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Diffstat (limited to 'src/include/utils/palloc.h')
| -rw-r--r-- | src/include/utils/palloc.h | 79 |
1 files changed, 64 insertions, 15 deletions
diff --git a/src/include/utils/palloc.h b/src/include/utils/palloc.h index 0ec6caabbb..4bfdedff7e 100644 --- a/src/include/utils/palloc.h +++ b/src/include/utils/palloc.h @@ -3,36 +3,85 @@ * 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) 1996-2000, PostgreSQL, Inc * Portions Copyright (c) 1994, Regents of the University of California * - * $Id: palloc.h,v 1.12 2000/01/26 05:58:38 momjian Exp $ + * $Id: palloc.h,v 1.13 2000/06/28 03:33:33 tgl Exp $ * *------------------------------------------------------------------------- */ #ifndef PALLOC_H #define PALLOC_H -#ifdef PALLOC_IS_MALLOC +/* + * 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 DLLIMPORT MemoryContext CurrentMemoryContext; + +/* + * Fundamental memory-allocation operations (more are in utils/memutils.h) + */ +extern void *MemoryContextAlloc(MemoryContext context, Size size); + +#define palloc(sz) MemoryContextAlloc(CurrentMemoryContext, (sz)) -#define palloc(s) malloc(s) -#define pfree(p) free(p) -#define repalloc(p,s) realloc((p),(s)) +extern void pfree(void *pointer); -#else /* ! PALLOC_IS_MALLOC */ +extern void *repalloc(void *pointer, Size size); -/* ---------- - * In the case we use memory contexts, use macro's for palloc() etc. - * ---------- +extern MemoryContext MemoryContextSwitchTo(MemoryContext context); + +/* + * 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)) + + +/* ---------------- + * Alignment macros: align a length or address appropriately for a given type. + * + * There used to be some incredibly crufty platform-dependent hackery here, + * but now we rely on the configure script to get the info for us. Much nicer. + * + * NOTE: TYPEALIGN will not work if ALIGNVAL is not a power of 2. + * That case seems extremely unlikely to occur in practice, however. + * ---------------- */ -#define palloc(s) ((void *)MemoryContextAlloc(CurrentMemoryContext,(Size)(s))) -#define pfree(p) MemoryContextFree(CurrentMemoryContext,(Pointer)(p)) -#define repalloc(p,s) ((void *)MemoryContextRealloc(CurrentMemoryContext,(Pointer)(p),(Size)(s))) -#endif /* PALLOC_IS_MALLOC */ +#define TYPEALIGN(ALIGNVAL,LEN) (((long)(LEN) + (ALIGNVAL-1)) & ~(ALIGNVAL-1)) + +#define SHORTALIGN(LEN) TYPEALIGN(ALIGNOF_SHORT, (LEN)) +#define INTALIGN(LEN) TYPEALIGN(ALIGNOF_INT, (LEN)) +#define LONGALIGN(LEN) TYPEALIGN(ALIGNOF_LONG, (LEN)) +#define DOUBLEALIGN(LEN) TYPEALIGN(ALIGNOF_DOUBLE, (LEN)) +#define MAXALIGN(LEN) TYPEALIGN(MAXIMUM_ALIGNOF, (LEN)) -/* like strdup except uses palloc */ -extern char *pstrdup(const char *pointer); #endif /* PALLOC_H */ |