/// <summary>
/// Abandon all the operations of the transaction instead of saving them.
/// </summary>
public void Abort()
{
if (!_released)
{
_released = true;
Txn.Abort(_txnPtr);
}
}
private void loadBtn_Click(object sender, EventArgs e)
{
ClearDisplay();
MemoryStream errStream = new MemoryStream();
MemoryStream msgStream = new MemoryStream();
TextWriter errWriter = new StreamWriter(errStream);
TextWriter msgWriter = new StreamWriter(msgStream);
Db db = null;
Txn txn = null;
Env env = null;
try {
env = new Env(EnvCreateFlags.None);
// configure for error and message reporting
env.ErrorStream = errStream;
env.ErrorPrefix = Path.GetFileName(Application.ExecutablePath);
env.MessageStream = msgStream;
// initialize environment for locking, logging, memory pool and transactions
Env.OpenFlags envFlags =
Env.OpenFlags.Create |
Env.OpenFlags.InitLock |
Env.OpenFlags.InitLog |
Env.OpenFlags.InitMPool |
Env.OpenFlags.InitTxn |
Env.OpenFlags.Recover;
env.Open(homeDir, envFlags, 0);
// create, configure and open database under a transaction
txn = env.TxnBegin(null, Txn.BeginFlags.None);
db = env.CreateDatabase(DbCreateFlags.None);
// set the BTree comparison function
db.BTreeCompare = AppCompare;
// error and message reporting already configured on environment
// db.ErrorStream = errStream;
// db.ErrorPrefix = Path.GetFileName(Application.ExecutablePath);
// db.MessageStream = msgStream;
DbBTree btree = (DbBTree)db.Open(
txn, myDb, null, DbType.BTree, Db.OpenFlags.Create, 0);
txn.Commit(Txn.CommitMode.None);
// create a sequence named '###sequence1' under a transaction
txn = env.TxnBegin(null, Txn.BeginFlags.None);
Sequence seq = btree.CreateSequence();
byte[] seqName = utf8.GetBytes("###sequence1");
DbEntry seqNameEntry = DbEntry.InOut(seqName);
seq.Open(txn, ref seqNameEntry, Sequence.OpenFlags.Create);
seq.Close();
txn.Commit(Txn.CommitMode.None);
// open sequence again, retrieve values and then remove the sequence
seq = btree.CreateSequence();
txn = env.TxnBegin(null, Txn.BeginFlags.None);
// seq.CacheSize = 1000; // cannot use transactions when CacheSize > 0
seq.Open(txn, ref seqNameEntry, Sequence.OpenFlags.None);
Int64 seqVal;
for (int indx = 0; indx < 500; indx++)
{
seqVal = seq.Get(txn, 1, Sequence.ReadFlags.None);
}
seq.Remove(txn, Sequence.RemoveFlags.None);
txn.Commit(Txn.CommitMode.None);
// add a few records under a transaction
Customer cust;
txn = env.TxnBegin(null, Txn.BeginFlags.None);
cust = new Customer("John Doe", "122 Yonge Street", "Toronto", "ON", "M5R 5T9", DateTime.Parse("Dec 22, 1965"));
AddRecord(btree, txn, cust, errWriter);
cust = new Customer("Jane Doby", "23 Bloor Street", "Oshawa", "ON", "L1H 2K9", DateTime.Parse("Jun 1, 1962"));
AddRecord(btree, txn, cust, errWriter);
cust = new Customer("Rusty Nail", "77 Bond Street", "Markham", "ON", "L3T 7Y8", DateTime.Parse("Sep 9, 1915"));
AddRecord(btree, txn, cust, errWriter);
cust = new Customer("Rosy Cheek", "11 Adelaide Street", "Whitby", "ON", "K3P 4H4", DateTime.Parse("Jan 2, 1980"));
AddRecord(btree, txn, cust, errWriter);
// this last one is a duplicate of the first record
cust = new Customer("John Doe", "1459 King Street", "Toronto", "ON", "N8N 2L0", DateTime.Parse("Apr 14, 1973"));
AddRecord(btree, txn, cust, errWriter);
txn.Commit(Txn.CommitMode.None);
msgWriter.WriteLine("==================================================");
msgWriter.WriteLine("K E Y S T A T I S T I C S");
msgWriter.WriteLine("==================================================");
// get a key range, under a transaction
txn = env.TxnBegin(null, Txn.BeginFlags.None);
keyStream.Position = 0;
formatter.Serialize(keyStream, "John Doe");
DbEntry key = DbEntry.InOut(keyStream.GetBuffer(), 0, (int)keyStream.Position);
DbBTree.KeyRange keyRange = btree.GetKeyRange(txn, ref key);
txn.Commit(Txn.CommitMode.None);
msgWriter.WriteLine();
string msg = "KeyRange for 'John Doe': Less = {0}, Equal = {1}, Greater = {2}";
msgWriter.WriteLine(string.Format(msg, keyRange.Less, keyRange.Equal, keyRange.Greater));
msgWriter.WriteLine();
// retrieve some database statistics
TxnStats stats = env.GetTxnStats(StatFlags.None);
DbBTree.Stats btstats = btree.GetStats(null, DbFile.StatFlags.None);
CacheFileStats[] cfStats = env.GetCacheFileStats(StatFlags.None);
// we can also have them written to the message stream
msgWriter.WriteLine("==================================================");
msgWriter.WriteLine("T R A N S A C T I O N S T A T I S T I C S");
msgWriter.WriteLine("==================================================");
msgWriter.WriteLine();
msgWriter.Flush();
env.PrintTxnStats(StatPrintFlags.None);
msgWriter.WriteLine();
msgWriter.WriteLine("==================================================");
msgWriter.WriteLine("L O G S T A T I S T I C S");
msgWriter.WriteLine("==================================================");
msgWriter.WriteLine();
msgWriter.Flush();
env.PrintLogStats(StatPrintFlags.All);
msgWriter.WriteLine();
msgWriter.WriteLine("==================================================");
msgWriter.WriteLine("L O C K S T A T I S T I C S");
msgWriter.WriteLine("==================================================");
msgWriter.WriteLine();
msgWriter.Flush();
env.PrintLogStats(StatPrintFlags.All);
msgWriter.WriteLine();
msgWriter.WriteLine("==================================================");
msgWriter.WriteLine("C A C H E S T A T I S T I C S");
msgWriter.WriteLine("==================================================");
msgWriter.WriteLine();
msgWriter.Flush();
env.PrintCacheStats(CacheStatPrintFlags.All);
msgWriter.WriteLine();
msgWriter.WriteLine("==================================================");
msgWriter.WriteLine("B T R E E S T A T I S T I C S");
msgWriter.WriteLine("==================================================");
msgWriter.WriteLine();
msgWriter.Flush();
btree.PrintStats(DbFile.StatPrintFlags.All);
}
catch (BdbException) {
if (txn != null && !txn.IsDisposed)
{
txn.Abort();
}
// errors are reported through error stream already
return;
}
catch (Exception ex) {
if (txn != null && !txn.IsDisposed)
{
txn.Abort();
}
errWriter.WriteLine(ex.ToString());
return;
}
finally {
if (db != null)
{
db.Close();
}
if (env != null)
{
env.Close();
}
msgWriter.Flush();
string msgText = utf8.GetString(msgStream.GetBuffer());
if (msgText != "")
{
msgBox.Text = msgText;
}
msgWriter.Close();
errWriter.Flush();
string errText = utf8.GetString(errStream.GetBuffer());
if (errText != "")
{
errBox.Text = errText;
tabControl.SelectTab("errorPage");
}
errWriter.Close();
}
}