System.Data.SQLite

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Overview
Comment:Fix potential race condition between SQLiteBase.CloseConnection (via GC) and SQLiteBase.ResetConnection (via pool) when used on the same connection handle object.
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SHA1: 0ed439a5e7c51b6f95bc3e1461ad1f03a4e45304
User & Date: mistachkin 2012-04-30 17:17:26.330
Context
2012-04-30
17:18
Remove superfluous using statement. check-in: b8fb8d4b6a user: mistachkin tags: tkt-996d13cd87
17:17
Fix potential race condition between SQLiteBase.CloseConnection (via GC) and SQLiteBase.ResetConnection (via pool) when used on the same connection handle object. check-in: 0ed439a5e7 user: mistachkin tags: tkt-996d13cd87
16:27
Remove superfluous lock from the static helper methods in the SQLiteBase class. check-in: c593d21c60 user: mistachkin tags: tkt-996d13cd87
Changes
Unified Diff Ignore Whitespace Patch
Changes to System.Data.SQLite/SQLite3.cs.
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    // resources belonging to the previously-registered functions.
    internal override void Close()
    {
      if (_sql != null)
      {
          if (_usePool)
          {
              SQLiteBase.ResetConnection(_sql);
              SQLiteConnectionPool.Add(_fileName, _sql, _poolVersion);

#if DEBUG && !NET_COMPACT_20
              Trace.WriteLine(String.Format("Close (Pool): {0}", _sql));
#endif
          }
          else








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    // resources belonging to the previously-registered functions.
    internal override void Close()
    {
      if (_sql != null)
      {
          if (_usePool)
          {
              SQLiteBase.ResetConnection(_sql, _sql);
              SQLiteConnectionPool.Add(_fileName, _sql, _poolVersion);

#if DEBUG && !NET_COMPACT_20
              Trace.WriteLine(String.Format("Close (Pool): {0}", _sql));
#endif
          }
          else
︙︙
Changes to System.Data.SQLite/SQLiteBase.cs. 
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/********************************************************
 * ADO.NET 2.0 Data Provider for SQLite Version 3.X
 * Written by Robert Simpson (robert@blackcastlesoft.com)
 * 
 * Released to the public domain, use at your own risk!
 ********************************************************/

namespace System.Data.SQLite
{
  using System;


  /// <summary>
  /// This internal class provides the foundation of SQLite support.  It defines all the abstract members needed to implement
  /// a SQLite data provider, and inherits from SQLiteConvert which allows for simple translations of string to and from SQLite.
  /// </summary>
  internal abstract class SQLiteBase : SQLiteConvert, IDisposable
  {











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/********************************************************
 * ADO.NET 2.0 Data Provider for SQLite Version 3.X
 * Written by Robert Simpson (robert@blackcastlesoft.com)
 * 
 * Released to the public domain, use at your own risk!
 ********************************************************/

namespace System.Data.SQLite
{
  using System;
  using System.Threading;

  /// <summary>
  /// This internal class provides the foundation of SQLite support.  It defines all the abstract members needed to implement
  /// a SQLite data provider, and inherits from SQLiteConvert which allows for simple translations of string to and from SQLite.
  /// </summary>
  internal abstract class SQLiteBase : SQLiteConvert, IDisposable
  {
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        int n = UnsafeNativeMethods.sqlite3_finalize_interop(stmt);
#else
        int n = UnsafeNativeMethods.sqlite3_finalize(stmt);
#endif
        if (n > 0) throw new SQLiteException(n, null);
    }

    internal static void CloseConnection(IntPtr db)
    {
        if (db == IntPtr.Zero) return;


#if !SQLITE_STANDARD
        int n = UnsafeNativeMethods.sqlite3_close_interop(db);
#else
        ResetConnection(db);
        int n = UnsafeNativeMethods.sqlite3_close(db);
#endif
        if (n > 0) throw new SQLiteException(n, SQLiteLastError(db));
    }


    internal static void ResetConnection(IntPtr db)
    {
        if (db == IntPtr.Zero) return;


