public void ReadWithSeeking()
{
int NumberOfBytes = AsyncFileStream.DefaultBufferSize * 2;
string path = GetFullPath("file");
FileStreamValidation.WriteValidatableFile(path, NumberOfBytes);
byte[] buffer = new byte[NumberOfBytes];
WithReadableStream(
path,
async stream =>
{
// Here we ping-pong around in the stream doing reads less than the buffer size.
// The intent is to verify that seeking properly flushes the partially-full read buffer.
// Read 1/4 of the stream, starting halfway
stream.Seek(AsyncFileStream.DefaultBufferSize, SeekOrigin.Begin);
await Read(stream, buffer, offset: AsyncFileStream.DefaultBufferSize, count: AsyncFileStream.DefaultBufferSize / 2);
// Read 1/4 of the stream, starting at the beginning
stream.Seek(0, SeekOrigin.Begin);
await Read(stream, buffer, offset: 0, count: AsyncFileStream.DefaultBufferSize / 2);
// Read 1/4 of the stream, again from the second half
stream.Seek(AsyncFileStream.DefaultBufferSize + (AsyncFileStream.DefaultBufferSize / 2), SeekOrigin.Begin);
await Read(stream, buffer, offset: AsyncFileStream.DefaultBufferSize + (AsyncFileStream.DefaultBufferSize / 2), count: AsyncFileStream.DefaultBufferSize / 2);
// Read 1/4 of the stream, again from the first half
stream.Seek(AsyncFileStream.DefaultBufferSize / 2, SeekOrigin.Begin);
await Read(stream, buffer, offset: AsyncFileStream.DefaultBufferSize / 2, count: AsyncFileStream.DefaultBufferSize / 2);
});
FileStreamValidation.ValidateBuffer(buffer, NumberOfBytes);
}
private static void VerifyReadingValidatableFile(string path, int numberOfBytes, int readSize)
{
FileStreamValidation.WriteValidatableFile(path, numberOfBytes);
using (var targetStream = new MemoryStream())
{
CopyReadableStream(path, readSize, targetStream);
FileStreamValidation.ValidateStream(targetStream, numberOfBytes);
}
}
