mirror of
https://github.com/MichaelGrafnetter/DSInternals
synced 2024-12-13 18:06:24 +00:00
528 lines
18 KiB
C#
Vendored
528 lines
18 KiB
C#
Vendored
// ---------------------------------------------------------------------------
|
|
// <copyright file="Session.cs" company="Microsoft">
|
|
// Copyright (c) Microsoft Corporation. All rights reserved.
|
|
// </copyright>
|
|
// ---------------------------------------------------------------------------
|
|
|
|
// ---------------------------------------------------------------------
|
|
// <summary>
|
|
// </summary>
|
|
// ---------------------------------------------------------------------
|
|
|
|
namespace Microsoft.Database.Isam
|
|
{
|
|
using System;
|
|
|
|
using Microsoft.Isam.Esent.Interop;
|
|
|
|
/// <summary>
|
|
/// A Session is the transactional context for the ISAM. It can be used to
|
|
/// begin, commit, or abort transactions that influence when changes made
|
|
/// to databases are kept or discarded.
|
|
/// <para>
|
|
/// The session object currently also controls which databases can be
|
|
/// accessed by the ISAM.
|
|
/// </para>
|
|
/// </summary>
|
|
public class IsamSession : IDisposable
|
|
{
|
|
/// <summary>
|
|
/// The instance
|
|
/// </summary>
|
|
private readonly IsamInstance isamInstance;
|
|
|
|
/// <summary>
|
|
/// The sesid
|
|
/// </summary>
|
|
private readonly JET_SESID sesid;
|
|
|
|
/// <summary>
|
|
/// The cleanup
|
|
/// </summary>
|
|
private bool cleanup = false;
|
|
|
|
/// <summary>
|
|
/// The disposed
|
|
/// </summary>
|
|
private bool disposed = false;
|
|
|
|
/// <summary>
|
|
/// The temporary database
|
|
/// </summary>
|
|
private TemporaryDatabase temporaryDatabase = null;
|
|
|
|
/// <summary>
|
|
/// The transaction level
|
|
/// </summary>
|
|
private long transactionLevel = 0;
|
|
|
|
/// <summary>
|
|
/// The transaction level identifier
|
|
/// </summary>
|
|
private long[] transactionLevelID = null;
|
|
|
|
/// <summary>
|
|
/// Initializes a new instance of the <see cref="IsamSession"/> class.
|
|
/// </summary>
|
|
/// <param name="isamInstance">The instance.</param>
|
|
internal IsamSession(IsamInstance isamInstance)
|
|
{
|
|
lock (isamInstance)
|
|
{
|
|
this.isamInstance = isamInstance;
|
|
Api.JetBeginSession(isamInstance.Inst, out this.sesid, null, null);
|
|
this.cleanup = true;
|
|
this.transactionLevelID = new long[7]; // JET only supports 7 levels
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Finalizes an instance of the IsamSession class.
|
|
/// </summary>
|
|
~IsamSession()
|
|
{
|
|
this.Dispose(false);
|
|
}
|
|
|
|
/// <summary>
|
|
/// Gets the instance that created this session.
|
|
/// </summary>
|
|
public IsamInstance IsamInstance
|
|
{
|
|
get
|
|
{
|
|
return this.isamInstance;
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Gets the ID of the session's current transaction.
|
|
/// </summary>
|
|
/// <remarks>
|
|
/// The transaction ID is incremented every time the session's current
|
|
/// transaction save point (level) reaches zero such that the session
|
|
/// is no longer considered to be in a transaction.
|
|
/// </remarks>
|
|
public long TransactionID
|
|
{
|
|
get
|
|
{
|
|
this.CheckDisposed();
|
|
return this.transactionLevelID[0];
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Gets the save point (level) of the session's current transaction.
|
|
/// </summary>
|
|
/// <remarks>
|
|
/// Every time a new transaction is begun, the save point (level) of
|
|
/// the session's current transaction is increased. Every time a
|
|
/// transaction is successfully committed or aborted, the save point
|
|
/// (level) of the session's current transaction is decreased. If the
|
|
/// save point (level) of the session's current transaction is zero
|
|
/// then the session is not considered to be in a transaction.
|
|
/// However, individual operations performed using the session will
|
|
/// still be in a transaction.
