Limpeza de assembly não usado

Artigo
05/07/2013

O exemplo AssemblyCleanup contém um procedimento armazenado .NET que limpa os assemblies não usados do banco de dados atual consultando os catálogos de metadados. Seu único parâmetro, visible_assemblies, é usado para especificar se os assemblies visíveis não usados devem ser descartados. Um valor ''false'' significa, por padrão, que somente os assemblies invisíveis não usados serão descartados, caso contrário, todos os assemblies não usados serão descartados. O conjunto de assemblies não usados são aqueles que não têm pontos de entrada definidos (rotinas/tipos e agregações) e não há assemblies usados referenciando-os direta ou indiretamente.

Pré-requisitos

Para criar e executar esse projeto, o seguinte software deve estar instalado:

SQL Server ou SQL Server Express. É possível obter o SQL Server Express gratuitamente no site de Documentação e exemplos do SQL Server Express
O banco de dados AdventureWorks, que está disponível no site do SQL Server Developer
.NET Framework SDK 2.0 ou posterior ou Microsoft Visual Studio 2005 ou posterior. Você pode obter o .NET Framework SDK gratuitamente.
Além disso, as seguintes condições devem ser atendidas:
A instância do SQL Server que você está usando deve ter a integração CLR habilitada.

Para habilitar a integração CLR, execute as etapas a seguir:

Habilitando a integração CLR

Execute os seguintes comandos Transact-SQL:

sp_configure 'clr enabled', 1

RECONFIGURE

Observação
Para habilitar o CLR, é necessário ter a permissão ALTER SETTINGS de nível de servidor, que é mantida implicitamente por membros das funções de servidor fixas sysadmin e serveradmin.

O banco de dados AdventureWorks deve estar instalado na instância do SQL Server que você está usando.
Se não for um administrador da instância do SQL Server que está sendo usada, você deverá solicitar que um administrador lhe conceda a permissão CreateAssembly para concluir a instalação.

Compilando o exemplo

Crie e execute o exemplo seguindo estas instruções:

Abra um prompt de comando do Visual Studio ou do .NET Framework.
Se necessário, crie um diretório para seu exemplo. Para este exemplo, usaremos C:\MySample.
Em c:\MySample, crie AssemblyCleanup.vb (para o exemplo do Visual Basic) ou AssemblyCleanup.cs (para o exemplo do C#) e copie o código de exemplo adequado do Visual Basic ou do C# (a seguir) no arquivo.
Compile o código de exemplo no prompt de linha de comando executando uma das seguintes ações, de acordo com sua opção de linguagem.
- Vbc /reference:C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.Data.dll,C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.dll,C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.Transactions.dll,C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.Xml.dll /target:library AssemblyCleanup.vb
- Csc /reference:C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.Data.dll /reference:C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.dll /reference:C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.XML.dll /target:library AssemblyCleanup.cs
Copie o código de instalação Transact-SQL em um arquivo e salve-o como Install.sql no diretório de exemplo.
Se o exemplo tiver sido instalado em um diretório diferente de C:\MySample\, edite o arquivo Install.sql conforme indicado para apontar para esse local.
Implante o assembly e o procedimento armazenado executando:
- sqlcmd -E -I -i install.sql
Copie o script de comando de teste Transact-SQL em um arquivo e salve-o como test.sql no diretório de exemplo.
Execute o script de teste com o seguinte comando
- sqlcmd -E -I -i test.sql
Copie o script de limpeza Transact-SQL em um arquivo e salve-o como cleanup.sql no diretório de exemplo.
Execute o script com o seguinte comando
- sqlcmd -E -I -i cleanup.sql

Código de exemplo

As listagens de código deste exemplo são as seguintes.

using System;
using System.Text;
using System.Diagnostics;
using System.Data.SqlClient;
using System.Collections.Generic;
using System.Globalization;
using Microsoft.SqlServer.Server;


    /// <summary>
    /// Defines a CLR user defined function CleanupUnusedAssemblies that drops 
    /// all the invisible assemblies with no references.
    /// </summary>
    public sealed class AssemblyCleanup
    {
        private SqlTransaction transaction;

        internal class AssemblySet
        {
            private Dictionary<int, object> m_dictionary;

            /// <summary>
            /// Initialize internal structures
            /// </summary>
            /// <returns></returns>
            public AssemblySet()
            {
                m_dictionary = new Dictionary<int, object>();
            }

