152 lines
5.6 KiB
C
152 lines
5.6 KiB
C
/*-------------------------------------------------------------------------
|
|
*
|
|
* 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) 1996-2024, 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;
|
|
|
|
/*
|
|
* A memory context can have callback functions registered on it. Any such
|
|
* function will be called once just before the context is next reset or
|
|
* deleted. The MemoryContextCallback struct describing such a callback
|
|
* typically would be allocated within the context itself, thereby avoiding
|
|
* any need to manage it explicitly (the reset/delete action will free it).
|
|
*/
|
|
typedef void (*MemoryContextCallbackFunction) (void *arg);
|
|
|
|
typedef struct MemoryContextCallback
|
|
{
|
|
MemoryContextCallbackFunction func; /* function to call */
|
|
void *arg; /* argument to pass it */
|
|
struct MemoryContextCallback *next; /* next in list of callbacks */
|
|
} MemoryContextCallback;
|
|
|
|
/*
|
|
* CurrentMemoryContext is the default allocation context for palloc().
|
|
* Avoid accessing it directly! Instead, use MemoryContextSwitchTo()
|
|
* to change the setting.
|
|
*/
|
|
extern PGDLLIMPORT MemoryContext CurrentMemoryContext;
|
|
|
|
/*
|
|
* Flags for MemoryContextAllocExtended.
|
|
*/
|
|
#define MCXT_ALLOC_HUGE 0x01 /* allow huge allocation (> 1 GB) */
|
|
#define MCXT_ALLOC_NO_OOM 0x02 /* no failure if out-of-memory */
|
|
#define MCXT_ALLOC_ZERO 0x04 /* zero allocated memory */
|
|
|
|
/*
|
|
* 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 *MemoryContextAllocExtended(MemoryContext context,
|
|
Size size, int flags);
|
|
extern void *MemoryContextAllocAligned(MemoryContext context,
|
|
Size size, Size alignto, int flags);
|
|
|
|
extern void *palloc(Size size);
|
|
extern void *palloc0(Size size);
|
|
extern void *palloc_extended(Size size, int flags);
|
|
extern void *palloc_aligned(Size size, Size alignto, int flags);
|
|
extern pg_nodiscard void *repalloc(void *pointer, Size size);
|
|
extern pg_nodiscard void *repalloc_extended(void *pointer,
|
|
Size size, int flags);
|
|
extern pg_nodiscard void *repalloc0(void *pointer, Size oldsize, Size size);
|
|
extern void pfree(void *pointer);
|
|
|
|
/*
|
|
* Variants with easier notation and more type safety
|
|
*/
|
|
|
|
/*
|
|
* Allocate space for one object of type "type"
|
|
*/
|
|
#define palloc_object(type) ((type *) palloc(sizeof(type)))
|
|
#define palloc0_object(type) ((type *) palloc0(sizeof(type)))
|
|
|
|
/*
|
|
* Allocate space for "count" objects of type "type"
|
|
*/
|
|
#define palloc_array(type, count) ((type *) palloc(sizeof(type) * (count)))
|
|
#define palloc0_array(type, count) ((type *) palloc0(sizeof(type) * (count)))
|
|
|
|
/*
|
|
* Change size of allocation pointed to by "pointer" to have space for "count"
|
|
* objects of type "type"
|
|
*/
|
|
#define repalloc_array(pointer, type, count) ((type *) repalloc(pointer, sizeof(type) * (count)))
|
|
#define repalloc0_array(pointer, type, oldcount, count) ((type *) repalloc0(pointer, sizeof(type) * (oldcount), sizeof(type) * (count)))
|
|
|
|
/* Higher-limit allocators. */
|
|
extern void *MemoryContextAllocHuge(MemoryContext context, Size size);
|
|
extern pg_nodiscard void *repalloc_huge(void *pointer, Size size);
|
|
|
|
/*
|
|
* Although this header file is nominally backend-only, certain frontend
|
|
* programs like pg_controldata include it via postgres.h. For some compilers
|
|
* it's necessary to hide the inline definition of MemoryContextSwitchTo in
|
|
* this scenario; hence the #ifndef FRONTEND.
|
|
*/
|
|
|
|
#ifndef FRONTEND
|
|
static inline MemoryContext
|
|
MemoryContextSwitchTo(MemoryContext context)
|
|
{
|
|
MemoryContext old = CurrentMemoryContext;
|
|
|
|
CurrentMemoryContext = context;
|
|
return old;
|
|
}
|
|
#endif /* FRONTEND */
|
|
|
|
/* Registration of memory context reset/delete callbacks */
|
|
extern void MemoryContextRegisterResetCallback(MemoryContext context,
|
|
MemoryContextCallback *cb);
|
|
|
|
/*
|
|
* 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);
|
|
extern char *pstrdup(const char *in);
|
|
extern char *pnstrdup(const char *in, Size len);
|
|
|
|
extern char *pchomp(const char *in);
|
|
|
|
/* sprintf into a palloc'd buffer --- these are in psprintf.c */
|
|
extern char *psprintf(const char *fmt,...) pg_attribute_printf(1, 2);
|
|
extern size_t pvsnprintf(char *buf, size_t len, const char *fmt, va_list args) pg_attribute_printf(3, 0);
|
|
|
|
#endif /* PALLOC_H */
|