|
|
/// </remarks>
|
|
public long TransactionLevel
|
|
{
|
|
get
|
|
{
|
|
this.CheckDisposed();
|
|
return this.transactionLevel;
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Gets the sesid.
|
|
/// </summary>
|
|
/// <value>
|
|
/// The sesid.
|
|
/// </value>
|
|
internal JET_SESID Sesid
|
|
{
|
|
get
|
|
{
|
|
return this.sesid;
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Gets or sets a value indicating whether [disposed].
|
|
/// </summary>
|
|
/// <value>
|
|
/// <c>true</c> if [disposed]; otherwise, <c>false</c>.
|
|
/// </value>
|
|
internal bool Disposed
|
|
{
|
|
get
|
|
{
|
|
return this.disposed || this.isamInstance.Disposed;
|
|
}
|
|
|
|
set
|
|
{
|
|
this.disposed = value;
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
|
|
/// </summary>
|
|
public void Dispose()
|
|
{
|
|
lock (this)
|
|
{
|
|
this.Dispose(true);
|
|
}
|
|
|
|
GC.SuppressFinalize(this);
|
|
}
|
|
|
|
/// <summary>
|
|
/// Creates a new database at the specified location
|
|
/// </summary>
|
|
/// <param name="databaseName">The file name (relative or absolute) at which the database will be created</param>
|
|
/// <remarks>
|
|
/// The new database will automatically be attached to the instance.
|
|
/// See Session.AttachDatabase for more information.
|
|
/// </remarks>
|
|
public void CreateDatabase(string databaseName)
|
|
{
|
|
lock (this)
|
|
{
|
|
this.CheckDisposed();
|
|
|
|
JET_DBID dbid;
|
|
Api.JetCreateDatabase(this.Sesid, databaseName, null, out dbid, CreateDatabaseGrbit.None);
|
|
Api.JetCloseDatabase(this.Sesid, dbid, CloseDatabaseGrbit.None);
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Attaches an existing database at the specified location
|
|
/// </summary>
|
|
/// <param name="databaseName">The file name (relative or absolute) at which the database will be attached</param>
|
|
/// <remarks>
|
|
/// Attaching a database to the instance enables that database to be
|
|
/// opened for access. When a database is attached, its file is
|
|
/// opened and so must be available to be locked as required. The
|
|
/// file will be held open until the database is detached or until the
|
|
/// instance is disposed.
|
|
/// </remarks>
|
|
public void AttachDatabase(string databaseName)
|
|
{
|
|
lock (this)
|
|
{
|
|
this.CheckDisposed();
|
|
|
|
AttachDatabaseGrbit grbit = AttachDatabaseGrbit.None;
|
|
|
|
if (this.isamInstance.ReadOnly)
|
|
{
|
|
grbit |= AttachDatabaseGrbit.ReadOnly;
|
|
}
|
|
|
|
Api.JetAttachDatabase(this.Sesid, databaseName, grbit);
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Detaches an attached database at the specified location
|
|
/// </summary>
|
|
/// <param name="databaseName">The file name (relative or absolute) at which the database will be detached</param>
|
|
/// <remarks>
|
|
/// Detaching a database from the instance will close its file and
|
|
/// will make it no longer possible to open that database.
|
|
/// </remarks>
|
|
public void DetachDatabase(string databaseName)
|
|
{
|
|
lock (this)
|
|
{
|
|
this.CheckDisposed();
|
|
|
|
Api.JetDetachDatabase(this.Sesid, databaseName);
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Determines if there is a database at the specified location
|
|
/// </summary>
|
|
/// <param name="databaseName">The file name (relative or absolute) at which the database may exist</param>
|
|
/// <returns>true if the database exists and is a valid database file, false otherwise</returns>
|
|
public bool Exists(string databaseName)
|
|
{
|
|
lock (this)
|
|
{
|
|
this.CheckDisposed();
|
|
|
|
try
|
|
{
|
|
AttachDatabaseGrbit grbit = AttachDatabaseGrbit.None;
|
|
|
|
if (this.isamInstance.ReadOnly)
|
|
{
|
|
grbit |= AttachDatabaseGrbit.ReadOnly;
|
|
}
|
|
|
|
Api.JetAttachDatabase(this.Sesid, databaseName, grbit);
|
|
|
|
try
|
|
{
|
|
Api.JetDetachDatabase(this.Sesid, databaseName);
|
|
}
|
|
catch (EsentDatabaseInUseException)
|
|
{
|
|
}
|
|
|
|
return true;
|
|
}
|
|
catch (EsentFileNotFoundException)
|
|
{
|
|
return false;
|
|
}
|
|
catch (EsentDatabaseInvalidPathException)
|
|
{
|
|
return false;
|
|
}
|
|
catch (EsentErrorException)
|
|
{
|
|
return true;
|
|
}
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Opens the database.