            /// <summary>
            /// Adds an assembly id into the current AssemblySet if it is not 
            /// already part of it.
            /// </summary>
            /// <returns></returns>
            public void Add(int assemblyId)
            {
                if (!m_dictionary.ContainsKey(assemblyId))
                {
                    m_dictionary.Add(assemblyId, null);
                }
            }

            /// <summary>
            /// Number of assembly ids stored in this instance
            /// </summary>
            /// <returns></returns>
            public int Count
            {
                get
                {
                    return m_dictionary.Count;
                }
            }

            /// <summary>
            /// Returns the comma-separated list of assembly ids contained in this instance
            /// </summary>
            /// <returns>string value that represents a comma-seperated list 
            /// of assembly ids</returns>
            public string ToCommaSeperatedList()
            {
                StringBuilder sb = new StringBuilder();

                if (m_dictionary.Count > 0)
                {
                    foreach (KeyValuePair<int, object> kv in m_dictionary)
                    {
                        sb.Append(kv.Key);
                        sb.Append(",");
                    }

                    sb.Length--; // remove the trailing comma
                }

                return sb.ToString();
            }
        }

        /// <summary>
        /// Initializes an instance of AssemblyCleanup with a SqlTransaction
        /// </summary>
        /// <returns></returns>
        private AssemblyCleanup(SqlTransaction transaction)
        {
            this.transaction = transaction;
        }

        /// <summary>
        /// Helper function that creates a SqlCommand object as part of the current 
        /// transaction
        /// </summary>
        /// <returns></returns>
        private SqlCommand CreateCommandInTransaction()
        {
            SqlCommand cmd = this.transaction.Connection.CreateCommand();

            cmd.Transaction = this.transaction;

            return cmd;
        }

        /// <summary>
        /// Helper function that constructs an AssemblySet instance using the 
        /// first column of the resultset resulting from the query that was passed in.
        /// </summary>
        /// <param name="query"></param>
        /// <returns></returns>
        private AssemblySet GetAssemblySetFromQuery(string query)
        {
            SqlCommand cmd = CreateCommandInTransaction();

            AssemblySet set = new AssemblySet();

            cmd.CommandText = query;
            using (SqlDataReader rd = cmd.ExecuteReader())
            {
                while (rd.Read())
                {
                    set.Add(rd.GetInt32(0));
                }
            }

            return set;
        }

        /// <summary>
        /// Constructs a DROP ASSEMBLY T-SQL statement using the AssemblySet 
        /// passed in as a parameter.
        /// </summary>
        /// <param name="set"></param>
        /// <returns></returns>
        private void DropAssemblies(AssemblySet unusedAssemblySet)
        {
            if (unusedAssemblySet.Count > 0)
            {
                StringBuilder assemblyNamesToDrop = new StringBuilder();

                // Gather the list of assembly names we will drop later
                SqlCommand cmd = CreateCommandInTransaction();

                cmd.CommandText = String.Format(CultureInfo.InvariantCulture,
                    "SELECT name FROM sys.assemblies WHERE assembly_id IN ({0});",
                    unusedAssemblySet.ToCommaSeperatedList());
                using (SqlDataReader rd = cmd.ExecuteReader())
                {
                    while (rd.Read())
                    {
                        assemblyNamesToDrop.Append("[");
                        assemblyNamesToDrop.Append(rd.GetString(0));
                        assemblyNamesToDrop.Append("],");
                    }
                }

                // Remove trailing comma
                assemblyNamesToDrop.Length--;

                // Drop all assemblies at the same time
                cmd.CommandText = String.Format(CultureInfo.InvariantCulture,
                    "DROP ASSEMBLY {0}", assemblyNamesToDrop.ToString());
                cmd.ExecuteNonQuery();
            }
        }

