109 lines
4.5 KiB
C#
109 lines
4.5 KiB
C#
//------------------------------------------------------------------------------
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// <copyright file="DbConnectionPoolAuthenticationContext.cs" company="Microsoft">
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// Copyright (c) Microsoft Corporation. All rights reserved.
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// </copyright>
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// <owner current="true" primary="true">harsudan</owner>
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// <owner current="true" primary="false">yuronhe</owner>
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//------------------------------------------------------------------------------
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using System;
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using System.Diagnostics;
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using System.Runtime.ConstrainedExecution;
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using System.Threading;
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namespace System.Data.ProviderBase
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{
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/// <summary>
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/// Represents the context of an authentication attempt when using the new active directory based authentication mechanisms.
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/// All data members, except_isUpdateInProgressCounter, should be immutable.
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/// </summary>
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sealed internal class DbConnectionPoolAuthenticationContext
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{
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/// <summary>
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/// The value expected in _isUpdateInProgress if a thread has taken a lock on this context,
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/// to perform the update on the context.
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/// </summary>
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private const int STATUS_LOCKED = 1;
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/// <summary>
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/// The value expected in _isUpdateInProgress if no thread has taken a lock on this context.
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/// </summary>
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private const int STATUS_UNLOCKED = 0;
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/// <summary>
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/// Access Token, which is obtained from Active Directory Authentication Library for SQL Server, and needs to be sent to SQL Server
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/// as part of TDS Token type Federated Authentication Token.
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/// </summary>
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private readonly byte[] _accessToken;
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/// <summary>
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/// Expiration time of the above access token.
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/// </summary>
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private readonly DateTime _expirationTime;
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/// <summary>
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/// A member which is used to achieve a lock to control refresh attempt on this context.
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/// </summary>
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private int _isUpdateInProgress;
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/// <summary>
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/// Constructor.
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/// </summary>
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/// <param name="accessToken">Access Token that will be used to connect to SQL Server. Carries identity information about a user.</param>
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/// <param name="expirationTime">The expiration time in UTC for the above accessToken.</param>
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internal DbConnectionPoolAuthenticationContext(byte[] accessToken, DateTime expirationTime) {
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Debug.Assert(accessToken != null && accessToken.Length > 0);
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Debug.Assert(expirationTime > DateTime.MinValue && expirationTime < DateTime.MaxValue);
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_accessToken = accessToken;
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_expirationTime = expirationTime;
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_isUpdateInProgress = STATUS_UNLOCKED;
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}
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/// <summary>
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/// Static Method.
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/// Given two contexts, choose one to update in the cache. Chooses based on expiration time.
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/// </summary>
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/// <param name="context1">Context1</param>
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/// <param name="context2">Context2</param>
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internal static DbConnectionPoolAuthenticationContext ChooseAuthenticationContextToUpdate(DbConnectionPoolAuthenticationContext context1, DbConnectionPoolAuthenticationContext context2) {
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Debug.Assert(context1 != null, "context1 should not be null.");
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Debug.Assert(context2 != null, "context2 should not be null.");
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return context1.ExpirationTime > context2.ExpirationTime ? context1 : context2;
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}
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internal byte[] AccessToken {
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get {
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return _accessToken;
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}
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}
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internal DateTime ExpirationTime {
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get {
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return _expirationTime;
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}
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}
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/// <summary>
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/// Try locking the variable _isUpdateInProgressCounter and return if this thread got the lock to update.
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/// Whichever thread got the chance to update this variable to 1 wins the lock.
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/// </summary>
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internal bool LockToUpdate() {
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int oldValue = Interlocked.CompareExchange(ref _isUpdateInProgress, STATUS_LOCKED, STATUS_UNLOCKED);
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return (oldValue == STATUS_UNLOCKED);
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}
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/// <summary>
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/// Release the lock which was obtained through LockToUpdate.
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/// </summary>
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[ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
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internal void ReleaseLockToUpdate() {
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int oldValue = Interlocked.CompareExchange(ref _isUpdateInProgress, STATUS_UNLOCKED, STATUS_LOCKED);
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Debug.Assert(oldValue == STATUS_LOCKED);
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}
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}
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}
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