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e3860ffa4d
The new indent version includes numerous fixes thanks to Piotr Stefaniak. The main changes visible in this commit are: * Nicer formatting of function-pointer declarations. * No longer unexpectedly removes spaces in expressions using casts, sizeof, or offsetof. * No longer wants to add a space in "struct structname *varname", as well as some similar cases for const- or volatile-qualified pointers. * Declarations using PG_USED_FOR_ASSERTS_ONLY are formatted more nicely. * Fixes bug where comments following declarations were sometimes placed with no space separating them from the code. * Fixes some odd decisions for comments following case labels. * Fixes some cases where comments following code were indented to less than the expected column 33. On the less good side, it now tends to put more whitespace around typedef names that are not listed in typedefs.list. This might encourage us to put more effort into typedef name collection; it's not really a bug in indent itself. There are more changes coming after this round, having to do with comment indentation and alignment of lines appearing within parentheses. I wanted to limit the size of the diffs to something that could be reviewed without one's eyes completely glazing over, so it seemed better to split up the changes as much as practical. Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
166 lines
4.2 KiB
C
166 lines
4.2 KiB
C
/*-------------------------------------------------------------------------
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*
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* itemptr.h
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* POSTGRES disk item pointer definitions.
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*
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*
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* Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/storage/itemptr.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef ITEMPTR_H
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#define ITEMPTR_H
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#include "storage/block.h"
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#include "storage/off.h"
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/*
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* ItemPointer:
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*
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* This is a pointer to an item within a disk page of a known file
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* (for example, a cross-link from an index to its parent table).
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* blkid tells us which block, posid tells us which entry in the linp
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* (ItemIdData) array we want.
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*
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* Note: because there is an item pointer in each tuple header and index
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* tuple header on disk, it's very important not to waste space with
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* structure padding bytes. The struct is designed to be six bytes long
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* (it contains three int16 fields) but a few compilers will pad it to
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* eight bytes unless coerced. We apply appropriate persuasion where
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* possible. If your compiler can't be made to play along, you'll waste
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* lots of space.
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*/
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typedef struct ItemPointerData
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{
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BlockIdData ip_blkid;
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OffsetNumber ip_posid;
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}
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/* If compiler understands packed and aligned pragmas, use those */
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#if defined(pg_attribute_packed) && defined(pg_attribute_aligned)
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pg_attribute_packed()
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pg_attribute_aligned(2)
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#endif
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ItemPointerData;
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typedef ItemPointerData *ItemPointer;
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/* ----------------
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* support macros
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* ----------------
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*/
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/*
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* ItemPointerIsValid
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* True iff the disk item pointer is not NULL.
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*/
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#define ItemPointerIsValid(pointer) \
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((bool) (PointerIsValid(pointer) && ((pointer)->ip_posid != 0)))
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/*
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* ItemPointerGetBlockNumberNoCheck
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* Returns the block number of a disk item pointer.
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*/
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#define ItemPointerGetBlockNumberNoCheck(pointer) \
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( \
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BlockIdGetBlockNumber(&(pointer)->ip_blkid) \
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)
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/*
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* ItemPointerGetBlockNumber
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* As above, but verifies that the item pointer looks valid.
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*/
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#define ItemPointerGetBlockNumber(pointer) \
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( \
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AssertMacro(ItemPointerIsValid(pointer)), \
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ItemPointerGetBlockNumberNoCheck(pointer) \
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)
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/*
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* ItemPointerGetOffsetNumberNoCheck
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* Returns the offset number of a disk item pointer.
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*/
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#define ItemPointerGetOffsetNumberNoCheck(pointer) \
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( \
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(pointer)->ip_posid \
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)
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/*
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* ItemPointerGetOffsetNumber
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* As above, but verifies that the item pointer looks valid.
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*/
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#define ItemPointerGetOffsetNumber(pointer) \
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( \
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AssertMacro(ItemPointerIsValid(pointer)), \
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ItemPointerGetOffsetNumberNoCheck(pointer) \
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)
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/*
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* ItemPointerSet
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* Sets a disk item pointer to the specified block and offset.
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*/
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#define ItemPointerSet(pointer, blockNumber, offNum) \
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( \
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AssertMacro(PointerIsValid(pointer)), \
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BlockIdSet(&((pointer)->ip_blkid), blockNumber), \
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(pointer)->ip_posid = offNum \
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)
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/*
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* ItemPointerSetBlockNumber
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* Sets a disk item pointer to the specified block.
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*/
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#define ItemPointerSetBlockNumber(pointer, blockNumber) \
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( \
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AssertMacro(PointerIsValid(pointer)), \
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BlockIdSet(&((pointer)->ip_blkid), blockNumber) \
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)
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/*
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* ItemPointerSetOffsetNumber
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* Sets a disk item pointer to the specified offset.
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*/
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#define ItemPointerSetOffsetNumber(pointer, offsetNumber) \
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( \
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AssertMacro(PointerIsValid(pointer)), \
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(pointer)->ip_posid = (offsetNumber) \
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)
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/*
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* ItemPointerCopy
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* Copies the contents of one disk item pointer to another.
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*
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* Should there ever be padding in an ItemPointer this would need to be handled
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* differently as it's used as hash key.
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*/
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#define ItemPointerCopy(fromPointer, toPointer) \
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( \
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AssertMacro(PointerIsValid(toPointer)), \
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AssertMacro(PointerIsValid(fromPointer)), \
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*(toPointer) = *(fromPointer) \
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)
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/*
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* ItemPointerSetInvalid
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* Sets a disk item pointer to be invalid.
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*/
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#define ItemPointerSetInvalid(pointer) \
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( \
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AssertMacro(PointerIsValid(pointer)), \
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BlockIdSet(&((pointer)->ip_blkid), InvalidBlockNumber), \
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(pointer)->ip_posid = InvalidOffsetNumber \
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)
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/* ----------------
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* externs
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* ----------------
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*/
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extern bool ItemPointerEquals(ItemPointer pointer1, ItemPointer pointer2);
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extern int32 ItemPointerCompare(ItemPointer arg1, ItemPointer arg2);
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#endif /* ITEMPTR_H */
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