/// <summary>
/// Reads the next complete log item from the file.
/// </summary>
/// <returns>The next log item in the file.</returns>
/// <remarks>
/// This method will block until a complete log item is available in the file.
/// </remarks>
public FieldLogItem ReadLogItem()
{
byte[] bytes;
FieldLogItemType type;
int pos = -1, length;
try
{
do
{
// Remember the log item start position in the file
pos = (int)fileStream.Position;
bool localWaitMode = WaitMode;
if (!localWaitMode && pos == fileStream.Length)
{
return(null);
}
// Read the item type and length
bytes = ReadBytes(4);
if (bytes == null)
{
if (closeEvent.WaitOne(0))
{
// Close was requested
isClosing = true;
WaitMode = false;
return(null);
}
if (!WaitMode && localWaitMode)
{
// Follow-up file has been noticed
return(null);
}
if (!localWaitMode)
{
throw new EndOfStreamException("Unexpected end of file.");
}
}
// Parse type and length data
type = (FieldLogItemType)((bytes[0] & 0xF0) >> 4);
bytes[0] = (byte)(bytes[0] & 0x0F);
if (BitConverter.IsLittleEndian)
{
Array.Reverse(bytes);
}
length = BitConverter.ToInt32(bytes, 0);
// Check whether this is a text item
if (type == FieldLogItemType.StringData)
{
// Read the item and add it to the text cache
byte[] stringBytes = ReadBytes(length);
// Parse the text data
string str = Encoding.UTF8.GetString(stringBytes);
// Add text to the cache
textCache[pos] = str;
}
}while (type == FieldLogItemType.StringData);
itemCount++;
return(FieldLogItem.Read(this, type));
}
catch (Exception ex)
{
throw new Exception(
"Error reading from the log file \"" + FileName + "\" at position " + fileStream.Position + " (starting at " + pos + "). " + ex.Message,
ex);
}
}
