/*
PACKET
======
Byte/ 0 | 1 | 2 | 3 |
/ | | | |
|0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|
+---------------+---------------+---------------+---------------+
0/ HEADER /
/ /
/ /
/ /
+---------------+---------------+---------------+---------------+
24/ COMMAND-SPECIFIC EXTRAS (as needed) /
+/ (note length in the extras length header field) /
+---------------+---------------+---------------+---------------+
m/ Key (as needed) /
+/ (note length in key length header field) /
+---------------+---------------+---------------+---------------+
n/ Value (as needed) /
+/ (note length is total body length header field, minus /
+/ sum of the extras and key length body fields) /
+---------------+---------------+---------------+---------------+
Total 24 bytes
*/
bool IRequest.WriteTo(WriteBuffer buffer)
{
// 0. init header
// 1. loop on header
// 2. loop on Key, if any
// 3. loop on Data, if any
// 4. done
switch (state)
{
case STATE_WRITE_HEADER:
// this will either get a Span that can fit the header data or nothing
// we will not write partial header
var span = buffer.Want(Protocol.HeaderLength);
if (span.IsEmpty) return true; // header does not fit into the request buffer
WriteHeader(span);
if (finalBody.IsEmpty) break; // no body, quit
writeOffset = 0;
if (finalBody.IsSingleSegment)
singleSegmentBody = finalBody.First;
else
bodyCopier = new SequenceCopier(finalBody, buffer);
state = STATE_WRITE_BODY;
goto case STATE_WRITE_BODY;
case STATE_WRITE_BODY:
// body is only one span, write it until it's gone
if (!singleSegmentBody.IsEmpty)
{
writeOffset += buffer.TryAppend(singleSegmentBody.Slice(writeOffset).Span);
if (writeOffset < singleSegmentBody.Length) return true;
Debug.Assert(writeOffset == singleSegmentBody.Length);
}
else
{
Debug.Assert(bodyCopier != null);
// body consists of munltiple spans; the SequenceCopier will process it
if (bodyCopier.Copy()) return true;
bodyCopier = default;
}
break;
default: throw new InvalidOperationException("undhandled state: " + state); // should not happen
}
state = STATE_DONE;
//bodyBuilder.Dispose();
finalBody = default;
return false;
}