/// <summary>
/// Closes the journal file.
/// </summary>
internal void Close()
{
lock (this) {
if (!is_open) {
throw new IOException("Journal file is already closed.");
}
data.Close();
data = null;
is_open = false;
}
}
/// <summary>
/// Opens the journal for recovery.
/// </summary>
/// <remarks>
/// This scans the journal and generates some statistics about the journal file
/// such as the last check point and the journal number.
/// </remarks>
/// <returns></returns>
/// <exception cref="IOException">
/// If the journal file doesn't exist.
/// </exception>
internal JournalSummary OpenForRecovery()
{
if (is_open) {
throw new IOException("Journal file is already open.");
}
if (!File.Exists(file)) {
throw new IOException("Journal file does not exists.");
}
// Open the random access file to this journal
data = new StreamFile(file, read_only ? FileAccess.Read : FileAccess.ReadWrite);
is_open = true;
// Create the summary object (by default, not recoverable).
JournalSummary summary = new JournalSummary(this);
long end_pointer = data.Length;
// If end_pointer < 8 then can't recovert this journal
if (end_pointer < 8) {
return summary;
}
// The input stream.
BinaryReader din = new BinaryReader(data.FileStream, Encoding.Unicode);
try {
// Set the journal number for this
this.journal_number = din.ReadInt64();
long position = 8;
ArrayList checkpoint_res_list = new ArrayList();
// Start scan
while (true) {
// If we can't Read 12 bytes ahead, return the summary
if (position + 12 > end_pointer) {
return summary;
}
long type = din.ReadInt64();
int size = din.ReadInt32();
// Console.Out.WriteLine("Scan: " + type + " pos=" + position + " size=" + size);
position = position + size + 12;
bool skip_body = true;
// If checkpoint reached then we are recoverable
if (type == 100) {
summary.last_checkpoint = position;
summary.can_be_recovered = true;
// Add the resources input this check point
summary.resource_list.AddRange(checkpoint_res_list);
// And clear the temporary list.
checkpoint_res_list.Clear();
}
// If end reached, or type is not understood then return
else if (position >= end_pointer ||
type < 1 || type > 32) {
return summary;
}
// If we are resource type, then load the resource
if (type == 2) {
// We don't skip body for this type, we Read the content
skip_body = false;
long id = din.ReadInt64();
int str_len = din.ReadInt32();
StringBuilder str = new StringBuilder(str_len);
for (int i = 0; i < str_len; ++i) {
str.Append(din.ReadChar());
}
String resource_name = str.ToString();
checkpoint_res_list.Add(resource_name);
}
if (skip_body)
din.BaseStream.Seek(size, SeekOrigin.Current);
}
} finally {
din.Close();
}
}
public SFFileStream(StreamFile file)
{
this.file = file;
}
/// <summary>
/// Opens the journal file.
/// </summary>
/// <param name="journal_number"></param>
/// <exception cref="IOException">
/// If the journal file exists.
/// </exception>
internal void Open(long journal_number)
{
if (is_open) {
throw new IOException("Journal file is already open.");
}
if (File.Exists(file)) {
throw new IOException("Journal file already exists.");
}
this.journal_number = journal_number;
data = new StreamFile(file, read_only ? FileAccess.Read : FileAccess.ReadWrite);
data_out = new BinaryWriter(new BufferedStream(data.FileStream), Encoding.Unicode);
data_out.Write(journal_number);
is_open = true;
}
public SFFileStream(StreamFile file)
{
this.file = file;
}
