mirror of https://github.com/citusdata/citus.git
131 lines
4.6 KiB
C
131 lines
4.6 KiB
C
/*-------------------------------------------------------------------------
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*
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* listutils.h
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*
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* Declarations for public utility functions related to lists.
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*
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* Copyright (c) Citus Data, Inc.
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef CITUS_LISTUTILS_H
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#define CITUS_LISTUTILS_H
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#include "postgres.h"
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#include "c.h"
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#include "nodes/pg_list.h"
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#include "pg_version_compat.h"
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#include "utils/array.h"
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#include "utils/hsearch.h"
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/*
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* ListCellAndListWrapper stores a list and list cell.
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* This struct is used for functionContext. When iterating a list
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* in separate function calls, we need both the list and the current cell.
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* Therefore this wrapper stores both of them.
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*/
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typedef struct ListCellAndListWrapper
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{
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List *list;
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ListCell *listCell;
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} ListCellAndListWrapper;
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/*
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* foreach_ptr -
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* a convenience macro which loops through a pointer list without needing a
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* ListCell, just a declared pointer variable to store the pointer of the
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* cell in.
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*
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* How it works:
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* - A ListCell is declared with the name {var}CellDoNotUse and used
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* throughout the for loop using ## to concat.
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* - To assign to var it needs to be done in the condition of the for loop,
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* because we cannot use the initializer since a ListCell* variable is
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* declared there.
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* - || true is used to always enter the loop when cell is not null even if
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* var is NULL.
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*/
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#define foreach_ptr(var, l) \
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for (ListCell *(var ## CellDoNotUse) = list_head(l); \
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(var ## CellDoNotUse) != NULL && \
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(((var) = lfirst(var ## CellDoNotUse)) || true); \
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var ## CellDoNotUse = lnext_compat(l, var ## CellDoNotUse))
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/*
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* foreach_int -
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* a convenience macro which loops through an int list without needing a
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* ListCell, just a declared int variable to store the int of the cell in.
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* For explanation of how it works see foreach_ptr.
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*/
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#define foreach_int(var, l) \
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for (ListCell *(var ## CellDoNotUse) = list_head(l); \
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(var ## CellDoNotUse) != NULL && \
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(((var) = lfirst_int(var ## CellDoNotUse)) || true); \
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var ## CellDoNotUse = lnext_compat(l, var ## CellDoNotUse))
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/*
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* foreach_oid -
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* a convenience macro which loops through an oid list without needing a
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* ListCell, just a declared Oid variable to store the oid of the cell in.
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* For explanation of how it works see foreach_ptr.
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*/
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#define foreach_oid(var, l) \
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for (ListCell *(var ## CellDoNotUse) = list_head(l); \
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(var ## CellDoNotUse) != NULL && \
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(((var) = lfirst_oid(var ## CellDoNotUse)) || true); \
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var ## CellDoNotUse = lnext_compat(l, var ## CellDoNotUse))
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/*
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* foreach_ptr_append -
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* a convenience macro which loops through a pointer List and can append list
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* elements without needing a ListCell or and index variable, just a declared
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* pointer variable to store the iterated values.
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*
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* PostgreSQL 13 changed the representation of Lists to expansible arrays,
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* not chains of cons-cells. This changes the costs for accessing and
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* mutating List contents. Therefore different implementations are provided.
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*
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* For more information, see postgres commit with sha
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* 1cff1b95ab6ddae32faa3efe0d95a820dbfdc164
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*/
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#if PG_VERSION_NUM >= PG_VERSION_13
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/*
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* How it works:
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* - An index is declared with the name {var}PositionDoNotUse and used
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* throughout the for loop using ## to concat.
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* - To assign to var it needs to be done in the condition of the for loop,
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* because we cannot use the initializer since the index variable is
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* declared there.
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* - || true is used to always enter the loop even if var is NULL.
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*/
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#define foreach_ptr_append(var, l) \
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for (int var ## PositionDoNotUse = 0; \
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(var ## PositionDoNotUse) < list_length(l) && \
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(((var) = list_nth(l, var ## PositionDoNotUse)) || true); \
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var ## PositionDoNotUse ++)
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#else
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#define foreach_ptr_append(var, l) foreach_ptr(var, l)
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#endif
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/* utility functions declaration shared within this module */
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extern List * SortList(List *pointerList,
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int (*ComparisonFunction)(const void *, const void *));
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extern void ** PointerArrayFromList(List *pointerList);
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extern ArrayType * DatumArrayToArrayType(Datum *datumArray, int datumCount,
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Oid datumTypeId);
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extern HTAB * ListToHashSet(List *pointerList, Size keySize, bool isStringList);
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extern char * StringJoin(List *stringList, char delimiter);
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extern List * ListTake(List *pointerList, int size);
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extern void * safe_list_nth(const List *list, int index);
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extern List * GeneratePositiveIntSequenceList(int upTo);
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extern List * GenerateListFromElement(void *listElement, int listLength);
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extern List * list_reverse(const List *list);
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#endif /* CITUS_LISTUTILS_H */
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