|
|
/// </summary>
|
|
/// <param name="databaseName">The file name (relative or absolute) at which the database will be opened</param>
|
|
/// <returns>
|
|
/// a Database object representing the database for this session
|
|
/// </returns>
|
|
/// <remarks>
|
|
/// A database must first be attached (or created) before it can be
|
|
/// opened successfully.
|
|
/// </remarks>
|
|
public IsamDatabase OpenDatabase(string databaseName)
|
|
{
|
|
lock (this)
|
|
{
|
|
this.CheckDisposed();
|
|
|
|
return new IsamDatabase(this, databaseName);
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Opens the temporary database.
|
|
/// </summary>
|
|
/// <returns>
|
|
/// A TemporaryDatabase object representing the temporary database for this session
|
|
/// </returns>
|
|
/// <remarks>
|
|
/// Only one temporary database is supported per instance.
|
|
/// </remarks>
|
|
public TemporaryDatabase OpenTemporaryDatabase()
|
|
{
|
|
lock (this)
|
|
{
|
|
this.CheckDisposed();
|
|
|
|
if (this.temporaryDatabase == null)
|
|
{
|
|
this.temporaryDatabase = new TemporaryDatabase(this);
|
|
}
|
|
|
|
return this.temporaryDatabase;
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Begins a new save point (level) for the current transaction on this
|
|
/// session. Any changes made to the database for this save point
|
|
/// (level) may later be kept or discarded by committing or aborting the
|
|
/// save point (level).
|
|
/// </summary>
|
|
/// <remarks>
|
|
/// Currently, there is a limit to how many save points (levels) are
|
|
/// supported by the ISAM. Approximately seven save points (levels)
|
|
/// are supported. Some ISAM functions also use some of these so the
|
|
/// effective limit will vary with circumstance.
|
|
/// </remarks>
|
|
public void BeginTransaction()
|
|
{
|
|
lock (this)
|
|
{
|
|
this.CheckDisposed();
|
|
|
|
Api.JetBeginTransaction(this.Sesid);
|
|
this.transactionLevel++;
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Commits the current save point (level) of the current transaction
|
|
/// on this session. All changes made to the database for this save
|
|
/// point (level) will be kept.
|
|
/// </summary>
|
|
/// <remarks>
|
|
/// <para>
|
|
/// It is illegal to call this method when the session is not currently
|
|
/// in a transaction. Use Session.TransactionLevel to determine the
|
|
/// current transaction state of a session.
|
|
/// </para>
|
|
/// <para>
|
|
/// Changes made to the database will become permanent if and only if
|
|
/// those changes are committed to save point (level) zero.
|
|
/// </para>
|
|
/// <para>
|
|
/// A commit to save point (level) zero is guaranteed to be persisted
|
|
/// to the database upon completion of this method.
|
|
/// </para>
|
|
/// </remarks>
|
|
public void CommitTransaction()
|
|
{
|
|
this.CommitTransaction(true);
|
|
}
|
|
|
|
/// <summary>
|
|
/// Commits the current save point (level) of the current transaction
|
|
/// on this session. All changes made to the database for this save
|
|
/// point (level) will be kept.
|
|
/// </summary>
|
|
/// <param name="durableCommit">
|
|
/// When true, a commit to save point (level) zero is guaranteed to be
|
|
/// persisted to the database upon completion of this method.
|
|
/// </param>
|
|
/// <remarks>
|
|
/// <para>
|
|
/// It is illegal to call this method when the session is not currently
|
|
/// in a transaction. Use Session.TransactionLevel to determine the
|
|
/// current transaction state of a session.
