/// <summary>
/// Performs undo or redo
/// </summary>
/// <param name="storeSnapshot"></param>
/// <param name="isUndo"></param>
/// <returns></returns>
private int Revert(StoreSnapshot storeSnapshot, TransactionType transactionType)
{
Debug.Assert(transactionType == TransactionType.Undo || transactionType == TransactionType.Redo);
int originalVersion = storeSnapshot.Version;
int transactionToRevert = 0;
try {
transactionToRevert = this.StartTransaction(storeSnapshot, transactionType);
if (0 < transactionToRevert)
{
foreach (ISnapTable snapTable in this.Tables)
{
snapTable.Revert(transactionToRevert);
}
return(this.Commit(withOmit: false));
}
} catch {
if (0 < transactionToRevert && storeSnapshot.IsEditor)
{
this.Rollback();
}
throw;
}
return(originalVersion);
}
/// <summary>
///Commits current transaction. Optionally if <paramref name="withOmit"/> set to true erases transaction from undo history
/// </summary>
/// <param name="withOmit"></param>
/// <returns></returns>
public int Commit(bool withOmit)
{
this.ValidateModification();
int v = this.Version;
RuntimeHelpers.PrepareConstrainedRegions();
try {} finally {
if (withOmit)
{
ValueList <TransactionType> .Address address = this.version.ItemAddress(this.version.Count - 1);
Debug.Assert(address.Page[address.Index] == TransactionType.Edit, "Only edit transactions can be omitted");
address.Page[address.Index] = TransactionType.Omit;
}
this.CompletedVersion = v;
this.editorThread = null;
this.editor = null;
LockFreeSync.WriteBarrier();
}
EventHandler handler = this.Committed;
if (handler != null)
{
handler(this, EventArgs.Empty);
}
return(v);
}
public ChangeEnumerator(StoreSnapshot store, int oldVersion, int newVersion)
{
Debug.Assert(0 < oldVersion && oldVersion <= newVersion && newVersion <= store.SnapStore.CompletedVersion);
this.enumerator = store.Tables.GetEnumerator();
this.oldVersion = oldVersion;
this.newVersion = newVersion;
}
/// <summary>
/// Constructs the table
/// </summary>
/// <param name="store"></param>
/// <param name="name"></param>
/// <param name="fields"></param>
public TableSnapshot(StoreSnapshot store, string name, params IField <TRecord>[] fields)
{
if (fields == null)
{
throw new ArgumentNullException(nameof(fields));
}
this.StoreSnapshot = store ?? throw new ArgumentNullException(nameof(store));
this.table = new SnapTable <TRecord>(store.SnapStore, name, 0, fields, true);
this.StoreSnapshot.Add(this, this.table);
}
public StoreSnapshot(StoreSnapshot store) : this(store.SnapStore.CheckFrozen())
{
foreach (ISnapTable snapTable in this.SnapStore.Tables)
{
if (snapTable.IsUserTable)
{
this.primaryKeyHolder.Add((IPrimaryKeyHolder)snapTable.CreateTableSnapshot(this));
}
}
}
/// <summary>
/// Starts new transaction. If successful then returns:
/// - number of the started transaction if it is Edit transaction
/// - number of transaction to revert if it is Undo/Redo transaction
/// If transaction was not started then returns 0.
/// </summary>
/// <param name="newEditor">StoreSnapshot that owns the transaction</param>
/// <param name="transactionType">Edit, Undo or Redo transaction</param>
/// <returns></returns>
private int StartTransaction(StoreSnapshot newEditor, TransactionType transactionType)
{
if (newEditor == null)
{
throw new ArgumentNullException("newEditor");
}
Debug.Assert(transactionType == TransactionType.Edit || transactionType == TransactionType.Undo || transactionType == TransactionType.Redo, "Wrong transaction type");
this.CheckFrozen();
int transaction = 0;
// any value of oldEditor other then null means this thread does not own the transaction
// null means this thread is exclusive owner of transaction
StoreSnapshot oldEditor = newEditor;
bool success = false;
RuntimeHelpers.PrepareConstrainedRegions();
try {
RuntimeHelpers.PrepareConstrainedRegions();
try {} finally {
oldEditor = Interlocked.CompareExchange <StoreSnapshot>(ref this.editor, newEditor, null);
}
if (oldEditor == null)
{
Debug.Assert(this.editor == newEditor, "Expecting to be current editor");
Debug.Assert(this.editorThread == null, "Editor thread should be null here");
if (this.version.Count == int.MaxValue)
{
throw new InvalidOperationException(Properties.Resources.ErrorTooManyTransactions);
}
this.editorThread = Thread.CurrentThread;
transaction = (transactionType == TransactionType.Edit) ? this.version.Count + 1 : this.RevertVersion(transactionType);
if (0 < transaction)
{
this.version.PrepareAdd();
success = true;
}
}
} finally {
if (success)
{
this.version.FixedAdd(ref transactionType);
}
else if (oldEditor == null)
{
Debug.Assert(this.editor == newEditor, "newEditor expected to be current editor");
this.editorThread = null; // this should be the first assignment
this.editor = null;
}
}
return(transaction);
}
/// <summary>
/// Reverts current transaction
/// </summary>
public void Rollback()
{
this.ValidateModification();
RuntimeHelpers.PrepareConstrainedRegions();
try { } finally {
foreach (ISnapTable snapTable in this.Tables)
{
snapTable.Rollback();
}
ValueList <TransactionType> .Address address = this.version.ItemAddress(this.version.Count - 1);
address.Page[address.Index] = TransactionType.Omit;
this.CompletedVersion = this.Version;
this.editorThread = null;
this.editor = null;
LockFreeSync.WriteBarrier();
}
}
/// <summary>
/// Copy constructor
/// </summary>
/// <param name="storeSnapshot"></param>
/// <param name="table"></param>
internal TableSnapshot(StoreSnapshot storeSnapshot, SnapTable <TRecord> table)
{
this.StoreSnapshot = storeSnapshot;
this.table = table;
this.StoreSnapshot.Add(this, this.table);
}
/// <summary>
/// Create TableSnapshot base on the TRecord.
/// </summary>
/// <param name="storeSnapshot"></param>
/// <returns></returns>
public ITableSnapshot CreateTableSnapshot(StoreSnapshot storeSnapshot)
{
Debug.Assert(this.IsUserTable);
return(new TableSnapshot <TRecord>(storeSnapshot, this));
}
/// <summary>
/// Starts new transaction, performs redo and commits.
/// If transaction was started successfully return new version of the store, otherwise return version of editor.
/// </summary>
/// <param name="storeSnapshot"></param>
/// <returns></returns>
public int Redo(StoreSnapshot storeSnapshot)
{
return(this.Revert(storeSnapshot, TransactionType.Redo));
}
/// <summary>
/// Starts new transaction
/// </summary>
/// <param name="storeSnapshot">Owner of the transaction</param>
/// <returns>true if the transaction started, false if other transaction is in progress</returns>
public bool StartTransaction(StoreSnapshot storeSnapshot)
{
return(0 < this.StartTransaction(storeSnapshot, TransactionType.Edit));
}