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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-04 12:19:15 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-04 12:19:15 +0000 |
commit | 6eb9c5a5657d1fe77b55cc261450f3538d35a94d (patch) | |
tree | 657d8194422a5daccecfd42d654b8a245ef7b4c8 /src/include/storage/block.h | |
parent | Initial commit. (diff) | |
download | postgresql-13-6eb9c5a5657d1fe77b55cc261450f3538d35a94d.tar.xz postgresql-13-6eb9c5a5657d1fe77b55cc261450f3538d35a94d.zip |
Adding upstream version 13.4.upstream/13.4upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/include/storage/block.h')
-rw-r--r-- | src/include/storage/block.h | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/src/include/storage/block.h b/src/include/storage/block.h new file mode 100644 index 0000000..d73e393 --- /dev/null +++ b/src/include/storage/block.h @@ -0,0 +1,121 @@ +/*------------------------------------------------------------------------- + * + * block.h + * POSTGRES disk block definitions. + * + * + * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * src/include/storage/block.h + * + *------------------------------------------------------------------------- + */ +#ifndef BLOCK_H +#define BLOCK_H + +/* + * BlockNumber: + * + * each data file (heap or index) is divided into postgres disk blocks + * (which may be thought of as the unit of i/o -- a postgres buffer + * contains exactly one disk block). the blocks are numbered + * sequentially, 0 to 0xFFFFFFFE. + * + * InvalidBlockNumber is the same thing as P_NEW in bufmgr.h. + * + * the access methods, the buffer manager and the storage manager are + * more or less the only pieces of code that should be accessing disk + * blocks directly. + */ +typedef uint32 BlockNumber; + +#define InvalidBlockNumber ((BlockNumber) 0xFFFFFFFF) + +#define MaxBlockNumber ((BlockNumber) 0xFFFFFFFE) + +/* + * BlockId: + * + * this is a storage type for BlockNumber. in other words, this type + * is used for on-disk structures (e.g., in HeapTupleData) whereas + * BlockNumber is the type on which calculations are performed (e.g., + * in access method code). + * + * there doesn't appear to be any reason to have separate types except + * for the fact that BlockIds can be SHORTALIGN'd (and therefore any + * structures that contains them, such as ItemPointerData, can also be + * SHORTALIGN'd). this is an important consideration for reducing the + * space requirements of the line pointer (ItemIdData) array on each + * page and the header of each heap or index tuple, so it doesn't seem + * wise to change this without good reason. + */ +typedef struct BlockIdData +{ + uint16 bi_hi; + uint16 bi_lo; +} BlockIdData; + +typedef BlockIdData *BlockId; /* block identifier */ + +/* ---------------- + * support macros + * ---------------- + */ + +/* + * BlockNumberIsValid + * True iff blockNumber is valid. + */ +#define BlockNumberIsValid(blockNumber) \ + ((bool) ((BlockNumber) (blockNumber) != InvalidBlockNumber)) + +/* + * BlockIdIsValid + * True iff the block identifier is valid. + */ +#define BlockIdIsValid(blockId) \ + ((bool) PointerIsValid(blockId)) + +/* + * BlockIdSet + * Sets a block identifier to the specified value. + */ +#define BlockIdSet(blockId, blockNumber) \ +( \ + AssertMacro(PointerIsValid(blockId)), \ + (blockId)->bi_hi = (blockNumber) >> 16, \ + (blockId)->bi_lo = (blockNumber) & 0xffff \ +) + +/* + * BlockIdCopy + * Copy a block identifier. + */ +#define BlockIdCopy(toBlockId, fromBlockId) \ +( \ + AssertMacro(PointerIsValid(toBlockId)), \ + AssertMacro(PointerIsValid(fromBlockId)), \ + (toBlockId)->bi_hi = (fromBlockId)->bi_hi, \ + (toBlockId)->bi_lo = (fromBlockId)->bi_lo \ +) + +/* + * BlockIdEquals + * Check for block number equality. + */ +#define BlockIdEquals(blockId1, blockId2) \ + ((blockId1)->bi_hi == (blockId2)->bi_hi && \ + (blockId1)->bi_lo == (blockId2)->bi_lo) + +/* + * BlockIdGetBlockNumber + * Retrieve the block number from a block identifier. + */ +#define BlockIdGetBlockNumber(blockId) \ +( \ + AssertMacro(BlockIdIsValid(blockId)), \ + (BlockNumber) (((blockId)->bi_hi << 16) | ((uint16) (blockId)->bi_lo)) \ +) + +#endif /* BLOCK_H */ |