|
protected Read ( |
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| reader | ||
| Résultat | void | |
/// <summary>
/// Read the records that should be retained in the sync file.
/// </summary>
/// <param name="stream">Stream for the sync file.</param>
/// <param name="purgeDate">Date before which records should be removed.</param>
/// <returns></returns>
private static byte[] ReadRecords(FileStream stream, long purgeDate)
{
byte[] buffer = null;
long offset = 0;
BinaryReader reader = new BinaryReader(stream);
RequestRecord record = new RequestRecord();
stream.Position = 0;
for (offset = 0; offset < stream.Length; offset += RECORD_LENGTH)
{
record.Read(reader);
// Check to see if the current record is newer than the purgeDate
// and isn't equal to zero. Zero date indicates the record should be
// removed from the history.
if (record.LastActiveDate > purgeDate && record.LastActiveDate != 0)
{
break;
}
}
if (offset > 0 && offset < stream.Length)
{
int length = (int)(stream.Length - offset);
buffer = new byte[length];
stream.Position = offset;
stream.Read(buffer, 0, length);
}
return(buffer);
}
/// <summary>
/// Read the records that should be retained in the sync file.
/// </summary>
/// <param name="stream">Stream for the sync file.</param>
/// <param name="purgeDate">Date before which records should be removed.</param>
/// <returns></returns>
private static byte[] ReadRecords(FileStream stream, long purgeDate)
{
byte[] buffer = null;
long offset = 0;
BinaryReader reader = new BinaryReader(stream);
RequestRecord record = new RequestRecord();
stream.Position = 0;
for (offset = 0; offset < stream.Length; offset += RECORD_LENGTH)
{
record.Read(reader);
// Check to see if the current record is newer than the purgeDate
// and isn't equal to zero. Zero date indicates the record should be
// removed from the history.
if (record.LastActiveDate > purgeDate && record.LastActiveDate != 0)
break;
}
if (offset > 0 && offset < stream.Length)
{
int length = (int) (stream.Length - offset);
buffer = new byte[length];
stream.Position = offset;
stream.Read(buffer, 0, length);
}
return buffer;
}
private void ProcessSyncFile()
{
// Record if the sync file exists to avoid repeated calls
// to the operating system.
if (_syncFileExists == false)
{
_syncFileExists = File.Exists(_syncFilePath);
}
if (_syncFileExists)
{
// Used to indicate if the process should be repeated.
bool repeatProcess = false;
// Lock the list of devices we're about to update to ensure they can't be
// changed by subsequent requests to this callback.
lock (_previous.Requests)
{
// Open the sync file for read access ensuring it's disposed
// as soon as possible.
FileStream stream = OpenSyncFilePath(FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
if (stream != null)
{
// Record the length of the file so that if it changes we can abandon this
// update and rely on a subsequent call to this methd to complete
// processing.
using (BinaryReader reader = new BinaryReader(stream))
{
long length = stream.Length;
RequestRecord record = new RequestRecord();
RequestRecord firstDevice = null;
long rows = length / RECORD_LENGTH;
for (long row = 0; row < rows; row++)
{
// Read the current row in reverse order. Capture EOF exceptions
// in case the file length has changed since we started processing.
try
{
stream.Position = ((rows - row) * RECORD_LENGTH) - RECORD_LENGTH;
record.Read(reader);
}
catch (EndOfStreamException ex)
{
// The file has been trimmed by another process. Break and
// allow the resulting call to this event to complete
// processing.
EventLog.Debug(ex);
break;
}
// If the current record is the same as the last one we got last time
// this method was called then stop processing more records.
if (record.CompareTo(_previous.lastRequest) == 0)
{
break;
}
// Update the memory version.
if (record.LastActiveDate == 0)
{
// Remove from the device as the last active date is zero.
_previous.Requests.Remove(record.Key);
}
else
{
// Update or insert a new record.
if (_previous.Requests.ContainsKey(record.Key))
{
_previous.Requests[record.Key] = record.LastActiveDate;
}
else
{
_previous.Requests.Add(record.Key, record.LastActiveDate);
}
}
if (firstDevice == null)
{
firstDevice = new RequestRecord(record);
}
}
// If the length of the file hasn't changed during the processing
// then update the last device record to limit the number of rows
// examined in future file changes.
if (length == stream.Length && firstDevice != null)
{
_previous.lastRequest = firstDevice;
}
// Signal to all the method again if the length of the file
// has changed during processing.
repeatProcess = length != stream.Length;
}
}
}
// If the file was altered during the processing then call the method
// again to capture any new records.
if (repeatProcess)
{
ProcessSyncFile();
}
}
}
private void ProcessSyncFile()
{
// Record if the sync file exists to avoid repeated calls
// to the operating system.
if (_syncFileExists == false)
_syncFileExists = File.Exists(_syncFilePath);
if (_syncFileExists)
{
// Used to indicate if the process should be repeated.
bool repeatProcess = false;
// Lock the list of devices we're about to update to ensure they can't be
// changed by subsequent requests to this callback.
lock (_previous.Requests)
{
// Open the sync file for read access ensuring it's disposed
// as soon as possible.
using (FileStream stream = OpenSyncFilePath(FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
{
if (stream != null)
{
// Record the length of the file so that if it changes we can abandon this
// update and rely on a subsequent call to this methd to complete
// processing.
long length = stream.Length;
BinaryReader reader = new BinaryReader(stream);
RequestRecord record = new RequestRecord();
RequestRecord firstDevice = null;
long rows = length/RECORD_LENGTH;
for (long row = 0; row < rows; row++)
{
// Read the current row in reverse order. Capture EOF exceptions
// in case the file length has changed since we started processing.
try
{
stream.Position = ((rows - row)*RECORD_LENGTH) - RECORD_LENGTH;
record.Read(reader);
}
catch (EndOfStreamException ex)
{
// The file has been trimmed by another process. Break and
// allow the resulting call to this event to complete
// processing.
EventLog.Debug(ex);
break;
}
// If the current record is the same as the last one we got last time
// this method was called then stop processing more records.
if (record.CompareTo(_previous.lastRequest) == 0)
break;
// Update the memory version.
if (record.LastActiveDate == 0)
{
// Remove from the device as the last active date is zero.
_previous.Requests.Remove(record.Key);
}
else
{
// Update or insert a new record.
if (_previous.Requests.ContainsKey(record.Key))
_previous.Requests[record.Key] = record.LastActiveDate;
else
_previous.Requests.Add(record.Key, record.LastActiveDate);
}
if (firstDevice == null)
firstDevice = new RequestRecord(record);
}
// If the length of the file hasn't changed during the processing
// then update the last device record to limit the number of rows
// examined in future file changes.
if (length == stream.Length && firstDevice != null)
_previous.lastRequest = firstDevice;
// Signal to all the method again if the length of the file
// has changed during processing.
repeatProcess = length != stream.Length;
reader.Close();
}
}
}
// If the file was altered during the processing then call the method
// again to capture any new records.
if (repeatProcess)
ProcessSyncFile();
}
}
