// The IDF that is adding data to this spill file calls Append to add some more. Each
// call to Append is accompanied by a completion handler that will be called once the
// appended data has been written to disk.
void Append(byte[] data, Cache.IAppendCompletion completion)
{
// This will be a count of the bytes written out of the data array
Int64 written = 0;
while (written < data.LongLength)
{
if (bufferedData == null) // no data is currently buffered to write
{
if (written == 0 && data.LongLength == writeBlockSize)
{
// fast path, write straight through without copying the buffer.
// This is used when spilling large, previously-cached IDFs as fast as
// possible, for which the client uses the WriteBlockSize property to match
// the Append calls to the buffer size.
bufferedData = new SpillBlock(data);
written = data.LongLength;
bufferedData.validLength = data.LongLength;
}
else
{
// make a new buffer for writing
bufferedData = new SpillBlock(writeBlockSize);
}
bufferedCompletions = new List <Cache.IAppendCompletion>();
}
// Copy some data into the buffer
Int64 space = bufferedData.data.LongLength - bufferedData.validLength;
Int64 needed = data.LongLength - written;
Int64 toWrite = Math.Max(needed, space);
Array.Copy(data, written, bufferedData.data, bufferedData.validLength, toWrite);
written += toWrite;
bufferedData.validLength += toWrite;
if (bufferedData.validLength == bufferedData.data.LongLength)
{ // the buffer is full---time to write it to disk
if (written == data.LongLength)
{
// this happens to coincide with finishing the append, so attach
// the completion. Otherwise the completion will be attached to a
// subsequent buffer, so it doesn't get called until the entire
// append block has been written out
bufferedCompletions.Add(completion);
}
// Send bufferedData to the disk, and reset it to null
QueueWrite();
}
}
// We have written out all the data now
if (bufferedCompletions != null)
{
// The buffer wasn't sent out at the end of the loop, so add
// our completion to the partially-written buffer, waiting for
// it to get written our in a subsequent Append or Flush.
bufferedCompletions.Add(completion);
}
// Record the amount of data we appended in this call
bytesAppended += data.LongLength;
}
// Enqueue an async write of the data currently being buffered, then zero out the buffer in
// preparation for more appends
private void QueueWrite()
{
handle.BeginWrite(bufferedData.data, 0, (int)bufferedData.validLength, WriteComplete, bufferedCompletions);
bufferedData = null;
bufferedCompletions = null;
}
// Enqueue an async write of the data currently being buffered, then zero out the buffer in
// preparation for more appends
private void QueueWrite()
{
handle.BeginWrite(bufferedData.data, 0, (int)bufferedData.validLength, WriteComplete, bufferedCompletions);
bufferedData = null;
bufferedCompletions = null;
}
// The IDF that is adding data to this spill file calls Append to add some more. Each
// call to Append is accompanied by a completion handler that will be called once the
// appended data has been written to disk.
void Append(byte[] data, Cache.IAppendCompletion completion)
{
// This will be a count of the bytes written out of the data array
Int64 written = 0;
while (written < data.LongLength)
{
if (bufferedData == null) // no data is currently buffered to write
{
if (written == 0 && data.LongLength == writeBlockSize)
{
// fast path, write straight through without copying the buffer.
// This is used when spilling large, previously-cached IDFs as fast as
// possible, for which the client uses the WriteBlockSize property to match
// the Append calls to the buffer size.
bufferedData = new SpillBlock(data);
written = data.LongLength;
bufferedData.validLength = data.LongLength;
}
else
{
// make a new buffer for writing
bufferedData = new SpillBlock(writeBlockSize);
}
bufferedCompletions = new List<Cache.IAppendCompletion>();
}
// Copy some data into the buffer
Int64 space = bufferedData.data.LongLength - bufferedData.validLength;
Int64 needed = data.LongLength - written;
Int64 toWrite = Math.Max(needed, space);
Array.Copy(data, written, bufferedData.data, bufferedData.validLength, toWrite);
written += toWrite;
bufferedData.validLength += toWrite;
if (bufferedData.validLength == bufferedData.data.LongLength)
{ // the buffer is full---time to write it to disk
if (written == data.LongLength)
{
// this happens to coincide with finishing the append, so attach
// the completion. Otherwise the completion will be attached to a
// subsequent buffer, so it doesn't get called until the entire
// append block has been written out
bufferedCompletions.Add(completion);
}
// Send bufferedData to the disk, and reset it to null
QueueWrite();
}
}
// We have written out all the data now
if (bufferedCompletions != null)
{
// The buffer wasn't sent out at the end of the loop, so add
// our completion to the partially-written buffer, waiting for
// it to get written our in a subsequent Append or Flush.
bufferedCompletions.Add(completion);
}
// Record the amount of data we appended in this call
bytesAppended += data.LongLength;
}
