Function WriteToCursorFile

pg_documentdb/src/infrastructure/cursor_store.c:333–371

* Given a cursor file that is created, writes a given document to that * cursor file. The file is written as * where length is the size of the pgbson including the * varlen header. * The data is buffered in memory and flushed every BLCKSZ bytes. */

 * The data is buffered in memory and flushed every BLCKSZ bytes.
 */
void
WriteToCursorFile(CursorFileState *cursorFileState, pgbson *dataBson)
{
	int32_t sizeRemaining = BLCKSZ - cursorFileState->pos;

	/* We don't have enough to write even the length - flush the buffer */
	if (sizeRemaining < 4)
	{
		FlushBuffer(cursorFileState);
	}

	int32_t dataSize = VARSIZE(dataBson);
	char *data = (char *) dataBson;

	/* Write the length to the buffer */
	memcpy(cursorFileState->buffer.data + cursorFileState->pos, &dataSize, 4);
	cursorFileState->pos += 4;

	/* Now write the file into the buffer and then write it out to the file */
	while (dataSize > 0)
	{
		sizeRemaining = BLCKSZ - cursorFileState->pos;
		if (sizeRemaining >= dataSize)
		{
			memcpy(cursorFileState->buffer.data + cursorFileState->pos, data, dataSize);
			cursorFileState->pos += dataSize;
			break;
		}
		else
		{
			memcpy(cursorFileState->buffer.data + cursorFileState->pos, data,
				   sizeRemaining);
			cursorFileState->pos += sizeRemaining;
			data += sizeRemaining;
			dataSize -= sizeRemaining;
			FlushBuffer(cursorFileState);
		}
	}
}


void