internal static void CompleteRowUpdate(SystemTransaction transaction, IMutableTable table, TableName tableName, RowId beforeRowid, RowId afterRowid)
{
IIndexSetDataSource[] ids = transaction.GetTableIndexes(tableName);
foreach (IIndexSetDataSource i in ids) {
i.Remove(beforeRowid);
i.Insert(afterRowid);
}
// TODO: check for constraint violations
table.Commit();
}
public void CommitTransaction(SystemTransaction transaction)
{
// If the transaction has had no changes, we return immediately
if (!transaction.HasChanges)
return;
// The transaction we are working on through this commit process,
SystemTransaction workingTransaction;
// If the given transaction is of the same commit version as the current,
// then the working transaction is the given transaction
lock (commitSyncRoot) {
// The list table ids we updated
List<long> modifiedTables = new List<long>();
// If the given transaction is of the same commit version, then the
// working version is the given. If there hasn't been a commit since
// the given transaction was created then no transaction merge is
// necessary.
if (transaction.CommitVersion == currentCommitVersion) {
workingTransaction = transaction;
// We make sure we update the 'modified_tables' list with the set of
// unique tables that were changed
List<long> alteredTableIds = transaction.AlteredTables;
alteredTableIds.Sort();
int sz = alteredTableIds.Count;
long lastTableId = -1;
// This goes through the altered table list provided by the
// transaction and creates a unique set of tables that were
// altered.
for (int i = 0; i < sz; ++i) {
long table_id = alteredTableIds[i];
if (table_id != lastTableId) {
modifiedTables.Add(table_id);
lastTableId = table_id;
}
}
}
// Otherwise we must create a new working transaction
else {
// -----------------
// Transaction MERGE
// -----------------
// This condition occurs when a transaction has been committed after
// the given transaction was created, and we need to move any updates
// from the committing transaction to the latest update.
workingTransaction = new SystemTransaction(this, db.CreateTransaction(), currentCommitVersion, transaction.User.Verified());
// SystemTable merges,
// First of all replay the general database updates as described in
// the journal (table and index creation/drops etc).
TransactionJournal tranJournal = transaction.Journal;
IEnumerator<JournalEntry> i = tranJournal.GetEnumerator();
// The list of tables created in this transaction
List<long> tablesCreated = new List<long>();
while (i.MoveNext()) {
JournalEntry entry = i.Current;
JournalCommandCode command = entry.Code;
long ident = entry.TableId;
// Table commands,
if (command == JournalCommandCode.TableCreate) {
// Copy the created table from the original transaction to the
// working transaction.
// We check the table exists in the transaction. If it doesn't
// it means the table was dropped.
if (transaction.TableExists(ident)) {
// Get the name of the object
TableName tname = transaction.GetObjectName(ident);
if (workingTransaction.TableExists(tname)) {
// Create fails, the table name exists in the current
// transaction
throw new CommitException("CREATE TABLE '" + tname + "' failed: table with name exists in " +
"current transaction");
}
// Otherwise copy the table
workingTransaction.CopyTableFrom(transaction, ident);
tablesCreated.Add(ident);
}
}
// When the table is structurally changed (columns, added/removed,
// etc)
else if (command == JournalCommandCode.TableAlter) {
long tableId = ident;
// If this table was created by this transaction, then we don't
// need to worry, we have the most recent version of the table
// structure.
// Otherwise, the table was altered during the transaction, so
// we need to copy the most recent version if it hasn't changed.
if (!tablesCreated.Contains(tableId)) {
// Check it exists in the current
// If it doesn't it means it was dropped
if (transaction.TableExists(tableId)) {
// Check the table exists
if (!workingTransaction.TableExists(tableId)) {
throw new CommitException("ALTER TABLE '" + transaction.GetObjectName(tableId) +
"' failed: table does not exist in the " + "current transaction");
}
// Check the version of the table we are dropping is the same
// version and exists.
long ver1 = transaction.GetTableVersion(tableId);
long ver2 = workingTransaction.GetTableVersion(tableId);
// If the versions are different, some modification has happened
// to the table so we generate an error
if (ver1 != ver2)
throw new CommitException("ALTER TABLE '" + transaction.GetObjectName(tableId) +
"' failed: Table was modified by a concurrent transaction");
// Okay, we can now copy the table. We drop the existing table
// and copy the new one over.
workingTransaction.DropTable(tableId);
workingTransaction.CopyTableFrom(transaction, tableId);
}
}
} else if (command == JournalCommandCode.TableDrop) {
long table_id = ident;
// Check the table exists
if (!workingTransaction.TableExists(table_id)) {
throw new CommitException("DROP TABLE '" + transaction.GetObjectName(table_id) +
"' failed: Table does not exist in the current transaction");
}
// Check the version of the table we are dropping is the same
// version and exists.
