/*-------------------------------------------------------------------------
*
* memnodes.h
* POSTGRES memory context node definitions.
*
*
* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/nodes/memnodes.h,v 1.35 2009/01/01 17:24:00 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef MEMNODES_H
#define MEMNODES_H
#include "nodes/nodes.h"
/*
* MemoryContext
* A logical context in which memory allocations occur.
*
* MemoryContext itself is an abstract type that can have multiple
* implementations, though for now we have only AllocSetContext.
* The function pointers in MemoryContextMethods define one specific
* implementation of MemoryContext --- they are a virtual function table
* in C++ terms.
*
* Node types that are actual implementations of memory contexts must
* begin with the same fields as MemoryContext.
*
* Note: for largely historical reasons, typedef MemoryContext is a pointer
* to the context struct rather than the struct type itself.
*/
typedef struct MemoryContextMethods
{
void *(*alloc) (MemoryContext context, Size size);
/* call this free_p in case someone #define's free() */
void (*free_p) (MemoryContext context, void *pointer);
void *(*realloc) (MemoryContext context, void *pointer, Size size);
void (*init) (MemoryContext context);
void (*reset) (MemoryContext context);
void (*delete) (MemoryContext context);
Size (*get_chunk_space) (MemoryContext context, void *pointer);
bool (*is_empty) (MemoryContext context);
void (*stats) (MemoryContext context, int level);
#ifdef MEMORY_CONTEXT_CHECKING
void (*check) (MemoryContext context);
#endif
} MemoryContextMethods;
typedef struct MemoryContextData
{
NodeTag type; /* identifies exact kind of context */
MemoryContextMethods *methods; /* virtual function table */
MemoryContext parent; /* NULL if no parent (toplevel context) */
MemoryContext firstchild; /* head of linked list of children */
MemoryContext nextchild; /* next child of same parent */
char *name; /* context name (just for debugging) */
} MemoryContextData;
/* utils/palloc.h contains typedef struct MemoryContextData *MemoryContext */
/*
* MemoryContextIsValid
* True iff memory context is valid.
*
* Add new context types to the set accepted by this macro.
*/
#define MemoryContextIsValid(context) \
((context) != NULL && \
(IsA((context), AllocSetContext)))
#endif /* MEMNODES_H */
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