        IntPtr stmt = IntPtr.Zero;
        int n;
        do
        {
            stmt = UnsafeNativeMethods.sqlite3_next_stmt(db, stmt);
            if (stmt != IntPtr.Zero)
            {
#if !SQLITE_STANDARD
                n = UnsafeNativeMethods.sqlite3_reset_interop(stmt);
#else
                n = UnsafeNativeMethods.sqlite3_reset(stmt);
#endif
            }
        } while (stmt != IntPtr.Zero);

        if (IsAutocommit(db) == false) // a transaction is pending on the connection
        {
            n = UnsafeNativeMethods.sqlite3_exec(db, ToUTF8("ROLLBACK"), IntPtr.Zero, IntPtr.Zero, out stmt);
            if (n > 0) throw new SQLiteException(n, SQLiteLastError(db));

        }
    }

    internal static bool IsAutocommit(IntPtr db)
    {
      if (db == IntPtr.Zero) return false;
      return (UnsafeNativeMethods.sqlite3_get_autocommit(db) == 1);








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        int n = UnsafeNativeMethods.sqlite3_finalize_interop(stmt);
#else
        int n = UnsafeNativeMethods.sqlite3_finalize(stmt);
#endif
        if (n > 0) throw new SQLiteException(n, null);
    }

    internal static void CloseConnection(SQLiteConnectionHandle hdl, IntPtr db)
    {
        if ((hdl == null) || (db == IntPtr.Zero)) return;
        lock (hdl)
        {
#if !SQLITE_STANDARD
            int n = UnsafeNativeMethods.sqlite3_close_interop(db);
#else
            ResetConnection(hdl, db);
            int n = UnsafeNativeMethods.sqlite3_close(db);
#endif
            if (n > 0) throw new SQLiteException(n, SQLiteLastError(db));
        }
    }

    internal static void ResetConnection(SQLiteConnectionHandle hdl, IntPtr db)
    {
        if ((hdl == null) || (db == IntPtr.Zero)) return;
        lock (hdl)
        {
            IntPtr stmt = IntPtr.Zero;
            int n;
            do
            {
                stmt = UnsafeNativeMethods.sqlite3_next_stmt(db, stmt);
                if (stmt != IntPtr.Zero)
                {
#if !SQLITE_STANDARD
                    n = UnsafeNativeMethods.sqlite3_reset_interop(stmt);
#else
                n = UnsafeNativeMethods.sqlite3_reset(stmt);
#endif
                }
            } while (stmt != IntPtr.Zero);

            if (IsAutocommit(db) == false) // a transaction is pending on the connection
            {
                n = UnsafeNativeMethods.sqlite3_exec(db, ToUTF8("ROLLBACK"), IntPtr.Zero, IntPtr.Zero, out stmt);
                if (n > 0) throw new SQLiteException(n, SQLiteLastError(db));
            }
        }
    }

    internal static bool IsAutocommit(IntPtr db)
    {
      if (db == IntPtr.Zero) return false;
      return (UnsafeNativeMethods.sqlite3_get_autocommit(db) == 1);
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Changes to System.Data.SQLite/UnsafeNativeMethods.cs.
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      try
      {
#if !PLATFORM_COMPACTFRAMEWORK
        IntPtr localHandle = Interlocked.Exchange(
          ref handle, IntPtr.Zero);

        if (localHandle != IntPtr.Zero)
          SQLiteBase.CloseConnection(localHandle);

#if DEBUG && !NET_COMPACT_20
        try
        {
          Trace.WriteLine(String.Format(
              "CloseConnection: {0}", localHandle));
        }
        catch
        {
        }
#endif
#else
        if (handle != IntPtr.Zero)
        {
          SQLiteBase.CloseConnection(handle);
          SetHandle(IntPtr.Zero);
        }
#endif

#if DEBUG
        return true;
#endif








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      try
      {
#if !PLATFORM_COMPACTFRAMEWORK
        IntPtr localHandle = Interlocked.Exchange(
          ref handle, IntPtr.Zero);

        if (localHandle != IntPtr.Zero)
          SQLiteBase.CloseConnection(this, localHandle);

#if DEBUG && !NET_COMPACT_20
        try
        {
          Trace.WriteLine(String.Format(
              "CloseConnection: {0}", localHandle));
        }
        catch
        {
        }
#endif
#else
        if (handle != IntPtr.Zero)
        {
          SQLiteBase.CloseConnection(this, handle);
          SetHandle(IntPtr.Zero);
        }
#endif

#if DEBUG
        return true;
#endif
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