long ver1 = transaction.GetTableVersion(table_id);
long ver2 = workingTransaction.GetTableVersion(table_id);
// If the versions are different, some modification has happened
// to the table so we generate an error
if (ver1 != ver2) {
throw new CommitException("DROP TABLE '" + transaction.GetObjectName(table_id) +
"' failed: Table was modified by a concurrent transaction");
}
// Drop the table
workingTransaction.DropTable(table_id);
}
// Index commands,
else if (command == JournalCommandCode.IndexAdd) {
long indexId = ident;
// The name of the table of the index
TableName indexTname = transaction.GetIndexName(indexId).TableName;
// If the above returns null, it means the index no longer
// exists so we skip
if (indexTname != null) {
// If the table doesn't exist in the working transaction,
if (!workingTransaction.TableExists(indexTname))
throw new CommitException("CREATE INDEX on '" + indexTname +
"' failed: table does not exist in the current transaction");
// Get the table id
long tableId = workingTransaction.GetTableId(indexTname);
// NOTE: This check ensures the index we copy from the transaction
// we are committing is correct and up to date. We should,
// perhaps, rewrite this to rebuild the index if there were
// concurrent modifications to the table.
// If the versions of the table we are creating the index on is
// different then we fail,
long ver1 = transaction.GetTableVersion(tableId);
long ver2 = workingTransaction.GetTableVersion(tableId);
// If the versions are different, some modification has happened
// to the table so we generate an error
if (ver1 != ver2) {
throw new CommitException("CREATE INDEX on '" + indexTname + "' failed: Table was modified by " +
"a concurrent transaction");
}
// Copy the created index,
workingTransaction.CopyIndexFrom(transaction, ident);
}
} else if (command == JournalCommandCode.IndexDelete) {
long indexId = ident;
// Drop the index. This fails if the index doesn't exist in the
// current version. Note that this will succeed if there were
// modifications to the table by a concurrent transaction.
workingTransaction.DropIndex(indexId);
}
// Otherwise unrecognized
else {
throw new ApplicationException("Unknown journal entry: " + command);
}
}
// Now replay the table level operations,
// The list of all tables changed during the lifespan of the
// transaction,
List<long> alteredTableIds = transaction.AlteredTables;
alteredTableIds.Sort();
long lastTableId = -1;
int sz = alteredTableIds.Count;
// For each table id that was altered,
for (int n = 0; n < sz; ++n) {
long tableId = alteredTableIds[n];
if (tableId != lastTableId) {
// The SystemTable object
SystemTable currentTable = workingTransaction.GetTable(tableId);
// If the table no longer exists we ignore the journal and go to
// the next table. We assume the table drop has not broken
// database integrity if we have reached this part.
if (currentTable != null) {
// Add this to the list of tables we updated
modifiedTables.Add(tableId);
// The table name
TableName tableName = currentTable.Name;
// The indexes on this table
SystemIndexSetDataSource[] indexes = workingTransaction.GetTableIndexes(tableName);
// The table from which we are merging in entries,
SystemTable toMerge = transaction.GetTable(tableId);
// Get the journal for this table id,
TransactionJournal journal = toMerge.Journal;
// Replay the operations in the journal,
IEnumerator<JournalEntry> ti = journal.GetEnumerator();
while (ti.MoveNext()) {
JournalEntry entry = ti.Current;
JournalCommandCode command = entry.Code;
RowId ident = entry.RowId;
if (command == JournalCommandCode.RowAdd) {
currentTable.CopyRowIdFrom(toMerge, ident);
// Update the indexes
foreach (IIndexSetDataSource idx in indexes) {
idx.Insert(ident);
}
} else if (command == JournalCommandCode.RowRemove) {
// This will commit exception if the row no longer exists.
currentTable.RemoveRowId(ident);
// Update the indexes
foreach (IIndexSetDataSource idx in indexes) {
idx.Remove(ident);
}
} else if (command == JournalCommandCode.ColumnAdd) {
// Can be ignored, this is handled by a structural change
// entry in the transaction log, and copying the table over
// from the lower version transaction.
} else if (command == JournalCommandCode.ColumnRemove) {
// Can be ignored, this is handled by a structural change
// entry in the transaction log, and copying the table over
// from the lower version transaction.
}
}
}
lastTableId = tableId;
}
}
// We have now successfully replayed all the operations on the working
// transaction. The following artifacts may now be in the database;
// 1) Unique constraints may be violated
// 2) Referential integrity may be violated
// 3) Check constraints need to be checked again if they contain
// nested query functions.
}
// Go through the list of updated tables and increment the commit
// version on each of them
foreach (long modifiedTableId in modifiedTables) {
workingTransaction.IncrementTableVersion(modifiedTableId);
}
// Check any deferred constraints on the working_transaction
// TODO: all the table/index merge functionality here...
try {
// And commit the working transaction
db.CommitTransaction(workingTransaction.State);
// Increment the commit version number
++currentCommitVersion;
} catch (Exception e) {
throw new CommitException("The database state failed to commit the transaction changes: " + e.Message, e);
}
}
}
