
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using MongoDB.Bson;
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using MongoDB.Bson.Serialization;
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using MongoDB.Bson.Serialization.IdGenerators;
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using MongoDB.Driver;
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using MongoDB.Driver.Builders;
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using NUnit.Framework;
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namespace MongoDB.DriverUnitTests.Jira.CSharp714
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{
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[TestFixture]
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public class CSharp714Tests
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{
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public class C
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{
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public int Id { get; set; }
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public Guid Guid { get; set; }
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}
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private MongoServer _server;
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private MongoDatabase _database;
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private MongoCollection<C> _collection;
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private IIdGenerator _generator = new AscendingGuidGenerator();
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private static int __maxNoOfDocuments = 100;
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[TestFixtureSetUp]
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public void TestFixtureSetup()
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{
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_server = Configuration.TestServer;
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_database = Configuration.TestDatabase;
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var collectionSettings = new MongoCollectionSettings() { GuidRepresentation = GuidRepresentation.Standard };
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_collection = _database.GetCollection<C>("csharp714", collectionSettings);
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_collection.Drop();
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}
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[Test]
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public void TestGuidsAreAscending()
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{
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_collection.RemoveAll();
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CreateTestData();
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// sort descending just so we are not retrieving in insertion order
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var cursor = _collection.FindAll().SetSortOrder(SortBy.Descending("Guid"));
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var id = __maxNoOfDocuments - 1;
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foreach (var c in cursor)
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{
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Assert.AreEqual(id--, c.Id);
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}
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}
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private void CreateTestData()
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{
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for (var i=0; i<__maxNoOfDocuments; i++)
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{
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_collection.Insert(new C { Id = i, Guid = (Guid)_generator.GenerateId(null, null) });
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}
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_collection.CreateIndex("Guid");
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}
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}
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}

‎MongoDB.DriverUnitTests/MongoDB.DriverUnitTests.csproj‎

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<Compile Include="GeoJsonObjectModel\GeoJsonPolygonTests.cs" />
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<Compile Include="Jira\CSharp542Tests.cs" />
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<Compile Include="Jira\CSharp653Tests.cs" />
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<Compile Include="Jira\CSharp714Tests.cs" />
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<Compile Include="MongoClientSettingsTests.cs" />
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<Compile Include="ReadPreferenceTests.cs" />
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<Compile Include="MongoCollectionSettingsTests.cs" />

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