        /// <summary>
        /// Serves as the stored procedure entry point and drives the process 
        /// of expanding the "assemblies in use" set, negating it, and 
        /// dropping the results
        /// </summary>
        /// <param name="visibleAssemblies">If set to true, will also drop 
        /// unused visible assemblies. Otherwise, will only drop unused invisible 
        /// assemblies.</param>
        /// <returns></returns>
        [Microsoft.SqlServer.Server.SqlProcedure()]
        public static void CleanupUnusedAssemblies(bool visibleAssemblies)
        {
            bool succeeded = false;
            SqlConnection conn;
            SqlTransaction transaction;
            string sqlStatement;
            AssemblySet assembliesToDrop;
            AssemblyCleanup assemblyCleanup;

            conn = new SqlConnection("context connection=true");
            conn.Open();
            transaction = conn.BeginTransaction();

            try
            {
                // Create a set of assemblies in use by looking at 
                // the metadata of the current database
                sqlStatement =
                    "DECLARE @UsedAssembly TABLE (AssemblyID int NOT NULL); " +
                    "DECLARE @RowCount int; " +
                    "INSERT INTO @UsedAssembly " +
                    "SELECT DISTINCT([assembly_id]) " +
                    "FROM sys.assembly_modules " +
                    "UNION " +
                    "SELECT [assembly_id] " +
                    "FROM sys.assembly_types; " +
                    "SET @RowCount = @@ROWCOUNT; " +
                    "WHILE @RowCount > 0 " +
                    "BEGIN " +
                    "INSERT INTO @UsedAssembly " +
                    "SELECT [referenced_assembly_id] " +
                    "FROM sys.assembly_references ar " +
                    "INNER JOIN @UsedAssembly ua " +
                    "ON ar.[assembly_id] = ua.AssemblyID " +
                    "WHERE NOT EXISTS (SELECT * FROM @UsedAssembly WHERE AssemblyID = [referenced_assembly_id]) " +
                    "SET @RowCount = @@ROWCOUNT; " +
                    "END;";

                if (visibleAssemblies)
                {
                    sqlStatement +=
                        "SELECT assembly_id " +
                        "FROM sys.assemblies " +
                        "WHERE assembly_id NOT IN (SELECT AssemblyID FROM @UsedAssembly);";
                }
                else
                {
                    sqlStatement +=
                        "SELECT assembly_id " +
                        "FROM sys.assemblies " +
                        "WHERE assembly_id NOT IN (SELECT AssemblyID FROM @UsedAssembly) " +
                        "    AND is_visible = 0;";
                }

                // This marks the beginning of the transaction
                assemblyCleanup = new AssemblyCleanup(transaction);

                // Assemblies that are currently in use
                assembliesToDrop
                    = assemblyCleanup.GetAssemblySetFromQuery(sqlStatement);

                assemblyCleanup.DropAssemblies(assembliesToDrop);

                // Mark as succeeded
                succeeded = true;
            }
            finally
            {
                // We must guarantee that we explicitly call either Commit() 
                // or Rollback() before we return.
                if (succeeded)
                {
                    transaction.Commit();
                }
                else
                {
                    transaction.Rollback();
                }
                conn.Dispose();
            }
        }
    }

Visual Basic

Imports Microsoft.SqlServer.Server
Imports Microsoft.VisualBasic
Imports System
Imports System.Collections
Imports System.Collections.Generic
Imports System.Data
Imports System.Data.SqlClient
Imports System.Diagnostics
Imports System.Globalization
Imports System.Text
Imports System.Transactions
Public NotInheritable Class AssemblyCleanup
    Private transaction As SqlTransaction

    Friend Class AssemblySet
        Private m_dictionary As Dictionary(Of Integer, Object)

        ''' <summary>
        ''' Initialize internal structures
        ''' </summary>
        ''' <returns></returns>
        Public Sub New()
            m_dictionary = New Dictionary(Of Integer, Object)
        End Sub

        ''' <summary>
        ''' Adds an assembly id into the current AssemblySet if it is not already part of it.
        ''' </summary>
        ''' <returns></returns>
        Public Sub Add(ByVal assemblyId As Integer)
            If Not m_dictionary.ContainsKey(assemblyId) Then
                m_dictionary.Add(assemblyId, Nothing)
            End If
        End Sub

        ''' <summary>
        ''' Number of assembly ids stored in this instance
        ''' </summary>
        ''' <returns></returns>
        Public ReadOnly Property Count() As Integer
            Get
                Return m_dictionary.Count
            End Get
        End Property

        ''' <summary>
        ''' Returns the comma-separated list of assembly ids contained in this instance
        ''' </summary>
        ''' <returns>string value that represents a comma-seperated list of assembly ids</returns>
        Public Function ToCommaSeperatedList() As String
            Dim sb As New StringBuilder()

