public unsafe void ReadAsync(ulong sourceAddress,
IntPtr destinationAddress,
uint readLength,
IAsyncResult asyncResult)
{
Overlapped ov = new Overlapped
{
AsyncResult = asyncResult,
OffsetLow = unchecked ((int)(sourceAddress & 0xFFFFFFFF)),
OffsetHigh = unchecked ((int)((sourceAddress >> 32) & 0xFFFFFFFF))
};
NativeOverlapped *ovNative = ov.UnsafePack(null, IntPtr.Zero);
/* Invoking the Native method ReadFile provided by Kernel32.dll
* library. Returns false, if request failed or accepted for async
* operation. Returns true, if success synchronously.
*/
bool result = Native32.ReadFile(logHandle,
destinationAddress,
readLength,
out uint bytesRead,
ovNative);
if (!result)
{
int error = Marshal.GetLastWin32Error();
/* Just handle the case when it is not ERROR_IO_PENDING
* If ERROR_IO_PENDING, then it is accepted for async execution
*/
if (error != Native32.ERROR_IO_PENDING)
{
Overlapped.Unpack(ovNative);
Overlapped.Free(ovNative);
throw new Exception("Error reading from log file: " + error);
}
}
else
{
//executed synchronously, so process callback
//callback(0, bytesRead, ovNative);
}
}
public unsafe void ReadAsync(ulong sourceAddress,
IntPtr destinationAddress,
uint readLength,
IOCompletionCallback callback,
IAsyncResult asyncResult)
{
Overlapped ov = new Overlapped(0, 0, IntPtr.Zero, asyncResult);
NativeOverlapped *ovNative = ov.UnsafePack(callback, IntPtr.Zero);
ovNative->OffsetLow = unchecked ((int)((ulong)sourceAddress & 0xFFFFFFFF));
ovNative->OffsetHigh = unchecked ((int)(((ulong)sourceAddress >> 32) & 0xFFFFFFFF));
uint bytesRead = default(uint);
bool result = Native32.ReadFile(logHandle,
destinationAddress,
readLength,
out bytesRead,
ovNative);
if (!result)
{
int error = Marshal.GetLastWin32Error();
if (error != Native32.ERROR_IO_PENDING)
{
Overlapped.Unpack(ovNative);
Overlapped.Free(ovNative);
// NOTE: alignedDestinationAddress needs to be freed by whoever catches the exception
throw new Exception("Error reading from log file: " + error);
}
}
else
{
// On synchronous completion, issue callback directly
callback(0, bytesRead, ovNative);
}
}