private void NotifyEventThread()
{
while (true)
{
_notifyResetEvent.WaitOne();
lock (this) {
// after a clear, we something get notified
// twice for the same entry
if (_notifying)
{
return;
}
_notifying = true;
}
try {
int oldest_entry = OldestEventLogEntry;
if (_lastEntryWritten < oldest_entry)
{
_lastEntryWritten = oldest_entry;
}
int current_entry = _lastEntryWritten - oldest_entry;
int last_entry = EntryCount + oldest_entry;
for (int i = current_entry; i < (last_entry - 1); i++)
{
EventLogEntry entry = GetEntry(i);
CoreEventLog.OnEntryWritten(entry);
}
_lastEntryWritten = last_entry;
} finally {
lock (this)
_notifying = false;
}
}
}
private void ReadEventLog(int index, byte [] buffer, ref int bytesRead, ref int minBufferNeeded)
{
const int max_retries = 3;
// if the eventlog file changed since the handle was
// obtained, then we need to re-try multiple times
for (int i = 0; i < max_retries; i++)
{
int ret = PInvoke.ReadEventLog(ReadHandle,
ReadFlags.Seek | ReadFlags.ForwardsRead,
index, buffer, buffer.Length, ref bytesRead,
ref minBufferNeeded);
if (ret != 1)
{
int error = Marshal.GetLastWin32Error();
if (i < (max_retries - 1))
{
CoreEventLog.Reset();
}
else
{
throw new Win32Exception(error);
}
}
}
}
public override void Delete(string logName, string machineName)
{
using (RegistryKey eventLogKey = GetEventLogKey(machineName, true)) {
if (eventLogKey == null)
{
throw new InvalidOperationException("The event log key does not exist.");
}
using (RegistryKey logKey = eventLogKey.OpenSubKey(logName, false)) {
if (logKey == null)
{
throw new InvalidOperationException(string.Format(
CultureInfo.InvariantCulture, "Event Log '{0}'"
+ " does not exist on computer '{1}'.", logName,
machineName));
}
// remove all eventlog entries for specified log
CoreEventLog.Clear();
// remove file holding event log entries
string file = (string)logKey.GetValue("File");
if (file != null)
{
try {
File.Delete(file);
} catch (Exception) {
// .NET seems to ignore failures here
}
}
}
eventLogKey.DeleteSubKeyTree(logName);
}
}
public override void EnableNotification()
{
if (file_watcher == null)
{
string logDir = FindLogStore(CoreEventLog.Log);
if (!Directory.Exists(logDir))
{
Directory.CreateDirectory(logDir);
}
file_watcher = new FileSystemWatcher();
file_watcher.Path = logDir;
file_watcher.Created += delegate(object o, FileSystemEventArgs e)
{
lock (this)
{
if (_notifying)
{
return;
}
_notifying = true;
}
// allow for file to be finished writing
Thread.Sleep(100);
// Process every new entry in one notification event.
try
{
while (GetLatestIndex() > last_notification_index)
{
try
{
CoreEventLog.OnEntryWritten(GetEntry(last_notification_index++));
}
catch (Exception ex)
{
// FIXME: find some proper way to output this error
Debug.WriteLine(ex);
}
}
}
finally
{
lock (this)
_notifying = false;
}
};
}
last_notification_index = GetLatestIndex();
file_watcher.EnableRaisingEvents = true;
}
private void NotifyEventThread(ManualResetEvent resetEvent)
{
if (resetEvent == null)
{
return;
}
while (true)
{
try {
resetEvent.WaitOne();
} catch (ObjectDisposedException) {
// Notifications have been disabled and event
// has been closed but not yet nulled. End thread.
break;
}
lock (_eventLock) {
if (resetEvent != _notifyResetEvent)
{
// A new thread has started with another reset event instance
// or DisableNotifications has been called, setting
// _notifyResetEvent to null. In both cases end this thread.
break;
}
if (_readHandle == IntPtr.Zero)
{
break;
}
int oldest_entry = OldestEventLogEntry;
if (_lastEntryWritten < oldest_entry)
{
_lastEntryWritten = oldest_entry;
}
int current_entry = _lastEntryWritten - oldest_entry;
int last_entry = EntryCount + oldest_entry;
for (int i = current_entry; i < (last_entry - 1); i++)
{
EventLogEntry entry = GetEntry(i);
CoreEventLog.OnEntryWritten(entry);
}
_lastEntryWritten = last_entry;
}
}
}
public override void EnableNotification()
{
_notifyResetEvent = new ManualResetEvent(false);
_lastEntryWritten = OldestEventLogEntry + EntryCount;
if (PInvoke.NotifyChangeEventLog(ReadHandle, _notifyResetEvent.Handle) == 0)
{
throw new InvalidOperationException(string.Format(
CultureInfo.InvariantCulture, "Unable to receive notifications"
+ " for log '{0}' on computer '{1}'.", CoreEventLog.GetLogName(),
CoreEventLog.MachineName), new Win32Exception());
}
_notifyThread = new Thread(new ThreadStart(NotifyEventThread));
_notifyThread.IsBackground = true;
_notifyThread.Start();
}
