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//------------------------------------------------------------------------------
// <copyright file="EntityClientCacheKey.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//
// @owner Microsoft
// @backupOwner Microsoft
//------------------------------------------------------------------------------
namespace System.Data.Common.QueryCache
{
using System;
using System.Collections.Generic;
using System.Data.Common.Internal;
using System.Data.EntityClient;
using System.Data.Metadata.Edm;
using System.Diagnostics;
using System.Globalization;
using System.Text;
/// <summary>
/// Represents EntityCommand Cache key context
/// </summary>
internal sealed class EntityClientCacheKey : QueryCacheKey
{
/// <summary>
/// Stored procedure or command text?
/// </summary>
readonly CommandType _commandType;
/// <summary>
/// Entity Sql statement
/// </summary>
readonly string _eSqlStatement;
/// <summary>
/// parameter collection token
/// </summary>
readonly string _parametersToken;
/// <summary>
/// number of parameters
/// </summary>
readonly int _parameterCount;
/// <summary>
/// Combined Hashcode based on field hashcodes
/// </summary>
readonly int _hashCode;
/// <summary>
/// Creates a new instance of EntityClientCacheKey given a entityCommand instance
/// </summary>
/// <param name="entityCommand"></param>
internal EntityClientCacheKey(EntityCommand entityCommand)
: base()
{
// Command Type
_commandType = entityCommand.CommandType;
// Statement
_eSqlStatement = entityCommand.CommandText;
// Parameters
_parametersToken = GetParametersToken(entityCommand);
_parameterCount = entityCommand.Parameters.Count;
// Hashcode
_hashCode = _commandType.GetHashCode() ^
_eSqlStatement.GetHashCode() ^
_parametersToken.GetHashCode();
}
/// <summary>
/// determines equality of two cache keys based on cache context values
/// </summary>
/// <param name="otherObject"></param>
/// <returns></returns>
public override bool Equals( object otherObject )
{
Debug.Assert(null != otherObject, "otherObject must not be null");
if (typeof(EntityClientCacheKey) != otherObject.GetType())
{
return false;
}
EntityClientCacheKey otherEntityClientCacheKey = (EntityClientCacheKey)otherObject;
return (_commandType == otherEntityClientCacheKey._commandType &&
_parameterCount == otherEntityClientCacheKey._parameterCount) &&
Equals(otherEntityClientCacheKey._eSqlStatement, _eSqlStatement) &&
Equals(otherEntityClientCacheKey._parametersToken, _parametersToken);
}
/// <summary>
/// Returns Context Hash Code
/// </summary>
/// <returns></returns>
public override int GetHashCode()
{
return _hashCode;
}
private static string GetTypeUsageToken(TypeUsage type)
{
string result = null;
// Dev10#537010: EntityCommand false positive cache hits caused by insufficient parameter type information in cache key
// Ensure String types are correctly differentiated.
if (object.ReferenceEquals(type, DbTypeMap.AnsiString))
{
result = "AnsiString";
}
else if (object.ReferenceEquals(type, DbTypeMap.AnsiStringFixedLength))
{
result = "AnsiStringFixedLength";
}
else if (object.ReferenceEquals(type, DbTypeMap.String))
{
result = "String";
}
else if (object.ReferenceEquals(type, DbTypeMap.StringFixedLength))
{
result = "StringFixedLength";
}
else if (object.ReferenceEquals(type, DbTypeMap.Xml))
{
// Xml is currently mapped to (unicode, variable-length) string, so the TypeUsage
// given to the provider is actually a String TypeUsage.
Debug.Assert(TypeSemantics.IsPrimitiveType(type, PrimitiveTypeKind.String), "Update GetTypeUsageToken to return 'Xml' for Xml parameters");
result = "String";
}
else if (TypeSemantics.IsEnumerationType(type))
{
result = type.EdmType.FullName;
}
else
{
// String/Xml TypeUsages are the only DbType-derived TypeUsages that carry meaningful facets.
// Otherwise, the primitive type name is a sufficient token (note that full name is not required
// since model types always have the 'Edm' namespace).
Debug.Assert(TypeSemantics.IsPrimitiveType(type), "EntityParameter TypeUsage not a primitive type?");
Debug.Assert(!TypeSemantics.IsPrimitiveType(type, PrimitiveTypeKind.String), "String TypeUsage not derived from DbType.AnsiString, AnsiString, String, StringFixedLength or Xml?");
result = type.EdmType.Name;
}
return result;
}
/// <summary>
/// Returns a string representation of the parameter list
/// </summary>
/// <param name="entityCommand"></param>
/// <returns></returns>
private static string GetParametersToken(EntityCommand entityCommand)
{
if (null == entityCommand.Parameters || 0 == entityCommand.Parameters.Count)
{
//
// means no parameters
//
return "@@0";
}
// Ensure that parameter DbTypes are valid and there are no duplicate names
Dictionary<string, TypeUsage> paramTypeUsage = entityCommand.GetParameterTypeUsage();
Debug.Assert(paramTypeUsage.Count == entityCommand.Parameters.Count, "entityParameter collection and query parameter collection must have the same number of entries");
if (1 == paramTypeUsage.Count)
{
// if its one parameter only, there is no need to use stringbuilder
return "@@1:" +
entityCommand.Parameters[0].ParameterName + ":" +
GetTypeUsageToken(paramTypeUsage[entityCommand.Parameters[0].ParameterName]);
}
else
{
StringBuilder sb = new StringBuilder(entityCommand.Parameters.Count * EstimatedParameterStringSize);
Debug.Assert(paramTypeUsage.Count == entityCommand.Parameters.Count, "entityParameter collection and query parameter collection must have the same number of entries");
sb.Append("@@");
sb.Append(entityCommand.Parameters.Count);
sb.Append(":");
string separator = "";
foreach (KeyValuePair<string, TypeUsage> param in paramTypeUsage)
{
sb.Append(separator);
sb.Append(param.Key);
sb.Append(":");
sb.Append(GetTypeUsageToken(param.Value));
separator = ";";
}
return sb.ToString();
}
}
/// <summary>
/// returns the composed cache key
/// </summary>
/// <returns></returns>
public override string ToString()
{
return String.Join("|", new string[] { Enum.GetName(typeof(CommandType), _commandType), _eSqlStatement, _parametersToken });
}
}
}
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