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/*-------------------------------------------------------------------------
*
* palloc.h
* POSTGRES memory allocator definitions.
*
* This file contains the basic memory allocation interface that is
* needed by almost every backend module. It is included directly by
* postgres.h, so the definitions here are automatically available
* everywhere. Keep it lean!
*
* Memory allocation occurs within "contexts". Every chunk obtained from
* palloc()/MemoryContextAlloc() is allocated within a specific context.
* The entire contents of a context can be freed easily and quickly by
* resetting or deleting the context --- this is both faster and less
* prone to memory-leakage bugs than releasing chunks individually.
* We organize contexts into context trees to allow fine-grain control
* over chunk lifetime while preserving the certainty that we will free
* everything that should be freed. See utils/mmgr/README for more info.
*
*
* Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/utils/palloc.h
*
*-------------------------------------------------------------------------
*/
#ifndef PALLOC_H
#define PALLOC_H
/*
* Type MemoryContextData is declared in nodes/memnodes.h. Most users
* of memory allocation should just treat it as an abstract type, so we
* do not provide the struct contents here.
*/
typedef struct MemoryContextData *MemoryContext;
/*
* CurrentMemoryContext is the default allocation context for palloc().
* We declare it here so that palloc() can be a macro. Avoid accessing it
* directly! Instead, use MemoryContextSwitchTo() to change the setting.
*/
extern PGDLLIMPORT MemoryContext CurrentMemoryContext;
/*
* Fundamental memory-allocation operations (more are in utils/memutils.h)
*/
extern void *MemoryContextAlloc(MemoryContext context, Size size);
extern void *MemoryContextAllocZero(MemoryContext context, Size size);
extern void *MemoryContextAllocZeroAligned(MemoryContext context, Size size);
#define palloc(sz) MemoryContextAlloc(CurrentMemoryContext, (sz))
#define palloc0(sz) MemoryContextAllocZero(CurrentMemoryContext, (sz))
/*
* The result of palloc() is always word-aligned, so we can skip testing
* alignment of the pointer when deciding which MemSet variant to use.
* Note that this variant does not offer any advantage, and should not be
* used, unless its "sz" argument is a compile-time constant; therefore, the
* issue that it evaluates the argument multiple times isn't a problem in
* practice.
*/
#define palloc0fast(sz) \
( MemSetTest(0, sz) ? \
MemoryContextAllocZeroAligned(CurrentMemoryContext, sz) : \
MemoryContextAllocZero(CurrentMemoryContext, sz) )
extern void pfree(void *pointer);
extern void *repalloc(void *pointer, Size size);
/*
* MemoryContextSwitchTo can't be a macro in standard C compilers.
* But we can make it an inline function if the compiler supports it.
*
* This file has to be includable by some non-backend code such as
* pg_resetxlog, so don't expose the CurrentMemoryContext reference
* if FRONTEND is defined.
*/
#if defined(USE_INLINE) && !defined(FRONTEND)
static inline MemoryContext
MemoryContextSwitchTo(MemoryContext context)
{
MemoryContext old = CurrentMemoryContext;
CurrentMemoryContext = context;
return old;
}
#else
extern MemoryContext MemoryContextSwitchTo(MemoryContext context);
#endif /* USE_INLINE && !FRONTEND */
/*
* These are like standard strdup() except the copied string is
* allocated in a context, not with malloc().
*/
extern char *MemoryContextStrdup(MemoryContext context, const char *string);
#define pstrdup(str) MemoryContextStrdup(CurrentMemoryContext, (str))
extern char *pnstrdup(const char *in, Size len);
#if defined(WIN32) || defined(__CYGWIN__)
extern void *pgport_palloc(Size sz);
extern char *pgport_pstrdup(const char *str);
extern void pgport_pfree(void *pointer);
#endif
#endif /* PALLOC_H */
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