|
|
/// </para>
|
|
/// <para>
|
|
/// A commit to save point (level) zero is guaranteed to be persisted
|
|
/// to the database upon completion of this method only if
|
|
/// durableCommit is true. If durableCommit is false then the changes
|
|
/// will only be persisted to the database if their transaction log
|
|
/// entries happen to be written to disk before a crash or if the
|
|
/// database is shut down cleanly.
|
|
/// </para>
|
|
/// </remarks>
|
|
public void CommitTransaction(bool durableCommit)
|
|
{
|
|
lock (this)
|
|
{
|
|
this.CheckDisposed();
|
|
|
|
CommitTransactionGrbit grbit = CommitTransactionGrbit.None;
|
|
if (!durableCommit)
|
|
{
|
|
grbit |= CommitTransactionGrbit.LazyFlush;
|
|
}
|
|
|
|
Api.JetCommitTransaction(this.Sesid, grbit);
|
|
this.transactionLevelID[--this.transactionLevel]++;
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Aborts the current save point (level) of the current transaction on
|
|
/// this session. All changes made to the database for this save point
|
|
/// (level) will be discarded.
|
|
/// </summary>
|
|
/// <remarks>
|
|
/// It is illegal to call this method when the session is not currently
|
|
/// in a transaction. Use Session.TransactionLevel to determine the
|
|
/// current transaction state of a session.
|
|
/// </remarks>
|
|
public void RollbackTransaction()
|
|
{
|
|
lock (this)
|
|
{
|
|
this.CheckDisposed();
|
|
|
|
Api.JetRollback(this.Sesid, RollbackTransactionGrbit.None);
|
|
this.transactionLevelID[--this.transactionLevel]++;
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Aborts the current save point (level) of the current transaction on
|
|
/// this session. All changes made to the database for this save point
|
|
/// (level) will be discarded.
|
|
/// </summary>
|
|
/// <remarks>
|
|
/// It is illegal to call this method when the session is not currently
|
|
/// in a transaction. Use Session.TransactionLevel to determine the
|
|
/// current transaction state of a session.
|
|
/// <para>
|
|
/// Session.AbortTransaction is an alias for
|
|
/// <see cref="IsamSession.RollbackTransaction"/>.
|
|
/// </para>
|
|
/// </remarks>
|
|
public void AbortTransaction()
|
|
{
|
|
this.RollbackTransaction();
|
|
}
|
|
|
|
/// <summary>
|
|
/// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
|
|
/// </summary>
|
|
void IDisposable.Dispose()
|
|
{
|
|
this.Dispose();
|
|
}
|
|
|
|
/// <summary>Gets the Transaction ID at the specifed Transaction Level.
|
|
/// </summary>
|
|
/// <param name="level">The Transaction Level.</param>
|
|
/// <returns>The Transaction ID at the specifed Transaction Level.</returns>
|
|
internal long TransactionLevelID(long level)
|
|
{
|
|
return this.transactionLevelID[level - 1];
|
|
}
|
|
|
|
/// <summary>
|
|
/// Releases unmanaged and - optionally - managed resources.
|
|
/// </summary>
|
|
/// <param name="disposing"><c>true</c> to release both managed and unmanaged resources; <c>false</c> to release only unmanaged resources.</param>
|
|
protected virtual void Dispose(bool disposing)
|
|
{
|
|
lock (this)
|
|
{
|
|
if (!this.Disposed)
|
|
{
|
|
if (this.cleanup)
|
|
{
|
|
if (this.temporaryDatabase != null)
|
|
{
|
|
this.temporaryDatabase.Dispose();
|
|
}
|
|
|
|
Api.JetEndSession(this.sesid, EndSessionGrbit.None);
|
|
this.cleanup = false;
|
|
}
|
|
|
|
this.Disposed = true;
|
|
}
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Checks whether this object is disposed.
|
|
/// </summary>
|
|
/// <exception cref="System.ObjectDisposedException">If the object has already been disposed.</exception>
|
|
private void CheckDisposed()
|
|
{
|
|
lock (this)
|
|
{
|
|
if (this.Disposed)
|
|
{
|
|
throw new ObjectDisposedException(this.GetType().Name);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
} |