src/include/cdb/tupchunk.h

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

/*-------------------------------------------------------------------------
 * tupchunk.h
 *	   The data-structures and functions for dealing with tuple chunks.
 *
 *-------------------------------------------------------------------------
 */
#ifndef TUPCHUNK_H
#define TUPCHUNK_H

/*--------------*/
/* Tuple Chunks */
/*--------------*/


typedef enum TupleChunkType
{
	TC_WHOLE,					/* Contains a whole tuple. */
	TC_PARTIAL_START,			/* Contains the starting portion of a tuple. */
	TC_PARTIAL_MID,				/* Contains a middle part of a tuple. */
	TC_PARTIAL_END,				/* Contains the final portion of a tuple. */
	TC_END_OF_STREAM,			/* Indicates "end of tuples" from this source. */
	TC_EMPTY,					/* Empty tuple */
	TC_MAXVAL					/* For range checks on type values. */
} TupleChunkType;



/* This is the size of a tuple-chunk header, as it appears in the packet that
 * comes from the network.	Thus, some values are packed into 2 bytes or 1
 * byte in this header.  The break-down is as follows:
 *
 *	  Offset	  Description			Size
 *		0	 Tuple Chunk Size		  2 bytes
 *		2	 Tuple Type				  2 byte
 *	 ------------------------------------------
 *							  TOTAL:  4 BYTES
 *
 * Yes, we could make this smaller. But we're doing lots of memcpy()s
 * of data immediately following these headers. Let's align the data on
 * 32-bit boundaries!
 */

#define TUPLE_CHUNK_HEADER_SIZE 4

/* see MPP-2099, let's not run into this one again! NOTE: the
 * definition of BROADCAST_SEGIDX is *key*.
 *
 * We don't support hash-motion to the QD, so any value that will not
 * appear in our hash-mapping (see nodeMotion.c) will work 
 * 
 * Before changing this value make sure that you look for all uses of
 * BROADCAST_SEGIDX */
#define BROADCAST_SEGIDX		-2 /* to avoid confusion with a QD-content-id, I'll avoid -1 */


#define ANY_ROUTE -100

#define GetSegIdx(x)			(x)
#define IsBroadcastSegIdx(x)	(GetSegIdx(x) == BROADCAST_SEGIDX)

/* Simple macros for accessing tuple-chunk headers; NOTE: we no longer
 * use network byte order */

/* add support for "inplace" chunk items */
#define GetChunkDataPtr(tcItem) \
	(((tcItem)->inplace != NULL) ? ((char *)((tcItem)->inplace)) : ((char *)((tcItem)->chunk_data)))

#define GetChunkDataSize(tcItem, sizep)	\
	do { uint16 sizeid; memcpy(&sizeid, (GetChunkDataPtr(tcItem)), sizeof(uint16)); *(sizep) = sizeid; } while (0)

#define GetChunkType(/* uint 8 * */tcItem, /* TupleChunkType * */typep) \
	do { uint16 typeid; memcpy(&typeid, (GetChunkDataPtr(tcItem) + 2), sizeof(uint16)); *(typep) = typeid; } while (0)

#define SetChunkDataSize(/* uint8 * */tc_data, /* uint16 */value) \
	do { uint16 val = (value); memcpy((tc_data), &val, sizeof(uint16)); } while (0)

#define SetChunkType(/* uint8 * */tc_data, /* TupleChunkType */value) \
	do { uint16 val = (value); memcpy(((tc_data)+2), &val, sizeof(uint16)); } while (0)

#endif   /* TUPCHUNK_H */