            If m_dictionary.Count > 0 Then
                For Each kv As KeyValuePair(Of Integer, Object) In m_dictionary
                    If (True) Then
                        sb.Append(kv.Key)
                        sb.Append(",")
                    End If
                Next

                sb.Length -= 1 ' remove the trailing comma
            End If

            Return sb.ToString()

        End Function
    End Class

    ''' <summary>
    ''' Initializes an instance of AssemblyCleanup with a SqlTransaction
    ''' </summary>
    ''' <returns></returns>
    Private Sub New(ByVal trans As SqlTransaction)
        Me.transaction = trans
    End Sub

    ''' <summary>
    ''' Helper function that creates a SqlCommand object as part of the 
    ''' current transaction
    ''' </summary>
    ''' <returns></returns>
    Private Function CreateCommandInTransaction() As SqlCommand
        Dim cmd As SqlCommand = transaction.Connection.CreateCommand()

        cmd.Transaction = Me.transaction

        Return cmd
    End Function

    ''' <summary>
    ''' Helper function that constructs an AssemblySet instance using the 
    ''' first column of the resultset resulting from the query that was passed in.
    ''' </summary>
    ''' <param name="query"></param>
    ''' <returns></returns>
    Private Function GetAssemblySetFromQuery(ByVal query As String) As AssemblySet
        Dim cmd As SqlCommand = CreateCommandInTransaction()
        Dim [set] As New AssemblySet()

        cmd.CommandText = query
        Dim rd As SqlDataReader = cmd.ExecuteReader()
        Try
            While rd.Read()
                [set].Add(rd.GetInt32(0))
            End While
        Finally
            rd.Dispose()
        End Try

        Return [set]
    End Function

    ''' <summary>
    ''' Constructs a DROP ASSEMBLY T-SQL statement using the AssemblySet 
    ''' passed in as a parameter.
    ''' </summary>
    ''' <param name="set"></param>
    ''' <returns></returns>
    Private Sub DropAssemblies(ByVal unusedAssemblySet As AssemblySet)
        If unusedAssemblySet.Count > 0 Then
            Dim assemblyNamesToDrop As New StringBuilder()

            ' Gather the list of assembly names we will drop later
            Dim cmd As SqlCommand = CreateCommandInTransaction()


            cmd.CommandText = String.Format(CultureInfo.InvariantCulture, _
                "SELECT name FROM sys.assemblies WHERE assembly_id IN ({0});", _
                unusedAssemblySet.ToCommaSeperatedList())
            Dim rd As SqlDataReader = cmd.ExecuteReader()
            Try
                While rd.Read()
                    assemblyNamesToDrop.Append("[")
                    assemblyNamesToDrop.Append(rd.GetString(0))
                    assemblyNamesToDrop.Append("],")
                End While
            Finally
                rd.Dispose()
            End Try

            ' Remove trailing comma
            assemblyNamesToDrop.Length -= 1

            ' Drop all assemblies at the same time
            cmd.CommandText = String.Format(CultureInfo.InvariantCulture, _
                "DROP ASSEMBLY {0}", assemblyNamesToDrop.ToString())
            cmd.ExecuteNonQuery()
        End If
    End Sub

    ''' <summary>
    ''' Serves as the stored procedure entry point and drives the process of 
    ''' expanding the "assemblies in use" set, negating it, and dropping 
    ''' the results.
    ''' </summary>
    ''' <param name="visibleAssemblies">If set to true, will also drop unused 
    ''' visible assemblies. Otherwise, will only drop unused invisible assemblies.</param>
    ''' <returns></returns>
    <Microsoft.SqlServer.Server.SqlProcedure()> _
    Public Shared Sub CleanupUnusedAssemblies(ByVal visibleAssemblies As Boolean)

        Dim succeeded As Boolean = False
        Dim conn As SqlConnection
        Dim transaction As SqlTransaction
        Dim sqlStatement As String
        Dim assembliesToDrop As AssemblySet
        Dim assemblyCleanup As AssemblyCleanup

        conn = New SqlConnection("context connection=true")
        conn.Open()
        transaction = conn.BeginTransaction()

        Try
            ' Create a set of assemblies in use by looking at 
            ' the metadata of the current database
            sqlStatement = "DECLARE @UsedAssembly TABLE (AssemblyID int NOT NULL); " & _
                "DECLARE @RowCount int; " & _
                "INSERT INTO @UsedAssembly " & _
                "SELECT DISTINCT([assembly_id]) " & _
                "FROM sys.assembly_modules " & _
                "UNION " & _
                "SELECT [assembly_id] " & _
                "FROM sys.assembly_types; " & _
                "SET @RowCount = @@ROWCOUNT; " & _
                "WHILE @RowCount > 0 " & _
                "BEGIN " & _
                "INSERT INTO @UsedAssembly " & _
                "SELECT [referenced_assembly_id] " & _
                "FROM sys.assembly_references ar " & _
                "INNER JOIN @UsedAssembly ua " & _
                "ON ar.[assembly_id] = ua.AssemblyID " & _
                "WHERE NOT EXISTS (SELECT * FROM @UsedAssembly WHERE AssemblyID = [referenced_assembly_id]) " & _
                "SET @RowCount = @@ROWCOUNT; " & _
                "END;"

            If visibleAssemblies Then
                sqlStatement += "SELECT assembly_id " & _
                    "FROM sys.assemblies " & _
                    "WHERE assembly_id NOT IN (SELECT AssemblyID FROM @UsedAssembly);"
            Else
                sqlStatement += "SELECT assembly_id " & _
                    "FROM sys.assemblies " & _
                    "WHERE assembly_id NOT IN (SELECT AssemblyID FROM @UsedAssembly) " & _
                    "    AND is_visible = 0;"
            End If

            ' This marks the beginning of the transaction
            assemblyCleanup = New AssemblyCleanup(transaction)

            ' Assemblies that are currently in use
            assembliesToDrop _
                = assemblyCleanup.GetAssemblySetFromQuery(sqlStatement)

            assemblyCleanup.DropAssemblies(assembliesToDrop)

            ' Mark as succeeded
            succeeded = True
        Finally
            ' We must guarantee that we explicitly call either Commit() 
            ' or Rollback() before we return.
            If succeeded Then
                transaction.Commit()
            Else
                transaction.Rollback()
            End If
            conn.Dispose()
        End Try
    End Sub
End Class

Esse é o script de instalação Transact-SQL (Install.sql) que implanta o assembly e cria o procedimento armazenado no banco de dados.

USE AdventureWorks;
GO
IF EXISTS (SELECT * FROM sys.objects WHERE name = N'CleanupUnusedAssemblies')
DROP PROCEDURE CleanupUnusedAssemblies;
GO

IF EXISTS (SELECT * FROM sys.assemblies WHERE name = N'AssemblyCleanupUtils') 
DROP ASSEMBLY AssemblyCleanupUtils;
GO
DECLARE @SamplesPath nvarchar(1024)

-- You may need to modify the value of the this variable if you have installed the sample someplace other than the default location.
Set @SamplesPath = 'C:\MySample\'

CREATE ASSEMBLY AssemblyCleanupUtils 
FROM @SamplesPath + 'AssemblyCleanup.dll' 
WITH permission_set = Safe;
GO

CREATE PROCEDURE CleanupUnusedAssemblies (
@visible_assemblies bit
) AS
EXTERNAL NAME [AssemblyCleanupUtils].[AssemblyCleanup].CleanupUnusedAssemblies;
GO

Esse é o test.sql, que testa o exemplo por meio da execução do procedimento armazenado.

USE AdventureWorks;
GO

PRINT 'Before cleanup...'
SELECT [name] FROM sys.assemblies;
GO

-- pass in false, which means the cleanup will only include invisible assemblies
EXEC dbo.CleanupUnusedAssemblies false;
GO

PRINT 'After cleanup'
SELECT [name] FROM sys.assemblies;

O Transact-SQL a seguir remove o assembly e o procedimento armazenado do banco de dados.

USE AdventureWorks;
GO

IF EXISTS (SELECT * FROM sys.objects WHERE name = N'CleanupUnusedAssemblies')
DROP PROCEDURE CleanupUnusedAssemblies;
GO

IF EXISTS (SELECT * FROM sys.assemblies WHERE name = N'AssemblyCleanupUtils') 
DROP ASSEMBLY AssemblyCleanupUtils;
GO

Consulte também

Conceitos

Cenários de uso e exemplos para a integração de CLR (Common Language Runtime)

Compartilhar via